80beats » Living World

Found: Dino-Munching Crocodiles Who Swam in the Sahara

Brett Israel — Fri, 20 Nov 2009 21:25:55 +0000

A thrilling set of ancient crocodile fossils have been unearthed in northern Africa. A “saber-toothed cat in armor” and a pancake-shaped predator are among the strange crocodile cousins whose bones have been found beneath the windswept dunes of the Sahara, archaeologists say [National Geographic News].

At a news conference organized by the National Geographic Society, which sponsored the research, scientists announced that the fossils represent 5 species; 3 new species and 2 that were previously known. These ancient croc ancestors, known as crocodilyforms, are unlike any crocodiles encountered in the Northern Hemisphere, according to the research team. Their findings are detailed in the journal ZooKeys.

The crocs were spectacularly diverse, and included a species that ate dinosaurs, two that grew up to 20 feet long, and two that had long legs for quick movement on land but also had long tails for swimming. The three new species are:

• BoarCroc (Kaprosuchus saharicus), a 20-foot meat-eater. It used its snout for ramming and three sets of dagger-shaped fangs for slicing dinosaurs it ate.

• PancakeCroc (Laganosuchus thaumastos): a 20-foot-long, squat fish-eater with a 3-foot long flat head with spike-shaped teeth.

• RatCroc (Araripesuchus rattoides), a 3-foot-long plant and grub eater with buckteeth used for digging [Chicago Sun-Times].

The two previously known species are nicknamed DuckCroc, a three-foot long, long-legged croc that feasted on fish and frogs, and DogCroc, another small and lanky croc that mostly ate plants and grubs.

“These species open a window on a croc world completely foreign to what was living on northern continents,” [researcher Paul] Sereno said of the unusual animals that lived 100 million years ago on the southern continent known as Gondwana [AP]. From the fossils, researchers believe that at least some of these crocs were equally at home on land and in the water. They roamed what is now Morocco and Niger at a time when the landscape was covered with lush plains and broad rivers. The crocs included meat eaters that could have devoured man—if any humans had existed at the time.

From studying the fossil skulls, the researchers made predictions about the crocs’ brain power. The scientists studied the animals’ brains by creating digital and physical casts from CT-scans, 3D X-rays. Both DogCroc and DuckCroc had broad, spade-shaped forebrains that looked different from those of living crocodiles [Telegraph]. Researcher Hans Larsson, who discovered the fossils of BoarCroc and PancakeCroc, said the brain models suggest these crocs had superior brain power compared to their modern ancestors, possibly because chasing after your meals on land requires more energy than milling around in the water waiting for your food to arrive.

Serano, the team leader, has a penchant for discovering the ancient crocs. He discovered SuperCroc—the largest of them all—nine years ago in the same region. His latest findings are the subject of “When Crocs Ate Dinosaurs,” which airs on the evening of Saturday, November 21, on the National Geographic Channel.

Image: Mike Hettwer, courtesy National Geographic

Star Trek-Style “Phaser” Paralyzes Worms With a UV Blast

Andrew Moseman — Fri, 20 Nov 2009 18:09:34 +0000

Feel like teaching a lesson to that pinhead-sized worm that’s been bothering you? According to a study in the Journal of the American Chemical Society, a material called dithienylethene plus a blast of UV light can stop a worm in the midst of its worming, rendering it temporarily paralyzed.

The researchers fed a light-sensitive material — a “photoswitch” known as dithienylethene — to the transparent worms. When exposed to ultraviolet rays, the molecule turned blue and the worms became paralyzed. Using visible light instead made the chemical turn colorless and the paralysis ended [LiveScience]. Scientists aren’t sure why the transparent nematodes became paralyzed, but they know dithienylethene changes shapes and suspect it interferes with the worm’s energy-producing metabolic pathways. Repeated cycles of UV-induced paralysis actually killed some of the worms.

