A different kind of smart: animals' cognitive shortcomings are as revealing as their genius. (2024)

Zola the crow is about to face a test that has baffled animals fromcanaries to dogs.

She's a wild New Caledonian crow, and for the first time,she's seeing a tidbit of meat dangling on a long string tied to astick. She perches on the stick, bends down, grabs the string with herbeak and pulls. But the string is too long. The meat still hangs out ofreach.

In similar tests, dogs, pigeons and many other species routinelyfalter. Some nibble at the string or keep tugging and dropping the samesegment. Some pull at a string that's not connected to food just asreadily as a string that is. Eventually many get the hang of reeling inthe tidbit, but they seem to learn by trial and error.

Zola, however, does not fumble. On her first attempt, she anchorsthe first length of string by stepping on it and immediately bends downagain for the next segment. With several more pulls and steps, Zola

reels in the treat.

Watching the crow, says Russell Gray, one of the researchers behindthe string-pulling experiment, "people say, 'Wow, it had aflash of insight.'" At first glance it seems Zola mentallyworked through the problem as a human might, devising a solution in anaha moment.

But Gray, of the University of Auckland in New Zealand, has hadenough of such supposed animal geniuses. Asking whether the crow solvesproblems in the same way a human would isn't a useful question, hesays. He warns of a roller coaster that scientists and animal loversalike can get stuck on: first getting excited and romanticizing a cleveranimal's accomplishments, then crashing into disappointment whensome killjoy comes up with a mundane explanation that's nothumanlike at all.

Gray is looking for a way to get off the roller coaster. InZola's case, he and his colleagues devised several differentvariations on the string-pulling test that would never trip up a human,and the crow's smooth performances fell apart. Whatever Zola wasdoing to solve the puzzle, Gray says, it's not full, humanlikeinsight.

That may disappoint some people, but not Gray. "Often we learnthe most when we see what we can change that makes the apparentlyimpressive performance collapse," he says.

He and a handful of other researchers are studying not only whatanimals can do, but also what they can't. Forget the animalEinsteins--give Gray the not-so-miraculous beasts that ace one versionof a test but flunk another.

After all, seeing an animal succeed at a mental challenge revealslittle about how it evolved that capacity. Evolution doesn'tproceed by astonishing leaps, but by baby steps. "I'minterested in halfway scenarios, intermediate scenarios," Graysays. These modest capabilities, he argues, offer the richestinspiration for understanding the small steps that build up into therich diversity of animals' mental powers.

Clever creatures

That's not to say that scientists haven't been lookingfor signs that animals have humanlike thought processes. Recent decadeshave seen a flood of reports that animals share some degree ofcapabilities once assumed to be uniquely human. Recently hatched chicksmanage simple addition and subtraction, correctly keeping track of whichof two hidden groups of familiar objects is larger. Foraging rock antslook as if they're among the very few animals to show true teachingbehavior. Sheep have sophisticated powers of facial recognition and canremember 50 of their fellows for two years. Black bears can learn tosort images into categories, such as bears versus humans. Dolphins canuse tools, carrying sponges that protect their sensitive snouts whileforaging.

None other than Charles Darwin noted many examples of humanlikecleverness in animals, which he celebrated as support forevolution's tenet of shared deep ancestry, says Sara Shettleworthof the University of Toronto.

The unintended result of Darwin's remarks was such uncriticalenthusiasm for anecdotes about clever animals, however, that a backlashstruck as early as 1894. That year, British psychologist C. Lloyd Morganpublished what's called Morgan's canon, the principle thatsuggestions of humanlike mental processes behind an animal'sbehavior should be rejected if a simpler explanation will do.

Still, people seem to maintain certain expectations, especiallywhen it comes to birds and mammals. "We somehow want to prove theyare as 'smart' as people," Shettleworth says. We want abird that masters a vexing string to be employing human-style insight.

Aha moments

New Caledonian crows face the high end of these expectations, aspossibly the second-best toolmakers on the planet.

