How Many Continents Does Katy Perry's "Roar" Video Take Place On Simultaneously?

The video for Katy Perry's newest single, "Roar," has been viewed almost 36 million times since it appeared online four days ago. In case none of those views were yours, a quick plot summary: A woman crash-lands in the jungle with an attractive but inconsiderate boyfriend in safari gear who's eaten by a tiger at 0:40. She's scared at first, but soon befriends a monkey, is bathed by a helpful elephant, and changes out of her old clothes into (spoiler alert!) a leopard bra. And sings.

On her road to empowerment, Katy gets help from a diverse array of animals. So diverse, in fact, that their being together in the jungle might be the most fantastical element of the video.

First there's the monkey, seen above inspiring Katy to turn her stiletto* into a spear. It's a capuchin, native to Central and South America.

What about the beast that disposed of the boyfriend? Katy sings "I've got the eye of the tiger," and she's got the whole body of it in her video. But tigers live only in Asia, so either the big cat or the monkey seems to have taken a wrong turn across an ocean somewhere.

Elephants can live in Asia as well, so maybe Katy's pachyderm friend (who does double duty as shower head and clothes hook) is in the right place. Asian elephants, though, have distinctively small ears that sit low on their heads. The fellows with the big flapping ears—on full display in the picture at the bottom of this page—are African elephants.

So now we're up to three landmasses at once. Perhaps this bird can settle the tie: it looks like a great hornbill, a tropical bird from Asia.

Then there's the creature whose teeth Katy is brushing in this scene. Its short and rounded snout, unlike a crocodile's long, pointed one, suggests it's an alligator. That's one more point for the Americas. (A crocodile's bottom teeth also protrude when its mouth is closed, while a gator's don't. But this prop only appears in the video with its mouth wide open. It may not have a hinge.) 

A crocodile would have given another point to Africa. Sorry, cradle of civilization! But wait—sneaking into the frame during the final seconds of the video is a baboon, a monkey that lives only in Africa (except for a desert-dwelling species in the southern tip of the Arabian Peninsula).

To break the three-way tie between continents, let's go back and take a closer look at the birds in the video. There are a couple of macaws, the striking parrots from Central and South America:

And key to the plot of the whole video is this red bird. Katy uses its feathers to build a lure that tempts the tiger, which she ultimately subdues in a roar-off and turns into her pet.

The red bird also provides a plot twist for our purposes. I sent the picture to ornithologist and Guardian blogger GrrlScientist for identification. "Oh wow," she wrote back, "a female eclectus parrot." The males are bright green with orange beaks, looking like a different species altogether. Eclectus parrots don't live alongside the capuchin, the elephant, or the tiger: they're native to northeastern Australia, New Guinea, and neighboring islands.

At least four parts of the world, then, are represented in Katy's jungle. (Don't worry about the leopard bra—our heroine fashioned it out of a scarf she was wearing on the plane.) It's a little surprising not to see a lion in the video, since it's the only animal aside from the tiger that actually appears in the song's lyrics. But then again, lions prefer the savanna to the forest. Maybe that would have been too unrealistic.

*I'm not sure of the species of shoe.


Images: screenshots from "Katy Perry - Roar."

Why Yellowstone's Grizzlies Should Be Grateful for Wolves

There's only one time a giant domino chain isn't fun: when you're a domino. Humans are great knockers-down of ecosystem domino chains, and sometimes we don't even know which species we've felled until we start propping things back up. When we knocked every last wolf out of Yellowstone National Park, for example, we didn't know how we were hitting bears at the other end of the chain.

When Yellowstone was first created, visitors were free to kill the animals. Then in the early 20th century, government "predator control" efforts gradually finished the job of wiping out the park's wolves. The last ones were killed in 1926. Wolves remained absent from Yellowstone until the mid-1990s, when officials lugged pens of them into the park and set them free.

William Ripple, an ecologist at Oregon State University, and his colleagues investigated how the return of wolves affected grizzly bears in Yellowstone. They compared data from old studies of bear scat to data collected after the wolves came back. Specifically, they wanted to know how many berries bears had been eating.

What do wolves have to do with berries? Nothing. But wolves kill elk—and elk eat all kinds of plants, including berry shrubs that bears would otherwise dine on.

For a few decades after wolves were wiped out of Yellowstone, the booming elk population was culled to keep it under control. But the elk culling ended in the 1960s. Ripple found that in the late 1960s, while the elk population was still low, bears had a relatively high percentage of fruit in their dung. Over the next 20 years, as the elk population more than tripled, the grizzlies' berry diet dropped to almost nothing. And in the late 2000s, after wolves had reestablished themselves in the park and elk numbers had dropped, a hearty helping of berries returned to bear diets.

The researchers also looked at berries themselves, choosing a representative plant called serviceberry. They saw that plants in fenced-off areas (where elk and other grazers can't reach them) had been growing for decades. Outside the fences, though, the berry plants were young—they had all sprung up after wolf reintroduction. The evidence all pointed the same way: more wolves means fewer elk, which means more berries, which means better-fed bears.

Berries are good for a grizzly's diet, the authors explain, because bears use them to fatten up before entering hibernation. Female bears will give birth during their winter doze, so having enough energy stored is crucial to the population's survival.

Ripple says there's not yet any evidence that having more berries in their diets is actually helping bears—his study didn't ask that question. But he is optimistic about the future of grizzlies in Yellowstone. "It is good to see that the bears can at times get significant calories from...the berries," he says. Berries made up as much as 39% of female grizzlies' diets in recent years.

Other studies have shown that beaver and bison numbers both increased after wolves came back to the park. This might be, the authors write, because herbivores have less competition now from the once-ubiquitous elk. All the species that were knocked down while the wolves were gone can now stand back up and give them a thank-you.

Images: Grizzly bear and wolf at Yellowstone from YellowstoneNPS (via Flickr); diagram from Ripple et al.; bear hug card from OldEnglishCo on Etsy (available for $4.71!).