Unsurprisingly, news of this worm stun-gun led to longing for Star Trek-style phasers, and the scientists, though skeptical, were good sports about it. As lead researcher Neil Branda said tactfully: “I’m not convinced there’s a legitimate use of turning organisms on and off in terms of paralysis, but until somebody tells me otherwise, I’m not going to say that there isn’t an application” [BBC News].

But while phasers remain a fantasy, light-activated materials certainly have a future in medical research. Light-activated drugs could be used to activate tumour-killing drugs once they reach a particular location in the body. Similar chemicals have been used before, but have required a steady supply of light – often harmful UV bandwidths – to stay active. The new compounds, known as diarylethenes, could be more useful because they can be switched on and off with a single light pulse, Branda says [New Scientist].

Image: Wiki Commons / Yonatanh

Spores in Mastodon Dung Suggest Humans Didn’t Kill Off Ancient Mammals

Brett Israel — Fri, 20 Nov 2009 12:00:53 +0000

A fungus found within ancient mammoth dung is providing scientists with clues about how the large ancient mammals collectively known as megafauna went extinct. The fungus, Sporormiella, produces spores in the dung of large herbivores. These are then preserved in the layers of mud and can provide an index of the number of these animals, or megafauna, that roamed the environment at a particular time [BBC News]. For a new study, researcher Jacquelyn Gill collected and analyzed spores in sediment samples from an Indiana lake and several sites in New York.

From Gill’s analysis, published in the journal Science, she concluded that North American megafauna began a slow decline around 15,000 years ago and vanished about 1,000 years later. The data suggests megafauna started going extinct much earlier than previously though, which basically wipes out two theories of their extinction.

There are several theories surrounding the extinction of North American megafuana, but there are a lot more questions than answers. Much of the uncertainty surrounding the extinction of the North American megafauna, which includes mastadons, saber-tooth tigers and giant ground sloths, is due to a scarcity of evidence and difficulty pinning down the timing of events. Several major events occurred around the same time the animals disappeared: Major environmental upheaval associated with the end of the Ice Age; an asteroid explosion over North America; and the arrival of man [Wired.com]. But the new data points to an extinction culprit other than an asteroid or comet impact, because the impact is believed to have occurred long after the megafauna began their decline.

If humans were responsible for the extinction, it would have to be settlers that came along before the Clovis people, which is another debate in itself. The Clovis culture is thought to have been the first civilization to take hold in North America around 13,300 years ago–after the bulk of the megafauna extinctions, according to the new analysis. But some researchers believe that earlier settlers walked the land before the Clovis people, and could have hunted the mastodons and mammoths. The new study adds crucial info to the fossil record, but it is likely to kindle, rather than quench, the debate over megafauna extinction.

Image: Barry Roal Carlsen, University of Wisconsin-Madison

Starfish Prepare for Hot Conditions by Taking a Long, Cold Drink

Brett Israel — Thu, 19 Nov 2009 11:22:15 +0000

Like humans, sea stars enjoy lounging on the shore during the hot summer months. But when they get too hot, they can’t run for shade, so they have a back-up plan—fattening themselves with cold ocean water before the tide recedes, according to new research published in the journal The American Naturalist. This finding shows that sea stars, or ochre starfish, aren’t as helpless as previously thought. The sea stars are likely cued during low tide that it’s a hot day, the researchers say, and that signals them to soak up more water during the next high tide. “It would be as if humans were able to look at a weather forecast, decide it was going to be hot tomorrow, and then in preparation suck up 15 or more pounds of water into our bodies,” said study researcher Brian Helmuth [LiveScience]. Talk about staying hydrated.

The researchers first studied starfish in an aquarium using heat lamps to simulate a scorching summer day, an infrared camera to measure their internal temperatures, and a scale to weigh the sea stars and determine how much water they had absorbed. The researchers say the amount of water a starfish absorbs can decrease its body temperature by almost 4 degrees Celsius. But researcher Sylvain Pincebourde is concerned that this novel strategy may have limitations in a rapidly changing world…. As oceans warm together with air temperature the thermoregulatory mechanism used by the starfish will cease to work, he warns. “The colder the sea water, the more it is able to lower its body temperature. The efficiency of this thermoregulation strategy therefore might be annihilated by ocean warming” [BBC News]. Yet another reason to get a handle on global carbon emissions.