Their tools are hooked sticks or strips made from spike-edgedleaves, and they use them in the wild to winkle grubs out of crevices.Gray first saw the process on a cold morning in a mountain forest in NewCaledonia, an island chain east of Australia. Over the course of days,he and crow researcher Gavin Hunt had gotten wild crows used to findingmeat tidbits in holes in a log. Once the birds were checking the logreliably, the researchers placed a spiky tropical pandanus plant besidethe log and hid behind a blind.

A crow arrived. It hopped onto the pandanus plant, grabbed thespiked edge of one of the long straplike leaves and began a series ofripping motions. Instead of just tearing away one long strip, the birdripped and nipped in a sequence to create a slanting stair-step edge ona leaf segment with a narrow point and awide base. The process took onlyseconds. Then the bird dipped the narrow end of its leaf strip into ahole in the log, fished up the meat with the leaf-edge spikes, swallowedits prize and flew off.

"That was my 'oh wow' moment," Gray says. Afterthe crow had vanished, he picked up the tool the bird had left behind."I had a go, and I couldn't do it," he recalls. Fishingthe meat out was tricky. It turned out that Gray was moving the leafshard too forcefully instead of gently stroking the spines against thetreat.

The crows' deft physical manipulation was what inspired Grayand Auckland colleague Alex Taylor to test Zola and other wild crows tosee if they employed the seemingly insightful string-pulling solutionsthat some ravens, kea parrots and other brainiac birds are known toemploy. Three of four crows passed that test on the first try, so nextthe researchers set out to test the crows' limits.

Gray and Taylor set up a platform instead of a perch, which limitedwhat the crows could see while pulling the string. The birds couldinvestigate the string and the dangling meat from the sides but had tohop onto the platform and pull the string up through a slot. Thesupposedly insightful toolmakers had a terrible time. Out of four birdsthat had never '. confronted a dangling tidbit, only one hauled inthe treat, and that was on the fifth try. Another bird failed at 10opportunities, pulling at the string 188 times but never stepping on it.

In another test, researchers laid the string on a table in S-curveloops. The birds could see the meat, but they wouldn't see itmoving closer until they'd pulled enough times to reach the lastsegment of string.

An animal with true insight, in theory, would recognize thatcontinuing to pull the string would eventually pull in the meat. But inthis setup, the birds "completely fail," Gray says. Some gavethe string a tug at first, but only one kept hauling. And that bird wasjust as happy to pull on a string not connected to meat as on one thatwas, Gray, Taylor and their colleagues reported in the Proceedings ofthe Royal Society B in a 2012 paper titled "An end toinsight?"

After seeing all this, the researchers proposed that Zola and theother crows had solved the first test--the perch with the hangingstring--not by insight in the human sense, but through an enhancedability to pay attention. New Caledonian crows, which do have relativelylarge brains for their body size, may be able to notice and absorb indetail the consequences of what they're doing. Reaching down tograb the dangling string isn't a big change from normal poking andexploring. And when the meat rises a bit, the birds absorb the positivefeedback and take another step-pull.

As mental prowess goes, Gray says, "that's not a miracle,just a small tweak in cognition."

Physics test

Researchers have done a similar kind of tweaking using experimentsbased on Aesop's fables. In one of the old tales, a thirsty crowfinds a jug partly full of water but can't reach down far enoughfor a drink. So the bird plops stones into the jug until the water levelrises.

Nathan Emery and Chris Bird of Queen Mary, University of Londontaught real-life rooks a version of this trick. The researchers gavebirds a tube partly filled with water and a waxworm bobbing on thewater's surface. The rooks readily dropped stones into the wateruntil they could grab the treat. (Orangutans in lab tests have solvedthe problem in their own way, taking mouthfuls of water from theirdrinking supply and spitting into the tube to raise the water level.)

