If they ever build a Wal-Mart at Machu Picchu, I will think of Collinsville Road.
I’m standing at the center of what was once the greatest civilization between the deserts of Mexico and the North American Arctic—America’s first city and arguably American Indians’ finest achievement—and I just can’t get past the four-lane gash that cuts through this historic site. Instead of imagining the thousands of people who once teemed on the grand plaza here, I keep returning to the fact that Cahokia Mounds in Illinois is one of only eight cultural World Heritage sites in the United States, and it’s got a billboard for Joe’s Carpet King smack in the middle of it.
But I suppose Cahokia is lucky. Less than ten miles to the west, the ancient Indian mounds that gave St. Louis the nickname Mound City in the 1800s were almost completely leveled by the turn of the century. Today only one survives, along with some photographs and a little dogleg road named Mound Street. The relentless development of the 20th century took its own toll on Cahokia: Horseradish farmers razed its second biggest mound for fill in 1931, and the site has variously been home to a gambling hall, a housing subdivision, an airfield, and (adding insult to injury) a pornographic drive-in. But most of its central features survived, and nearly all of those survivors are now protected. Cahokia Mounds may not be aesthetically pristine, but at 4,000 acres (2,200 of which are preserved as a state historic site), it is the largest archaeological site in the United States, and it has changed our picture of what Indian life was like on this continent before Europeans arrived.
An Illinois state representative wants to ban lion meat from his state, raising an obvious question: just who is eating this stuff?
Illinois Rep. Luis Arroyo’s Lion Meat Act would make it “unlawful for any person to slaughter a lion or for any person to possess, breed, import or export from this State, buy, or sell lions for the purpose of slaughter.”
Arroyo says he believes at there are at least two sites in Illinois selling African lion meat, according to the Associated Press, though the legislator did not identify them by name.
Crawford Allan, an illegal wildlife trade expert for the conservation group World Wildlife Fund, said lions are farmed for meat in the United States to sell in restaurants.
“We have no evidence that lion trade in the U.S. is illegal,” he said.
Richard Czimer, owner of Czimer’s Game and Sea Foods Inc. in Homer Glen, Illinois, sometimes buys USDA-certified lion meat.
In his view, Arroyo’s proposed lion-meat ban is “trying to curtail a choice” in what people eat.
“He’s discriminating against all my customers and everybody who wants to try something new,” said Czimer.
Czimer pointed out that hundreds of thousands of cattle are killed per day, while there are far fewer lions killed. In 2012 for instance, Czimer was able to purchase only two lions.
Yet “eating carnivores is mostly not a good idea,” argued Luke Hunter, president of Panthera, a U.S. based wild-cat conservation group that works with National Geographic’s Big Cats Initiative.
For one, carnivore populations worldwide are dwindling—the African lion is listed as threatened by the International Union for Conservation of Nature, and is endangered in certain West African countries. (See lion pictures.)
Though wild lions aren’t killed for food, there’s concern that weak or poorly regulated laws regarding the ownership, breeding, and trade of captive big cats in the U.S.—in particular tigers—could fuel the black market for big-cat parts,Will Gartshore, senior program officer for U.S. Government Relations at WWF, said in an email.
Handling wild-carnivore carcasses can also be dangerous, Hunter said. Since the predators end up eating so many different animals, they accumulate parasites and diseases. In 2007, for instance, a biologist in Arizona contracted primary pneumatic plague after dissecting a cougar carcass and died shortly after.
Added Luke Dollar, grant-program director of the Big Cats Initiative: “While these aren’t lions that have a realistic chance of roaming the African plains some day, the use of them for food animals has to be considered ethically questionable.”
Exotic Meat on the Menu
Of course, that doesn’t stop some people from consuming exotic meat. In the United States, some people eat legally hunted black bear—which is not considered threatened—Hunter said, especially in late autumn after the animal has foraged all summer.
The U.S.-based company Exotic Meats and More sells such oddities as iguana, llama, camel, according to its website. A similar purveyor, Buy Exotic Meats, offers emu, yak, and snapping turtle, among other animals.