William J. Ripple, Robert L. Beschta, Jennifer K. Fortin, & Charles T. Robbins (2013). Trophic cascades from wolves to grizzly bears in Yellowstone Journal of Animal Ecology DOI: 10.1111/1365-2656.12123

Rats Sniff to Communicate, Not Just to Smell

There's more to a pair of rat noses than meets the eye. Like tiny, leashless dogs, rats like to sniff each other all over when they meet. Yet not all of this sniffing is aimed at gathering scents. Some of it seems to transmit messages such as "I'm in charge" or "Be cool" or "Please don't bite my face."

Rats and other animals give off odors from the "face, flanks, and anogenital region," says neuroscientist Daniel Wesson of Case Western Reserve University. So it's not surprising that these regions are where rats aim their sniffers when they cross paths. To find out whether there might be more going on, though, Wesson outfitted rats with head-mounted devices that measured the speed of their sniffs. Then, after recording videos of these rats encountering each other, he looked at how sniff frequency lined up with different stages of the rodents' interaction.

He saw that all rats sped up their sniffing when their noses were pointed at each other's flanks or rear ends. But when the rats were sniffing each other's faces, their behavior depended on whether they were socially dominant or subordinate. Higher-ranking rats sped up their sniffing as usual. Lower-ranking rats slowed down their own sniffing in response.

This seemed to be an "appeasement signal," akin to climbing into one's own locker when the school bully approaches. Wesson found that when subordinate rats didn't give this signal—when they kept up their sniffing at the usual rate—dominant rats were quicker to pick a fight.

To further test this idea, Wesson treated the insides of the rats' noses with zinc sulfate, making them temporarily lose their sense of smell. Even though they weren't gathering any odors, rats kept on sniffing. And when they were face-to-face, they acted the same as always: dominant rats sniffed faster, while subordinate ones slowed down to avoid trouble. "This sniffing behavior was interestingly resilient," Wesson says.

Sniffing seems to be a form of communication for rats—but only sniffing in the face, not other body parts. Wesson says this may be because face sniffing is an especially vulnerable position for a rat or other animal to be in. When their eyeballs and whiskers and biting parts are all in close proximity, maybe it's a good time for rats to make clear that they don't want a fight.

Alternately, face-to-face might be the only way a rat can detect another rat's sniffing; maybe the signal wouldn't get through if it were aimed at the tail end. "These are different theories we are testing now," Wesson says. There may also be ultrasonic squeaks or other signals invisible to humans that contribute to the conversation between two rats.

If rats use sniffing for communication, and not only for gathering smells, do other social sniffers do the same thing? "I would predict so," Wesson says. "Other rodents likely use this behavior, as could possibly cats and dogs." He points out that neighborhood dogs who meet on a walk will sniff each other, then either part peacefully or start fighting. Some signal in their sniffing behavior may make the difference, though this idea would have to be tested.

That's not to say dogs or rats aren't also gathering actual smells when they sniff. It would be "frankly silly" to discount the importance of smell in an animal's life, Wesson says. It seems there's much more going on, though, when an animal sticks its nose into the world.


Wesson, D. (2013). Sniffing Behavior Communicates Social Hierarchy Current Biology DOI: 10.1016/j.cub.2013.02.012

Image: Daniel Wesson.

From Mastiff to Miniature Poodle, Dogs Know Each Other by Sight

Anyone who's walked a dog and seen it spring to attention when another dogs rounds a corner—even though that animal is still a full block away—may have wondered how exactly dogs recognize each other. What makes a golden retriever perk up its ears and wag its tail at an approaching greyhound but not, say, a stroller? Why does it ever occur to a dachshund to play with a pit bull in the park? Why don't average-sized dogs chase toy breeds away as if they were squirrels?

You might assume dogs, with their powerful noses, are getting an advantage from scent. Perhaps dog breeds all smell the same, despite looking wildly different. A new study, though, shows that dogs can find each other by sight alone. Dogs are able to spot another dog, no matter the breed, from among a crowd of other animals. Scientists don't know how they do it.

Since other animals such as sheep, macaques, and cows have shown in the lab that they can recognize their peers by sight, scientists in France asked whether dogs could do this when challenged with a full complement of breeds. To understand the magnitude of the problem a dog faces, consider that there are 400 to 500 registered dog breeds. Dogs are more diverse than any other animal species on Earth. Furthermore, their vision isn't that great. If Fido wants to find a mate, though, he'd better know the difference between a Pomeranian and a fluffy cat.

Bertrand Deputte of the National Veterinary School at Alfort, France, and his coauthors recruited nine dogs for their study. All the dogs were pets owned by veterinary students. They were a mix of male and female, and mostly mixed-breeds.

In each stage of the experiment, a dog sat facing two screens on tables while a human stood behind it. (The human experimenter, to make absolutely sure he didn't give any hints, stood motionless and wore dark glasses.) On the experimenter's command, the dog walked forward and chose one of the two screens by placing its paw on a table.

Choosing the correct picture got the dog a food reward. But what was "correct" shifted over the course of the experiment, as the researchers took the dogs through a series of challenges.

In early sessions, dogs won a treat if they chose a screen showing a dog's face over an empty screen. They they had to choose a dog's face over a cow's face, where the dog and cow were the same every time but kept swapping screens. Then the dogs had to generalize: the screens showed dog and cow faces the subjects hadn't seen before, and they had to choose the dog. 

At last came the main challenge: dogs versus everything else. One screen showed a dog's face (a different dog every time) and the other showed some non-dog species (cow, cat, rabbit, human, bird, and so on). Every picture was zoomed in on the animal's head, so that the canine subjects couldn't get any clues from body size or shape—not to mention movement, sound, or smell. Some faces were shown straight on; others were in profile or three-quarters view. Nevertheless, every dog in the experiment succeeded.

"We were rather surprised by the ease dogs had," Deputte says, "in spite of huge variability of dog breeds and the variety of animal and humans faces that constituted the other category." All nine dogs, once they'd learned what the human experimenter wanted, could consistently pick out the dog faces on the screens.

