SLA Biomedical & Life Sciences Division Blog

Smaller, But Not Necessarily Less Fierce Forebears: The Great White Shark, Carcharodon carcharias, and Tyrannosaurus rex Did Not Have the Gigantic Ancestors Once Supposed

While it seems entirely coincidental,  it is not without some irony that stories about two of the most fierce  giant predators in the earth’s history, the Great White Shark, and Tyronnosaurus rex, should surface within the same week.

What makes it even more poignant, is the fact that both monsters were disclosed to have had, not the giant evolutionary great grandparents that had been scientifically assigned to them up to now by paleontologists and other evolutionary biologists, but rather far more modestly sized forebears.

The news stories were largely derived from the more substantial,  fossil-based scientific articles cited below, particularly Ehret, Hubble and McFadden  in the case of the Great White, and by Sereno et al.,  for the T. rex.

Megalodon is Not the Ancestor the Great White,

Although Both Evolved into the Apex Predators of Their Respective Times

The Great White’s story essentially has it disinherited by the largest shark ever to have lived , Carcharadon megalodon (hereafter simply  megalodon).

This  previously favored  ancestral link actually had made a lot of sense. Both the Great White and the ancestral megalodon  are, or were,  apex predators. No other creature ate them. They ate all other creatures. In a sense, they were too big, at least at the adult stage, to be eaten by anything else, or at least, to be swallowed whole.

Scientifically reasonable estimates of the top size of the Great White run as high as 26 feet, although 21 feet seems to be the longest reliably measured. Megalodon  is conservatively estimated to have measured between 59-67 ft.

 The heaviest Great White is estimated to have  weighed 5,000 lbs, although they are more reliably and routinely found to range from 1500-2400 lbs. Megalodons  ran up to 100,000 pounds, each.

A Shared Taste for Marine Mammals

The comparison between the Great White and megalodon made even further sense, when one considered their preferred diets. While Great Whites primarily eat large fish, their preferred prey are  marine mammals: from small seals to the occasional elephant seals or walrus (although the latter generally frequents waters colder than are commonly frequented by Great Whites).  Megalodons also preferred mammals, but in their case, those mammals were actually whales.  (See a remarkable study by Orangel, Garcia & Cozzuol , cited below, where fossils of the sharks and their victimized whales, with bite marks in the skeletons,  have been found together.)

Teeth That Looked Somewhat Alike,  But had Different Modes of Action:

The  Serrated Knife That Slashes Versus a Serrated Axe That  Buries Itself Deeply Into the Victim

The calculated bite force of both species is also impressive, relative to their contemporaries at least. The Great White has the highest biting force per square inch  of any contemporary fish (about 3600 pounds ….about three times the force of a lion’s bite), while the megalodon had a 40,000 pounds per square inch pressure bite. (Meaning that megalodon could literally pierce and crush the skulls of whales, not merely rip into their flesh. )

But ironically, it was ultimately the teeth in that  bite that reassigned the Great White to another ancestor, an extinct  fish more alike the modest  (but still rather fierce) mako shark (Isurus  hastalis).  

Part of the evidence favoring this reassignment  was owing to finding that this fossil  Isurus  clearly had  a substantially intact vertebral column very similar to the Great White (an  evidentiary rarity for fossilized sharks since  shark spines are made of highly perishable, semi-solid, somewhat elastic cartilage and are hardly ever well preserved).

But even more importantly, examination of  this fossil Isurus,  disclosed an amazingly well-preserved abundance of teeth, many of which were in exact order, and which under systematic microscopic characterization, were  a far better match for the contemporary Great White, and its dentitition,  than the teeth and jaws that have been reconstructed for the megalodon, even though the teeth of both the Great White and megalodon are triangular and jagged.

The  jaggedness of Great White shark teeth, amplified further when examined closely under a microscope, seem to have evolved independently of megalodon . They seem particularly suited to  the Great White’s way of dealing with contemporary marine mammals,  such as the most sizeable ( sometimes hundreds of pounds) seals.

Great Whites bite into the flesh of their victims with a slashing motion and then let go: Leaving the prey mammal to bleed out and die, before feasting on it. The particular jaggedness of those Great White teeth are  custom made for making  cuts into soft tissue that cause profuse bleeding.

As has been demonstrated through the fossil record of the whale victims of megalodon, megalodon’s giant teeth functioned y more like  pierce-and-bury-deeply-into-the-victim   axe blades, albeit peculiar axes  in the sense of the largely triangular shape of virtually all shark teeth, and having axe-heads with  plenty of serrations.  

Tyrannosaurus  Started Out More Like A BMW Smart Car

Than It Did A Souped-Up Abrams Battle Tank

A fossil find that was smuggled from China, and landed in the hands of a Massachusetts eye doctor in the early 1990s, has also turned the story of the evolution of T. rex on its head.

Henry Kriegstein, the aforementioned ophthalmologist, was a hobbyist collector of fossils. He bought a large fossil that was still largely encased in its stone matrix at a Fossil Fair in Tucson.  He was told that it had been sold to the exhibitor at the fair, by another dealer in Japan, and made what he assumed was a legal and ethical purchase.

On the assumption that this was a juvenile version of a tyrannosaurus cousin called a Tabosaurus,  he sent it off to a firm out West which specializes in identifying and sometimes freeing up fossils from the surrounding material.

Scientists associated with that lab advised Kriegstein that this was no tabosaur, but rather a wholly new species.

Ultimately, Kriegstein decided to turn the fossil over to the man who is arguably the hottest vertebrate paleontologist of the most recent decade, Paul Sereno  of the University of Chicago. 

The team of Sereno  et al. published their formal  findings in Science, in an advanced  online version available to members of the American Association for the Advancement of Science (AAAS), the publisher of Science, with the conventional print version  being made available for the general public several weeks later.  

However, popular press reports such as that of Aschenbach in The Washington Post, and the separate news items from AAAS staff writers Berardelli and Bryn (all cited below), plus 27 pages of supplementary material already made available to all, enable us to reconstruct much of the story.

Kriegstein’s fossil turned out to be what has come to be named Raptorex kreigsteini (the Kriegstein being the family name of its donor, something applied in honor of the gift and to honor the donor’s Holocaust-urviving relatives.)

While this new species weighed only about 1% of what an adult T. rex would (100– 150  lbs. versus 13,000 lbs.) its anatomy indicated a very similar hunting style, using the tools which are now understood to have made T. rex so formidable.

These included a head, very large  relative to the rest of the body ( a tyrannosaur trait)  that had very large teeth, for classic tyrannosaurid attack and prey capture, plus flared nostril openings for the keen sense of smell now attributed to T. rex,  appropriate for searching out prey.

The relative size of the legs (front limbs tiny and back limbs  immensely large relative to the rest of the body) also matched T. rex. This creature was made for speed in running down and lunging forward onto its victims.

So, how could they be sure they were not dealing with a juvenile T.rex?

Two answers:

First, when the approximate location of the fossil’s original  finding was uncovered,  a district of Inner Mongolia that once was known for its prehistoric  lakes, it became possible to analyze the fossil’s home strata and estimate its having been  layed down some  60,000,000 years earlier than the first known appearance of T. rex.

Second, by creating some microthin slices of the one of the bones of the fossil dinosaur --- which  indicate age somewhat  like  tree rings do ----- it was clear that the specimen was a young adult, that was several years old, and that the  connections  of bones into joints were reasonably mature. In other words, perhaps the specimen had a year of developmental growth left, but that essentially it was at its adult size.

After the articulated fossil Raptorex kriegsteini has been thoroughly studied, it will be returned to the proper authorities In the Peoples Republic of China, the place from which it was surreptitiously taken.

Tony Stankus, FSLA, [email protected] Professor, Life Sciences Librarian  & Science Coordinator

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville AR 72701-4002

Voice: 479-409-0021

Fax: 479-575-4592

Aschenbach, J. (2009). Unveiled: The surprisingly small precursor of T. rex.  Washington Post, September 18,  2009 issue, Section A, page A6.

Berardelli, P. (2009). T. rex, meet your great grandfather. http://sciencenow.sciencemag.org/cgi/content/full/2009/917/1

Bryn, Brandon. 2009. Science: Tiny T.  rex started the trend of terrifying traits. American Association for the Advancement of Science  News. Newsarchive.  www.Aaas.org/news/releases/2009/0917_tyrannosaur.shtml

Caill, G.M., Smith, W.D., Mollett, H.F., & K.J. Goldman. 2006. Age and growth studies of chondrichthyan  fishes: The need for consistency in terminology, verification, validation, and growth function. Environmental Biology of Fishes, 77, 211-228.

Carroll, S.B. (2009) In a shark’s tooth, a new family tree. The New York Times, September 15, 2009, final edition, Section D, page 1.

Ehret, D.J., Hubbell, G., &  McFadden, B.J. (2009). Exceptional preservation of the white shark Carcharadon (laminformes, Lamnidae) from the early Pliocene of Peru. Journal of Vertebrate Paleontology, 29, (1), 1-13.

Kimley, A,  & Ainley, eds. (1996).  The Great White Sharks. San Diego, Academic  Press.

Nyberg, K.G., Ciampaglio, C.N., & Wray, G.A. (2006). Tracing the ancestry of the great white shark, Carcharadon carcharias, using morphometric analyses  of fossil teeth. Journal of Vertebrate Paleontology, 26, 806-814.

Orangel, A.A., Garcia, L., & Cozzuol, A.M. (2008). Giant-toother white sharks and cetacean trophic interaction from the Pliocene Caribbean Paraguana Formation. Paleontologische Zeitschrift, 82, (2), 204-208.  

Randall, J.E. 1987. The size of the great white shark Carcharadon carcharias.  Science, 181, 169-170.

Sereno, P.C., Tan, L., Brusatte, Kriegstein, H.J.,  Zhao, X, & Cloward, K. (2009). Tyrannosaurid skeletal design first evolved at small body size.  Science, epub ahead of print. Supporting online material already available at www.sciencemag.org/cgi/content/full/1177428/DC1

Shimada, K.  (2002). Dental homologies in lamniform sharks (Chondroichtyes: Elasmobranchii).  Journal of Morphology, 251, 3-72.

Shimada, K. (2003).  The relationship between tooth size and total body length in the white shark , Carchardaron carcharias (Lamniformes: Lamnidae). Journal of Fossil Research, 35, 28-33.

Shimada, K. (2005). Phylogeny of lamniform sharks (Chonricthyes: Elasmobranchi) and the contribution of dental characters to lamniform systematics, Paleontological Research, 9, 55-72.

Will You Be Finding A Burmese Python, Python molurus bivittatus, In Your Neighborhood Any Time Soon? Conflicting Views About The Further Spread Of This Invasive Species Within the United States

The Burmese python,   Python molorus bivittarus ,  is native to much of Southeast Asia, including the country of Myanmar (formerly Burma). It  can be found in Laos, Vietnam, Cambodia, Thailand, parts of Southern China, Northern India, and Nepal, and even across the Malacca Straits into the Indonesian archipelago.   

The Burmese python is a favored pet of  quite literally tens of  thousands of snake fanciers in the US. Until recently, several thousand were imported into the US every year for hobbyists. Now, because the python population in its natural geographic boundaries of Asia  has been threatened by overexploitation for export,  many are raised within this country by the pet trade for resale to novice owners.

But the Burmese python is also  a nightmare for many conservationists who fear that it will upset the balance of nature wherever else  it goes.

What Makes this Snake So Popular Among Collectors?

This snake has an attractively patterned skin.  Indeed, shoes and fashion accessories commonly used to be made using their skins and were a sign of affluence and high social  status among  wealthy urban women in the US and Europe. 

The snake also allows for bragging rights among its largely  male pet owners. It  is one of the top ten snakes in  size and weight. It can grow multiple feet in a year, and indeed it continues to grow for as long as it lives.  It is by no means unusual to find year-old specimens that are several feet long that weigh in  at more than  80 pounds. Adult specimens in the range of twenty feet and well over 200 pounds are not that rare in either the wild or in captivity. (The champion  for size and weight appears to have been a 27 foot snake that lived in a zoo,  weighing in at over 400 pounds).

While the snake is not thought to be particularly aggressive in the wild, in captivity, it tends to feed more often than other large snakes (although it can also go periods as long as a year without feeding). These instances of prey capture and devouring  can provide a peculiar, if somewhat sadistic to some tastes, sort of entertainment for lovers of large snakes as pets. (The highly adaptive digestive physiology of these particular pythons is among the most studied in the world, because of its inclusion of rapid organ shrinkage and expansion, depending on the size or abundance of game or its lack.

What Makes this Python so Scary to the Rest of Us?

While not a poisonous snake, this  python is a particularly  effective hunter-killer. It grasps its prey with a mouth full of very sharp backward facing teeth, from which the prey can only escape by cutting itself severely during the attempt. Once the victim is trapped by these teeth, the python  then whips its very muscular body around the unfortunate prey’s midsection. Once encoiled,  the prey is squeezed so tight that it cannot breathe. Indeed crushed rib-cages  are common among victims of a python attack.  Pythons have tremendous strength, and while it is a very rare occurrence, they can kill adult humans whose size and weight approximates their own, and perhaps even humans who are a little larger than they are. The deaths of small children through python attacks are still rare, but more common.

How Have Burmese Pythons Invaded the American Wilderness?

The most plausible theory, and one borne by an abundance of anecdotal evidence, suggests that most of these invasive Burmese pythons have been released into the wild by snake fanciers who could no longer physically restrain them,  or sustain the building of ever larger  housing for them, once they had reached the ten foot or  hundred pound weight  point.  They are often, with great effort, hoisted into a cage, placed in or on a car or truck, and abandoned in the brush, a local forest, or by a lake, away from their former place of captivity.

Why Don’t They Just Die from this Abandonment?

The short answer is that many do die, particularly if the surroundings are too dry (these pythons generally require a body of water nearby), too cold (pythons do not generally tolerate freezing weather, provide too little cover (pythons generally require overhanging bushes , tall grasses, or hollows in the ground and/or trees for hiding in ambush most of the day), or are without sources of food that will sustain them. (The larger they get, the less likely it is that insects and small (meaning weighing only a few ounces each)  birds, amphibians, reptiles, or mammals, will sustain them. )

Survival of Individual Adults Snakes Released in the Wild

Isolated released adult pythons, particularly those that have attained  larger sizes, can survive if not exactly thrive, in rather marginal climatic areas, as long as they have some of the above mentioned environmental  requirements, for some times of the year. This is partly because these pythons can sometimes thermoregulate themselves so as to raise their body temperature higher than the ambient temperature, and thereby survive cold, if not persistently freezing,  spells. They can also go a long time, if they have to, without eating, as long as they have had at least one good meal (something rather large animal-wise) in the last several months. Finally, there are not many predators in the United States which live in areas where the python can survive, who are large enough to kill an adult python. Bears, mountain lions, and perhaps a wolf pack could do it, but their zones of habitation, do not usually coincide with those where one would find surviving released pythons.  Coyotes, foxes, hawks, eagles, and owl can manage juveniles, but not adults. But the randomly released adult pythons   placed in environmentally marginal areas cannot reproduce for both reasons of  both scarcity of resources, and the simple fact that there are not a lot of other pythons around with which to mate (although there are some reports of parthogeneis).