Eating African lion meat is unusual around the world—including on the predator’s home continent, where the meat is not considered palatable, Hunter said.
Yet there is a taste for meat of threatened wild animals in other parts of the world—”too many species to list,” said Allan.
For example, he said that rare species on the menu include great apes in West and Central Africa; sturgeon caviar worldwide; freshwater turtles and tortoises in Asia; Asiatic black bears for bear paw soup in China; marine turtles in Latin America and the Caribbean, West Africa, and Southeast Asia; and some whales in Japan, South Korea, and Iceland.
Wild Animals Fair Game in Asia
By far the most exotic meat consumers live in Asia, where “most wild species are fair game,” Hunter noted. “In Thailand in Vietnam, there are often wild meats available in restaurants”—including tiger.
In some Asian countries, tourist attractions called tiger parks secretly operate as front operations for tiger farming—butchering captive tigers for their parts and offering a potential market for wild-tiger poachers too, according to National Geographic magazine’s 2010 story on Asia’s wildlife trade.
“Tibetans wear tiger-skin robes; wealthy collectors display their heads; exotic restaurants sell their meat; their penis is said to be an aphrodisiac; and Chinese covet their bones for health cures, including tiger-bone wine, the ‘chicken soup’ of Chinese medicine,” that article reported.
Hunter estimates there are between 4,000 to 5,000 tigers in captivity that are being bred for their parts and meat. (See pictures of tigers in trouble.)
Lion bones from Africa are being traded to China as a substitute for tiger bones for tonic wine as well, WWF’s Allan noted.
Panthera’s Hunter said that Illinois’s Lion Meat Act would be more effective if it promoted “conservation on the ground, rather than banning a fairly inconsequential trade of lion meat in the state,” he said. (Learn how you can help protect big cats.)
“People might spend 10-to-15 bucks on a gourmet lion burger—I’d rather that …. they spend that on a conservation organization working to protect cats in the wild.”
Looking up? Adult A. afarensis too may have been adapted to tree life (artist’s reconstruction).
Photograph by Dave Einsel, Getty Images
Rear view of juvenile A. afarensis’skull, shoulder blades, and vertebrae. Photograph courtesy Zeray Alemseged, Dikika Research Project.
for National Geographic News
Published October 26, 2012
What made us human? Part of the answer may rest on the shoulders of a 3.3-million-year-old toddler.
Like ”Lucy,” the fossil child was a member of the speciesAustralopithecus afarensis, pioneers of upright walking. Yet her apelike shoulder blades hint that our forebears may have taken longer than we thought to fully come down to earth, a new study says.
Figuring out when the tree-to-ground transition took place is immensely important to understanding how we became who we are. Bipedalism, after all, gave prehumans a literal head’s-up on approaching predators and freed up hands for stone tools, which in turn gave access to more types of food, including brain-boosting animal proteins—among other advantages.
Video: How the Australopithecus Afarensis Baby Was Found
The tiny fossils—including the only known complete A. afarensis scapula, or shoulder blade—add to evidence that that giant stride was more a series of faltering steps.
“What we’re showing is that bipedalism wasn’t this sudden change that took shape in an early common ancestor,” said study co-author David Green, an anatomy professor at Midwestern University in Downers Grove, Illinois.
“As bipedalism was developing, there were other forms of locomotion that were still important.”
(See an interactive time line of human evolution.)
Clinging to the Branches of the Human Family Tree?
“Selam,” or ”Lucy’s baby,” or ”Dikika baby”—as the A. afarensis three-year-old has been variously nicknamed—spent millions of years encased in rock inEthiopia’s Dikika region, where the shady forests she knew have long since given way to desert. (See pictures of the Dikika baby.)
After discovering Selam in 2000, Zeresenay Alemseged spent 11 years flecking away sandstone to free what remained of her bones. For the new study, the California Academy of Sciences anthropologist and colleagues compared her fossils with those of living apes, humans, and other early human species.