To prove the dogs really knew their stuff, researchers also reversed the task and had dogs pick out the picture that wasn't a dog. They aced this test too.

"We couldn't tell how the dogs succeeded" at grouping dog faces from various breeds and different angles all into one category, Deputte says. He believes his results show that dogs have a "concept of dog." Somehow, our pets know immediately whether the animal walking toward them is dog or not-dog. Along with knowing when to sniff the approaching animal's rear end, this may be a power we hopeless humans will never understand.


Autier-Dérian D, Deputte BL, Chalvet-Monfray K, Coulon M, & Mounier L (2013). Visual discrimination of species in dogs (Canis familiaris). Animal cognition PMID: 23404258

Images: George Thomas (Flickr); Dominique Autier-Dérian/Animal Cognition

UPDATE: Bertrand Deputte has clarified that his coauthor Dominique Autier-Dérian did the experimental work for this study.

Hyenas Show It's Better to Be Creative than Try, Try Again

It's not a sentiment you'll see on an inspirational poster anytime soon: When facing a problem, sheer persistence is not enough. At least, not if you're a hyena. Presented with a latched box holding a hunk of meat, wild hyenas tried hard to extract the food. Their success depended on their fearlessness and the number of different strategies they tried, but not on hard work.

Spotted hyenas (Crocuta crocuta) are hardy and adaptable animals. They're resourceful hunters, taking down prey alone or in groups, and they navigate complex social situations among their clans. They're the most common large carnivore in sub-Saharan Africa. To study the animals' problem-solving skills, Michigan State University graduate student Sarah Benson-Amram challenged a wild population of spotted hyenas with a meat-filled puzzle.

For a year, Benson-Amram drove through Kenya's Masai Mara National Reserve administering pop quizzes to hyenas. Whenever she spotted a subject, she stopped the car and deposited  a box made of steel bars on the ground. Then she pulled away, parked, and watched what happened. Hyenas that approached the box could see (and smell) a tantalizing, two-kilogram piece of raw meat inside. The box had handles on the sides that let hyenas drag it or flip it over. But the key was to find a bolt that slid sideways, releasing a swinging door and letting the hyena at the prize. 

Sixty-two hyenas participated ("volunteered" would be overstating it) in the study. The individuals could be told apart by their spot patterns and other distinctive features. Some only took the test once, while others that crossed Benson-Amram's path more often ended up becoming repeat subjects.

Hyenas were scored on how long they waited to approach the box, how long they spent trying to open it, and how many different behaviors they tried—including investigating, biting, digging, flipping the box over, and pushing or pulling it. They were also scored, of course, on whether they ever got the darn thing open.

The hyenas didn't fare very well. Only 9 individuals, a little under 15 percent of the total, ever succeeded in getting the meat. (Was the task too difficult? "We have an adult female hyena in our study area that can open refrigerators," Benson-Amram says, so she knew at least some hyenas could manage simple doors and latches. "But it turned out this was not a skill that most of them have.")

The hyenas that aced the test weren't more likely to be young or old, female or male, or of a certain social status. But they did differ from flunking hyenas in factors that might be called personality traits.

According to a paper published last week in Proceedings of the Royal Society B, two traits helped hyenas solve the puzzle. The first was not being afraid of new things. Benson-Amram scored the animals' "neophobia" based on how long they spent near the box before they touched it. Hyenas that were more fearful were less likely to get the box open in the end.

The second factor that helped them open the box was how many different behaviors they tried. Hyenas that had more ideas about approaching the puzzle—biting the latch, turning the box over, pushing it with their paws—were more likely to find the solution.

Persistence didn't hurt. Animals that gave up quickly didn't succeed. But animals that spent more time working on the box didn't do significantly better. Even though hyenas that failed the test spent an average of almost four and a half minutes trying to open the box the first time they saw it, if they didn't have enough ideas about approaching the puzzle, they wouldn't get the meat.

Benson-Amram says that in the field of animal behavior, "personality" describes how an animal behaves across a range of situations. Since she only tested hyenas in one situation, she can't speak to their personalities in general. Still, boldness and creativity clearly helped hyenas open the puzzle box. "On this task, that personality trait was helpful," Benson-Amram says.

Innovative thinking and fearlessness, the keys to solving the puzzle, showed up more often in young hyenas. Juveniles didn't outdo adults in getting the meat out of the box, maybe because the heavy puzzle was harder for them to maneuver. But in different circumstances, younger hyenas might have been the best problem solvers.

"Hyenas constantly have to innovate solutions to new problems in order to deal with the highly varied challenges in their environment," Benson-Amram says. "They take down zebras that could kill them with a strong kick and they compete with lions for resources." Trying a variety of approaches when they face a new challenge might help hyenas survive, just as it helped some of them pass her test.

The same tactic might help humans find solutions too. In studies of human infants, Benson-Amram notes, researchers have found that babies who use a wider range of behaviors when facing a new problem are more likely to solve  it. Creative thinking might be the trait that lets humans adapt to our own landscape and confront the problems that, like the steel box, appear inexplicably in our paths.


Benson-Amram S, & Holekamp KE (2012). Innovative problem solving by wild spotted hyenas. Proceedings. Biological sciences / The Royal Society PMID: 22874748

Image: Still frame from a video of a hyena opening the puzzle box, from Sarah Benson-Amram and Kay E. Holekamp.

New OCD Symptom: Tail Chasing

The comments on online forums are sometimes resigned, sometimes plaintive. One four-year-old "has always has some OCD issues," reports Brookey77, "especially when it comes to tennis balls. When he was a pup, he sucked on them as a baby would suck on a pacifier...Then he started eating them...For the last few months, he has been eating his leg."

An 8-month-old pitt bull is "a shadow chaser," says ultimatek9. "She is fine at night and when it is overcast, but when the sun comes out she goes into a trance. She locks onto the shadows and will start salivating and trembling."