Survival of Pythons in Optimal Climates: The Everglades National Forest Story

The  presence of isolated, released-by-owners Burmese pythons within the Everglades Natural Forest has been known for over 20 years, and solid proof of their successful reproduction in the wild (while long inferred from the hundreds killed in run-overs by cars and trucks ) came with the discovery of an actual breeding nest filled with a healthy clutch of eggs in 2007, by University of Florida researchers. 

The Florida Everglades represents an American version of a  seemingly ideal climate for Burmese pythons. It has hundreds of square miles of watery swamp, tall grasslands, a semi-tropical canopy of trees in some places, and  an absolute abundance of wild game. Indeed, it is primarily because of that game (as large as adult deer, but also including a number of endangered birds and mammals) and the displacing of other  predators within the food chain (including several native snakes, most of which at adulthood are less than half the size of a Burmese python) that active efforts are now being undertaken to eradicate the Burmese python as an unwelcome invasive species. About the only consideration suggesting that this is an unwise move, has been the increase in number of another invasive species, the Giant African (or Gambian) rat, a seemingly ideal food source  for the pythons, which would act as a control on these 8 pound monsters.

The original working hypothesis,  that the abundant local alligator population, or its less common coastal analogue, the American crocodile, (or perhaps the rarer still  Florida  panther) would simply control the python population by attacking and eating it, has proven to be false.

In fact, just the opposite has occurred, and there are increasing report of pythons eating the alligators and crocodiles.

 A  National Geographic report noted that when a thirteen foot python killed and subsequently swallowed a six foot alligator, the snake’s belly burst, so there is probably an upper limit on the size of adult alligators that can be taken. Nonetheless, it is entirely possible for pythons to reduce the number of alligators and crocodiles by preferentially preying on their young. Alligators and crocodiles guard their nests, and females initially do escort their juveniles to water,  but will guard them for only a short time. They become fair game for the pythons at that point.

How Far Will They Spread in America?

Two papers from two different research groups published in the last year have quite diverging viewpoints on the potential range of Burmese pythons in America.

The first to be published was authored by the team of Gordon Rodda, Catherine Jarnevich, and Robert Reed. They work in the Invasive Species Branch of the Fort Collins Science Center, a unit of the US . Geological Survey.  They basically asked themselves: What areas of the US have the right cluster of average temperature and precipitation (and thereby rivers and lakes) that would support reproducing colonies of Burmese pythons? 

Their answer was startling. They suggest that coastal areas from Delaware,  southwards on the east coast, and from Oregon down to California on the west coast were clearly possible places for reproducing populations, based on releases to the wild,  and that much of non-coastal Texas, Oklahoma, Arkansas,  Louisiana, Mississippi, Alabama, Georgia and the Carolinas, was similarly favorable.

They furthered postulated that under global warming in coming decades, as temperature rose even in the northern states, parts of Washington state, Colorado, Illinois, Indiana, Ohio, West Virginia, Pennsylvania, and even New Jersey and New York might prove hospitable.

But an exactly opposite scenario is being put forward in a later publication by a team from Biology Departments at the City University of New York and the College of Staten Island. Professors R. Alexander Pyron, Frank T. Bubrink and Timothy Guiher, suggest that the climate models used by the US Geological Survey team were faulty in that they relied on average values for temperature, precipitation, and the like. The New Yorkers basically say that these averages do not account for extremes (such as  prolonged cold snaps or droughts) that could kill off significant number of pythons, and prevent those colonies from ever becoming self-sustaining.

The New York team suggests that mapping the ideal microenvironments or ecological niches, where the python-killing extremes are rarely found is the better way to go.  The resulting model, which also includes a global warming component, shows that  Southern Florida (where released pythons are already thriving) and Southern Texas (where few released pythons have been found, with none of them  found to be breeding), are about the only places within the continental US that would prove to be reliably optimal for the pythons.

The arguments of both papers have strengths and weaknesses. The New York team basically assumes that the natural spread of Burmese pythons from their stronghold in Florida will be stopped by highly unfavorable dry zones that would have to be traversed by the snakes themselves. This presupposes that those places never have flooding rains;  a situation ideal for Burmese python dispersal, owing to the fact they are excellent swimmers. They also deride the idea that released pythons elsewhere are likely to become progenitors of viable reproducing colonies, because they say such releases are likely to have already happened time and again by irresponsible owners in other parts of the country, to no avail.  They suggest that this lack of success on the part of these released pythons  is because only those two named spots within the US reliably provide the necessary ecological niche. In  other words, releasing snakes just anywhere is not going to cause them to thrive, because, on average, the conditions are right. They have to be right  virtually  all the time.

But the US Geological Survey team can counter that their own method of using average values for temperature and precipitation does a very good job of predicting the areas of Asia where the Burmese python in fact, does thrive. Furthermore, their model takes into account better the python’s  remarkable thermoregulatory capacity (including its use in incubating of its eggs), a factor that would enable it to expand northwards despite adverse temperature clines. 

Which team is right is a matter for debate, one  that may prove well worth watching, particularly if you’re afraid of say, 15 foot-long snakes weighing  over 150 pounds showing up at your poolside.

Tony Stankus, FSLA, Professor,  Life Sciences Librarian & Science Coordinator

University of Arkansas Libraries MULN 223 E

Fayetteville AR 72701-4002

Voice: 479-409-0021

Fax: 479- 575- 4592

 

Brien, M. L., Cherkiss, M. S., Johnson, V. M., Mazzotti, F. J., & Snow, R. W. (2007). Python Molurus bivittatus (Burmese python). Clutch size. Herpetological Review, 38(3), 342-343.

Burns, J. M., Williams, T. M., Secor, S. M., Owen-Smith, N., Bargmann, N. A., & Castellini, M. A. (2006). New insights into the physiology of natural foraging. Physiological and Biochemical Zoology, 79(2), 242-249.

Cox, C. L., & Secor, S. A. (2007). Effects of meal size, clutch, and metabolism on the energy efficiencies of juvenile Burmese pythons, Python molurus. Comparative Biochemistry and Physiology Part A Molecular & Integrative Physiology, 148(4, Sp. Iss. SI), 861-868.

Cox, C. L., & Secor, S. M. (2008). Matched regulation of gastrointestinal performance in the Burmese python, Python molurus. Journal of Experimental Biology, 211(7), 1131-1140.

Gilman, V. (2006). Photo in the news: Python bursts after eating gator (update). www.nationalgeographic.com/news/2005/10/1006_051006pythoneatsgator.html

 Greene, D. U., Potts, J. M., Duquesnel, J. G., & Snow, R. W. (2007). Python molurus bivittatus. Herpetological Review, 38(3)

Groot, T. V. M., Bruins, E., & Breeuwer, J. A. J. (2003). Molecular genetic evidence for parthenogenesis in the Burmese python, Python molurus bivittatus. Heredity, 90(2), 130-135.

Harvey, R.G., Brien, M.L., Cherkiss, M.S., Dorcas, M., Rochford, M., Snow, R.W. & Mazzoti, F.J. (2008) Burmese pythons in South Florida.University of Florida. Institute of Food and Agricutural Sciences. IFAS Publication Number WEC-242.

Hicks, J. W., & Bennett, A. F. (2004). Eat and run: Prioritization of oxygen delivery during elevated metabolic states. Respiratory Physiology & Neurobiology, 144(2-3), 215-224.

Holmberg, A., Kaim, J., Persson, A., Jensen, J., Wang, T., & Holmgren, S. (2002). Effects of digestive status on the reptilian gut. Comparative Biochemistry and Physiology Part A Molecular & Integrative Physiology, 133A(3), 499-518.

Kaplan, M. (1994). The keeping of large pythons: Realities and Responsibilities. Melissa Kaplan’s Herp Care Collection www.anapsid.org/colorburm.html

 

Krysko, K. L., Nifong, J. C., Snow, R. W., Enge, K. M., & Mazzotti, F. J. (2008). Reproduction of the Burmese python (Python molurus bivittatus) in Southern Florida. Applied Herpetology, 5(1), 93-95.

McCue, M. D., Bennett, A. F., & Hicks, J. W. (2005). The effect of meal composition on specific dynamic action in Burmese pythons (Python molurus). Physiological and Biochemical Zoology, 78(2), 182-192.

Ott, B. D., & Secor, S. M. (2007). Adaptive regulation of digestive performance in the genus Python. Journal of Experimental Biology, 210(2), 340-356.

Overgaard, J., & Wang, T. (2002). Increased blood oxygen affinity during digestion in the snake Python molurus. Journal of Experimental Biology, 205(21), 3327-3334.

Perry, N. D., Hanson, B., Hobgood, W., Lopez, R. L., Okraska, C. R., Karem, K., et al. (2006). New invasive species in southern Florida: Gambian rat (Cricetomys gambianus). Journal of Mammalogy, 87(2), 262-264.

Pyron, R. A., Burbrink, F. T., & Guiher, T. J. (2008). Claims of potential expansion throughout the U. S. by invasive python species are contradicted by ecological niche models. PLoS One, 3(8): e2931.

Rodda, G. H., Jarnevich, C. S., & Reed, R. N. (2009). What parts of the US mainland are climatically suitable for invasive alien pythons spreading from Everglades National Park? Biological Invasions, 11(2), 241-252.

Secor, S. M. (2008). Digestive physiology of the Burmese python: Broad regulation of integrated performance. Journal of Experimental Biology, 211(24), 3767-3774.

Secor, S.M. & Diamond, J. (1998). A vertebrate model of extreme physiological regulation. Nature, 395, 659-662.

Snow, R. W., Brien, M. L., Cherkiss, M. S., Wilkins, L., & Mazzotti, F. J. (2007). Dietary habits of the Burmese python, Python molurus bivittatus, in Everglades National Park, Florida. Herpetological Bulletin, (101), 5-7.

Snow, R. W., Johnson, V. M., Brien, M. L., Cherkiss, M. S., & Mazzotti, F. J. (2007). Python molurus bivittatus (Burmese python). nesting. Herpetological Review, 38(1)

Starck, J. M., & Beese, K. (2001). Structural flexibility of the intestine of Burmese python in response to feeding. Journal of Experimental Biology, 204(2), 325-335.

Wikipedia entry. Burmese python. http://en.wikipedia.org/wiki/Burmese_Python

Do Snake Venoms Evolve According to the Prey They Are Intended to Kill, Or Do Snakes Just Dial Up the Dosage or Concentration of Whatever Venom They Have to the Size of the Prey in their Sights?

Snake venoms are overwhelmingly composed  of dissolved protein  mixtures which typically exert their action on a victim in one of the following three ways, and sometimes in combination:

·        Hemotoxins. Depending on their mix of proteins, these can either cause the blood to clot precipitously, causing cardiovascular blockages (essentially heart attacks) in extreme cases, or alternatively, cause it to thin so quickly that the victim bleeds out.  This is one of the  modes of action of rattlesnake venoms.

 

·        Neurotoxins.  These disrupt either or both the voluntary and autonomic nervous system of the victim, rendering it incapable of escape, and in extreme cases, cause the victim to stop breathing or to convulse. This is the primary  mode of action of cobra venoms.

 

·         Tissue Necrotizers:  These basically break down the muscular and connective tissue at the site of the bite, and basically cause an ever expanding dead zone until the toxin is so diluted as to lose effect. Often the victim dies before this can happen. This is the mode of action of the fer-de-lance the most prominent perpetrator of poisonous snake bites in Latin America.

The popularity of proteomics and the wider availability of its instrumentation  leads to “venomics” & confirms evolutionary relationships & distinctions  among the many differing families  of poisonous snakes

 

Can you tell a venomous snake just by a chemical analysis of its venom?

The short, and historically most orthodox answer,  is, yes.

For most of the history of snake venom studies , the relatively small number of total analyses achieved indicated that most snakes tend to have signature venom protein mixes.

Now, given the widespread use of automated proteomics analyzers and advances in protein sequence informatics, much of this  old work is being confirmed with more  complete analyses of more venoms from more snakes and especially from differing families of snakes. Indeed, you can now search a variety of biomedical, chemical and pharmaceutical  databases under “Venomics” for on-point papers.

 And the new results can be extended to say that snakes that are in the same genus tend to have rather similar, if not always quite identical, cocktails of toxins.

Such variations as are found, are thought to be minor,  the results of random genetic drift, and to be incidental to the  study of  either the lineage, the  or day-to-day functioning of the snake.

There is  some thought that evolutionary relationships suggested by traditional morphological characters or modern genomics ,  can predict,  with reasonable certainty what venom toxins given families of snakes are likely to share, even before all their members are tested.

As a kind of real-world proof of the all-in-the-family nature  of protein toxins , consider that snake antivenoms (which work on biochemical recognition and disabling of venom proteins through binding them up)  work best when customized to the type of specific snake that does the biting. Such antitoxins are called monovalents, and are the treatment of choice whenever available.

But  given that maintaining a large and varied collection of monovalent antivenoms  is not always practical in areas where there are many possible different poisonous snakes which bite, some polyvalent vaccines have had to be developed which counteract, to some degree,  venoms from a variety of unrelated species.

Despite their polyvalent intent, their comparative effectiveness is positively correlated  with snakebites  that are evolutionarily related to the species from which the original pharmaceutical venom/vaccine was drawn.  In other words, antivenom that derives from a specific type of cobra,  is likely to work better with other persons bitten by somewhat different cobras, than it is to work on people bitten by rattlesnakes.

The prevalent theory is that the biosynthesis of toxins is likely to be highly conserved  over many generations and over differing populations of snake families  because their venom seems so central to the function of the snake, and that even incidental variations in toxins caused my random mutations could come at a cost to the snake in reduced prey killing capacity.

But  the dismissal of the significance of small differences in toxin blends within related snakes  is now being challenged,  and variations are being seen as having some meaningful function, and not just being blips in encoding that have no real life meaning to the snake.

Why have differing toxins within the same family of snakes? Couldn’t the snake just adjust the dosage to the size of the prey?

Differing types of snakes have differing quantities of venom available for hunting or defense, but certain general rules can predict among populations of the same snakes which will have more venom on average.

Generally, the older the snake of a given species is , the larger it is, and therefore the larger its storage and potential supply of venom for “envenomation, ”  when compared to younger and smaller snakes of the same species.

Furthermore female snakes generally have significantly more venom than males for two  readily  understood reasons: They are generally larger than males and have larger heads, and the head is where most of the venom production and storage is confined in all but a tiny handful of snake species.

But, it turns out that many adult snakes, whether large or small,  are actually thrifty in their use of venom.

They adjust the amount of venom to the size of their prey.  A mouse might get less venom per bite  than a gopher, for example.