Image: flickr / laszio-photo

Nanosilver Puts the Hurt on Microbes—and Maybe Fish, Too

Andrew Moseman — Wed, 18 Nov 2009 17:56:46 +0000

Toys, refrigerators, washing machines, socks—more and more products contain silver nanoparticles. It’s no wonder: These particles, which measure less 100 nanometers (smaller than a single HIV virus), can kill microbes on contact. But, researcher Darin Furgeson says, nanosilver can also escape into ecosystems and cause serious damage to fish embryos. Furgeson’s team published its results in the journal Small.

In one new experiment, Furgeson, a professor of pharmaceutical sciences, exposed zebrafish embryos to silver nanoparticles in a laboratory, and found that some died and others were left with dramatic mutations. “Some of the fish became extremely distorted, almost making a number nine or a comma instead of a linear fish,” he said [Scientific American]. Eyes, tails, and other body parts turned out malformed in the fish that survived.

Just how much nanosilver gets into the environment? A separate study from Environmental Science & Technology washed nine kinds of nanosilver-containing textiles, including some “anti-bacterial and anti-odor socks” that are already on the market. The researchers found that anywhere from less than 1 percent to as high as 45 percent of the silver came out in the first wash. Most of the silver was in the form of coarse particles of greater than 450 nanometers, suggesting that mechanical stress in the washing machine was responsible for most of the release [The New York Times], and that the nanoparticles might have aggregated to reach that size.

Those nanoparticles flushed out by a washing machine can end up in both fish habitats and drinking water supplies. Furgeson says his fish experiments could help show whether nanosilver is a health concern for humans, too. “Zebrafish have similar tissues and organs to us,” Furgeson said. “They don’t have lungs, but they do have a liver, kidneys and heart – though it is only two chambered – and they have a blood-brain barrier” [Scientific American].

Image: Wiki Commons / Kristof vt

In Galapagos Finches, Biologists Catch Evolution in the Act

Brett Israel — Tue, 17 Nov 2009 22:15:47 +0000

On the Galapagos Islands, where Charles Darwin’s observations led to his evolutionary theory, scientists are now reporting that they’re witnessing a single species splitting into two, according to a new paper in the Proceedings of the National Academy of Sciences.

A husband and wife team, Peter and Rosemary Grant of Princeton University, have spent the past 36 years studying Darwin’s finches, technically know as tanagers. Darwin’s observations of the birds during his voyage to the Galapagos on the HMS Beagle helped him arrive at the idea of evolutionary divergence: when different populations of a single species become geographically isolated, and evolve in different directions. The Grants have pushed that work further, with decades of painstaking observations providing a real-time record of evolution in action. In the PNAS paper, they describe something Darwin could only have dreamed of watching: the birth of a new species [Wired.com]. The process has been taking place with the help of a little bit of chance and a special song.

The split began in 1981 when an unusually large male finch from Santa Cruz island arrived on the island where the Grants were based, Daphne Major. The biologists tagged the bird number 5110, and followed him and his offspring through seven generations total. In the fourth generation a drought killed off all the descendants except one male and one female. These offspring became isolated because they have the avian equivalent of a strange accent. These finches learn their songs from their father, and the Grants suggest that 5110 sang the songs from his birth home of Santa Cruz then modified his come-hither ballad by roughly copying the Daphne Major birds’. This imperfect copying, they suggest, has over time acted as a barrier to interbreeding [Nature News]. So the immigrant bird’s descendants have bred only with each other for three generations.

The Grants say there’s no clear rule for when to declare a reproductively isolated population a new species, and also note that the birds descended from 5110 could still die out. But whatever happens, their legacy will remain: New species can emerge very quickly — and sometimes all it takes is a song [Wired.com].