Dogs with compulsion may pace, chase imaginary flies, or lick their flanks until they get sores, despite their owners' best efforts to make them stop. Certain breeds are especially vulnerable. A staple of canine compulsion is tail chasing, which frequently strikes bull terriers and German shepherds. On one forum, user MatrixsDad complains that his German shepherd "is constantly chasing and barking at her tail...She comes up and puts her backside against anyone who's standing around so she can get a better view of her tail before she starts chasing it."

Although they may seem like nothing more than cute YouTube material, dog compulsions can turn unfunny fast. A user called Fodder describes a cocker spaniel that used to chase and bite his tail whenever stressed. "Finally the day came—we pulled into the garage where he had been staying and he was cowering on the steps...as I got closer I realized that he was sitting in a puddle of his own blood. He had chewed his tail completely off."

Because of the apparent similarities between human OCD and dog compulsions, researchers led by Katriina Tiira at the University of Helsinki decided to investigate just how close the connection is. They gave detailed questionnaires to the owners of 368 German shepherds, bull terriers (standard and miniature), and Staffordshire bull terriers. Among their subjects, 218 were tail chasers.

The first clear similarity between tail chasing and human OCD is that they have a genetic component. In humans, OCD is estimated to affect 1 to 3 percent of the population in general. But the twin of a lifetime OCD sufferer has at least a 25 percent chance of OCD himself. Likewise, the fact that certain breeds of dogs chase their tails more suggests that somewhere in the breeding process, that tendency was embedded in their DNA.

The questionnaires turned up many similarities between obsessive dogs and humans. One was the early onset of the behavior: Human OCD often shows up in childhood or adolescence; tail chasing began for the greatest number of dogs in the study between 3 and 6 months old. Some dogs only tail chased occasionally, while others couldn't get enough and repeated the behavior several times a day. And some dogs also seemed to freeze or go into a trance, a symptom similar to one in human OCD patients called "obsessional slowness."

Certain factors appear to make dogs more or less likely to be tail chasers. Owners reported that tail-chasing dogs had been separated from their mothers earlier as puppies. Dogs that live with a lot of other dogs, though, don't chase their tails as often.

Dogs given vitamin and mineral supplements by their owners were less likely to tail chase, and so were females that had been neutered. This might mean that the presence of certain vitamins, or absence of certain hormones, makes tail chasing less likely. However, the authors acknowledge, it could also mean that owners who neuter their dogs or give them supplements are treating the dogs in some other way that lowers their risk of obsessive behaviors.

A subset of the dog owners in the study also filled out a questionnaire on the "personality" of their pets. Tail chasers were shyer and likely to have additional compulsions. Senior author Hannes Lohi says this resembles anxieties and behavioral inhibitions in human OCD sufferers.

"Our major aim is to identify new anxiety genes" in dogs, Lohi says. Those genes could teach us about how these conditions develop in dogs as well as in humans, who share the same environment and aren't that far off physiologically. We might even learn about new treatment avenues in humans. An earlier study found a genetic region that's linked to a flank-sucking obsession in Dobermanns—and the same region has been tied to human OCD and autism. But the new study found no connection between that genetic area and tail chasing.

It's likely, the authors write, that obsessive behaviors in dogs have many different origins and manifestations. The same seems to be true of humans. Hunting down the roots of these behaviors in our canine companions, then, might help us cure our own kinds of tail chasing.




Tiira K, Hakosalo O, Kareinen L, Thomas A, Hielm-Björkman A, Escriou C, Arnold P, & Lohi H (2012). Environmental effects on compulsive tail chasing in dogs. PloS one, 7 (7) PMID: 22844513


Image: Tim Mowrer/Flickr

Accounting for Taste: Why a Bear, but Not a Seal, Will Steal Your Cupcake

Humans aren't the only mammals with a sweet tooth. Omnivores from beagles to grizzlies can detect a wide range of flavors and enjoy the taste of sugar. But other mammals with narrow carnivorous diets have been subjected to evolution's "use it or lose it" decree. These meat-eaters are genetic mutants without working taste receptors for sweets. Not only do they not want your cupcake, but they can't even taste it.

Researchers led by Peihua Jiang at Monell Chemical Senses Center in Philadelphia wanted to know how often evolution has removed tastes from animals' repertoires. Omnivores such as humans can detect five basic tastes: sweet, sour, bitter, salty, and umami (a meaty flavor). Previous studies had shown that cats, though, are indifferent to sweetness. Cats were also known to have a mutation in the gene for the sweet taste receptor, rendering it nonfunctional. Had other carnivores' sweet receptors met the same fate?

For 12 carnivore species, the authors sequenced the genome section containing the sweet taste receptor. In just 5 of these species, the gene was intact. These included the aardwolf, Canadian otter, spectacled bear, raccoon, and red wolf.

It was presumably not practical to round up all these animals and give them tests to confirm that they like sugar. But the authors were able to test four spectacled bears, a charismatic South American species. When given a choice between a bowl of plain water and a bowl of sugar water, the bears strongly preferred the sugar water. They even enjoyed some artificial sweeteners (Splenda, for instance, but not NutraSweet).

Spectacled bear: Yes cupcakes.

The other 7 carnivore species in the study had mutations in their sweet taste receptors. These animals came from widely separated branches of the mammal family tree: sea lion and seals; Asian small-clawed otter; hyena; fossa (a cat-like creature from Madagascar); and banded linsang (a secretive jungle creature from Southeast Asia).

Though, again, the authors didn't recruit any hyenas or jungle cats for their study, they did bring in two Asian small-clawed otters for testing. The otters were given the same bowls of sweetened and unsweetened water that the bears tasted. But the otters were totally indifferent to sugar water.

Asian small-clawed otter: No cupcakes.

An aardwolf, since you asked: Yes cupcakes, yes termites.

Finally, the researchers looked at the dolphin genome, which had been previously published. Not only was the dolphin's sweet taste receptor mutated, but so was the receptor for umami flavor. There seemed to be no intact gene for a bitterness receptor, either.