Although as a general rule, given a choice between small and large prey , larger snakes will choose larger prey, and are willing to “spend the venom”  in order to get the larger meal.

The saw-scaled viper family and their venoms

A particularly  interesting comparison test of the venoms of four kinds of  saw-scaled vipers done by Barlow et al. (2009, cited below).

These four related viper species  are a genuine menace to public health in that they cause the majority of snakebite cases in North Africa and the adjacent Middle East.

 (The fact that some of them kill harmful vermin, may, of course be an offsetting factor, before deciding that they all should be wiped out indiscriminately.)

A comparison of the  electrophoretic separations of major toxin proteins  from the four different types of saw-scaled viper  showed that they were indeed, matching in the major protein bands,  something predictable owing to conventional thinking about the molecular evolution of snake venoms.

But there was a surprising amount of variation in the minor bands.

And this was also reflected in the fact that in the Middle East and in Northern Africa, saw scale viper antivenoms were markedly more effective against  Middle Eastern saw scale viper bites than they were against the bites of  the North African saw scale vipers that were presumed to be their evolutionarily closest relatives.

The drop off in effectiveness is notable in clinical terms and makes follow-up injections or IV drips of antivenom necessary more often in North Africa than they were in the Middle East.

A question arose:  Beyond any clinical significance, did these  variant protein toxins  have a purpose in the life of the snake?  Or, were they just the result of geographic isolation and random genetic drift?

Prey size vs. prey type: Which  plays a bigger role in the  evolution of venoms?

One competing theory of comparative venom toxicity  is that snakes within the same general family of snakes that prey on larger animals will eventually evolve   not only to produce more of the same general type of venom,  but also evolve higher, and therefore more potent concentrations of venom, with which to immobilize and kill their “big game.”

Its principal rival theory  is that differing prey  specialists within the same general family of snakes are more likely to require,  and eventually develop over succeeding generations venoms that gradually become more distinct, depending for success in killing prey, not so much on increasing the amount or the concentration of venom injected,   but rather on matching  the prey’s particular susceptibility to the venom.

Saw scale vipers represent a wonderful set of relatives upon which to test these competing outlooks.

Several types of saw scaled vipers have become small mammal specialists (usually eating rodents)  in terms of their prey.  Most of these are in the Middle East.

Others have a mixed diet of rodents and invertebrates.

(Most commonly in the Middle East and Africa, the invertebrates are various types of scorpions. )

Still others are almost exclusively scorpion feeders. These vipers are found only in North Africa.

It should be understood that even the biggest scorpions are but a fraction of the size and weight of the mice and rats typically consumed by either the rodent specialist,  or the mixed-diet-consuming saw scale  vipers.

Consequently “big game venom” should actually be more toxic to little game, because of its overall increased potency.

In other words, it may not be necessary to shoot a big-game venom cannon ball to kill a scorpion, but if it were to happen,  the cannon ball should surely be lethal to the scorpion.

Using ingenious methods, such as directly injecting carefully calibrated, matching fluid amounts of venom directly into  test scorpions from all four types of saw scale viper, and then seeing which venoms were, “ounce for ounce” more deadly, the team found something unexpected.

The “big game hunters”  of rats and mice, who would presumably need more toxicity to bring down their big game, actually  had venom that was notably less toxic to the small size game of scorpions, than the venom   of the mixed-bag-diet hunters.

And even more  intriguingly,   the mixed-bag-hunter venom was still less toxic to the scorpions than that of the specialized scorpion hunters.

The most toxic & effective venoms against the small game of scorpions, came from scorpion specialists, not from big-game or mixed-game specialists, who routinely had to knock down and kill bigger game.

In other words, the venom of North African scorpion specialists had become distinct enough through evolutionary adaptation to its prey, to make a difference in the life of its particular type of saw scale viper.

And maybe that distinction was now big enough to explain why Middle Eastern antivenom vaccines against North African saw scale vipers were seeing decreased efficiency.

Are the prey utterly without their own evolutionary defenses against specially  evolved snake venom?

This would seem to be the case, but in a number of settings, various ground squirrels, gophers and badgers, whose paths frequently intersect with predatory snakes like rattlers, seem to have grown immune to the local venom (see, for example Hayes, Lavin-Murcio & Kardong, 1995, cited below). This is also the case with some eels that live alongside sea snakes that hunt for eels (Heatwole & Pran, 1995).

Whether or not this leads to the evolutionary  alteration of the local snake venom to make if effective once again, has not yet been studied.

But in a particularly intriguing case, a poisonous sea snake that has become a fish egg eating specialists, and therefore has no need to immobilize and kill its prey (the eggs don’t run away and are not guarded by their parent fish) has actually evolved venom of greatly reduced toxicity, seeming to spare itself unnecessary toxin protein production (Li, Fry & Manjunatha Kini, 2005).

 

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIIroy Avenue

Fayetteville, AR 72701-4002

Voice: 479-575-4031

Fax: 479-575-4592

 

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Biardi, J. E., Chien, D. C., & Coss, R. G. (2005). California ground squirrel (Spermophilus beecheyi) defenses against rattlesnake venom digestive and hemostatic toxins. II.  Journal of Chemical Ecology, 31(11), 2501-2518.

Calvete, J. J., Escolano, J., & Sanz, L. (2007). Snake venomics of bitis species reveals large intragenus venom toxin composition variation: Application to taxonomy of congeneric taxa. Journal of Proteome Research, 6(7), 2732-2745.

Chander, R., Batra, M., Singh, D., Kumar, Y., Rawat, S., & Kumar, S. (2006). A new in-vitro agglutination technique for potency estimation of antisnake venom serum (ASVS). Toxicon, 48(8), 1011-1017.

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Chen, H., Tsai, H., Wang, Y., & Tsai, I. (2008). P-III hemorrhagic metalloproteinases from Russell's viper venom: Cloning, characterization, phylogenetic and functional site analyses. Biochimie, 90(10), 1486-1498.

Chippaux, J.P., Williams, V. & White, J. 1991. Snake venom variability: Methods of study, results and interpretation. Toxicon, 29, 1279-1303.

Chippaux, J.P. (1998). Snake-bites: Appraisal of the global situation. Bulletin of the World Health Organization, 76, 515-524.

Daltry, J.C., Wuster, W. & Thorpe, R.S. 1996. Diet and snake venom evolution. Nature, 379, 537-540.

Furtado, M. F. D., Travaglia-Cardoso, S. R., & Rocha, M. M. T. (2006). Sexual dimorphism in venom of Bothrops jararaca (serpentes : Viperidae). Toxicon, 48(4), 401-410.

Galan, J. A., Sanchez, E. E., Bashir, S., & Perez, J. C. (2005). Characterization and identification of disintegrins in Crotalus horridus venom by liquid chromatography and tandem matrix-assisted laser desorption ionization-quadrupole ion trap time-of-flight (MALDI-QIT-TOF) mass spectrometry. Canadian Journal of Chemistry-Revue Canadienne De Chimie, 83(8), 1124-1131.

Gibbs, H. L., & Rossiter, W. (2008). Rapid evolution by positive selection and gene gain and loss: PLA(2) venom genes in closely related Sistrurus rattlesnakes with divergent diets. Journal of Molecular Evolution, 66(2), 151-166.

Gibbs, H. L., Sanz, L., & Calvete, J. J. (2009). Snake population venomics: Proteomics-based analyses of individual variation reveals significant gene regulation effects on venom protein expression in Sistrurus rattlesnakes. Journal of Molecular Evolution, 68(2), 113-125.

Gutierre, J.M., Theakston, R.D., & Warrell, D.A. (2006). Confronting the neglected problem of snake bite envenoming: The need for a global partnership. PLoS Medicine, 3, article number  e150.

Hayes, W.K., Lavin-Murcio, P. & Kardong, K.V. 1995. Northern Pacific rattlesnakes (Crotalus viridis oreganus) meter venom when feeding on prey of different sizes. Copeia, 1995, 337-343.

Heatwole, H. & Pran, N.S. 1995. Resistance of sympatric and allopathetic eels to sea snake venoms. Copeia, 1995, 136-147.

Jurado, J. D., Rael, E. D., Lieb, C. S., Nakayasu, E., Hayes, W. K., Bush, S. P., et al. (2007). Complement inactivating proteins and intraspecies venom variation in Crotalus oreganus helleri. Toxicon, 49(3), 339-350.

King, R.B., Bittner, T.D. Queral &-Regil, A. & Cline, J.H. (1999).  Sexual dimorphism in neonate and adult snakes. Journal of Zoology, 247, 19-28.

Kordis, D. & Gubensek, F. 2000. Adaptive evolution of animal toxin multigene families. Gene, 261, 43-52.

Li, M. Fry, B.G. & Manjunatha Kini, R. 2005. Eggs-only diet: Its implication for the toxin changes and ecology of the marbled sea snake (Aipysurus eydouxii). Molecular Biology & Evolution, 22, (4), 934-941.

Mackessy, S. P., Sixberry, N. A., Heyborne, W. H., & Fritts, T. (2006). Venom of the brown treesnake, Boiga irregularis: Ontogenetic shifts and taxa-specific toxicity. Toxicon, 47(5), 537-548.

Markland, F.S. (1998). Snake venoms and the hemostatic system. Toxicon, 36: 1749-1800.

Menezes, M. C., Furtado, M. F., Travaglia-Cardoso, S. R., Camargo, A. C. M., & Serrano, S. M. T. (2006). Sex-based individual variation of snake venom proteome among eighteen Bothrops jararaca siblings. Toxicon, 47(3), 304-312.

Mora, J., Mora, R., Lomonte, B. & Gutierrez, J.M. (2008). Effects of Bothrops asper snake venom on lymphatic vessels: Insights into a hidden aspect of envenomation. PLoS Neglected Tropical Diseases, 2,  (10), article number 318.

Pahari, S., Bickford, D., Fry, B. G., & Kini, R. M. (2007). Expression pattern of three-finger toxin and phospholipase A(2) genes in the venom glands of two sea snakes, Lapemis curtus and Acalyptophis peronii: Comparison of evolution of these toxins in land snakes, sea kraits and sea snakes. BMC Evolutionary Biology, 7, 175.

Pimenta, D. C., Prezoto, B. C., Konno, K., Melo, R. L., Furtado, M. F., Camargo, A. C. M., et al. (2007). Mass spectrometric analysis of the individual variability of Bothrops jararaca venom fraction. evidence for sex-based variation among the bradykinin-potentiating peptides. Rapid Communications in Mass Spectrometry, 21(6), 1034-1042.

Powell, R. L., Reyes, S. R., & Lannutti, D. I. (2006). Molecular barcoding, DNA from snake venom, and toxinological research: Considerations and concerns. Toxicon, 48(8), 1095-1097.

Queiroz, G. P., Pessoa, L. A., Portaro, F. C. V., Furtado, M. d. F. D., & Tambourgi, D. V. (2008). Interspecific variation in venom composition and toxicity of Brazilian snakes from Bothrops genus. Toxicon, 52(8), 842-851.

Salazar, A. M., Rodriguez-Acosta, A., Giron, M. E., Aguilar, I., & Guerrero, B. (2007). A comparative analysis of the clotting and fibrinolytic activities of the snake venom (Bothrops atrox) from different geographical areas in Venezuela. Thrombosis Research, 120(1), 95-104.

Sanz, L., Gibbs, H. L., Mackessy, S. P., & Calvete, J. J. (2006). Venom proteomes of closely related Sistrurus rattlesnakes with divergent diets. Journal of Proteome Research, 5(9), 2098-2112.

Siegel, R.A. & Collins, J.T., eds.  (1993). Snakes: Ecology and Behavior. New York McGraw-Hill.

Soto, J. G., Powell, R. L., Reyes, S. R., Wolana, L., Swanson, L. J., Sanchez, E. E., et al. (2006). Genetic variation of a disintegrin gene found in the American copperhead snake (Agkistrodon contortrix). Gene, 373, 1-7.

Soto, J. G., White, S. A., Reyes, S. R., Regalado, R., Sanchez, E. E., & Perez, J. C. (2007). Molecular evolution of PIII-SVMP and RGD disintegrin genes from the genus Crotalus. Gene, 389(1), 66-72.

Steuten, J., Winkel, K., Carroll, T., Williamson, N. A., Ignjatovic, V., Fung, K., et al. (2007). The molecular basis of cross-reactivity in the Australian snake venom detection kit (SVDK). Toxicon, 50(8), 1041-1052.

Thorpe, R. S., Pook, C. E., & Malhotra, A. (2007). Phylogeography of the Russell's viper (Daboia russelii) complex in relation to variation in the colour pattern and symptoms of envenoming. Herpetological Journal, 17(4), 209-218.

Tsai, I., Tsai, H., Saha, A., & Gomes, A. (2007). Sequences, geographic variations and molecular phylogeny of venom phospholipases and three finger toxins of eastern india Bungarus fasciatus and kinetic analyses of its Pro31 phospholipases A(2). FEBS Journal, 274(2), 512-525.

Tsai, I., Tsai, H., Wang, Y., Tun-Pe, & Warrell, D. A. (2007). Venom phospholipases of Russell's vipers from Myanmar and eastern India - cloning, characterization and phylogeographic analysis. Biochimica Et Biophysica Acta-Proteins and Proteomics, 1774(8), 1020-1028.

Wagstaff, S. C., Laing, G. D., Theakston, R. D. G., Papaspyridis, C., & Harrison, R. A. (2006). Bioinformatics and multiepitope DNA immunization to design rational snake antivenom. PLoS Medicine, 3(6), 832-844.

Warrell, D.A. (2004). Clinical toxicology of snakebite in Africa and the Middle East/ Arabian  peninsula. . In,Meier, J. & White, J.,  eds., Handbook of Clinical Toxicology of Animal Venoms and Poisons. Boca Raton, FL: CRC Press, 433-492.

House Cats as Killers of Vermin and Wildlife

There is an astonishing amount of serious  biological and veterinary literature on the ordinary cat, Felis  catus,  as hunter, killer, and often gift-giver to its owners,  of small animals, or at least  of their body parts. Much of  this documentation has to do with their alleged potential to decimate wildlife populations, including endangered species.

Killer Cats as Heroes

The largest proportion of both pro-and-anti-cat-as-hunter-killer folklore and science appears to come from England, where there are strong lobbies of both cat and bird lovers.

(British rodent  lovers do not appear as well organized.)

The most important role of cats as heroes in history appears to have been as killers of rats that were the primary hosts of the fleas that carried bubonic plague during the Middle & Early Modern Ages. Curiously, this link between the beneficial effect of having cats and having those cats keep down the number of  rats in the household was realized in London only after the mayor ordered the killing of all cats, on the presumption that it was the cats that were the problem. He reverses himself only after he found that the scofflaws lived longer, and imported cats became a hot commodity.