The team found that the sockets of Selam’s shoulder joints point upward, as they do in apes. Likewise, the bony ridge that runs along her shoulder blades is set at a similar angle as in chimpanzees.
These apelike shoulders, along with previously recognized climbing-friendly features, would have allowed Australopithecus species to do a number of things better than humans: raising their arms above their heads, hanging from branches, plucking fruit, and hoisting their bodies into trees.
“The fact that they still maintained the gorilla-like scapula, the long and curved fingers, the short clavicles [collarbones], and a torso which would probably have been funnel shaped, is testament to the presence of an arboreal lifestyle in addition to being fully bipedal,” said Alemseged, a National Geographic Society emerging explorer. (National Geographic News is part of the Society.)
In other words—whereas humans can climb trees, if we put our minds to it—A. afarensis was likely truly at ease in the trees and on the ground, according to the study, published Friday in the journal Science.
Case closed? Not quite.
A Puzzle Piece, but What’s the Big Picture?
According to University of Missouri paleoanthropologist Carol Ward, the study “provides more evidence of the primitive nature of these animals, so that’s really exciting, and it’s a key piece of the puzzle.”
Ward agreed that the shoulder development of the growing A. afarensis ”doesn’t seem particularly humanlike.” But, she added, “it’s hard to know exactly what that means.”
Some of the shoulder measurements of adult australopithecines in the study, she said, seem similar to those for human species, especially Neanderthals. And “Neanderthals are very clearly not climbing trees.”
(Related: ”‘Lucy’ Was No Swinger, Walked Liked Us, Fossil Suggests.”)
Study co-author Green conceded that one adult Australopithecus specimen from Ethiopia has a shoulder blade ridge with an apparently more horizontal, humanlike angle. But, he countered, two Australopithecus shoulder bones from South Africa “are even more apelike than afarensis’.”
“Great Fossil” but No Smoking Gun
Scott Simpson, a paleoanthropologist at Case Western Reserve University in Cleveland, said Selam is “a great fossil.”
“But,” he added, “I don’t think it’s the smoking piece of information that says these guys were climbing trees.”
The “transition to bipedality caused a complete reorganization of the body,” altering the pelvis, various knee and ankle bones, the spine, and the foot, he said. But this new analysis “hinges on a very narrow part of the musculoskeletal system.”
If the study had taken in the whole skeleton, he said, “I think we would learn a lot more about what’s going on.”
Green, the study co-author, responded that shoulder blades “have been shown in primates and in mammals to be a very reliable indicator of an animal’s locomotor and behavioral habits.”
“As far as looking at the whole body,” he added, “it’s something we’re planning.”
(Also see ”‘Lucy’ Kin Pushes Back Evolution of Upright Walking?”)
A. Afarensis No Match for a Chimp
Despite their differences, the researchers agree on the basics: A. afarensis was an upright walking creature that also climbed trees.
Case Western’s Simpson thinks they probably climbed like modern humans, “as opposed to exhibiting any special adaptations to arboreality.”
The University of Missouri’s Ward agreed, arguing that, if climbing were part of A. afarensis’ lifestyle, evolution would have left the species with “the really key bits of climbing anatomy, like the grasping foot.”
Another thing they can all agree on: A. afarensis would have been no match for a chimp or gorilla in negotiating the forest canopy, as study co-author Alemseged pointed out.
But Alemseged maintains that the species was nevertheless a natural climber. In the trees, its apelike shoulders, long fingers, and other adaptations, he argues, would have allowed it to overcome the handicap of a bipedal body.
Good thing, too.“A species of small stature with almost no technology, which feeds on leaves and fruits and lives in a very dangerous world, needs to nest, evade predators, and to feed itself,” he said.
“For those reasons”—in addition to the fossil evidence—”I think an arboreal lifestyle was an important and key element of Australopithecus afarensis.”
Image courtesy Jennifer Peters and Michael Taylor, Nikon Small World
What looks like a tangle of Christmas lights is actually the brain of a zebrafish embryo, winningly photographed for the 2012 Small World Microphotography Competition.