It seems incredible that an animal could be so deficient in tasting. But previous studies have suggested that dolphins can't taste sugar and have a reduced ability to taste bitterness. A close look at their tongues reveals only a few taste bud-like structures. The same is true of the sea lion: It has barely any taste buds, and has a mutated gene for the umami receptor as well as sweet.

They wouldn't have much chance to taste their food even if they did have taste buds, though, because neither sea lions nor dolphins chew their prey. They both gulp down fish whole.

Dolphin: No cupcakes, no chewing.

Despite these similarities, sea lions and dolphins lost their taste separately. Their lineages took to the sea separately and 15 million years apart. Their genetic mutations, too, are different.

In fact, out of all the genetic anomalies the researchers found in carnivores' sweet taste receptors, no two mutations were the same. This means that again and again, evolution has removed the ability to taste sugar from carnivores. There must be some cost, then, to keeping unnecessary taste receptors. When animals evolve to consume an all-meat diet, it's better for them to prune their unnecessary tastes. And when they evolve to swallow their food whole, it seems there's not much need to taste anything.

Even within close families of mammals, evolution has tweaked individual species' taste receptors as they evolved different diets. Black bears love raisins but also enjoy insects and fish; panda bears, which only eat bamboo, can't taste umami. Though many bats feed on fruit, the vampire bat only eats blood and can't taste sugar.

Taste receptors aren't purely for enjoyment, though. A bitter or sour taste can be our clue that a food is spoiled or toxic. So it's surprising that even the bitter taste receptor, which evolved for our protection, can apparently be thrown away. 

Maybe when animals have a strictly specialized diet (of fish, or bamboo, or blood) they can rely on their eyes and other senses to ensure they're eating the right thing. But we omnivores have to decide on our diets by taste. It means we must think harder about what we're eating--but it also means we can enjoy every flavor of cupcake.

Jiang, P., Josue, J., Li, X., Glaser, D., Li, W., Brand, J., Margolskee, R., Reed, D., & Beauchamp, G. (2012). Major taste loss in carnivorous mammals Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1118360109

Images: bear Cburnett/Wikimedia Commons; otter Patrick Gijsbers/Wikimedia Commons; aardwolf Dominik Käuferle/Wikimedia Commons; dolphin Just Taken Pics/Flickr.

Note: This post was originally titled "Accounting for Taste: Why a Bear, but Not an Otter, Will Steal Your Cupcake." But my attentive husband pointed out that there was a type of otter in the sugar-tasting group, as well as the sugar-ignoring one. I should admit now that I actually don't know whether any of these animals steals pastries.

Dogs Understand Us Better than Our Closest Relatives

Does your dog understand you when you point at something? If so, this may be one of the few pop intelligence quizzes on which it can outscore a chimpanzee.

Previous studies had shown that dogs can pass a test in which a human points to a container and the dog must look inside it to find food. Human one-year-olds can pass this kind of test too. But chimpanzees have a hard time with it. Researchers at the Max Planck Institute for Evolutionary Anthropology in Germany wondered if these previous tests were unfair to chimpanzees. Would changing the setup of the experiment prove that chimps really do understand our gesturing?

In previous versions of the experiment, chimpanzees had been seated behind a barrier, while dogs were in the same room as the humans. Additionally, the objects that the animals were asked to choose between usually sat between the human experimenter and the chimpanzee--so the human didn't actually need the chimps' help to lift a container and get the food underneath. Perhaps the chimpanzees understood just fine when the human experimenter pointed to a cup, but thought, "Get it yourself, big-brain."

So the German researchers leveled the playing field between the two non-human species. They added a barrier between human and dog to make their setup more like the chimps'. They put the objects they were pointing to on the far side of their animal subjects, so the humans really couldn't reach the objects themselves. They also replaced containers and hidden food with boring, inedible objects, such as a rope or a sponge. Then they gathered 32 dogs and 20 chimps. ("For practical reasons," the authors write, "the studies of the chimpanzees and the dogs were conducted separately.")

First came a warm-up phase in which the experimenter encouraged the animal to fetch a single object (in exchange for a treat) by saying "Give it to me!" This taught the animals to associate the voice command with retrieving an object. But the experimenter didn't point or look at the object she wanted.

For the experiment itself, there were two objects in the room instead of one. The experimenter pointed to the one she wanted and repeated the "Give it to me!" command, moving her eyes between the animal and the desired object to make her point clearer. The dog or chimp had to turn around, retrieve the correct object, and bring it back to the experimenter to get a treat.

The chimpanzees flunked the test. While they consistently picked up one of the two objects and brought it back to the researcher, they only picked the correct object half the time. But the dogs, as a group, performed significantly better than if they were guessing. (And they did even better when the barrier between them and the human experimenter was removed.)

It's not that chimpanzees don't follow other animals' gazes. Previous studies found that great apes will look where a human is looking to check for anything of interest. But they don't seem to understand that gaze as a form of communication. And pointing with a finger--which is really just an exaggerated way to show where you're looking--doesn't help them.

Dogs, on the other hand, have evolved to be highly attuned to what humans want. As long as they pee outside and perform the duties we assign them (sheep herding, duck retrieving, company keeping) we give them food and warm place to stay.

Of course, dogs' understanding of human gestures will depend somewhat on their personal experiences with their owners. In this study, many of the individual dogs did not perform any better than chance. But earlier studies have shown that young puppies can understand human finger-pointing, while young wolves don't understand it as well.

The fact that chimps don't understand pointing as a form of communication suggests this isn't a universal ape gesture. They can follow a gaze and understand that other individuals have different perspectives; and the captive chimps in this study should have been especially used to communicating with people. But, fittingly enough, the gesture that says "go and fetch that thing for me" seems to be specifically human.


Kirchhofer, K., Zimmermann, F., Kaminski, J., & Tomasello, M. (2012). Dogs (Canis familiaris), but Not Chimpanzees (Pan troglodytes), Understand Imperative Pointing PLoS ONE, 7 (2) DOI: 10.1371/journal.pone.0030913


Photo: by me.