Much better documented is the history of the British Postal Service in the 1860s (www.postalheritage.org.uk).  Rats were chewing up the sacks of mail before they could be delivered, tarnishing the reputation of an agency that in London, routinely made three delivery runs daily to each address. (Almost as good as e-mail and no  SPAM).

For a six month trial, three cats were hired with a food allowance of  the equivalent of about a US dime per week in an attempt to reduce the rat population in a central mail sorting building .  The trial was a smash success, and the rats  got a pay raise.

Their success was replicated in post offices all around the UK, and a number of particularly good hunter-killers became celebrities. Most notable among these was Tibs the Great, a 23 lb. cat, who was the scourge of rodents for 14 years, and who in 1965, merited an obituary in  the national trafe magazine of postal workers.

The British Postal Service retired its last cat in 1984 after having switched to plastic mail sacks which were presumably  less palatable to the rats.

Who owns cats? Who feeds cats? Does feeding a cat reduce its predatory drive?

In the US,  according to the US Humane Society,  www.HSUS.org

 one in three households owns a cat or cats. While a somewhat larger percentage  own a dog,  cats clearly outnumber dogs in the US because most American households that own cats have  more than one, while most households own only one dog at a time.

Is there a demographic profile of a typical cat owner?  While both genders, and all types and sizes of families do own cats, the  core demographic is a   middle aged or older  unmarried woman living alone  who routinely pays over $100 per veterinary visit, and considers it money well spent.

(I would venture to say that the vast majority of librarians in the US own cats. I do not because my wife is allergic.)

This is exactly the same demographic for people who are likely to feed feral cats. Indeed, the majority of people who feed stray cats in the US are also owners of well-cared-for  house cats. While they typically own one to three cats themselves, they also feed, on average, 5-7 feral cats. (see Centzone & Levy, 2002, cited below).

Curiously, about one in ten college students  also feed stray cats near their dorms, according to a study done at the University of Florida. Most of these students come from homes where cats are “a part of the family” and are well cared for (see Levy et al., cited below).

The problem from the viewpoint of some wildlife ecologists is that even well fed cats tend to hunt and kill other species at what some  conservationists feel are alarming rates. This characteristic has been termed in an article in Nature (May, 1988) “feline delinquency.”

Just  what do these cats kill, and presumably eat or offer to their owners as tribute?

Every single study from the references below that attempted a global inventory of all animals killed by cats, rather than focusing on just one type of animal, clearly indicated the following preferences.

Rodents are always first > Birds second by 10 percentage points or more> Frogs &  Lizards  a distant third>  Large Insects and Fish an even more  distant fourth.

And, contrary to the experience of the British Postal Service, cats in most urban centers studied these days  kill about  nine times as many mice as rats, in part because unlike a mouse that will weigh a few ounces, an adult rat weighs about ¾ of a pound and will fight back, often in conjunction with defensive actions by its fellow rat pack mates.  This does not mean that rats are not taken when they are alone, and opportunity strikes, it means that cats will often not attack a pack of rats.

The  trouble, as mentioned earlier,  usually does not lie with defenders of rodents (although small marsupials and indigenous species of mice, rats, chipmunks, squirrels, rabbits,  and the like are mentioned in the literature) but mostly with birds.

In almost every country in which there has been a study, colorful, popular songbirds are the prey about which there are the most complaints of disproportionate killings by cats.

In the US, certain endangered bluebirds and hummingbirds are thought to be particularly frequent prey of barn cats. In the UK, it tends to be house sparrows and starlings.

 (Note to the British: You can have all of our billions of US starlings, which were in fact descendants of a misguided plan to introduce every bird mentioned by Shakespeare to Central Park in NYC!).

But time and time again, the worst case scenarios appear to involve  exotically plumed  native species and ground nesting sea birds on islands where the cats basically have a field day with naïve and often defenseless prey.

In these situations, there is general agreement that introduced cats had,  or could have if allowed to be introduced,   a very detrimental influence on species richness and diversity.

But remedial application of this consensus viewpoint  is not  fool proof.  

The law of unintended consequences (see Bergstrom et al, 2009 cited below) came into play when a successful plan of invasive cat extermination from World Heritage Island, a place that was intended to be restored to its pre-modern  pristine condition as a model of environmental remediation was carried out.

It resulted in an explosion of rabbits that catastrophically devastated the native vegetation leading to massive soil erosion.

The ecologists in charge thought that the presence of an infectious disease agent among the rabbits would control their numbers, only to see the rabbits’  immune systems apparently outrun the best laid plans of (controlling mice, rabbits ) and men.

How is Cat Predation Scientifically Studied Today?

The most common means of tracking kill rates for cats that are what are scientifically termed IOHC (In and Out of the House Cats) is the neighborhood census of tribute offerings of whole animals or body parts.

This has been done by phone surveys and  mailed-in responses to questionnaires sent to cat owners, but these have depended perhaps too much on the skills of cat owners in  sorting out the species of  prey presented, and offering well-intentioned, but sometimes inexpert  information on whether the prey was old or young, healthy or sick, etc.

There was also the problem of cat owners who were ashamed or embarrassed or even disbelieving that their cats could be such effective hunter-killers, and this might have led to underreporting of kills.

This was sometimes thought to be offset to some degree by claims made by “macho” cat owners  that seemed boastful at the time of their study, of their cats being champion hunter-killers. (As we shall see shortly, these may not have been idle boasts or exaggerations.)

Today most studies involve the scientists making the rounds of homes,  interviewing the cat owners,  and collecting the “tribute” specimens themselves whenever present,  and bringing them back to the lab for more exact analyses, and more reliable numbers.

But there is an even more recent development. A new kind of motion-sensing accelerometer, developed by Japanese scientists (see Watanabe  et al., 2005 cited below)   can be mounted on cats. It  records the very particular pounce motion of a cat  leaping down on a kill so as to enable the scientifically accurate counting of number of attempts at wildlife capture. The  felid family from cats to cheetahs, have a much higher kill-to-attack ratio than do dogs, by the way, so there is much hope for an even more accurate counting through this newer technology, even if not all pounces yield kills.

What Have We Learned Lately?

·        That the commonsense remedy of having the house cat wear a bell or other signaling device on its collar   is somewhat effective in reducing wildlife kills, especially of birds, although studies disagree on the degree.

·        That cold and rainy weather actually deters most house cats from time spent hunting, even though it might be argues that the added calories would be beneficial to them, assuming that the caloric cost of hunting is not itself too  high.

·        That except for feeding cats to the point of such morbid obesity that they cannot easily move about, feeding one’s cat well or with particular types of food, does not appear to damp the hunting and killing instinct of the vast majority of house cats to any noticeable degree. Keeping the cat confined indoors is about the only sure deterrent, and even then,  the occasionally emerging  house mouse, or the bird or insect that flies in through the window, is likely to be hunted down and killed.

·        Among the more intriguing findings is that suburban and rural prey seem more vulnerable than urban prey, even though the urban prey have fewer places to hide from  or evade a determined cat. The country mouse may have more routes of escape, but also may be more naïve.  

·        That urban birds that primarily feed on the ground do bolt sooner and fly away faster, and more often, at the approach of cats, than do their rural and suburban fellow species, (and than do some tree feeders). But these seemingly skittish inner city  birds have also evolved a much speedier ground pecking, scratching and foraging behavior so that they can, like many urban dwellers, eat and run in a New York minute.

·        Cats in newer real estate  subdivisions quickly learn that the borderline between the well kept lawn and the undeveloped bushes and trees is the best hunting ground. In other words, suburban cats are excellent boundary patrollers.

·        That a small percentage of cats are in fact, super-hunter-killers. About 10% of cats account  for as much as 50% of the kills in some neighborhoods under study. These cats are often domestically fed in much the same manner and allowed outside    to much the same extent as their less bloodthirsty neighboring cats. (Tibs the Great was apparently one of these…. A candidate for being the current U.S. champ appears to be Sammy the Serial Killer cat, whose saga is the subject of a blog at  SammyTheKiller.com)

·        That rats are apparently able to distinguish the scent of the super-hunter-killer-cats as derived from cat collars,  and more noticeably show alarm and avoidance behaviors, and conversely, show markedly less excitement when exposed to less effective predatory cats.

·        That cats appear to help cull the population of urban birds that are not thriving, particularly in terms of those victimized birds having  reduced body fat, which some authorities suggest indicates a starving or struggling bird. What   may cause the deaths of more of the well-fed birds with plentiful body fat  appears be collisions with moving vehicles and flying into buildings. There are some studies that suggest that the bird body fatness that helps the bird survive cold weather or migrate longer distances also reduces  the ability of the bird to make sudden turning maneuvers while flying. In other words, vehicular collisions and flying into building windows may be at least as significant in the reduction of urban bird populations as the cats culling of weak or sick birds.

·        That,  ironically, in some studies in the UK, the cities that have the greatest population density of cats per area, also have the greatest density of birds!

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville AR 72701-4002

Voice: 479-409-0021

Fax: 479-575-4952

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Baker, P.J., Bentley, A.J., Ansell, R.J. & Harris, S. (2005). Predation by domestic cats in an urban area. Mammal  Review, 35, 302-312.

Barrat, D.G. (1997). Predation by house cats, Felis  catus (L.) in Canberra, Australia. I. Prey composition and preference. Wildlife Research, 24, 263-277.

Barrat, D.G. (1998). Predation by house cats, Felis catus (L.)  in Canberra, Australia. II. Factors affecting the amount of prey caught and estimates of the impact on wildlife. Wildlife Research, 25, 475-487.

Beckerman, A. P., Boots, M., & Gaston, K. J. (2007). Urban bird declines and the fear of cats. Animal Conservation, 10(3), 320-325.

Bergstrom, D. M., Lucieer, A., Kiefer, K., Wasley, J., Belbin, L., Pedersen, T. K., et al. (2009). Indirect effects of invasive species removal devastate World Heritage Island. Journal of Applied Ecology, 46(1), 73-81.

Bonnaud, E., Bourgeois, K., Vidal, E., Kayser, Y., Tranchant, Y., & Legrand, J. (2007). Feeding ecology of a feral cat population on a small Mediterranean island. Journal of Mammalogy, 88(4), 1074-1081.

Bruske, G. R., Vendruscolo, L. F., & Ramos, A. (2007). Two inbred rat strains contrasting for anxiety-related behaviors show similar levels of defensive responses to cat odor. Behavioral and Brain Functions, 3, 17.

Centzone, L.A. & Levy, J.K. 2002. Characteristics of free-roaming cats and their caretakers.  Journal of the American Veterinary Medical Association, 220, 1627-1633.

Churcher, P.B. & Lawton, J.H. (1987). Predation by domestic cats in an English village.  Journal of Zoology, 212, 439-455.

Donlan, C. J., & Wilcox, C. (2008). Diversity, invasive species and extinctions in insular ecosystems. Journal of Applied Ecology, 45(4), 1114-1123.

Fitzgerald, B.M. 1990. Is cat control needed to protect urban wildlife? Environmental Conservation, 17, 168-169.

Gillies, C. A. (2007). Notes on New Zealand mammals 5. How far did a neighbour's pet cat venture into Trounson Kauri park? New Zealand Journal of Zoology, 34(4), 335-336.

Gillies, C.A. & Clout, M. 2003. The prey of domestic cats (Felis catus) in two suburbs of Aukland City, New Zealand. Journal of Zoology, 259, 309-315.

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Kays, R.W. & DeWan, A.A. (2004). Ecological impact of inside/outside house cats around a suburban nature preserve. Animal Conservation, 7, 273-283.

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THE SAND FLY & LEISHMANIASIS: IS AN UNFAMILIAR INSECT VECTOR & A NEGLECTED INFECTIOUS DISEASE COMING TO A HOME NEAR YOU WITH A RETURNING VETERAN, RECENT IMMIGRANT, OR VACATIONING WORLD TRAVELER?

The More Familiar Mosquito & the Less Familiar Sand Fly Operate as Disease Vectors Using Similar Strategies

Few people in the modern western world, especially  in its northern latitudes,  have heard of sand flies or Leishmaniasis (named after a Scottish medical researcher,  William Leishman), but many more are likely to become aware of both of them, owing to some changes in the world’s medical geography and epidemiology.

Fortunately, by applying some of their understanding of the mosquito’s propensity for  transmittal of malaria, one can gain a basic insight into why and how sand flies can transmit Leishmaniasis.

Most scientifically-literate people today understand that malaria is a disease carried by infected female mosquitoes,  and transmitted to biting victims during the mosquito’s  biting  of humans and other warm-blooded animals, in their quest for a blood meal.

Female mosquitoes  need that  blood meal in order to have more vigorous eggs with protein supplies that are adequate for viability.

 When setting up the bite,  the mosquitoes initially  transmit some enzymes that keep the victim’s blood flow going, so that the wound does not close off, clot,  and prematurely deprive them of  that necessary blood.

Coincidentally, during the biting and enzyme injection prior to the blood withdrawal, the mosquitoes also transfer any malarial protozoan parasites they have contracted on their travels from blood source to blood source.  

Mosquitoes can certainly live and reproduce without the parasites, and not all mosquitoes are even capable of carrying these parasites.

But the more animals and humans that are around to be bitten that already have malarial parasites in their blood stream, the more likely it is that other animals and humans without the parasites, will get them once the mosquito bites the “wrong” victim before he gets to the uninfected victim, and bites him or her.

Sand Flies

Like the mosquitoes,  not all sand flies can carry the disease of Leishmaniasis, and about a third of the known species  of sand flies do not.

But those sand flies that can carry  Lesihmaniasis are almost as ubiquitous as malaria-carrying mosquitoes.

Since sand flies are only about a third as large as mospquitoes, many of their victims do not initially notice that they have been bitten.

Many sites where humans have been bitten show no signs of a wheal such as are seen with mosquito bites, and those lesions that do develop often take weeks or months, although some people have an essentially allergic blistering reaction that is more obvious.

Both   mosquitoes and sand flies favor hotter climates, although the sand fly does not need the abundance of water most commonly associated with mosquitoes and their larvae.

The primary areas of sand fly infestation in the Old World are Central Asia (including especially Iraq, Iran, & Afghanistan), portions of South East Asia, and Northern Africa.

 However, Southern Europe, including Italy, Southern France, Spain, Portugal, and Greece, are seeing a resurgence of sand flies and Leishmaniasis, and even Northern & Central Europeans are coming down with it, after decades and indeed, sometimes centuries without cases in a given district.  

The variety of sand flies that carry Leishmaniasis in the Old World are from the subfamily called the Phlebotominae.

Both of the Americas have sand flies, although Latin America, and especially Brazil,  has the greatest concentration of both vectors and Leishmaniasis by far.

The variety of sand flies that carry Leishmaniasis in the New World are from the subfamily Lutzomyia.

The Varieties of Leishmaniasis

Despite the differences of insect variety and even species differences in the particular parasites, the major types, signs and symptoms  of Leishmaniasis disease are essentially the same in both Hemispheres.

The most common type is cutaneous Leischmaniasis. About 1.5 million new cases are estimated worldwide each year of this type, and about 12 millions cases seem recurrent or chronic.