Winners of the international contest were announced Tuesday. This shot—taken by Jennifer Peters and Michael Taylor of St. Jude Children’s Research Hospitaland magnified 20 times—took first prize. It’s believed to be the first image ever to show the formation of the blood-brain barrier in a live animal.
The barrier is a protective system of cells that filter the blood that flows to the brain. It allows nutrients and other necessities to pass but keeps out bacteria and other pollutants.
To create this shot, Peters and Taylor injected fluorescent proteins into a transparent zebrafish embryo. That let them see the brain’s endothelial cells—which line the inner surface of blood and lymphatic vessels—and watch the development of a blood-brain barrier in real-time.
Their three-dimensional image was made with a confocal microscope, which colors blood vessels differently at different depths. (Confocal lenses capture light from a single plane of focus, rather than all available light.) Peters and Taylor stacked their colored images and compressed them into a single shot to show the complexity of the phenomenon they witnessed.
Rough surf breaks over the storm-battered dunes of Cape May, New Jersey, on October 29.
Photograph by Mel Evans, AP
The endangered piping plover nests on open beaches. Photograph by Joel Sartore, National Geographic
National Geographic News
Published October 30, 2012
The devastating superstorm that hit the U.S. East Coast this week didn’t just wreak havoc on human communities—the spawn ofHurricane Sandy also damaged habitat for coastal bird species. (See “Hurricane Sandy: Why Full Moon Makes ‘Frankenstorm’ More Monstrous.”)
We talked to Bryan Watts, director of the Center for Conservation Biology in Williamsburg, Virginia, to get a bird’s-eye perspective on the disaster.
How do birds react to hurricanes?
When birds encounter a storm like this, they’re basically in scramble mode just like we are.
Are you worried about birds dying?
We have mortality events with these hurricanes, [especially with] birds that are either migrating or in vulnerable situations. Although surprisingly we have tracked several whimbrels with satellite transmitters that have flown directly through these storms. Last fall, we tracked a whimbrel named Chinquapin right into Hurricane Irene that successfully [landed] in the Bahamas.
Many birds must have lost their homes.
Birds that require low habitats—marshes, beaches, dunes—all of those species would have been displaced. When you see all the water, most of the public thinks about houses and infrastructure. For us we think of birds being displaced. But a lot of [species such as the] barred owl would go completely underwater in storms like that. (See shorebird pictures.)
Does that mean they drown?
Maybe—beaches, dunes, and marshes are teeming with birds this time of year and all of these habitats went underwater, causing inhabitants to seek higher ground. (Also see ”Migrating Birds Escaped Worst of Gulf Oil Spill.”)
Do the habitats typically recover?
[There can be] fairly long-term habitat effects. If you remember Hurricane Hugo in the 1980s, it had a huge impact on habitat in North Carolina. It pretty much decimated red-cockaded woodpecker habitat [a species that depends on old-growth forests] in the Francis Marion National Forest.
When Hugo came through, it snapped off trees all through what was once the best population [of red-cockaded woodpeckers] at the time. So there are times when hurricanes can hit the wrong place and have lasting impacts on species. Some of the groups we’d expect to be most affected are ones that depend on coastal habitats, such as piping plovers, Wilson’s plovers, least terns, etc. The barrier islands that these species use are reshaped and flattened, so their breeding habitat is impacted. (See more bird pictures.)
On the other end we have species that are inconvenienced for a short time like we are, and ride it out like we would.
Any predictions about Sandy’s long-term impact on bird habitat?
It looks to me like the main lasting effect of this is going to be a coastal reshaping. It may change some of the outer beach habitats change, and that may last years. All of the marshes within the Mid-Atlantic and all the way up through northern New England went underwater. All of those species would have had to go to higher ground. But that will be a relatively short-term response.
I read that hurricanes can sometimes help ecosystems.