If You Give an Opossum a Mozzarella Stick

When the bus driver pulled away and I was left standing with a dozen near-strangers in the lobby of Durham's Museum of Life and Science, I admit I felt some doubt.

It was the second day of Science Online 2012, a conference-meets-mothership for bloggers, researchers, and other science communicators. We'd been promised a tour, but that promise had come electronically from yet another person I didn't know. I began to wonder how much time we could kill in the gift shop if needed, and where exactly in North Carolina I was. Then Keeper Mikey appeared, wearing a baseball cap and a big grin, and told us we were going to see some bears today.

I learned several things that afternoon. Outside, on the trail, we ran into three boys who ranged from knee-height to thigh-height. I asked them if they'd seen any animals they liked. "I saw a snake!" the biggest brother said. "But it would be cool if there was a tiger." In the spirit of the museum's tinier visitors, I'm going to present our adventures in modified children's book titles.

Make Way for Alligators

The first thing Mike did after leading us into a staff-only hallway was disappear behind another door. "You stay put," he called behind him, "It's venomous down here!" Without leaving us much time to wonder what that meant, Mike reappeared holding Phoebe.

I learned from Phoebe that baby alligators are pretty irresistible. Mike wanted us to take turns petting Phoebe on her back, but we convinced him to let us hold the alligator ourselves. "Just promise you won't yell at me if she gets nippy," he said. Phoebe was a good sport, looking around and blinking with her upside-down eyelids while a succession of humans held her around the belly. (Later, on the bus, one woman confessed that she thought Phoebe felt like a purse. "Technically," someone else countered, "a purse feels like Phoebe.")

I had also never figured alligators for intelligent animals. But Mike told stories of his work at other alligator facilities, where the animals knew their names and would come when called. He said he could yell out the name of an alligator, see its wake approaching him in the water, and pass it a meatball on a stick when it stopped near the shore. Summoning alligators isn't a talent I'd be quite so excited about.

If You Give an Opossum a Mozzarella Stick

Most of the animals at the museum are rescues, used for education because they're too tame or injured to go back to the wild. While juggling an extraordinarily squirmy opossum, Mike let us in on a secret: Opossums go nuts for mozzarella sticks. In fact, he seemed to know the favorite food of every animal under his care. Lemurs love Craisins. Black bears don't care too much for raw sweet potato, but they love it after it's been cooked with a little vanilla. Doesn't sound too bad to me, either.


Everybody Bites

No matter how cuddly the animals look, sometimes they want to chew on your fingers. Mike gave this potbellied pig a stern "No nipping!" command as it stood on its hind legs to greet us. Potbellied pigs are highly intelligent ("Smarter than your dog!") and often kept as pets.

This pig's companion was named, Mike told us regretfully, Miss Piggy. Any animals that arrives at the museum with a name gets to keep it--no matter how much that name pains the staff. The center receives plenty of cast-off pet reptiles, for example: "People say, 'Oh, this is my iguana, his name's Iggy,'" Mike said. "Of course it is." We met a lizard named Godzilla, a donkey named Lightning, and a gecko named Gordon.

Go, Wolf, Go!

I'd never seen a red wolf before, and that's probably because there are only a few hundred of them alive in the world. The two at the Museum of Science and Nature belong to the government--they have numbers, not names.

Mike told us they're hoping for cubs this year, but so far the male and female wolf haven't hit it off. He described watching video footage of the wolves one night: The male lay down a safe distance from where the female was sleeping and closed his eyes. Later in the night, he opened his eyes, crept a little closer to the female, and slept again. He kept sneaking closer to her throughout the night until she finally woke up and growled, sending the male slinking away.

Since the red wolf population at one time dipped to only a handful of breeding individuals, today's population isn't healthy by genetic standards. When a whole population is closely related, there aren't likely to be individuals with genetic mutations that give them different strengths. This means a virus or a shift in climate could wipe out the whole population in one go.

One member of our tour suggested solving this problem by irradiating the animals before releasing them in the wild. "I'm joking, by the way," she added for the benefit of everyone live-tweeting.


Where the Wild Nerds Are
We'd been on our tour for at least an hour when two members of the group suddenly burst out with, "Oh! It's so nice to meet you!" and shook each other's hands. Mike looked totally baffled. I told him that plenty of people at the conference knew each other by their Twitter handles but hadn't met face-to-face before. He looked only slightly less baffled.


One Lemur, Two Lemur, Red Lemur, Ringtail

While Mike went into the ring-tailed lemur enclosure and fed them Craisins, we called down to him with questions: What's their social structure like? (Matriarchal.) Why do they carry their tails up in the air when they walk? (To signal to each other in tall grass.) What are those collars for? (They're radio collars so the lemurs can be tracked through the woods if they escape.)

"Are they soft?" someone yelled down.

Mikey looked up at us and nodded, grinning.




Cloudy with a Chance of Bears

It began to sprinkle while we headed out to see the animals we'd all been waiting for: the black bears. When we arrived, two were huddled in a cave and the other two were high on a cliff, hidden except for their faces. Mike led us into a shed and through a series of padlocked metal gates. The last gate, which he kept closed, looked directly onto the enclosure. "You stay here," Mike said. "I'm going to go on the roof and throw raisins."

He disappeared, and a few moments later the bears began to trot toward us. A bear that had been on the cliff shimmied backward down an incline, checking behind her, like a toddler descending stairs. Curious to see who was visiting, another bear came right up to the fence we were behind and stood up against it. Cameras flashed. We gaped at the bear's big paw pads, looked it in the eyes. Mike returned and called us around to a fenced-in area at the side of the shed.

The bears have been taught various commands; they stood up, sat down, and followed Mike back and forth (their round teddy-bear bodies bouncing) in exchange for spoonfuls of raisins. This is so that, if the bears need a physical exam or to have blood drawn, a veterinarian will be able to interact with them easily. We witnessed the bears' different personalities: Virginia licked up raisins delicately, while Gus tried to gobble the whole plastic spoon. If Mikey ignored them for too long, they snuffled up behind him to get attention.