The typical manifestation of this disease are bulbous swelling and sometimes subsequent collapse and disfiguring erosion of the skin, much as seen in leprosy. 

The lesions can look ghastly but many victims report that they are relatively painless, and even without medical treatment, a substantial portion of them resolve over the course of some months. (The painlessness of many cases is hypothesized to be owing to a mild neurotoxic effect of the sand fly salivary enzymes.)

Those that do not resolve typically have  two follow-on courses.

The most common, and even more disfiguring sequelae or variant is muco-cutaneous  Leishmaniasis. Here the mouth and nose become bulbous or cratered and less reversibly disfigured. Victims often become social pariah.

But by far the most serious type (and it is not clear that this must be preceded by the cutaneous type in many cases) is called visceral Lesihmaniasis.  Unlike cutaneous and even muco-cutaneous Leishmaniasis, this type is very often fatal in the half a million cases that start anew each year.

 

Visceral Leishmaniasis is characterized by the swelling of organs under the the skin and massive bloating of body parts, particularly the liver and the spleen. Internal bleeding and multi-organ system failure are the proximate causes of death.

The theory of why some patients develop the cutaneous or muco-cutaneous forms while others develop the far more serious visceral type, tends to revolve around the types and amounts of very potent blood-clot busting salivary gland-produced enzyme, maxadilan, that are found in the particular species of sand fly that does the biting.

It seems that those species with the most maxadilan, or with the maxadilan molecular conformations that are the most potent, disproportionately cause the visceral type, while those with less maxadilan or with maxadilan of a milder conformation, seem to cause the cutaneous and muco-cutaneous types.

A curious connection has been found between areas of the world where aluminum ions are abundant in the soils and water, and either the sand flies or the victims, an increased incidence or severity of Leishmaniasis, but this is, as yet, a side show compared to other lines of investigation.

Prevention and Chemotherapy of Leishmaniasis

Much as is the case with malaria, an ounce of prevention of sand fly prevention  is worth more than a pound of Leishmaniasis cure.

Owing to current military deployments today, the US Army and Marine Corps are perhaps the most aggressive researchers and practitioners of sand fly exposure reduction today. (see Vickery et al., 2008, cited below)

The most common Lesihmaniasis preventatives are the liberal use of bodily applications of DEET, and wearing clothing that covers as much of the body as the usually intense heat of the climate allows for.

Netting, which must be as much as 3x as fine in mesh, and treated with insecticide, has shown a good deal of efficiency.

Fortunately, sand flies have not developed as many cases of resistance to insecticides as have mosquitoes and a  relatively wide assortment can still be sprayed to good effect.

Now, there is a great deal of interest in identifying sand fly pheromones and using them to trap the sand flies, keeping them out of homes and tents altogether.

The news has not been as good with drugs after infection.

Some critics suggests that this is because the overwhelming proportion of Lesihmaniasis sufferers are desperately poor individuals in Third World countries, who are unlikely to be able to repay the drug discovery companies for the cost of developing new and better drugs.

Nonetheless, new drugs do come out intermittently, when governments provide incentives to investigate and manufacture anti-Leishmanials under “orphan drug” incentives.

Traditionally, the  most commonly used  drugs involve antimony-containing compounds. They require admission to a clinic for safe administration, are potentially toxic, expensive and have begun to lose their effectiveness on some subtypes of Leishmaniasis.

The antibiotic amphotericin has become a second line choice, and its cost has come down. Nonetheless, it is still generally administered by IVs performed in clinics, making it still rather expensive for patients who must stop work and travel many miles, often over days.

Curiously, the particular effectiveness of amphotericin for Lesihmaniasis was discovered in patients with AIDS and opportunistic bacterial  infections who coincidentally also had Leishmaniasis.

It has likewise proved useful for those IV drug addicts who contract Leishmaniasis through sharing needles.  

Milotefosine is a follow-on drug that has received World Health Organization backing, and is taken orally. Its cost is yet even more reasonable, but it too has run into some resistance problems.

There is an acceleration of interest and research in developing vaccines, particularly those that short-circuit the salivary proteins whose enzymes keep the skin’s blood flow from clotting so that the sand fly can obtain its blood meal before it clots.

The process by which salivary maxadilan proteins are synthesized in the sand fly and its mechanism of dispersal in its victim are increasingly well understood, and targeting these processes on a proteomic or transcriptomic scale provides  hope for the future.

Will Leishmaniasis become prevalent again in the Northern latitudes of the economically advanced world, for example, in the US?

A disproportionate number of cases of Leishmaniasis cases in Southern and Central Europe seem to involve natives who have returned from vacationing  in Lesihmaniacal endemic hot zones, as well as the influx of recent immigrants from those areas.

Livestock, and companion animals, particularly dogs, also seem to be reservoirs of the parasites.

Once again, infected people or animals, provide a home for the parasite, and local sand flies can themselves become infected by “foreign Leishmaniasis” parasites   through biting an infected person, and then pass it on to uninfected individuals through subsequent bites.

In the US, although there has always been a small number of Leishmaniasis cases in the Mid-South (e.g. Texas, Arkansas, Louisiana), a spike has been predicted owing to the number of veterans returning home form service in Iraq and Afghanistan. 

1300 US soldiers and marines have already contracted Leishmaniasis in these countries and it cannot always be detected or treated before these troops return home.

However, in one of the most intriguing studies (Claborn et al., 2008, cited below) it was determined that between two forts where many soldiers return from tours of duty in Iraq and Afghanistan, one had an environment that was conducive to sand flies, while the other one did not.

Fort Bragg in North Carolina is surrounded by cultivated pine forest, and well-plowed farms. While the heat there is sufficient to sustain a significant sand fly population, these two  types of ground cover do not.

By contrast, Fort Campbell in Kentucky is  characterized by deciduous forests and prairie land, which are not only hot enough  to sustain a sand fly population, but which both have the right vegetation and ground cover to help sand flies thrive.

Here’s hoping that biomedical librarians everywhere become increasingly proficient in the use of the first weapon against Leishmaniasis, credible scientific and clinical information.

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 322 E

365 North McIlroy Avenue

FayettevilleAR 72701-4002

Voice: 479-409-0021

Fax: 479-575-4592

 

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Alvar, J., Yactayo, & Bern, C. (2006). Leishmaniasis and poverty. Trends in Parasitology, 22, 552-7.

Andrade BB, de Oliveira CI, Brodskyn, C. , Barral, A., et al. (2007). Role of sand fly saliva in human and experimental Leishmaniasis: Current insights.  Scand J Immunol. 66, (2-3), 122-7.

 Bates PA. Transmission of Leishmania metacyclic promastigotes by phlebotomine sand flies.  (2007).  Int J Parasitol. 37(10):1097-106.

Bates, P. A. (2008). Leishmania sand fly interaction: Progress and challenges. Current Opinion in Microbiology, 11(4), 340-344.

Champagne, D.E. (2005). Antihemostatic molecules from saliva of blood-feeding arthropods. Pathophysiology of Haemostasis & Thrombosis, 34 (4-5), 221-7.

Claborn, D., Masuoka, P., Morrow, M. & Keep, L. (2008). Habitat analysis of North American sand flies near veterans returning from Leishmaniasis-endemic war zones. International Journal of Health Geographics, 7,  article number 65.

Cortes, S., Afonso, M.O., Alves-Pires, C. & Campino, L. (2007). Stray dogs and Leishmaniasis in urban areas. Emerging Infectious Diseases, 13, 1431-2.

Croft, S.L., Sundar, S., Fairlamb, AH. 2006. Drug resistance in Leishmaniasis. Clinical Mircrobiological Reviews,  19, 111-6.

Dujardin JC, FAU - Campino, L., Campino L, Canavate, C., Dedet, J., et al. (2008). Spread of vector-borne diseases and neglect of Leishmaniasis, Europe.  Emerg Infect Dis. 14, (7):1013-8.

Gomes, R., Teixeira, C., Teixeira, M.J., et al. (2008). Immunity to a salivary protein of a sand fly vector protects against the fatal outcomes of visceral Leishmaniasis in a hamster model. Proceedings of the National Academy of Sciences, 195, (22), 7845-7850.

Hamilton JG.  (2008). Sand fly pheromones: Their biology and potential for use in control programs. Parasite 15(3):252-6.

 Joshi A, FAU - Narain, J. P., Narain JP,  Prasittisuk, C., Bhatia, R., et al. (2008). Can visceral Leishmaniasis be eliminated from Asia? J Vector Borne Dis. 45, (2):105-11.

 Kassi M, FAU - Kasi, P. M., Kasi PM, FAU - Marri, S. M., Marri SM, FAU - Tareen, I., et al. 2008. Vector control in cutaneous leishmaniasis of the old world: A review of literature.  Dermatol Online J. 14, (6):1.

Kedzierski L, Zhu, Y., Zhu Y, Handman, E., & Handman E. (2006).  Leishmania vaccines: Progress and problems.  Parasitology 133 Suppl.,  S87-112.

 Khatami A, FAU - Firooz, A., Firooz A, Gorouhi, F., Gorouhi F, Dowlati, Y., et al. Treatment of acute old world cutaneous Leishmaniasis: A systematic review of the randomized controlled trials.  J Am Acad Dermatol. 57, (2):335.e1-29.

Kumari, S., Kumar, A., Samant, M. et al. (2008). Proteomic approaches for discovery and new targets for vaccine and therapeutics against visceral Lesihmaniasis. Proteomics: Clinical Applications, 2, (3), 372-386.

Lerner EA, Iuga, A. O., Iuga AO, & Reddy VB. 2007. Maxadilan, a PAC1 receptor agonist from sand flies. Peptides 28, (9):1651-4.

Lines, J. Chikununya in Italy: Globalisation is to blame, not climate change. BMJ, 335, 576.

Maingnon, R., Khela, A., Sampson, C. et al. (2008). Aluminum: A natural adjuvant in Leishmania transmission via sand flies? Transactions of the Royal Societyof Tropical Medicine & Hygiene, 102 (11), 1140-2.

Malik, A.N.J., John, L. Bryceson, A.D.M. & Lockwood, D.N.J. (206). Changing pattern of visceral leishmaniasis, UK, 1985-2004.  Emerging Infectious Disease, 12, 1257-9.

Milon, G. (2008). Leishmania parasites: Could we consider them as living organisms per se? Microbes and Infection, 10(9), 1077-1081.

Oliveira, LF., Jochim, R.C., Valenzuela, J.G. et al. 2009. Sand flies, Leishmania, and transcriptome-borne solutions. Parasitology International, 58, (1), 1-5.

Prates, D.B.,  Santos, L.D., Miranda, J.C. et al. (2008). Changes in the amounts of total salivary gland proteins of Lutomyia longipalpis (Diptera: Psychodidae) according to age and diet. Journal of Medical Entomology, 45, (3), 409-413.

Rando, D. G., Avery, M. A., Tekwani, B. L., Khan, S. I., & Ferreira, E. I. (2008). Antileishmanial activity screening of 5-nitro-2-heterocyclic benzylidene hydrazides. Bioorganic & Medicinal Chemistry, 16(14), 6724-6731.

Ready, P. D. (2008). Leishmaniasis emergence and climate change. Revue Scientifique et Technique-Office International Des Epizooties, 27, (2), 399-412.

Reddy VB, FAU - Li, Y., Li Y, & Lerner EA. (2008). Maxadilan, the PAC1 receptor, and leishmaniasis.  J Mol Neurosci.,  36(1-3):241-4.

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Valenzuela, J.G., Garfield, M., Rowton,  E.D. & Pham, V.M. (2004). Identification of the most abundantly secreted proteins from the salivary glands of the sand fly, Lutzomyia longipalpis, vector of Leishmania chagasi. Journal of Experimental Biology, 207, (21), 3717-3729.

Vickery, J.P., Tribble, D.R., Putnam, S.D., McGraw, T., Sanders, J.W., Armstrong, A.W., & Riddle, M.S. (2008). Factors associated with the use of protective measures against vector-borne diseases among troops deployed to Iraq and Afghanistan. Military Medicine, 173, (11), 1060-1067.

Volf, P., Hostomska, J., & Rohousova, I. (2008). Molecular crosstalks in Leishmania-sand-fly-host relationships. Parasite, 15(3), 237-243.

Wheat, W. H., Pauken, K. E., Morris, R. V., & Titus, R. G. (2008). Lutzomyia longipalpis salivary peptide maxadilan alters murine dendritic cell expression of CD80/86, CCR7, and cytokine secretion and reprograms dendritic cell-mediated cytokine release from cultures containing allogeneic T cells. Journal of Immunology, 180, (12), 8286-8298.

What is Regenerative Medicine? And What Will an Easing Of Restrictions on Embryonic Stem Cell Research Mean for this Field?

On March 9, 2009, President Obama lifted some sanctions initially imposed during the George W. Bush presidency on the study and use of human embryonic stem cells, a development of great importance for the new field of regenerative medicine.

 

 

 Regenerative   medicine today largely focuses on using cultured stem cells to replace adult specialized cells that are no longer operating well,  or operating at all.

 

 

The causes for the cellular malfunction or absence may be damage from  infectious diseases or trauma, collateral damage from tumor removal,  x-ray or chemotherapy treatments, as well as inherited diseases.

 

But most often   the need for cell replacement appears to be age-related.

 

Why do Cells Need to Be Replaced?

 

There is overwhelming evidence that specialized cells in adults lose much of   their ability to divide into health functioning cells with time.

 

Yet transplanting wholly mature and specialized cells that perform the same function as the adult cells that are failing in an organ or body part has been only marginally successful to date.

 

 

Immunological rejection and the fact that the transplanted older cellular  materials may themselves senesce, has often lead to rather short-terms restorative gains, if there are any gains at all.

 

The transplanted cells undergo only so many cell cycles of mitosis and then shut down.

 

 

Why are Stem Cells Good Candidates as Replacement Cells?

 

 

Stem cells share a property with many cancer cells. They can multiply forever, given the right environment and nutrients. In a sense, they are a self-perpetuating source of raw material for eventual cell replacement therapies.

Just as importantly,  stem cells have the ability, with the right prompting,  to transform themselves into specialized cells that can be transplanted.

 

 

 

 

The theory is that they will remain vital longer than do the usually  transplanted adult cells and tissues, and sometimes they do not provoke immunological rejection as soon or as extensively. 

 

The union of these two abilities basically means that, if all things go well, the regenerative physician-scientist has a kind of cellular clay deposit that replenishes itself and that clay can be spun and fired into a wide variety of specialized pots and vases, that subsequently hold up well.

 

 

Are All Stem Cells The Same?

 

 

There are two basic types of stem cells.

 

 

 

 

By far, the most promising to date have been human embryonic stem cells. These show the greatest flexibility in what kinds of cells and tissue they can be made to become in the lab.

