December 10, 2012
If you’ve ever had a violent encounter with a porcupine, it probably didn’t end well. The large rodents are most well-known for the coat of some 30,000 barbed quills that cover their backs, an evolutionary adaptation to protect against predators. Although they appear thin—even flimsy—once quills lodge in your flesh, they’re remarkably difficult and painful to get out.
Recently, a group of scientists led by Jeffrey Karp of Harvard decided to closely investigate just what makes these quills so effective. As they report in an article published today in the Proceedings of the National Academy of Sciences, their analysis revealed a specialized microscopic barbed structure that enables the quills to slide into tissue extremely easily but cling to it stubbornly once it’s in place.
Each cylindrical quill, it turns out, is coated with backwards-facing barbs interspersed with smooth, scale-like structures. When a porcupine brushes up against an adversary (or against anything else), it sheds its quills; the barbs around the circumference of the quill act like the teeth on a slicing serrated knife, providing a cleaner cut into tissue and making penetration easier. Once the quill has dug into the other animal, these same barbs have the opposite effect, lifting up and preventing the needle from sliding out easily.
The researchers took a rather interesting approach to arrive at these findings: They measured how much force it took to push in and pull out porcupine quills into pig skin and raw chicken meat. They then performed the same experiment with other quills, which they’d rendered smooth by carefully sanding off all the barbs.
All this research had a greater purpose than merely satisfying the authors’ curiosity about porcupines. Like velcro (inspired by plants’ burrs that get stuck on your clothing) and tape-based adhesives (inspired by the sticky coating on geckos’ hands and feet), the scientists studied the characteristics that made the barbs so effective in hopes of developing next-generation hypodermic needles.
If one could be designed that would require less force to penetrate human tissue, it might mean less pain with your next flu shot. The quills’ staying power could be useful for needles that need to stay in place for a longer period of time, like an I.V. drip.
As a proof-of-principle, the team made replica porcupine quills made out of plastic and put them through the same battery of tests on tissue and skin. The plastic quills worked like a charm. The researchers speculate that such technology could someday be incorporated into a range of medical applications beyond hypodermic needles, such as staples that hold wounds together during healing and adhesives used to hold drug delivery systems in place.
December 5, 2012
The iconic caveman in popular culture is Fred Flintstone: slow-witted and unskilled. In general, we think of the cave art produced by prehistoric people as crude and imprecise too—a mere glimmer of the artistic mastery that would blossom millenia later, during the Renaissance and beyond.
If this is your impression of prehistoric humans, a new study published today in PLOS ONE by researchers from Eotvos University in Budapest, Hungary, might surprise you. In analyzing dozens of examples of cave art from places such as Lascaux, the group, led by Gabor Horvath, determined that prehistoric artists were actually better at accurately depicting the way four-legged animals walk than artists from the 19th and 20th centuries.
The researchers evaluated the prehistoric artists on the basis of the landmark 1880s finding by British photographer Eadweard Muybridge that horses (and, it was later discovered, most four-legged animals) move their legs in a particular sequence as they walk. The “foot-fall formula,” as it’s called, goes LH-LF-RH-RF, where H means ‘hind,’ F means ‘fore,’ and L and R mean ‘left’ and ‘right,’ respectively. At the time of Muybridge, this was thought to be an entirely novel discovery.
Except, as it turns out, prehistoric people apparently knew it too—and got it right in their drawings the majority of the time. Of the 39 ancient cave paintings depicting the motion of four-legged animals that were considered in the study, 21 nailed the sequence correctly, a success rate of 53.8%. Due to the number of combinations of how a four-legged animal’s gait can be depicted, the researchers state that mere chance would lead to a 26.7% rate of getting it right. Cavemen artists knew what they were doing.
When the researchers looked at 272 paintings and statues of four-legged animals made during modern times but before Muybridge’s findings in the 1880s, such as a famous horse sketch by Leonardo da Vinci, it turned out that these more recent artists were much worse: They only got the sequence right 16.5% of the time. Remarkably, even the 686 paintings and statues studied that were made more recently than 1887, after scientists knew for sure how four-legged animals walked, still got it right just 42.1% of the time.
Even apart from artists, a sizable number of depictions of four-legged animals made during the 20th century specifically for the sake of accuracy got the sequence wrong too, according to references used in the study. Out of 307 renditions analyzed, just 58.9% of depictions in natural history museums were correct, along with 56.9% of those in taxidermy catalogues, 50% of animal toy models and 36.4% of illustrations in animal anatomy textbooks.