Disturbance is a part of the ecosystem process. It’s generally thought that some forests in the [U.S.] Southeast that experience hurricanes regularly [are adapted to hurricanes], so that disturbances are a major proponent of how that community is structured. Hurricanes disrupt habitats and so in that way create a patchwork of different age forests in the landscape and that promotes overall diversity. The further you can [move] away from Hurricane Alley the less that’s true—when you get into the Northeast, which is mostly hardwood-based and experiences hurricanes every few decades, hurricanes are not a driving force for how communities are structured, [and hurricanes] can have a lasting effect. (Watch hurricane videos.)
Did bird species evolve to live with hurricanes?
Yes. The best example we have of that is our coastal barrier islands, which go from open sand to dune and even to shrub. A number of our species, such as the federally endangered piping plover, rely on open beach sandy habitats for nesting. Left undisturbed, beaches will progress from open sand to dune grassland to shrubland to forest. It is regular disturbance by storms that keeps beaches open. It sets back their progression to other habitats. In that sense it is a renewal—just as fire reverts forest back to grassland.
How do you think bald eagles are faring after Hurricane Sandy?
New Jersey has a hundred pairs—I suspect they will have lost some trees and nests.
Can birds sense that they should seek higher ground?
Birds are better than we think they are at figuring out ways to survive—I think most of them made it out OK.
Hurricane Sandy’s storm surge pushes seawater into New York City’s Carey Tunnel on Monday.
Photograph by Andrew Burton, Getty Images
A rat emerges from a hole in a Brooklyn subway station. Photograph by Julie Jacobson, AP.
for National Geographic News
Published October 31, 2012
New York City’s rats have arrived. In the wake ofsuperstorm Sandy, residents of the city are soon likely to see them by the thousands, since the rodents have been driven from flooded subway tunnels.
When weather is drier, the rats seem to love living under the soil, and can dig deeper than water can seep. They could even have been safe in their burrows as the storm swept the city Monday. But many likely were out on the hunt for food.
“They’re in the subway, in spite of the subway,” said exterminator Benett Pearlman of New York-based Positive Pest Management Corp. The underground systems are the first things rats reach when breaking through the soil in search of sustenance. This perpetual hunger likely killed many as floodwaters washed back through their tunnels into their nests, probably killing the sick, the elderly, and new mothers with their young.
The many thousands that made it out alive—most using the same stairways people use, Pearlman said—were trapped aboveground on Tuesday, hunkering down behind trash bins and under cars until nightfall.
Sandy has brought a feast to their feet. New sources of food are washing out of the waterways and along flooded streets, including loads of rotting trash, other rats, pigeons, and fish. The well-fed rats will burrow beneath buildings under cover of night to establish new homes, sliding into holes as small as a half inch (1.3 centimeters)—the width of their skulls—even though their bodies can measure up to 18 inches (46 centimeters) long.
(Related: ”Hurricane Sandy Pictures: Floods, Fire, Snow in the Aftermath.”)
As for New York’s other ubiquitous wildlife, Tufts University animal behavioristRobert Cook thinks pigeons are in an excellent position when the city is flooded and windy. They’re originally cliff-dwelling birds, so skyscrapers suit them, Cook said. They’ll find a safe place to get out of the wind, then fly to new food sources.
“There’s a reason rats and pigeons are so successful around humans,” he says, “They’re well adapted to what we do.”
Koshik the Asian elephant can “speak” five Korean words by tucking his trunk inside his mouth.
Photograph by Ahn Young-joon, AP
for National Geographic News
Published November 2, 2012
In a grainy video shot in a cavernous room at South Korea’s Everland Zoo, anAsian elephant stands at attention, his trunk in his mouth.
“Choah,” he tells the camera. “Choah, annyong. Anja.” In English: “good,” “good,” “hello,” and “sit down.”
Watch Koshik Speak Korean
Six years ago, this video clip, sent by the flummoxed staff of the Everland Zoo, hit the inbox of elephant-communication researcher Joyce Poole of ElephantVoices. The footage was the first look scientists would have of Koshik, the Korean-speaking elephant.
“This is amazing,” Poole, a Conservation Trust grantee for the National Geographic Society, had written at the time. (National Geographic News is part of the Society.)