 

 

These cells are obtained, as their name suggests,  from donated fertilized human embryos (usually “surplus” embryos that the mother-to-be now feels no need for keeping around because  she has already had a successful pregnancy or pregnancies).

 

 

 

 

These intact embryos  are sacrificed, by being torn apart,  at an early stage of their development, when the cellular components retain  the essential quality of being unspecialized or more technically “undifferentiated.” 

 

 

 

 

The now separated embryonic cells are plated onto petri dishes, where,  with the right growth medium, they thrive, until they are directed to develop into the more specialized cells that are required.

 

 

 

 

However, there are also adult stem cells. These have been derived from bone marrow, liver lobes, fat deposits, skin, umbilcal cords, and other tissues.

 

 

 

 

A key difference in their processing is that   in many instances they have to have their  “inflexible” adult specialization knocked out of them through switching off some of their regulatory genes.

 

 

 

 

In  other words, they have to lose the ability to do certain highly specialized tasks that are “used to doing”  in order to be retrained.

 

 

 

 

In return for this, they assume a child-like plasticity to grow in petri dishes with much the same vigor as do the embryonic stem cells, and after a time, they can be re-programmed into the cells that are needed for a particular patient’s replacement needs.

 

 

 

 

Reprogrammed adult stem cells actually have the possibility of being derived from the very patient who needs the cell replacement, meaning that they have the potential to have almost zero chance of being rejected.

 

 

 

 

What Obstacles Need to Be Overcome in Order for Stem Cell Research to Fulfill its Clinical Promise?

 

 

 

 

There is no getting around the fact that many people, even those who are scientifically very well-informed, feel that destroying human embryos is destroying human life, and are therefore opposed to this line of research on moral grounds.

 

 

 

 

Those who disagree with that argument say that the embryos would  likely be destroyed anyway, so that there is no point in letting them go to waste.

The counterpoint to that argument is that a market will develop for producing human embryos directly for embryonic stem cell research, and support for the idea and underlying cell culture technology of cloning humans embryos will be accelerated.

 

 

 

 

Apart from the moral arguments, there  is   an unfortunate, and  occasionally observed tendency of some introduced embryonic stem cells to form tumors rather than healthy functioning replacement tissues, and as yet this cannot be predicted or controlled.

 

 

Some of the most intensive work today is focused on characterizing markers (usually cell surface proteins)  for healthy versus suspect stem cells, and for identifying subpopulations of stem cells that seem more promising than others.

 

 

 

 

Because, without  marker screening,  the embryonic stem cell cure could be as bad or worse than the disease.

 

 

 

Finally, two essential stem cell and tissue engineering  technologies need to be greatly expanded.

 

 

 

 

The first is the enhanced tailoring of the chemical,  physical and even dynamical  environments (petri dishes  shaken or not shaken, rotated or not rotated, inverted or right-side-up, with structural scaffolds or without them) of the undifferentiated cell cultures, so they can be induced to be exactly the right kinds of specialized cells.

 

 

 

 

There are conceivably hundreds of different specialized cells   that  are needed, but not yet hundreds of surefire ways of making them, to the exclusion of other cell types.

 

 

 

Second, even once the right types of cell are arrived at in pure culture, how are they to be stored before being administered, and in what medium are they to be administered?

 

 

 

Right now, many stem cells are apparently being frozen for storage, but it is not clear that this does not sometimes destroy or alter the functionality of some of the stem cells after thawing.

 

 

 

Means of administration of stem cells include the development of solutions that will not kill either the stem cells or the tissues surround the site of injection.

 

 

 

This is a serious consideration because different sites in the body have subtly different biochemical pH balances,  ionic concentrations, and mechanical pressures involved. 

 

 

 

Likewise, time-release gels or sponge-like matrices are being developed so that the cells are released more gradually, or so that they will not be attacked by adverse conditions on site before they can become established.

 

 

 

What Are The Types Of Condition Or Body Parts That Are Under The Most Study?

 

 

 

The list of target diseases is growing. By far the greatest level of research has been in areas of neuroregeneration, for conditions like Parkinson’s disease and spinal cord injury.

 

 

 

Coming in at something like second place is diabetes research, followed by bone and joint work, especially cartilage repair.

 

 

 

Work on eye diseases and the kidney have been less common, but are increasing.

 

 

 

But the greatest surge in recent months has been in revascularization of damaged heart tissue and cardiac vessels.

 

 

 

More diseases and organ systems are likely to be targeted for a stem cell program, given that some restrictions that have limited the embryonic stem cell side have been swept aside.

 

 

 

Progress in basic understanding and prototypical storage and delivery systems will accelerate.

 

 

 

When will actual “cures” be had?

 

 

 

The best guess is somewhere in the 10-15 year range.

 

 

 

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville, AR 72701-4002

Voice: 479-575-4031

Fax: 479-575-4592

 

 

 

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The Evolutionary Psychology of Women’s Preferences for Differing Types of Men at Different Times of Their Reproductive Cycles & Men’s Responses To Them

A very recent paper in Biology Letters (Durante & Li cited below) reports that the level of certain female hormones, in this case, estradiol (American spelling) appears to influence the propensity of women to mate “opportunistically.”

That last phrase, “mate opportunistically,”  is becoming an established term in a field with increasing scientific validity called evolutionary psychology.

Despite the use of the term “psychology,” the overall field has considerable participation from researchers in clinical medicine ( particularly those in endocrinology, medical genetics,  and obstetrics/gynecology), and by basic scientists in the fields of sensory physiology and physical anthropology.

It should be stated outright that the vast bulk of studies deal with heterosexual attractions and relationships, and moreover, the researchers neither make value judgments on personal choices among consenting  adults nor do they condone or advocate behavior that is unlawful or known to be detrimental to children.

Women’s Preferences in Male Mates According to Contemporary Studies in Evolutionary Psychology

Study and research in evolutionary psychology involves many different topical subdivisions, but this blog will focus on what the field itself calls “reproductive strategies.”

A core question is: What do women, consciously or unconsciously,  look for in mates, and when do they do that looking most intensely?

Evolutionary psychology basically posits that despite whatever overt and intellectually well-though-out  statements given by even  highly educated women upon being interviewed, of what  they seek in male sexual partners (at least in economically developed Western societies in North & South America,  Europe, Australia,  New Zealand and the more prosperous parts of Asia), underlying biological urges that have been encoded as offspring survival genes govern their reproductive behavior and  probably actually drive who and what arouses them and when.

Hormones & Assessments of Attractiveness

There are a plethora of studies (many of them cited below) that show a very strong connection between hormone levels in the sexual behaviors of both women and men.

Probably the most  striking finding is that each gender is a pretty good if unconscious estimator of the times of the month when women of reproductive age seem to be most interested in sexual activity.

The levels of certain hormones, particularly estradiol and somewhat surprisingly testosterone, in women make those women feel more attractive and sexually aroused, not only  in their own judgment of themselves, but among their fellow women’s judgment of them, and especially in how the aroused women  estimate that men will be  attracted to them, as compared to mens’ attraction at those times when their hormone levels are not so high.

This persistent finding has been confirmed through a wide variety of means of measuring both the hormone levels of women being studied, and interviewing the same women about their own desirability and attractiveness , and interviewing and videotaping women making desirability or attractiveness  judgments about other women, and men making judgments about the same women.  There is a surprising degree of concordance among all these groups.

Given that most women do not carry a hormone meter to estimate the levels in themselves, in other women, or even in men, and therefore cannot be consciously, cognitively certain of them, how do they unconsciously project and self-rate their relative attractiveness and arousability?

Frankly, they do so by looking at their own faces and bodies, which turns out to be the same way other women and men unconsciously gauge them.   Ratings of  the facial attractiveness  of women at, or near, peak monthly fertility are actually higher than ratings of the same faces at other phases of the month. In addition, their own unconscious scanning of desirable males kicks into high gear, and their preferences for differing types of male shifts, often dramatically, if only temporarily.

Short-Term Sex Partners Versus Long-Term Mates

Most of these studies and arguments concerning sexual behavior from the viewpoint of   evolutionary psychology and the strong effects of hormones and acquiring good genes for their children, would be of perhaps  academic interest only, if they did not have, in fact, real life consequences and strong explanatory power for actual behaviors.

There is ample medical evidence through the analysis of  DNA records of children and parents in economically advanced countries, ironically often undertaken for reasons apart from legal determinations of paternity, most commonly for testing for inherited diseases, that the apparent father, that is, the man who thinks, acts, and financially and emotionally supports a child,  as if he is surely the parent of that particular  child,  is not in fact, the biological father.

This excludes children who are adopted or children who are the result of known prior relationships.

A meta-analysis of 17 studies by Bellis et al (cited below) indicates that the range is somewhere between eight-tenths of one percent and thirty percent, but is  overall around three children out of 100, with variations understandably based on local culture, economic and social mores.

Evolutionary  psychology tends to explain this surreptitious   mating on the woman’s part by a short-term shift of interest in, and  visceral need for,  really “masculine” appearing men, who figuratively (and according to some studies physiologically) exude the air of dominance over other men, even if this is not the woman’s  overtly stated preference, or even their unconscious preference for most of the rest of the month.

For the sake of imagery, women who feel themselves to be at the highest level of sexual  attractiveness  and  willingness to have sex are always going to pick a Tony Soprano (as opposed to say, a Tony Stankus) because he is seen as the ultimate alpha male.

Evolutionary psychologists suggests that this goes back to females seeking the very strongest male among a clan to father their children so that the resulting children would be more likely to be strong owing to the father’s genes for size, vigor and strength.

Under the strong man-good genes strategy, both mother and children would ideally be better protected, and better provided with resources, because potentially, the putative father becomes emotionally invested in them to boot, and in particular defend them against any aggressive males who intend them harm.

Men reciprocate this attraction by unconsciously or otherwise seeking out women who appear to be more confident about their own sexual attractiveness. They are primed for this partly by their own raised levels of testosterone, and the presence of attractive women raises the boldness of their  attempts to seek opportunities to have sex with these women, at least in part because the women’s   mere presence, and the women’s both conscious and unconscious behavior towards those men, increases the men’s  testosterone levels.

Videotaped studies show that women in such situations will flirt more often and more aggressively, even if they are unaware that they are doing so.

Pheromones, Attractiveness & Arousability

One area of ongoing controversy is whether or not men (or women) give off sexually exciting pheromones that  unconsciously stimultate women to take a higher interest in having sex with them.

The preponderance of evidence say yes, but this has not yet resulted in after-shaves or colognes for men (or women)  that claim to have pheromones that demonstrably accomplish this mission, despite advertising claims to the contrary.

One of the very most intriguing studies shows that when a male experimenter conducts a surreptitious test (meaning that no odor can be detected at the conscious level)  of male-derived  sexually attractive odorants among heterosexual women,  results will indicate an increase in the mood or state of sexual arousal of the women subjects, as opposed to having a female experimenter perform the same experiment with the same tiny dosage of pheromone.

The most important finding here  is not that the sexually arousing odorant is somehow fake or ineffective,  because theoretically  it should work the same despite the gender of the experimenter, but rather that the presence of the male potentiates the susceptibility of the women to the odorant’s arousing effect.

Ironically, the source of the male pheromones that appear to result in the greatest arousal on the part of women in serious scientific tests,  comes  from the armpit sweat of men, although armpit-sweat-smelling aftershaves and colognes seem not likely to find a successful market, for some strange reason.

Of course, pheromones and the primitive drive of having the alpha-male in the room be your sex partner in order to have optimal progeny are by no means the only factors that govern women’s attractiveness for men of a given type at times of their peak fertility.

Well educated women  in economically  advanced countries also prefer men who are bosses in their company or organization, as opposed to being mere staff employees. They prefer taller men as opposed to shorter men.  They prefer more educated men as opposed to less  educated men, and in particular, they prefer wealthier men to men or lesser means.

Evolutionary psychologists explain these preferences in the context of their being more modern proxies for evidence of dominance and  virility.  Unconsciously,  these men appear to have the right genes to pass on to have kids who turn out to be more competitive in the modern world.

 But this does not always lead to instant switching of partners in today's world.

 Studies in social psychology show that highly attractive higher-status females are more likely to abandon a financially or otherwise underpeforming male partner before  regularly having sex with a more successful male that she has since identified as more to her liking using criteria that grow more stringent with her own rise in power and self-esteem. The higher the achievement of the female, the more likely it seems that serial monogamy, rather than surreptitious flings will result.

 

Is There A Time When the Slow & Steady Nice Guy Wins Out In Ratings of Attractiveness by Females?

Do women’s stated or unconscious preferences for men of a given type change when they are not at peak fertility?

The preponderance of evidence suggests that they do.

Curiously, their preference for men in their ratings of facial attractiveness indicates that when they are not at the most  fertile peak, and in fact when they are at their highest level of progesterone, and essentially feeling the most ordinary and normal (as it were) they drop their preference for pictures of tough-guy, hypermasculine men, and go for images of men that have been computer “feminized.”

The evolutionary psychology of this phenomenon is that such men would be better long-term nurturers,  even if they were not the actual fathers.

Unfortunately for such men, some studies are showing that hypermasculine men who also show an interest to attractive and fertile females  in fathering their babies (which does not necessarily mean that they are equally interested nurturing them in the long run) are more likely to be successful in having sex with these females,  resulting in what evolutionary psychologists call an increasing number of cases of  “paternal discrepancy”.

In other words, the mild-mannered steady guy has much more risk of raising some alpha male’s child unawares, because this evolutionary combination yields the best of both worlds for the mother and the child, because the short-term acquisition of the strongman genes  by the mother and the long-term partnering in the  good nurturing of the child, are both more reliably obtainable through this subterfuge.

Of course, this has the propensity of mild-mannered men raising alpha-male sons who are more likely to sense the discordant paternity, and ironically the sons may end up having  the evolutionary psychology that makes them identify and behave like their biological fathers, in dominating mild-mannered males, perhaps including their own fathers.

Men Are So Obvious in What Attracts Them! (But They Often Agree With Women in Ratings of Attractiveness)

To the surprise of some, men and women have fundamentally the same preferences and propensities in rating women’s faces as attractive. Symmetry of facial features and a certain proportionality among them is highly valued.

Curiously men and women also tend to agree, in part, on what constitutes an attractive body.

Both rate those  women more highly who have a ratio in which the waist is significantly narrower than the hips, even though the absolute measurements may be larger or smaller in different cultures. In other words, you could have a twenty four inch waist, or a thirty inch waist, and the key is that your hips ought to be proportionally larger, up to a point.

This almost universal preference low waist-to-hip ratio seems to fly in the face of arguments that would suggest that women with large amounts of body fat around their stomach, would have ample stores of energy that would ensure better the survival of the children that she would nurse, particularly  in times of food scarcity.

Therefore you would think that evolutionary theory would predict that  these fat women would seem to be preferred partners for virile males who seek to have many healthy offspring.

But except for isolated cultures, obese women are not rated very highly in scales of attractiveness by either men or women.