Although the amount of art studied in each group varies greatly, the accuracy rate for animal depictions in prehistoric times is noteworthy. How could prehistoric humans possibly be this skilled at depicting animals such as bulls, antelopes and wild horses? For a potential answer, consider the way these ancient artists probably thought about the animals: as prey.
For prehistoric humans, “the observation of animals was not merely a pastime, but a matter of survival,” the study’s authors write. “Compared to artists of latter eras, when people were not as directly connected to nature, the creators of such cave paintings and carvings observed their subjects better and thus they depicted the walk of the animals in a more life-like manner.”
November 15, 2012
If, while watching this video, you thought of the classic arcade/cell phone/graphing calculator game Snake, you’re not the only one. This is a Illacme plenipes millipede, long thought extinct and rediscovered seven years ago. For an utterly unusual animal, one thing stands out: With up to 750 legs, it has more than any other creature found so far, including 9,999 other species of millipedes.
Yesterday, the first full description of the species was published in the joural ZooKeys. The study was led by Paul Marek of the University of Arizona. The millipede is known only from 17 live specimens Marek’s team found in a home range that is remarkably specific: three small wooded areas strewn with Arkose sandstone boulders in the foothills of San Benito County, California, near San Francisco.
The rareness of the millipede meant that from 1928 until 2005—when Marek, then a Ph.D. student, found a few specimens in the woods near San Juan Bautista—most scientists had simply assumed the species had gone extinct. Over the past seven years, Marek and his colleagues have taken several trips to the area, typically searching for hours before finding a single specimen clinging to the side of a boulder or tunneling four to six inches down into the ground.
In studying these specimens under a microscope, Marek has discovered a number of surprising characteristics that go beyond its legs. ”It basically looks like a thread,” Marek told LiveScience. “It has an uninteresting outward appearance, but when we looked at it with SEM [scanning electron microscopes] and compound microscopes, we found a huge, amazingly complex anatomy.”
The new analysis revealed that the millipede has no eyes, disproportionately long antennae and a rudimentary fused mouth adapted for sucking and piercing plant structures. It also has specialized body hairs on its back that produce silk, which may be used as a defense mechanism to clear bacteria off the millipedes’ bodies.
Of course, the legs are the most striking part of the species’ anatomy. Despite the name millipede, no species are known to have 1,000 legs, but Illacme plenipes comes closest (its Latin name actually means “in highest fulfillment of feet”). The male specimens examined had at most 562 legs, but the females had more, with the winner at 750.
Most millipedes have somewhere between 80 and 100 legs. Marek and his colleagues speculate that this species’ extreme legginess could be a beneficial adaptation for subterranean tunneling or even for clinging to the boulders widely found in the species’ habitat.
DNA analysis has revealed that its closest cousin, Nematozonium filum, lives in Africa, with the two species’ ancestors apparently splitting apart sometime soon after the breakup of Pangea, more than 200 million years ago.
The team has tried to grow the millipedes in a lab but has so far been unable to. They caution that the species could be extremely endangered—in 2007, they stopped searching for wild specimens out of fears that they were depleting the population—and advocate for a formal protection listing, so scientists will have the time to learn more about them before the millipedes go extinct.
November 5, 2012
In December 2010, visitors to Opape Beach, on New Zealand’s North Island, came across a pair of whales—a mother and her calf—that had washed ashore and died. The Department of Conservation was called in; they took photos, collected tissue samples and then buried the corpses at a site nearby. At first, it was assumed that the whales had been relatively common Gray’s beaked whales, widely distributed in the Southern Hemisphere. (You can see the graphic images here, should you wish.)
Months later, when researchers analyzed the tissue DNA, they were shocked. These were spade-toothed whales, members of the world’s rarest whale species, previously known only from a handful of damaged skulls and jawbones that had washed ashore over the years. Until this find, no one had ever seen a complete spade-toothed whale body. The researchers scrambled to exhume the corpses and brought them to the Museum of New Zealand Te Papa Tongarewa for further analysis.
“This is the first time this species—a whale over five meters in length—has ever been seen as a complete specimen, and we were lucky enough to find two of them,” said biologist Rochelle Constantine of the University of Auckland, one of the authors of a paper revealing the discovery that was published today in Current Biology. “Up until now, all we have known about the spade-toothed beaked whale was from three partial skulls collected from New Zealand and Chile over a 140-year period. It is remarkable that we know almost nothing about such a large mammal.”
The species belongs to the beaked whale family, which is relatively mysterious as a whole, mostly because these whales can dive to extreme depths and for very long periods—as deep as 1,899 meters and for as long as 30 minutes or more. Additionally, the majority of beaked whale populations are thinly distributed in very small numbers, so of the 21 species in the family, there are thorough descriptions of only three.