The Grant’s are currently in Japan accepting the Kyoto Prize in basic science for their life’s work.

Image: flickr / putneymark

Extinct Goat Tried out Reptilian, Cold-Blooded Living (It Didn’t Work)

Andrew Moseman — Tue, 17 Nov 2009 15:55:56 +0000

Say you’re a goat stuck on a Mediterranean island with scarce food and no way to leave. How do you survive? The strange species Myotragus answered that question by getting small, and, most unusually, adopting the cold-bloodedness normally seen in reptiles.

In a paper in this week’s Proceedings of the National Academy of Sciences, researchers say that the now-extinct dwarf goat managed to survive thousands of years of resource scarcity by adjusting its metabolism to match how much food was available. The discovery marks the first time scientists have seen this cold-blooded survival strategy in mammals. The surprising skill likely allowed the goats to endure potentially fatal periods of scarcity on what is now the Spanish island of Majorca [National Geographic News].

Paleontologists figured out this oddball habit of Myotragus by analyzing its bones, as well as those of reptiles that lived in the same time and place. The bones of cold-blooded reptiles, such as the crocodiles, have parallel growth lines that cyclically come to a halt before starting up again…. Similar to tree rings, these lines match the growth cycles of animals. Warm-blooded species, on the other hand, exhibit uninterrupted, fast bone growth [Discovery News].

Taking on cold-blooded characteristics allowed Myotragus to survive, but it came at a price. The goats were born only as big as a large rat, and spent years growing to adult size, which was just more than a foot and a half in height. They probably had small brains and small eyes, and moved about sluggishly to save energy.

Coauthor Meike Köhler says those factors spelled doom when a new threat reached the island: people. “The postcranial skeleton indicates that this animal was not able to run, jump, or move fast around, and [would have been] easy prey,” [National Geographic News], Köhler says.

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Image: Wiki Commons / Xavier Vázquez

T. Rex May Have Been a Hot-Blooded, Sweaty Beast

Eliza Strickland — Thu, 12 Nov 2009 11:32:32 +0000

The world domination achieved by such fearsome bipedal dinosaurs as the T. rex may have been a result of their warm-blooded biology, according to new research. For decades, scientists assumed that because dinosaurs resembled lizards, they were cold-blooded as well, their internal temperature rising and falling with the outside world. However, birds are warm-blooded, and the fact that birds seem to be descended from dinosaurs raises the question of whether their ancestors were as well [LiveScience]. The new study, published in the journal PLoS ONE, examined the anatomy of 14 species of bipedal dinosaurs, and argues that many of them needed more energy to power their massive leg muscles than a cold-blooded metabolism could provide.

Lead researcher Herman Pontzer based his findings on the estimated amount of energy dinosaurs must have expended moving about. Recent research by Dr Pontzer has shown that the energy cost of walking and running is strongly associated with leg length. Hip height – the distance from the hip joint to the ground – can predict the observed cost of locomotion with 98 per cent accuracy for a wide range of land animals [Telegraph]. The research team also used measurements of fossilized leg bones to determine the leg muscle mass of each species, and found that the muscles would have required a great deal of energy during walking and running.

The dinosaurs would have benefited from a warm-blooded metabolism, Pontzer says, because they could have been agile and active even when the temperature dipped, and could have therefore spread through areas with colder climates. But there would also have been a downside: Maintaining a stable internal temperature … costs a lot of energy and requires the animals to feed more regularly [The Guardian]. At any rate, the new results aren’t likely to convince paleontologists who aren’t in the warm-blooded camp, and you can expect the debate to continue.

Image: PLoS ONE / Herman Pontzer, et al.

Elephant Seals Take Naps During Slow Dives Through the Sea

Andrew Moseman — Wed, 11 Nov 2009 21:39:05 +0000

For elephant seals, at least, there is some rest for the weary.