For what it is worth, the same is increasingly true on ratings the sexual attractiveness of obese men.

Only smokers now do worse than fat people of either of either gender in polling.

However, evolutionary psychology now  suggests that modern medical thinking on abdominal obesity as posing a multitude of serious health risks for the woman, and therefore burdens on the male and on the children, seems to have already been encoded genetically over the course of human evolution.

In other words, a chronically sick female is optimal for neither the male nor the offspring, and genes that lead to that adverse body type will be ultimately selected against.

What is the dominant physical trait that men in Western cultures seek after an acceptable waist-to-hip ratio?

Well, it’s  breast size, of course. 

Apart from East Asia, which has an outright revulsion to the notion of large breasts as being attractive features (Barbie dolls have to be modified in order to sell successfully there), large, and prominently projecting  breasts are the premier runaway (if not fashion model runway) successes as male attractants.

Two  studies are particularly illuminating, if not surprising. In a pair of serious scientific studies by Gueguen (cited below), videotapes of women in which they wore the same outfits, but had bras that allowed them progressively to increase their bust size, experienced more men “hitting on them” in night clubs and actually had more male (but not female) car drivers pick them up when they were hitchhiking,  when they  displayed the larger breasts versus the smaller ones.

(Hitchhiking in Europe is a far safer, more common, and even socially promoted practice,  particularly for teens and the 20 year old confederate who was used in the study.)    

Evolutionary psychology suggests that this is owing to large breasts being a good advertisement for healthy nutritional status, optimal reproductive potential,  and overall good health, a finding, that while unpopular in some quarters, I’m sure, actually appears true in modern medicine and recent studies of physical anthropology.  (see Jasienska et al, cited below).

But in any case, evolutionary psychology is not as much destiny as unconscious reproductive propensity, and it is scarcely infallible. If it were,  would not everyone who is reading this blog with eyeglasses or contact lenses not be here, owing to genes for bad eyesight? 

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223E

365 North McIlroy Avenue

Fayetteville, AR 72701-4002

Voice: 479-409-0021

Fax: 479-575-4592

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Nagelkerke, N. J., Bernsen, R. M., Sgaier, S. K., & Jha, P. (2006). Body mass index, sexual behaviour, and sexually transmitted infections: An analysis using the NHANES 1999-2000 data. BMC Public Health, 6, 199.

Nakdimen, K.A. (1984). The physiognomic basis of sexual stereotyping. American Journal of Psychiatry, 141, (4), 499-503.

Rhodes, G., Yoshikawa, S., Palermo, R., Simmons, L.W., Peters, M., Lee, K., Halberstadt, J. & Crawford, J.R. (2007). Perceived health contributes to the attractiveness of facial symmetery, averageness, and sexual dimorphism. Perception, 36, (4), 1244-1252.

Roney, J.R., Hanson, K.N., Durante, K.M. & Maestripieri, D. (2006). Reading men’s faces: Women’s mate attractiveness judgements track men’s testosterone and interest in infants. Proceedings of the Royal Society of London B – Biological Sciences, 273, (1598), 2169-2175.

Singh, D. 2004. Mating strategies of young women: Role of physical attractiveness. Journal of Sex Research, 41 (1), 43-54.

Singh, D., Renn, P. & Singh, A. (2007). Did the perils of abdominal obesity affect depiction of feminine beauty in the sixteenth to eighteenth century British literature? Exploring the health and beauty link. Proceedings of the Royal Society of London B – Biological Sciences, 274 , 891-894.

Swaddle, J.P. & Reierson, G.W. (2002). Testosterone increases perceived dominance but not attractiveness in human males. Proceedings of the Royal Society of London B – Biological Sciences, 269, (1507), 2285-2289.

Thorne, F., Neave, N., Scholey, A., Moss, M. & Fink, B. (2002). Effects of putative male pheromones on female ratings of male attractiveness: Influence of oral contraceptives and the menstrual cycle. NeuroEndocrinology Letters, 23, (4), 291-297.

Tovee, M. J., Reinhardt, S., Emery, J. L., & Cornelissen, P. L. (1998). Optimum body-mass index and maximum sexual attractiveness. Lancet, 352,  (9127), 548.

Welling, L. L., Jones, B. C., DeBruine, L. M., Conway, C. A., Law Smith, M. J., Little, A. C., et al. (2007). Raised salivary testosterone in women is associated with increased attraction to masculine faces. Hormones and Behavior, 52(2), 156-161.

Welling, L. L., Jones, B. C., DeBruine, L. M., Smith, F. G., Feinberg, D. R., Little, A. C., et al. (2008). Men report stronger attraction to femininity in women's faces when their testosterone levels are high. Hormones and Behavior, 54(5), 703-708.

Winman, A. 2004. Do perfume additives termed pheromones warrant being termed pheromones. Physiology & Behavior, 82, (4), 697-701.

Zebrowitz, L.A., Olson, K. & Hoffman, K. (1993). Stability of babyfacedness and attractiveness across the lifespan. Journal of Personality and Social Psychology, 64, (3), 453-466.

The Origins of Darwin’s Success, His Penchant for Writing Books & the Question of Inheriting Genius & Passing It on to Descendants

2009 is  the bicentennial of Charles Darwin’s birth and numerous celebrations and publications devoted to his works and life abound.  One of the most intriguing is a special supplement to volume 372 of the world-class medical publication, The Lancet,  issued December, 2008.

While there are many interesting essays within it,  this blog will  take note of two of them, while recommending all the others to the reader’s attention.

 One essay touches on Darwin as a scientific writer of his times, and why he preferred authoring entire books in an age when articles in  journals had already become the principal means by which scientists communicated their results.

The other essay deals with the somewhat touchy issue of Darwin’s ancestors and his descendants, with the idea that perhaps studying this can tell us a bit about whether the Darwin family penchant for producing geniuses was  primarily genetic, or that the Darwin’s family success was  due in no small  part to the role of cumulative educational, social, and financial advantages.

Or   to the contrary of either proposition,  was the family genius inevitably dissipated over succeeding generations, much as dynastic  fortunes can be?

Darwin & the Ways and Means of Communicating Science in the Victorian Age

Richard Horton is the editor-in-chief  of The Lancet, and is the author of the piece on Darwin’s writing, ( supplement pages s76-s84.)

One of the most important  things Horton notes was that Darwin was, far and away, more gladly a writer of books, rather than a writer of articles in scientific journals.

This is intriguing for modern librarians in that most of our scientific and clinical clientele have largely abandoned book writing, except for chapters  that effectively function as review articles in advanced texts  or reference works.

(A good test of changed priorities is to ask  today’s molecular biologist what he would do with $5,000 more in his or her library budget…..the answer will be invariably the reinstatement of a journal lost to budget cuts or perhaps starting a subscription to a new journal   title from either the Cell or Nature  presses. The mention of buying books would be very secondary, if it happened at all. )

There were several reasons for Darwin’s preference of books as outlets.

Darwin seemed not to care a great deal about establishing priority of discovery, something at which the more quickly prepared article and more frequently issued periodical  already had a clear  advantage.

Part of this may have had to do with  Darwin’s rather presumptuous belief that virtually no other scientist was  likely to come up with “his” overarching hypotheses of evolution. 

Darwin  was  quite wrong in this case, as a self-trained explorer named Alfred Russell Wallace,  was doing pretty much exactly that.

 

When Wallace sent Darwin a journal  article manuscript with his own ideas of evolution,  Darwin was afraid he had been scooped.

But  mutual friends arranged to have  separate preliminary articles on evolution,   one by Wallace and one by Darwin.  published in the same  issue of the Proceedings of the Linnean Society) effectively giving each the same time stamp, so to speak.

Luckily for Darwin, his book a year later reached a far greater audience in both lay and scientific communities,  and he got almost all the credit in succeeding generations.  

Wallace was in no position to contest this.

Wallace was wholly without financial backers,  without a university  pedigree ,  and without social connections. He eventually had to ask Darwin for a loan just  to get by.

Surely the theory ought to have been Wallace-Darwin or Darwin-Wallace in the same way that DNA’s discovery was Watson & Crick and perhaps even ought to have been Watson, Crick & (Rosalind) Franklin, after the pioneering  x-ray crystallographer who took the micrographic pictures of DNA  that Watson & Crick used, but died of breast cancer before she could get her share of  the Nobel Prize.

It is interesting to note that the Linnean Society   of London, publishers of the Wallace and Darwin  early articles on evolution in their journal, has as its highest award the Darwin-Wallace Medal, in recognition of their mutual worthiness of being honored as founders of evolutionary theory.

Darwin also preferred writing books to articles because he could practice his own unique literary style, much as he pleased. Darwin fancied himself a great writer, and took enjoyment in developing a  signature  approach to framing his arguments with colorful allusions and multiple examples that were not part of  an increasingly dispassionate, and numerical-data-driven  style that had become de rigeur for journal article writing.  

Insofar as can be determined, Darwin had proof-readers but no real literary editors for his books, who could demand rewrites.   

Darwin in particular did not feel that he should have had to revise  his books prior to their publication to suit nonscientists because  he thought that book reviewers ought to be of a certain level of education and sophistication that they would naturally be able to follow his arguments.  Those who could not, well, the book was simply above their station in life. (Darwin did make those changes between editions that he personally felt warranted owing to changed scientific developments, however.)

Darwin also preferred writing books as opposed to relying on journal  articles because he anticipated (correctly) that his breakthrough ideas of evolution  were big  enough and sufficiently intriguing to be  recognized as a newsworthy  achievement by the book-buying upper classes of society. The book-buying classes were quite a bit larger  the scientific journal-reading audience.

In point of fact, Darwin’s books  sold very, very well right off the bat,  and he could have (but did not need to) live off his considerable royalties. Darwin was arguably as much a celebrity, if somewhat an eccentric one, in his own Victorian era in England as was Einstein (also an eccentric)  in Europe and the metropolitan US between World Wars I & II.

Darwin is often portrayed as a kind of lonely, antisocial recluse, but in fact, he   was well-connected with high society, partly through attending Cambridge University where in his youth he studied very little and partied very hard, along with other scions of other monied families,  and partly through his many well-to-do and socially well-connected relations.

His father married into the Wedgewood China fortune, and other relatives were prosperous gun makers (ironically they were Quaker pacifists  despite the fact that the guns were sold largely to the military). Darwin himself married his first cousin, another  heiress to the Wedgewood fortune.

The Darwins as a whole displayed a penchant for intermarrying with the financial, academic, and socially-connected elites of their day, a fact played out in the frequent and sometimes confusing recurrence of  similar names between generations.

The fact that  Darwin socialized less as he grew older had more to do with his extreme hypochondria, rather than from a lack of  people who personally knew him well or appreciate his books. (if there were genetic disadvantages to the Darwin family genes, they seem to reside in assorted bouts of depression and an inexplicable string of odd dyspepsias upon which they famously dwelled excessively in discussions with their friends and acquaintances.)

Finally, Darwin assumed that the Victorian passion of the wealthy  for having large personal libraries in one’s home would continue unabated into the future, and that these books would provide him with an enduring  legacy.

He looked upon his books and their illustrations as likely to stand the test of time in terms of being bought,  housed and actually browsed or read, owing to their fine production quality long after he died.   Darwin saw them as collectible classics: elegantly written, nicely plated, and sold by a prestigious publisher who was likely to stay long in business.

What Factors Made Darwin Such A Stunning Success?  Good Genes or the Inheritance of Money and Other Cumulative Advantages?

In a piece in the same  supplement, (pages s40-s44), David Sharp, makes the point that Darwin was definitely descended from a line of well-published scientific intellectuals, with the confounding variable that most of them were also very wealthy, and could afford to become amateur scientists (there being very few full-time scientists, apart from university professors).  

Virtually all  of Darwin’s male relatives were university educated, a rarity in his day, but not so among those of Darwin’s social class.

Darwin had a grandfather, Erasmus Darwin  (1731-1802)  who was arguably the most noted scientific writer on botany, zoology and medicine of his day, with several well-selling compendia and textbooks.

There was also  a notable bachelor uncle (a Robert Darwin from Elston, as opposed to Robert Darwin, father of  Charles Darwin, who was the result of Erasmus’s second marriage) who wrote a Botany treatise  that went through three editions.

Darwin’s  own father,  was a physician who wrote relatively little, but what was written was published in the leading scientific journals of the day.

Ultimately, three of  Darwin’s older relations, were Fellows of the Royal Society of London, the epitome of scientific recognition at the time (and pretty much now as well among the British, save for winning the Nobel Prize).

In Darwin’s own generation, Darwin’s  younger cousin,  Francis Galton (1822-1911), another  Fellow of the Royal Society, was arguably the most famous anthropologist, psychometrician,  and statistician of his age.  Galton  developed the field of biological measurement and statistics today known as Biometry.

 Galton was arguably an even more  prodigious and controversial writer than Darwin,  stressing  the differences between people in terms of various physical traits and mental capabilities. He is thought of today as the founder of the Eugenics movement, which sought to rid society of “mental defectives”  through diminished breeding among “the lower classes,”  and increased fertility among the  educated wealthy. 

Galton  ultimately decided that genius was largely hereditary, based on tracing the biographies of the eminent men of science  of his day. He  found that the number of  scientists present in first degree relatives was greater than in those related as second degree relatives, which in turn was greater than those who were third degree relatives. 

Unfortunately, even now this result seems inextricably tied to the fact that the only people who could afford to be scientists in that generation were largely the wealthy. Galton seemed to have codified the convention in Victorian fiction of the better off people almost always having those unfortunate poor cousins who were so perplexing  with which to deal.

Furthermore,  Galton seemed to be  blind to  the obvious influence of grandfathers, fathers and uncles on career choice in  the young  men of the upper class family, which was likely to be very strong, and indeed, in many cases, the grandsons, sons and nephews were ordered to do as they were told, or they would be cut off from the family fortune.

Darwin was something of a rebel in that his father first sent him off to become a physician, and when Darwin failed to make any progress along those lines, the plan was to have him become a member of the clergy.

Fortunately, the opportunity to go on a voyage of exploration presented itself, and Darwin’s wealthy Wedgewood uncle prevailed on  Darwin’s  father to let the young Darwin do so, without cutting the young man off from his allowance.

 Darwin was not paid any  salary for five years during that voyage. He simply lived off his private income all that time.  

Darwin had  three sons that, like their father, grandfather, great grandfather  and assorted uncles,  were also named Fellows of the Royal Society.

George (1845-1912) was a professor of Mathematics & Astronomy at Cambridge; Francis (1848-1925) taught Botany at the same university; Horace (1851-1928) was a prosperous maker of scientific instrumentation in that university town.

Charles Galton Darwin (1887-1962), another Fellow of the Royal Society, and son of the Math & Astronomy professor,  George, became the director of the prestigious National Physical Laboratory of the UK, an institution roughly parallel to the National Institute of Science & Technology in the US.

