The Moral: Aesop Knew Something About Crows

ScienceTake: Those Clever Crows

Scientists are trying to understand the limits to the well-established intelligence of crows.

Crows and their relatives, like jays and rooks, are definitely in the gifted class when it comes to the kinds of cognitive puzzles that scientists cook up.

They recognize human faces. They make tools to suit a given problem.

Sometimes they seem, as humans like to say, almost human. But the last common ancestor of humans and crows lived perhaps 300 million years ago, and was almost certainly no intellectual giant.

So the higher levels of crow and primate intelligence evolved on separate tracks, but somehow reached some of the same destinations. And scientists are now asking what crows can’t do, as one way to understand how they learn and how their intelligence works.

One very useful tool for this research comes from an ancient Greek (or perhaps Ethiopian), the fabulist known as Aesop. One of his stories is about a thirsty crow that drops pebbles into a pitcher to raise the level of water high enough that it can get a drink.

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Researchers have modified this task by adding a floating morsel of food to a tube with water and seeing which creatures solve the problem of using stones to raise the water enough to get the food. It can be used for a variety of species because it’s new to all of them. “No animal has a natural predisposition to drop stones to change water levels,” said Sarah Jelbert, a Ph.D. student at Auckland University in New Zealand, who works with crows.Photo

New Caledonian crows can use tools to solve problems, such as getting at hard to reach food.CreditMick Sibley

New Caledonian crows, rooks, Eurasian jays, and humans (past age 5) can do it, said Ms. Jelbert, who noted that great apes can do a slightly different version.

But in the latest experiment to test the crows, Ms. Jelbert, working with Alex Taylor and Russell Gray of Auckland and Lucy Cheke and Nicola Clayton of the University of Cambridge in England, found some clear limitations to what the crows can learn. And those limitations provide some hints to how they think.

The birds, Ms. Jelbert and her colleagues reported in PLOS One last month, were wild New Caledonian crows trapped for the experiment and then released.

The crows were first trained to pick up stones. This is not something they do in the wild. They then dropped the stones into a dry tube to gain a reward. Then they took the Aesop’s test, in several different situations.

The birds learned not to drop the stones in a tube of sand with a treat. And they correctly chose sinking objects rather than floating ones, and solid rather than hollow objects to drop in the water.

But if part of the tube apparatus was hidden, the birds could not learn. They also didn’t seem to be able to learn that the water would rise more quickly with fewer stones in a narrow tube.

This suggests two things, said Ms. Jelbert. They weren’t just learning abstract rules, because otherwise they would have been able to learn where to drop the stones to make the water rise even if they couldn’t see what was going on.

And second, the need to see the results of the behavior suggested they did seem to have “a level of causal understanding.” These are just hints, though, in terms of understanding how crows learn and think, said Ms. Jelbert, “we’re still very much at the beginning.”

ORIGINAL: NYTimes

By James Gorman

April 10, 2014

Welcome Your New Primate Overlords: Chimp Tech Is on the Rise

ORIGINAL: Geeks Are Sexy

While the human tech world rages and swoons over the new iPad (¿Gorilla Display perhaps?), our primate cousins are at the height of what Discovery News is calling the Great Chimp Tech Boom. Poking at ants with a stick hardly seems like a newly integrated, top-of-the-line technological feat. But for chimpanzees, this recent development in “cultural variation,” or behavior specific to a community rather than a species as a whole, is more important than you’d expect. According to renowned British anthropologist Jane Goodall, technology among chimpanzees is improving and being adopted more rapidly than previously expected.

Just a couple of chimpanzees fishing for ants with tools they built. No big deal. Image: Robert O’Malley

Chimpanzees are more closely related to humans than any other living species — so closely, in fact, that in 2003 a team of biologists suggested moving chimps to the human branch of the family tree. It’s unsurprising, then, that chimpanzees also exhibit the highest rate of cultural variation of any non-human species. A team of evolutionary anthropologists and other animal behavior researchers, including Goodall, have identified at least 39 community-specific behaviors within different groups of chimps, which range from methods of swatting flies (some groups use leaves, while others employ the ‘index squash,’ or one-fingered smash-it-till-it’s-dead method) to variations on simple tools, like using stones to crack open nuts versus smashing them against the ground with a heavy piece of wood, for example.

Ant fishing (that’s the “poking at ants with a stick” thing) is an amazing example of cultural variation for a couple of reasons. Firstly, it requires a tool (that’s the stick), which is used to retrieve super-tasty ants and termites from their nests with ease. And even the stick has seen improvements; in 2009 a group of chimps were observed fraying the ends of their sticks to allow more surface area for catching ants and termites. But there’s another, more important reason ant fishing is a big deal: it’s the first novel adaptation outside of captivity that we’ve witnessed moving from one group into another. (The study’s authors call this “intercommunity cultural transmission.”) According to a new report in the latest issue of Current Anthropology, ant fishing is really catching on, and it’s all thanks to a sharp-witted chimp named Trezia.

Trezia is a wild chimpanzee who lives in Gombe Stream National Park, home to Jane Goodall (the report’s co-author) and her beloved Kasekela chimpanzee community. When Trezia was transferred to the Kasekela group from the separate Mitumba community, her wit and ease made her a favorite among her new family. But the Kaseleka chimps didn’t fish for ants. But they learned how eventually, because Trezia didn’t stop fishing for ants just because she lived in a new group. For her, this was normal, everyday behavior; in 1982, ant fishing was declared a customary behavior within Trezia’s Mitumba home group. It appeared in 1994 in the Kaseleka group (after Trezia’s relocation), and as of 2010 is considered customary there as well.

Of course, chimps aren’t the only primates to surprise observers with their technological prowess. Young gorillas have recently been spotted dismantling snare traps left by poachers, a development that’s both incredible and something of a relief. An ingenious Japanese macaque named Imo figured out that washing the grit off of sweet potatoes made them better to eat, and in so doing taught an entire population of macaques to wash their food. And in a group of capuchin monkeys in Brazil, not only is cracking palm nuts with stones the preferred method of midday snack procurement, the monkeys are choosing the optimal stones for the job by testing the rocks for sturdiness and weight before wasting any time using them as hammers. What’s next? Our money is on agriculture and figure-flattering winter wear.