To see if the behavior extended to a related group of birds, NicolaClayton and her colleagues tested Eurasian jays. "The birds oftenwalk around the tubes having a good look first," says Clayton, whostudies the evolution of animal cognition at the University of Cambridgein England. Soon two of five jays began to drop stones into the water toscore a waxworm. Those two also learned a preference for dropping inpieces of rubber that sink instead of foam chunks that float uselesslyon the surface. "This is especially striking because when we testedchildren, the children don't pass this version of the task untilquite late in development," Clayton says. One 5-yearold grasped thevalue of sinking objects, but overall the successful children averagedmore than 8 years of age.

Then researchers devised a counterintuitive set-up, offering threetubes partly filled with water. The treat floated in the middle one, butthat tube was too narrow for a stone. The only way a jay or child couldscore the treat (kids got tokens to exchange for stickers instead ofwaxworms) was to drop stones into one of the outer tubes that had ahidden connection to the narrow middle tube. Jays just didn't getit, but a substantial number of 8- to 10-year-olds did, although"most of them didn't understand why the setup worked,"Clayton says. "They attributed it to magic."

Neither the jays nor the kids managed the trickiest tasks the wayan adult human would. But like Gray, Clayton is intrigued by the partialsuccesses. In the last test, she speculates, children may be better ablethan jays to accept the counterintuitive quirk of the secretly connectedtube. "Without a belief in magic," she says, "jays failto figure it out."

Reading minds

Besides studying how birds solve physical problems, Clayton hastested the notion that a bird can imagine, in some sense, what'sgoing on in another animal's head. People have this ability, calledtheory of mind, but proposing, as Clayton does, that the Westernscrub-jay can infer what another bird is thinking is a strikingconclusion.

Scrub-jays cache food, and possess prodigious powers forremembering where. They also steal from each others' caches, withhigher-ranking birds tending to steal from lower-ranked birds. Claytonhas found that if a bird with a larcenous past knows it's beingwatched as it stashes a tidbit, it's likely to later shift thecache to an unobserved location. This suggests that the birds havesomething like a theory of mind, Clayton says, because they understandthat the bird watching them may come steal their stores. Yet nonthievesaren't as likely to recache the food. So jays that steal mayproject their own behavior onto other birds that are watching them.

Elske van der Vaart of the University of Amsterdam has been lookingfor a simpler explanation. Maybe the birds are not relying on somethingeven close to a human's theory of mind, she and her colleaguessuggested in PLOS ONE in 2012. Maybe all the hiding and rehiding is justa side-effect of something as simple as stress. Beingwatched isstressful, the researchers say, as is failing to find a cache. Inexperiments with virtual birds in a computer simulation, flusteredindividuals that were being watched and following a simple rule (theycached as far away as possible from observers) hid and rehid their hoardmuch as real scrub-jays do.

But real birds don't behave like simulated birds, Clayton andCambridge colleague James Thorn reported in January in PLOS ONE. Given achance to hide peanuts in ice cube trays, birds cached about the samenumber of treats in both more and less stressful conditions."Sometimes the simplest explanation is not the best," Claytonsays.

So the debate about theory of mind continues. Van der Vaart saysthe supposedly serene ice cube-tray situations might have held hiddenstresses that confounded the results. And other predictions fromcomputer simulations still need testing. "I certainly do thinkit's possible that [crows and related species] could have somethinglike a theory of mind, and it would be very exciting if they did,"she says. "But right now, I don't think we know enough to beable to say one way or the other."

Flub factor

Research on elephant insight and chimps' understanding of thephysical world has approached the question of limits from the otherdirection, with scientists tweaking tests that animals normally flub todiscover what specific factors let them improve.

Chimps may not understand how the physical world works well enoughto attribute phenomena to underlying causes such as gravity, solidityand other such qualities- or at least that's been a long-standingproposal. Amanda Seed of the University of St. Andrews in Scotlandisn't so sure. "The difference between human and ape folkphysics may not be as clear-cut as that," she says.

In a classic lab test, chimps seem not to grasp basic cause andeffect. To coax a treat out of a device called a trap tube, an animalhas to use a stick to poke the treat to one end. If nudged in the wrongdirection, the food tumbles irretrievably into a hole. "Chimpsappeared not very good at telling that their food would fall into atrap," Seed says.