“I can’t see any chance that it is being faked, and it is certainly a human voice that is being imitated.” She passed the clip to colleagues. Somebody needed to check this out—could this possibly be genuine?
Fast-forward six years, and confirmation has finally arrived in a new study led by one of Poole’s former colleagues, Angela Stoeger of the University of Vienna. Koshik, Stoeger said, is definitely for real.
(Also see ”‘Talking’ Whale Could Imitate Human Voice.”)
An Elephant With an Ear for Language
To reach this conclusion, Stoeger and her team first had to verify that Koshik’s sounds were words at all. According to the elephant’s trainers, he had a six-word vocabulary, including annyong (“hello”), aniya (“no”), anja (“sit down”), and choah (“good”).
So the team played 47 recordings of the imitations to native Korean speakers who’d never heard the elephant before, and instructed them to simply write down whatever they heard. “They knew they were listening to an elephant, but they didn’t know what they were supposed to hear,” explained Stoeger, whose study appeared recently in the journal Current Biology.
But even to the human ears, the words were readily understandable and transcribed. Vowels were easiest for the subjects to make out, and when reports contradicted each other, it was almost always over consonants, which Koshik still struggles with.
“It’s not a hundred percent” accurate, said Stoeger. “But still, if you don’t know at all what you’re going to hear, it’s even difficult to understand the best parrot imitating human speech.”
To ensure these weren’t variants of natural elephant calls, the researchers also compared Koshik’s words to typical Asian elephant sounds, and found that they were completely different. However, they were dead ringers for the intonations and frequency of the commands of his trainers, whom the researchers believe are the subjects of Koshik’s imitations.
A Tongue-in-Cheek Approach
The fact that Koshik talks pales compared with how he talks. When humans make an o sound, they pull in their cheeks and pout their lips out into a rounded circle. Elephants don’t have that cheek-lip structure—they long ago traded it in for trunks—so it’s anatomically impossible to make those sounds.
Koshik sidesteps this problem by sticking the tip of his trunk into his mouth and moving his lower jaw, essentially MacGyvering his vocal tract.
“He really developed a new way of sound production,” Stoeger said. “Naturally, Asian elephants don’t do this.”
In fact, the only instance of an animal behavior even coming close to Koshik’s tool-aided mimicry is in orangutans, which tweak the frequency of their normal calls with their hands or leaves.
“It’s really fascinating. I’m amazed. And excited,” said Caitlin O’Connell-Rodwell, an elephant-communications specialist at Stanford University who was not involved in the study.
The very first evidence that elephants could even do vocal imitations only came out in 2005, and featured African elephants imitating trucks and noises from other elephant species, she said.
(See ”Killer Whale Barked Like Sea Lion, Tapes Reveal.”)
“That was a beginning,” O’Connell-Rodwell said. “But this is crossing species and creating a much harder vocalization to emit.”
The Elephant in the Room
Vocal imitation in the animal kingdom is already a rarity, and imitations of human speech even more so. Parrots can do it, as could a harbour seal named Hoover and a beluga whale from San Diego.
Researchers believe the feat requires not only the appropriate vocal machinery—or ingenious trunk-tinkering—but also a strong social affiliation with people. Hoover, for example had been hand-reared by a fisher, and the beluga had his trainers.
Koshik started his imitations—or trainers first recognized his imitations—when he was 14 years old, after spending much of his adolescence isolated from other elephants.
“Elephants are highly complex, social, and intelligent animals with individual personalities,” said ElephantVoice’s Poole.
“They are able to produce an incredible variety of sounds in a wide range of contexts,” said Poole, who was not involved in the latest research.
“One might turn the question around: Given their remarkable social complexity and demonstrated flexibility, their significant cognitive capabilities, and their physical capacities, why should we be so surprised that they imitate sounds in their environment?”
A vendor sharpens knives ahead of Eid al-Adha, or the Festival of Sacrifice, in Karachi, Pakistan, on October 25. Celebrated by Muslims worldwide, the festival commemorates the willingness of the Prophet Abraham (Ibrahim) to sacrifice his son in obedience to God.