These marine mammals undertake epics migrations of thousands of miles, in which they might not return to land for as long at eight months. But elephant seals don’t have the same talent as whales and dolphins, which can have one hemisphere of their brains sleep while the other stays awake, so marine biologists weren’t sure how the seals managed to doze off while at sea. A new study in Biology Letters, however, suggests the seals might sleep as they drift slowly downward.

Past research had identified certain types of dives that include a period of slow descent that might be a siesta of sorts, for resting or digesting [The New York Times]. So scientists tagged a half-dozen young northern elephant seals off the California coast with instruments that tracked the seals’ positions and modeled their dives in three dimensions.

The monitors revealed that the seals periodically flip onto their backs and slip into slow, spiraling dives. The seals wobble as they drift down, and most of the time their bodies follow circular paths toward the bottom of the sea, said study co-author Russel Andrews…. “[They] resemble a leaf that has dropped from a tree branch and is falling toward the ground, fluttering from side to side,” he said [National Geographic]. It seems likely, the scientists say, that the seals catch a quick nap during these long drifts; in fact, once in a while they strike bottom without even noticing.

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Image: flickr / Mikebaird

NASA’s Plan to Irradiate Monkeys Raises Cruelty Concerns

Brett Israel — Tue, 10 Nov 2009 14:30:10 +0000

If NASA ever wants to send astronauts on long-term space flights, it needs to know how radiation will affect the crew. Testing humans obviously isn’t going to happen, so NASA is funding a round of experiments to study how radiation effects monkeys, the first time monkeys have been used as test subjects by NASA in decades. The point of the experiments is to understand how the harsh radioactive environment of space affects human bodies and behavior and what countermeasures can be developed to make long-duration spaceflight safe for travelers beyond Earth’s protective magnetic shield [Discovery News]. The monkey studies will advance previous radiation experiments with rats and mice and will focus on how radiation affects the monkeys’ central nervous system.

Researchers will expose 18 to 28 squirrel monkeys with a small dose of radiation, similar to what astronauts would receive on a round trip flight to Mars. The monkeys, previously trained to perform a variety of tasks, will be tested to see how the exposure affects their performance [Telegraph] at different times after exposure to gamma rays. The monkeys will not be killed during the experiments, and after testing staff and veterinarians will look after them for the rest of their lives at Harvard Medical School’s McLean Hospital in Boston.

As you might expect, the experiment’s funding announcement is causing a stir among animal rights groups like the Physicians Committee for Responsible Medicine (PCRM) and People for the Ethical Treatment of Animals (PETA). PCRM sent an appeal to NASA urging them to halt the experiments, which they are branding as “one giant leap backward for NASA.” They are also arguing that the research is “cruel” since it violates NASA’s own guidelines for animal treatment and that it’s “unnecessary” since long-term spaceflight still seems like a pipe dream. NASA’s animal testing policy, established in 1996, asserts that “the minimization of distress, pain and suffering is a moral imperative” and emphasizes that experimenters must weigh the burdens of animal subjects against potential societal benefits [Scientific American].

In response to the criticism, NASA’s administrator Charles Bolden restated the agency’s commitment to deep space travel and the necessity of radiation testing. Jack Bergman, who will lead the research, said “there’s a long-standing commitment on the part of NASA to deep space travel and with that commitment comes a need for knowing what kinds of adverse effects deep space travel might have, what are the risks to astronauts,” Bergman said. “That’s not been well assessed” [Discovery News]. Bergman will conduct the experiments at NASA’s Space Radiation Laboratory at the Department of Energy’s Brookhaven National Laboratory in New York.

Image: flickr / suneko

Mother Tongue, Indeed: Newborn’s Cries Mimic Mama’s Accent

Brett Israel — Fri, 06 Nov 2009 19:43:46 +0000

Babies pick up their parents’ accents while still in the womb, according to a new study. After studying the crying patterns of 30 French and 30 German newborns, researchers concluded that the French newborns cried with a rising “accent” while the German babies’ cries had a falling inflection [BBC News]. The researchers believe that by mimicking their mothers’ inflections, the babies are attempting to form an early bond with their mothers.