Two great grandsons of Darwin became neuroscientists.  Richard Darwin Keynes,  born in 1919,  (and also related to the family of the famous economist John Maynard Keynes) is the author of over 90 papers in the Journal of Physiology,  with  eight in Nature, and others in the Proceedings of the Royal Society of London.   Keynes successfully exploited the squid and its giant axon as a model for electrical signal propagation in the nervous system through the flow of sodium and calcium ions. (A  1957  paper on the subject,   see below,  has been cited a remarkable  596 times.)

Horace Basil Barlow (born 1921) is not only related to Darwin but to Darwin’s most notable  teacher, a  Cambridge University professor named Barlow. This generation of Darwin-Barlow is an expert in visual perception. One of his papers  in the Journal of Physiology   of 1965 on retinal responses within living rabbit eyes which  are tracking direction and speed (see below) , has been cited a stunning 763 times. He also has several other very prominent papers in Nature and Science.

Unsurprisingly at this point, both are also Fellows of the Royal Society.  

So it might seem that there is ample evidence that genius, or at least scientific genius, is largely inherited, a belief that Darwin himself held, if publically less so than the controversial Galton.

But if it had not been for the voyage of the Beagle, something for which Darwin had no special training apart from a hobbyist’s interest in Nature as well as the social and academic connections to get himself recommended to the Admiralty in spite of this,  the authors in this supplement note that Darwin might well have lived a genteel but rather less famous life, with sons, grandsons, and great-grandsons, (and daughters)  who became something successful at something very much apart from science.

And in fact, this is the case with the majority of his great, great grandchildren.

So was luck also just as much a factor?

Although Darwin became himself less and less religious, over time, the following quotation from Ecclesiastes 9:11 might prove particularly appropriate in describing  this key factor in the outcomes of the lives of eminent people and their families, apart from the inheritance  of wealth and connections, and the genetics of genius :

 “I saw that the race is not always to the swift, nor the battle to the strong, neither yet bread to the wise, nor yet riches to men of understanding, nor yet favour to men of skill; but time and chance happeneth to them all.”

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville, AR 72701-4002

Voice:  479-409-0021

Fax: 479-575-4592

 

Three  Notable Scientific Papers by Darwin’s Descendants

Barlow, H.B., & Levick, W.R. (1965). Mechanism of directionally selective units in rabbit retina. Journal of Physiology,   London. 178 (3), 477.

Galton, F. (1879). Inquiries into human faculty: Psychometric experiments. (reprinted  2004). American Imago, 61, (3), 365-378.

Hodgkin, A.L. & Keynes, R.D. (1957). The movements of labeled calcium in squid giant axons. Journal of Physiology, London. 138 (2), 253-281.

Ants, Social Caterpillars, Traffic Jams that Don’t Happen, Audrey Dussutour, Jean-Henri Fabre, & the Continuing Fascination of Insect Behavior

154 years separate the birthdates of   the founder of insect behavioral  studies, Jean-Henri Fabre, and one of his most promising intellectual descendants today, Audrey Dussutour.

Both share certain affinities, apart from their emphasis on the ways and means of interaction in insect societies.

Both are of French ancestry, indeed both come from Southern France, although Dussutour  was initially college-educated at the rather prestigious  Paul Sabatier University in the large city of Toulouse, in Southwestern France, while Fabre was educated in Southeastern France, in Avignon,  a rather small city at what is even now, primarily a schoolteacher’s college, the Ecole Normale de Vauclose, as opposed to the more prestigious university in town.

Fabre had a rather circumscribed career geographically. He taught grade school in  the neighborhood, then moved on to  a small college on the island of Corsica to the south, from which he was driven by bouts of malaria. He finally landed  at a  prep school back  in Avignon, the latter which fired him in 1870,  largely because he admitted girls to his science classes, a practice specifically denounced from the pulpit. (Ironically, he had paid for his early school fees by serving as an altar boy at daily Mass.)

Audrey Dussutour is clearly a beneficiary of  the enlightened policy admitting bright women (as well as bright men) to   education and careers in science, not only in France but around the world. She has  pursued post-doctoral studies not only in France, but in Belgium, Canada, and Australia and collaborated with scientists in the U.S.,  before resuming  her career in France at the Center for Research in Animal Cognition in Toulouse.

Both Fabre and Dussurtour are award-winning scientists, with the primary distinction being that Fabre  had to wait until he was 84 before achieving any academic celebrity, according to an interesting account of Fabre’s life  published as an introduction by Edwin Way Teale,  to a 1957 translation of  Fabre’s selected works.  (cited below)

In 1910, the last of Fabre’s ten-volume series of chatty and often humorous accounts of  insect behavior was published, and ironically, it was the glowing  reviews by prominent literary critics rather than any  raves in scientific journals that made him an “instant celebrity.”  

He had in fact,  been writing about insect behavior for 30 years by then -----an estimated  850, 000 of his words were  in print at the time---- but he was virtually unnoticed and certainly unsponsored by any university or government agency.  

Eventually, realizing that they had a national treasure on their hands in the person of Fabre and in his immense corpus of  charming and highly literate writings on nature,  the French government gave him its  highest award, the Legion of Honor.  

Fabre was granted a federal pension for the last four years of his life,  just in the nick of time,  for he was going blind.  He was also elected to the leading scientific societies and academies in Europe at the time: London, Brussels, Stockholm, Geneva, and St. Petersburg (places by and large that he never got to see.)  

When asked what he wanted to have engraved at the foot of a life-sized statue being erected in his honor, he said “Laboremus!”. This Latin exhortation  has two possible connotations . It can mean: “Let us all diligently work. ”  Or it can mean, “Hey, Stop looking at this statue and get to your place of business!).

Dussutour is only 30 years old, but the quality of her work has already been recognized by no fewer than five financial awards  for her advanced studies.

 Arguably the most notable recent coup was  inclusion of a popularization of her  her work in the Le Monde Prize Collection of University Research, named after France’s most important newspaper, Le Monde.  The paper  sponsors the award, to inform the public about promising work in the arts and  sciences from rising stars in the university system, through essays, written by the researchers, that are deliberately intended to be more accessible to the lay reader.

Fabre would particularly approve of this development as he detested the impersonal turgid style favored by  scholarly journals in his time (and often in ours). He is quoted as saying that academic prose is valued far more for being obscure and capable of being understood only by the few, rather than for being interesting and capable of being understood by the many.

Given the relative youth of her career, it is not too surprising that Dussutour has dealt with a smaller variety  of insects than did Fabre ( who literally wrote about  hundreds of different types) , but what is strikingly similar is a shared emphasis on ants, and to a lesser degree social caterpillars.

Dussutour  deals with many of the many of the same themes as Fabre, but obviously she enjoys and employs  all of the more sophisticated science that has been learned in the interim. (It should be noted that in many respects, Fabre  was a somewhat atavistic  natural historian and   curmudgeon, and had little use for overarching theories, like evolution,  that would have helped him make sense of animal behavior in a larger context.)

Dussutour’s   works  seek the answers  to Fabre-like questions like: How is that ants don’t get into traffic jams? How is it that ants don’t bump into each other when cutting leaves in tight spaces much more than they do when they do leaf-cutting in spacious quarters?  How do ants and social caterpillars make group decisions? What factors   governs decisions about whether or not ants will climb over or around walls? What components of an ant’s diet seem to govern the size of the colony: carbohydrates, fats, proteins?

I suspect that Fabre would be quite pleased in the work of this fellow countrywoman, and highly worthy  intellectual heiress of his scientific tradition.

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223-E

365 North McIlroy Avenue

Fayetteville, AR 72701-4002

Voice: 479-409-0021

Fax:  479-575-4592

By & About Fabre

Many of Fabre’s works have been re-issued in translation as collections of essays that all deal with a particular insect or insect relative, even though Fabre himself may not have written all of the reissued essays at the same time or in the same sequence.  Some of these works have been made available from the University Press of the Pacific;  Project Gutenberg Full-Text has scanned in a number as well.

Bicknell, P.F. (1923). The Human Side of Fabre. NY: The Century Company.

Fabre, J.H. (with an Introduction and Interpretive Comments by Edwin Way Teale.) (1957) The Insect World of J. Henri Fabre. NY: Dodd, Mead & Company.

LeGros, G.V. (1913). Fabre, Poet of Science. London: T. Fisher Unwin.

              Selected Works of Audrey Dussutour & A Commentary by Kathryn Knight of the Journal of Experimental Biology

Colasurdo, N., Dussutour, A., & Despland, E. (2007). Do food protein and carbohydrate content influence the pattern of feeding and the tendency to explore of forest tent caterpillars? Journal of Insect Physiology, 53(11), 1160-1168.

Dussutour, A., Beshers, S., Deneubourg, J. L., & Fourcassie, V. (2007). Crowding increases foraging efficiency in the leaf-cutting ant Atta colombica. Insectes Sociaux, 54(2), 158-165.

Dussutour, A., Deneubourg, J. L., Beshers, S., & Fourcassie, V. (2009). Individual and collective problem-solving in a foraging context in the leaf-cutting ant Atta colombica. Animal Cognition, 12(1), 21-30.

Dussutour, A., Deneubourg, J. L., Beshers, S., & Fourcassie, V. (2009). Priority rules govern the organization of traffic on foraging trails under crowding conditions in the leaf-cutting ant, Atta colombica. Journal of Experimental Biology  212, 499-505.

Dussutour, A., Deneubourg, J. L., & Fourcassie, V. (2005a). Amplification of individual preferences in a social context: the case of wall-following in ants. Proceedings of the Royal Society B-Biological Sciences, 272(1564), 705-714.

Dussutour, A., Deneubourg, J. L., & Fourcassie, V. (2005b). Temporal organization of bi-directional traffic in the ant Lasius niger (L.). Journal of Experimental Biology, 208(15), 2903-2912.

Dussutour, A., Fourcassie, V., Helbing, D., & Deneubourg, J. L. (2004). Optimal traffic organization in ants under crowded conditions. Nature, 428(6978), 70-73.

Dussutour, A., Nicolis, S. C., Deneubourg, J. L., & Fourcassie, V. (2006). Collective decisions in ants when foraging under crowded conditions. Behavioral Ecology and Sociobiology, 61(1), 17-30.

Dussutour, A., Nicolis, S. C., Despland, E., & Simpson, S. J. (2008). Individual differences influence collective behaviour in social caterpillars. Animal Behaviour, 76, 5-16.

Dussutour, A., & Simpson, S. J. (2008a). Carbohydrate regulation in relation to colony growth in ants. Journal of Experimental Biology, 211(14), 2224-2232.

Dussutour, A., & Simpson, S. J. (2008b). Description of a simple synthetic diet for studying nutritional responses in ants. Insectes Sociaux, 55(3), 329-333.

Dussutour, A., Simpson, S. J., Despland, E., & Colasurdo, N. (2007). When the group denies individual nutritional wisdom. Animal Behaviour, 74, 931-939.

Knight, K. (2009). Inside JEB:   Ants obey road rules to keep traffic flowing. Journal of Experimental Biology 212, i.

Nicolis, S. C., Despland, E., & Dussutour, A. (2008). Collective decision-making and behavioral polymorphism in group living organisms. Journal of Theoretical Biology, 254(3), 580-586.

Nicolis, S. C., & Dussutour, A. (2008). Self-organization, collective decision making and resource exploitation strategies in social insects. European Physical Journal B, 65(3), 379-385.

Peters, K., Johansson, A., Dussutour, A., & Helbing, D. (2006). Analytical and numerical investigation of ant behavior under crowded conditions. Advances in Complex Systems, 9(4), 337-352.

 

 

Will Global Warming & Increased CO2 Increase Crop Yields?

One of the few upsides  found when exploring  global warming scenarios is based on the assumption that  since green plants thrive on carbon dioxide (and there will be much more of it) for photosynthesis and since warmth tends more than cold to promote growth (and there will be more warmth), farmers who grow green plant crops should, on the whole,  thrive.  

This hypothesis has been tested in greenhouses with generally positive confirmations.

The problem with this overall proposition  is that it has run counter   to recent experience for most countries and crops, with China and plantains being  notable exceptions.  There is substantial agreement that world yields of wheat, rice, and corn (maize), as well as soybeans are trending down with increases in atmospheric CO2 and warmth.

Why would this be so?

Having More CO2 May Not Be All That Helpful If Other Inputs Do Not Match It

Having more CO2 may not help plants if they do not have access to increased water, nitrogen,  potash, and the right soil conditions, at the same time. It’s something like having more flour. By itself,  more flour does not mean you can bake a bigger cake. You also have to have baking powder, shortening, eggs, water, and other ingredients, or you are just going to get a modestly risen but  pasty  lump of dough.

Reports of Average Increases In Seasonal Temperature   Are Misleadingly Mild

Reports that on average, a region has an increase of 2 degree Fahrenheit over previous years , tend to smooth  over a number problems.

The first problem is that spikes of hot temperatures tend to occur more frequently, even if they do not last many days. It is not a case of each day being two degrees warmer; it is generally a case of more incidences of heat spells.

Location, Location, Location

Another poorly understood phenomenon is that temperature spikes tend to have more consequential effects  at the margins of the range  where a given crop can be cultivated. In other words, if  a region was on the borderline of being too hot for the crop, but the crop was still viable most of the time in the past, raises in the frequency of heat spells will tend to shut down the area altogether. This tends to have serious implications for farmers in those marginal regions  who depend largely on one cash crop. This is particularly the case in some of the poorest countries, and their farmers often have limited access to retool their operations to make them more viable with some sort of alternative crop.

Bad Timing

 A third problem is that the timing of heat waves is often at least as important as their duration.  Certain life stages in green plants  that reproduce sexually (which are most of the world’s cash crops) can be quite  temperature-sensitive.

This is particularly the case with pollen viability, pollen germinative ability, stigma viability, and ovule viability.

Given that an enormous number of crops are essentially providers of food as seeds ( grains, nuts) or  fruits with seeds (virtually all tree crops, and many vine crops) failures along these lines have immediate consequences for this year’s crop for the table, and may also diminish the amount and quality of seed for sowing for the follow-on crop.

Pollinator & Pest Problems Tend to Increase with  Spikes in Temperature

One consequence of timing  disruptions in plant life cycles caused by heat spikes  is that pollinators like bees,  butterflies, moths, and even birds, end up arriving too late or too early to do their jobs effectively.

Perversely,  reductions in killing frosts tend to allow more plant pests or their eggs  to overwinter and heat spikes may promote earlier  hatching or a higher rate of hatching success among  herbivores.

Both of these phenomena may extend to weeds that compete for resources with the crops.

It’s Not All Doom & Gloom

It is nonetheless worthwhile to consider that modern plant breeding has a  history of coming up with solutions to changes in climate, and, some colder regions that are now not notably crop productive may well experience a surge in productivity.

Whether either of these will offset downturn in crop yields owing to spikes in temperature,  may well be the most important plant science story of our time.

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223-E

365 North McIlroy Avenue

Fayetteville, AR 72701-4002

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Fax: 479-475-4592

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