We were sorry to leave the bears and the center's other inhabitants, including Keeper Mike, the friendliest animal of all. Virginia was nice enough to pose for a picture with us before we left. 

Meanwhile, Gus turned away and scratched his rear end at length on the corner of the shed. He wasn't feeling quite as sentimental.

Photos by me, except for the final photo provided by @CogSciLibrarian. You can find more photos (better than mine) at this Storify. Thanks to Mikey Romano for a terrific afternoon!

Are You Yawning Because Your Brain's Hot?

Everyone knows yawning is the pinkeye of social cues: powerfully contagious and not that attractive. Yet scientists aren't sure what the point of it is. Is yawning a form of communication that evolved to send some message to our companions? Or is the basis of yawning physiological, and its social contagiousness unrelated? A new paper suggests that yawning--even when triggered by seeing another person yawn--is meant to cool down overheated brains.

We're not the only species that feels compelled to yawn when we see others doing it. Other primates, and possibly dogs, have been observed catching a case of the yawns. But Princeton researcher Andrew Gallup thinks the root cause of yawning is in the body, not the mind. After all, we yawn when we're alone, not just when we're with other people.

Previously, Gallup worked on a study that involved sticking tiny thermometers into the brains of rats and waiting for them to yawn. The researchers observed that yawning and stretching came after a rapid temperature rise in the frontal cortex. After the yawn and the stretch, rats' brain temperatures dropped back to normal. The authors speculated that yawning cools the blood off (by taking in a large amount of air from outside the body) and increases blood flow, thereby bringing cooler blood to the brain.

If yawning's function is to cool the brain, Gallup reasoned, then people should yawn less often when they're in a hot environment. If the air outside you is the same temperature as your body, it won't make you less hot.

To test that theory, researchers went out into the field--namely, the sidewalks of Tuscon, Arizona--in both the winter and the summer. They recruited subjects walking down the street (80 people in each season) and asked them to look at pictures of people yawning. Then the subjects answered questions about whether they yawned while looking at the pictures, how much sleep they'd gotten the night before, and how long they'd been outside.

The researchers found that the main variable affecting whether people yawned was the season. It's worth noting that "winter" in Tuscon was a balmy 22 degrees Celsius (71 degrees Fahrenheit), while summer was right around body temperature. In the summer, 24% of subjects reported yawning while they looked at the pictures. In the winter, that number went up to 45%.

Additionally, the longer people had been outside in the summer heat, the less likely they were to yawn. But in the winter, the opposite was true: People were more likely to yawn after spending more time outside. Gallup speculates that because the testing took place in direct sunlight, subjects' bodies were heating up, even though the air around them remained cooler. So a yawn became more refreshing to the brain the longer subjects stood outside in the winter, but only got less refreshing as they sweltered in the summer.

The study used contagious yawning rather than spontaneous yawning, presumably because it's easier to hand subjects pictures of yawning people than to aggressively bore them. Gallup notes that contagious and spontaneous yawning are physically identical ("a stretching of the jaw and a deep inhalation of air," if you were wondering), so one can stand in for the other. Still, it would be informative to study people in a more controlled setting--in a lab rather than on the street, and preferably not aware that they're part of a yawning study.

A lab experiment would also allow researchers to directly observe whether their subjects yawned, rather than just asking them. In the field, researchers walked away while subjects were looking at the pictures, since people who know they're being watched are less likely to yawn. But self-reported results might not be accurate. The paper points out that "four participants in the winter condition did not report yawning during the experiment but yawned while handing in the survey to the experimenter."

Still, it seems there's real connection between brain temperature and yawning. It will take more research (and more helplessly yawning subjects) to elucidate exactly what the connection is. Even if brain temperatures always rise right before a yawn and fall afterward, cooling the brain might not be the point of the yawn--another factor could be causing the impulse to yawn, and the temperature changes could be a side effect. Studying subjects in a truly cold environment, and showing that they are once again less likely to yawn (because outside air would cool their brains too much), would provide another piece of evidence that temperature triggers the yawn in the first place.

None of this tells us why yawning is so catching, though. Personally, I think I yawned at least a thousand times while reading and writing about this paper. Maybe I should have taken some advice from an older study by Andrew Gallup, which found that you can inhibit yawning by breathing through your nose or putting something chilly on your forehead.

Photo: Wikipedia/National Media Museum

Andrew C. Gallup, & Omar Tonsi Eldakar (2011). Contagious yawning and seasonal climate variation. Frontiers in Evolutionary Neuroscience

Is the Aging Brain Uniquely Human?

Even if you stay free of Alzheimer's disease, the normal aging process is fairly destructive to your brain. Neurons disappear, connections lose their strength, protein gunk builds up, and the whole brain shrinks. Areas controlling learning and memory are among the hardest hit. A new study claims that our crumbling brains aren't just a fact of normal aging. Instead, they may be unique in the animal kingdom, the result of an evolutionary bargain our species has struck.

Chet Sherwood at George Washington University led the study, which put humans and captive chimpanzees of various ages through MRI scanners. The humans ranged from ages 22 to 88. Chimps were between 10 and 45 years old, because 45 years is about as long as chimps can live in the wild (more on that in a moment).

In humans, the researchers found a pattern of decreasing brain volume throughout life that accelerated into old age. That pattern was missing in chimpanzees, whose brains seemed to maintain a consistent size.

Chimpanzees were used because they're our closest living relatives; we've been apart for only about 6 million years of evolution. The authors reason that because chimps' brains don't shrink as they age, our own brain degeneration must be a product of our recent evolution. We've developed brains that are big and energy-hungry, and to judge from our global population size, throwing our resources into our noggins seems to have been a good evolutionary strategy.