Of these species, the spade-toothed whale may have been the most mysterious. Scientifically known as Mesoplodon traversii, it was named after Henry H. Travers, a New Zealand naturalist who collected a partial jawbone that was found on Pitt Island in 1872. Since then, a damaged skull found on White Island in the 1950s and another found on Robinson Crusoe Island off the Coast of Chile in 1986 are the only evidence of the species.
Because the whales were never seen alive, scientists knew nothing of their behavior. In the paper, they are described as “the least known species of whale and one of the world’s rarest living mammals.”
“When these specimens came to our lab, we extracted the DNA as we usually do for samples like these, and we were very surprised to find that they were spade-toothed beaked whales,” Constantine said. To determine that, the researchers compared mitochondrial DNA from both of the stranded whales’ tissue samples and found that they matched that from the skulls and jawbones collected decades ago. “We ran the samples a few times to make sure before we told everyone,” Constantine said.
The researchers note that New Zealand’s national policy of collecting and sequencing DNA from all cetaceans washed ashore has proven especially valuable in cases like these—if this policy weren’t in place, no one might ever have known that the body of a spade-toothed whale had been seen for the first time.
This delayed discovery of a species that has been swimming the oceans all along hints at how much we still don’t know about the natural world—especially the oceans—even in this well-informed age. “It may be that they are simply an offshore species that lives and dies in the deep ocean waters and only rarely wash ashore,” Constantine said, explaining how it could take so long to find the species for the first time. “New Zealand is surrounded by massive oceans. There is a lot of marine life that remains unknown to us.”
November 1, 2012
Last week, we reported on a beluga whale discovered off the coast of California that had learned to make noises that sound just like human speech. Well, an Asian elephant named Koshik that lives at the Everland Zoo in South Korea has done one better. Even if you don’t speak Korean, you’ll be impressed by the video above: He’s learned to convincingly mimic five different words of the notoriously difficult language while stuffing his trunk in his mouth.
As described in paper published today in Current Biology, zoo staff say that Koshik is capable of uncannily emulating five commonly used Korean words: annyong (hello), anja (sit down), aniya (no), nuo (lie down) and choah (good). They first discovered that the now 22-year-old elephant could do this in 2006—and the cognitive researchers from the University of Vienna and elsewhere who wrote the study on Koshik’s speech say that the the circumstances of his adolescence might account for this unusual ability.
Koshik was the only elephant in the zoo for the first five years of his life, a period crucial for elephant bonding and socialization. “We suggest that Koshik started to adapt his vocalizations to his human companions to strengthen social affiliation, something that is also seen in other vocal-learning species—and in very special cases, also across species,” Angela Stoeger of the University of Vienna, the lead author of the paper, said in a statement. During this formative stage, Koshik was so desperate to connect with others that he learned to mimic the words most commonly said to him by trainers and zoo visitors, in order to generate a response from them.
Whatever his motivation, Koshik’s way of accurately replicating these five words is especially unusual. The elephant vocal tract is radically larger than a human’s, so to match the pitch and timbre of human speech, Koshik stuffs his trunk in his mouth, altering the shape of the vocal tract as he makes the words.
Several bird species, including parrots and mynah birds, have been known to mimic human speech. There are anecdotal accounts of domesticated elephants doing so as well—Batyr, a longtime resident of a Kazakhstan zoo, was said to have a vocabulary of more than 20 Russian and Kazakh phrases—but his abilities were never scientifically tested. Critics said that his supposed abilities merely reflected the fact that observers expected to hear the words after being told that he was capable of making them.
In this case, the researchers performed a number of tests in order to definitively determine whether Koshik actually mimics human words. To start, they played audio recordings of Koshik’s words to native Korean speakers and asked them to write down what they heard. “We found a high agreement concerning the overall meaning, and even the Korean spelling of Koshik’s imitations,” Stoeger said. They also acoustically evaluated his speech and found that, in terms of frequency, it differed from typical wild elephant calls and much more closely matched those of Koshik’s human trainer, Kim-Jong Kap.
Of course, there’s no evidence Koshik actually understands the meaning of his words, just that saying them can elicit the attention of people. Nevertheless, the fact that such a highly intelligent species has been found to be physically capable, at least, of making human-like noises, should be encouraging. After years of efforts to train apes to say words, scientists have come to the conclusion that although they may be smart enough to learn meaning (as demonstrated with sign language), they lack the fine motor control of the vocal tract necessary for speech. If elephants are physically capable of mimicking words, it leaves open the possibility that we could someday teach them to speak, too.