Scientists already knew that a baby in the womb can memorize sounds from the outside world, and is particularly sensitive to the melodies of her mother’s language. But the new research showed an “extremely early” impact of native language and confirmed that babies’ cries are their first proper attempts to communicate specifically with their mothers [Reuters]. The data support the idea that crying seeds language development for infants, according to the scientists, who published their research in the journal Current Biology.

To hear the different between German and French crying babies for yourself, click here to listen.

Image: flickr / chalky lives

Can Your Pet Catch & Spread Swine Flu? Yes, If Your Pet’s a Ferret

Eliza Strickland — Fri, 06 Nov 2009 15:32:26 +0000

News that an Iowa cat has been diagnosed with swine flu has sparked a new round of concerns, as pet-owners worry both that their furry companions could get sick, and that their pets could pass the virus on to other humans. The 13-year-old, mixed-breed cat showed the symptoms of lethargy, sneezing and coughing typical to sick cats [ABC News]. The veterinarians who treated him say that several people in the cat’s home had been experiencing flu-like symptoms, and lab work confirmed that the feline had the H1N1 virus.

Happily, the cat is expected to make a full recovery. But both vets and public health officials are rushing to reassure the public that one sick cat probably does not indicate a coming crisis. While it’s possible that more cats will be diagnosed with the swine flu, vets point out that the virus was circulating for more than six months before the first cat case was discovered, indicating that the virus probably doesn’t jump from species to species very easily. Doctors also note that there’s very little chance that a cat will spread the virus to humans: Even when inter-species transmissions do occur, the H1N1 virus seems more likely to move from humans to animals, rather than the other way around [HealthDay News].

There have been no reported cases of dogs catching the virus, but there is one type of pet that is known to be vulnerable. Ferrets are generally susceptible to the seasonal flu, and the AP reported Wednesday that H1N1 infection has been confirmed in two ferrets, one in Nebraska and the other in Oregon. “Not only can they be infected with the flu but they are clearly able to transmit the flu back to people,” Treanor said [HealthDay News]. But the bottom line appears to be: Unless you’re a ferret-owner, you probably have nothing to worry about.

Image: flickr / theogeo

The Secret Lives and Loves of Great White Sharks

Brett Israel — Wed, 04 Nov 2009 21:15:05 +0000

Great white sharks, much like humans, tend to stick to familiar turf, according to new research. Also like a lot of people, they like to hang out along the coastal waters of California. Sharks tagged with acoustic devices often spent up to 107 days at four key sites along the central and northern California coast where seals and sea lions are abundant: Southeast Farallon Island, Tomales Point, Año Nuevo Island and Point Reyes [LiveScience]. A few of the fearsome predators were tracked as far inland as the Golden Gate Bridge, apparently in search of snacks, say the researchers. The study, the largest and most detailed study of North American great white sharks, provides evidence contrary to the popular notion of great white sharks swimming aimlessly in the ocean.

The sharks under study divided most of their time between three locations: Northern California, Hawaii, and an area that the researchers called the white shark café, a spot in the open ocean about halfway between the Baja Peninsula and the Hawaiian Islands. Exactly what goes on at the café is still unknown–although researchers suspect it may be a hot spot for mating. Lead researcher Salvador Jorgensen explains that male white sharks “converge in a very specific area of the cafe,” Jorgensen said, while female sharks move in and out of the area. “It adds a little more evidence to the argument that this could be an important reproductive area” [Washington Post].

The scientists tracked the snaggly toothed predators between 2000 and 2008 from the Bay Area to San Diego, Hawaii and back as the sharks followed a route that was carried out with surprising precision and under a strict time frame [San Francisco Chronicle]. These great whites have been isolated from other great white sharks near Australia and South Africa for so long that they are now genetically distinct. The study was published in the journal Proceedings of the Royal Society B.