Since splitting from our ape relatives, we've also evolved longer life spans. Women, in particular, are a curiosity because they can live decades past their fertile years. Evolutionary biologists have hypothesized that keeping infertile elderly women around is no accident, because these grandmothers can bolster the success of their own genes by helping to take care of their grandchildren. The authors of the chimp study suggest that these helpful grandmothers are to blame for our degenerating brains: we've evolved long lifespans and brains that can't quite keep up.

The grandmother hypothesis, though, is hard to prove. And though 45 is elderly for a chimpanzee in the wild, the authors acknowledge that chimps under medical care in captivity can live into their 60s. Is a human today who lives into her 80s, thanks to medical care and disease prevention, comparable to a chimp in the wild? Or is a human "in the wild" better represented by someone in a southern African country with a life expectancy in the 30s or 40s?

If this study included chimpanzees at the true upper end of their age potential, it might provide more insight. The authors acknowledge that some previous studies have shown different results; for example, a study of brain mass that included chimpanzees up to age 59 did find some shrinkage with age.

The authors assume our damaging brain decline is a byproduct of evolution, but don't ask whether it might come from extending our life spans even further than evolution intended. Some perspective might come from studying another animal that no longer lives "in the wild": domestic dogs. Wolves live six to eight years in the wild, but many kinds of pet dogs can live for twice that long.

Even though they're not close to us in evolutionary terms, dogs age much like humans do. Their brains shrink in old age, especially in the prefrontal cortex and the hippocampus--the same areas that are particularly vulnerable in humans. Dogs develop cognitive problems and behavioral changes. Their brains even accumulate deposits of amyloid-beta, the protein gunk that appears in humans and is linked to Alzheimer's disease. Maybe our aging brains are not only the result of our exceptional smarts, then, but also of our domestication.


Sherwood, C., Gordon, A., Allen, J., Phillips, K., Erwin, J., Hof, P., & Hopkins, W. (2011). Aging of the cerebral cortex differs between humans and chimpanzees Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1016709108

Is Bo Obama a Fraud?

A hypoallergenic dog, we're told, is one that politely keeps its dander to itself and makes the air safer for allergy sufferers to breathe. Yet a new study claims to have debunked the whole notion of the allergy-friendly dog. Is this fair?

Researchers from the Henry Ford Health System in Detroit studied a group of 173 homes that had both a baby and exactly one dog. After surveying each dog's owners about its breed, size, and how much time the dog spent indoors, the researchers collected a sample of dust from the floor of the baby's bedroom. They then measured the amount of dog allergen in each sample (the main allergy-causing ingredient in dog dander is a molecule called Can f 1).

The families' dogs came from 60 different breeds. Researchers divided these dogs into hypoallergenic and non-hypoallergenic groups and looked for a difference in the amount of allergen the dogs left on their floors. Since "hypoallergenic" is not a label that's been defined scientifically--the problem that drove this study in the first place--the researchers tried several different methods to group the dogs. In their looser groupings, they put any dog that turned up in an internet search for allergy-free animals into the hypoallergenic category. They tried including, or not including, mutts with one supposedly hypoallergenic parent. In the strictest grouping, they considered only purebreds defined by the American Kennel Club as hypoallergenic, and compared them to all other dogs.

No matter how they sliced it, though, the researchers couldn't come up with a significant difference in the allergen level between the homes of hypoallergenic and non-hypoallergenic dogs. Furthermore, only 10 homes had no detectable amounts of allergen in their dust samples, and none of these homes held hypoallergenic dogs. "We found no scientific basis to the claim hypoallergenic dogs have less allergen," author Christine Cole Johnson said in a press release. (The paper will be published online here.)

So have we all been lied to? Is this dog, famously invited into the First Family because it wouldn't trouble little Malia's allergies, part of a large-scale deception?

The headlines would have you believe so: There's No Such Thing as Hypoallergenic Dogs, they say. Hypoallergenic Dogs Are Just a Myth. Don't Waste Your Money.

The authors of the study say it's unclear how the idea of the hypoallergenic dog originated, though it was in the late 20th century that the concept became popular. In a previous study, researchers shaved hair off of dogs of several breeds and measured the allergen present. Those authors found that although there was significant variation between breeds, there was also plenty of variation between individual dogs. And they found that poodles, dogs commonly called hypoallergenic, had a high level of allergen on their fur compared to other breeds. Christine Johnson and her co-authors wanted a more meaningful measurement of how much allergen was in the atmosphere of dog-owning homes, so they collected dust from the floors rather than fur from the dogs themselves.

However, neither study measured the amount of allergen in the air, where it's actually inhaled by allergy sufferers. Allergen that's settled on the floor might be a good approximation of what was previously in the air--except that Can f 1, the allergen being measured, has two major sources: the fur and the saliva. Dogs that are heavy droolers, or ardent crumb seekers, could be depositing allergens all over the floor without necessarily impacting how much is in the air.

"Hypo-" means "less," not "none." The American Kennel Club says that dogs producing less dander "generally do well with people with allergies," and recommends 11 breeds to try. But this study didn't have a large enough sample size to look at individual breeds; it could only compare groups of dogs. So while the study didn't find an obvious difference between supposedly hypoallergenic dogs--as a group--and other dogs, the study did not show that there's no such thing as a hypoallergenic dog.

If you're looking for a dog that doesn't trigger your allergies, you'd be better off spending some time around the dog itself than relying on an internet categorization. The variation between individual dogs' dander production might be more important than their breeds, anyway. Whether or not some breeds are truly hypoallergenic, science owes it to the allergy-ridden to create useful tests and meaningful labels for dogs. No one should have to live in fear of Bo.

Bo: Official White House photo by Chuck Kennedy.

Charlotte E. Nicholas, M.P.H., Ganesa R. Wegienka, Ph.D., Suzanne L. Havstad, M.A., Edward M. Zoratti, M.D., Dennis R. Ownby, M.D., & Christine Cole Johson, Ph.D. (2011). Dog allergen levels in homes with hypoallergenic compared with nonhypoallergenic dogs American Journal of Rhinology & Allergy