Why We Love It
“I love the juxtaposition of the golden, glamorous-looking sparks with the colder, bluish tone of the work shirt.”—Amina El Banayosy, photo intern
African wild dogs in a natural habitat: Botswana’s Okavango Delta (file picture).
Photograph by Chris Johns, National Geographic
for National Geographic News
Published November 5, 2012
In a “worst nightmare” situation, 11 African wild, or painted, dogs killed a two-year-old Pennsylvania boy Sunday after he had fallen into an enclosure at the Pittsburgh Zoo, zoo officials confirmed at a press conference Monday.
One of the dogs was shot after it wouldn’t leave the boy’s body. The others have been quarantined.
“The zoo feels terrible that this tragic accident happened,” said Barbara Baker, chief executive of the Pittsburgh Zoo, which remains closed until further notice.
Why did the carnivores attack the boy? We contacted African wild dog expertsRosie Woodroffe, senior research fellow at London’s Institute of Zoology, and Kim McCreery, of the African Wild Dog Conservancy in Tucson, Arizona, to get some insight into the animals’ behavior.
Tell me a little bit about African wild dogs.
Kim McCreery: They live in packs, similar to wolves. They’re a family group. Mom, dad, and older siblings take care of the pups. They even have babysitters at the den. Pups get to eat first, unlike other group-living carnivores.
In terms of their social organization, they’re very similar to human families.
We [McCreery and African Wild Dog Conservancy co-founder Bob Robbins] have studied their behavior for years. Wild dogs have a high investment in friendly and submissive behaviors. They don’t bare their canines like other dogs. Rather, they do a lip curl, which is very hard to notice.
Are African wild dogs threatened?
McCreery: They are classified as endangered by the IUCN [International Union for Conservation of Nature]. Habitat fragmentation and persecution [by people] are their two main threats. (Take an endangered-animal quiz.)
Why do you think the Pittsburgh Zoo dogs attacked the boy who’d fallen into their habitat?
McCreery: We can’t really say. My colleague [Bob Robbins] and I have been talking about it. What happened yesterday was a tragedy. And we don’t know exactly what happened.
In the wild, we have never been threatened by wild dogs, and we’ve spent countless hours in the African bush.
Rosie Woodroffe (via email): Of course, this is a sad and traumatic event, which must have been horrific for the child’s family and for the witnesses. I have children of this sort of age myself and really feel for the family’s loss.
The first point I’d like to make is that wild dogs are not dangerous to people in the wild. I have never heard of an attack on people, and where I work in Kenya, people—including small children herding goats or walking to school—encounter wild dogs on foot regularly, yet local people are not afraid of them.
I have personally walked up to wild dogs many times and never once felt threatened. (See African wild dog pictures.)
The second thing to point out is that wild dogs are extremely bold and curious. For example, if you drive up to them in a vehicle, they are likely to come up to have a look rather than run away. So, if something unusual falls into their enclosure, I would expect the whole pack to immediately rush up to investigate.
So, I would imagine the wild dogs’ perspective on this event would be: What just fell into our enclosure? Let’s go and see!It’s not scary, but it’s moving—let’s bite it (assuming they did; I don’t know if they did)! Our keepers are trying to distract us, but this thing is new and way more interesting.
Would wild dogs have behaved differently than the captive wild dogs at the Pittsburgh Zoo?
McCreery: Captive-bred animals can behave differently than their wild counterparts, but there is nothing we can say with certainty as it relates to this tragedy. The context in captivity is so different than in the wild.
Anything else you want to say about wild dogs?
Woodroffe: When all is said and done, wild dogs are predators and have the instinct to pursue prey. Free-ranging wild dogs are curious about people but afraid of them at close quarters … yet in captivity I would expect that fear to be much reduced, as they see people at close quarters every day.
Nevertheless, I very much doubt that this was a predatory attack.
Had these dogs been serious about killing such a small child for food, I think that such a large pack would have done a great deal more damage in the time the child was in the enclosure. A wild pack of that size would dismember prey of that size within seconds and consume it within minutes.