Image: flickr / hermanusbackpackers

In Controversial Scent Lineups, a Dog’s Nose Picks Out the Perp

Brett Israel — Wed, 04 Nov 2009 19:10:04 +0000

Curvis Bickham spent eight months in prison for a triple-homicide because a police dog confused his scent with that of the killer. Now Bickham and others who spent months in jail after dogs linked their scents to evidence from crimes they did not commit are filing a lawsuit claiming Texas authorities falsely arrested and imprisoned them, their attorney said Tuesday [AP]. In a scent lineup, dogs sniff items found at a crime scene, and then sniff jars swabbed with the suspects’ scents and the scents of others not involved in the crime. When the dogs link crime scene and suspect, that evidence is often relied on heavily in court by the prosecution. Alaska, Florida, New York and Texas all use scent lineups to link suspects to crimes.

Dogs are used all the time to fight crime—from sniffing out bombs and drugs to locating dead bodies. However, scent lineups have critics barking. They say the lineups are poorly controlled, and argue that avoiding cross-contamination is basically impossible. The main target of the current lawsuit is Fort Bend County Deputy Keith Pikett—whose home-trained bloodhounds identified the suspects. A 2004 F.B.I. report warned that dog scent work “should not be used as primary evidence,” but only to corroborate other evidence. In several of the cases that were based on Deputy Pikett’s dogs, however, the scent lineups appear to have provided the primary evidence, even when contradictory evidence was readily available [The New York Times]. Deputy Pikett, by his own estimation, has conducted thousands of scent lineups.

The three men who filed the lawsuit against Deputy Pickett were all eventually set free after contradictory evidence proved their innocence. The Innocence Project of Texas, a legal defense organization … released a report last month that excoriated dog scent lineups as a “junk science injustice” [The New York Times]. Dog scent lineups bring to mind another high profile forensic science debate in Texas that many believe led to the execution of an innocent man. Now that the science behind dog scent lineups is coming under the same scrutiny, one can’t help but wonder if scent lineups might have led to a similar outcome.

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Image: flickr / contadini

Kenya’s Man-Eating Lions Not as Man-Hungry as Previously Thought

Brett Israel — Tue, 03 Nov 2009 13:57:49 +0000

According to legend, the infamous Tsavo man-eating lions dined on 135 people near a Kenyan labor camp prior to their capture in 1898. The two maneless lions have been a crowd favorite at Chicago’s Field Museum, where the stuffed beasts have been on display for over 80 years. But after analyzing fragments of the lions’ bones and fur, scientists at the University of California in Santa Cruz have determined that the true number of humans eaten by the lions was likely closer to 35. By comparing isotopes in the lions’ samples with their normal prey of zebra, wildebeest and buffalo, with other lions, and with the remains of 19th century Kenyans, the scientists estimated that one of the lions ate 24 humans, while the other ate 11 [Chicago Tribune]. The results suggest that the lions hunted together but didn’t always share food, which makes the pair the first example of a cooperative hunting group that ate different prey.

The two lions developed a taste for man after drought, pestilence, and hunting killed of most of their usual prey, according to previous research. Also, the Tsavo lions lived near a slave trading route, which offered easy access to sick, injured, or dead slaves. The lions dragged people from tents at night…. After nine months of this, the beasts were finally killed in December [Nature News]. The recent analysis suggests one of the lions had developed a toothache, which made eating humans easier than devouring its normal prey. The study attributes 24 deaths to one cat, or 30 per cent of its diet, and 11 deaths to the other, just 13 per cent of its food [New Scientist].

Colonel John H. Patterson, a British engineer, shot the lions and then wrote a book about their killing spree, claiming that “28 railroad workers and scores of unfortunate Africans” had been killed [Chicago Tribune]. Some believe that in order to boost the selling price of the lions, he exaggerated the lions’ man-killing ways and inflated the death count to 135. Patterson sold the lion skins for $5,000 to the Field Museum in 1924.

The current study appears in the journal Proceedings of the National Academy of Sciences.

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Image: flickr / lisa andres