Unlike crocodiles, alligators, such as this Texas specimen, have supersensitive dots only on their snouts.
Photograph by Matt Hansen, My Shot
for National Geographic News
Published November 8, 2012
They may be lethal, leathery, and literally armored to the teeth, but crocodilesand alligators, it turns out, are sensitive types. Their snouts, in fact, are even more touch-sensitive than human fingertips, a new study says.
Part of the crocodilian reptile order, alligators have some 4,000 of tiny, raised black spots, or domes, on their heads, particularly along their jaws, inside their mouths, and between their teeth. Crocodiles have a similar setup, plus a liberal sprinkling over the rest of their bodies, bringing their total to about 9,000.
Scientists have known about these bumps—called integumentary sensory organs, or ISOs—for more than a century. But for a long time their purpose was a mystery.
Perhaps, some biologists suggested, the domes have a waterproofing purpose. Or maybe they detect faint electrical fields given off by prey—or salt, to alert crocs to unsafe drinking water.
In 2002 an alligator study seemed to crack the mystery. Croc dots, it revealed, could detect ripples from even a single drop of water-and therefore even very weak prey movements. (See ”Rare Pictures: Crocodile Attacks Elephant.”)
Until now, though, a couple of big questions continued to intrigue scientists: How did the domes work—and just how sensitive are they?
Feeling the Unfeelable
Vanderbilt University student Duncan Leitch took it upon himself to solve the mysteries. The results of his croc research appear today in a Journal of Experimental Biology report coauthored with his advisor, biologist Ken Catania.
After taking a croc-handling course (pro tip: poke an unruly croc on the nose—especially sensitive due to those dots), Leitch ordered relatively small alligators from refuges and crocodiles from commercial breeders.
Video: Duncan Leitch Working With Crocs
Examining domes on 18 American alligators and 4 Nile crocodiles, he found that the spots contained touch receptors tuned specifically to pressure and vibration, plus a host of raw nerve endings. (Related: ”Crocodiles Have Strongest Bite Ever Measured, Hands-on Tests Show.”)
The domes didn’t respond to salt or electricity, but they did respond to the touch of von Frey filaments—hairlike, standardized wires used to gauge sensation levels. In fact, some of the domes turned out to be so sensitive they could detect pressures too small to measure via the filaments.
“My professor and I didn’t believe at first that they could be that reactive,” Leitch said. “We closed our eyes and tried to tickle each other with [the filaments] on our fingertips, and neither of us could even feel it.”
Later, using croc carcasses, the researchers stained the dome nerves with dye and traced them back to the brain. They turned out to be tied into a system stemming from the trigeminal nerve—associated with biting, chewing, and swallowing. Go figure.
(Pictures: Biggest Crocodile Ever Caught?)
Why So Touchy?
The new croc-sensitivity study “is really valuable,” said Kent Vliet, co-chair of the Association of Zoos & Aquariums’ Crocodilian Advisory Group.
“This was exactly what I had hoped somebody would do with ISOs, in terms of really looking at the distribution and the electrophysiology, because that’s really the way to answer these questions about function in a tiny sense organ like this.”
But why would alligators and crocodiles need such supersensitive skin? Leitch has his suspicions.
He’s certain the animals use their mouths to feel for and snap up food (he videotaped crocodiles doing exactly that).
And mother crocodilians also use their mouths to help their young out of their shells and to hold the offspring between their jaws for protection. “That definitelywould require a great deal of sensitivity,” he said.
(Also see ”Robot Revolution: New Material Sensitive as Human Skin.”)
Future studies, Leitch hopes, will map out how the bumps’ sensations are represented in the reptiles’ brains—and perhaps uncover why crocodiles have bumps on their whole bodies, whereas on alligators, only the snouts have domes.
And, given his apparently undiminished enthusiasm, he may be just the guy to find out.
“What’s interesting to me is that such a scaly animal, one that’s so heavily armored, could have a sensitivity that rivals or surpasses our tactile abilities,” Leitch said. “But they have all these little tactile areas that are so exquisitely sensitive—it seems really amazing.”