In one of Seed's first chimp experiments, she redesigned thetrap so the chimps could poke with their fingers instead of a stick. Ina video of the new experiment, a chimp stands in front of a clearplastic box and without much ado, pokes a finger through a series oflittle holes, working a tidbit along in the correct direction and safelyout of the box.

The problem may have been the same one faced by floundering humanpool players who spend too much time watching the cue instead of theball. Chimps may not have a different conception of surfaces and holesthan people do, but rather a different capacity to focus attention orremember. Without the tool to distract them, they may absorb more ofwhat poking around in the tube is actually doing.

Revealing such hidden animal talents requires devising the rightkind of test, which often takes a bit of ingenuity. Preston Foerder ofthe University of Tennessee at Chattanooga was testing for insight inelephants, for instance, by putting food out of reach and providing astick as a tool for getting it. Working with three elephants at theSmithsonian National Zoological Park in Washington, D.C., Foerder foundthat they readily picked up a stick. But instead of pointing it athard-to-reach food, they banged the walls, scratched themselves andthrew it around. "This was about three months of research off andon, and I was commuting from New York City to do it," he says."Then I had my own insight."

Foerder moved the food and sticks outdoors and provided a cube ortub that could be moved over to the food if an elephant wanted to standon it. In its seventh session of straining toward the food, 7-year-oldelephant Kandula moved the cube into position as a stepstool and snaggedsome fruit (SN Online: 8/24/11). "Elephants are more olfactory thanvisual," Foerder says, and sniff with their trunks. When holding astick, their trunks face the wrong direction for detecting what thestick is poking, and the trunk openings may even be closed. Theexperience points out that people may have to step outside their primatebiases to get an idea of what another animal can do, Foerder says.

In the end, experiments that test animals' cognition bydetermining when they succeed and when they fail may reveal more abouthuman minds than other species'. Whether humankind truly wants tofind all it looks for isn't so clear. hom*o sapiens is hardly modestabout its brainpower, perhaps wanting to discover a bit of mentalkinship while remaining mental kings.

Explore more

* Sara J. Shettleworth. "Clever animals and killjoyexplanations in comparative psychology." Trends in CognitiveSciences. November 2010.

RELATED ARTICLE: Blurring the boundaries.

New studies suggest that a variety of animals may have some versionof the fancy mental powers once ascribed only to humans. It's noteasy to discern what's going through another species' mind, sothese bold claims will need big proof. At the same time, a growing bodyof research suggests that humans share a number of largely unconscious,so-called irrational processes with other animals.--Susan Milius

Honeybees | ABSTRACT CONCEPTS

The miniature brains of honeybees may be able to learn abstractconcepts such as "same versus different" or "above versusbelow." In experiments, researchers teach bees these notions bytraining them to fly toward a symbol that represents a concept, forexample illustrating the idea of "above" with an icon sittingabove a line. Researchers show the bees symbols that look different buthave the same meaning of "above," and eventually bees tend tomake the right choice when they see a new symbol. The insects seem to belearning something beyond mere association of a specific symbol with areward, and in one recent experiment were even able to learn twoabstract concepts, left/right and above/below, simultaneously, MartinGiurfa of Paul Sabatier University in France and colleagues reported in2012.

Dolphins | SYNTAX

Language may be one of human-kind's most gloriousachievements, but decades of experiments suggest that bottle-noseddolphins can learn sophisticated communication. Louis Herman of theUniversity of Hawaii and his colleagues taught dolphins an invented signlanguage that requires an understanding of syntax--a way to stringtogether words and phrases to create meaning. The dolphins coulddistinguish between commands such as "person surfboard fetch"to bring a surfboard to a person and "surfboard person fetch"to tow a person riding a surfboard. Now, Vincent Janik of the Universityof St. Andrews in Scotland has used microphones to eavesdrop on dolphintalk in the wild. Individual dolphins develop distinctive whistles thatthey use when meeting at sea, he and a colleague reported in 2012.

Primates | FUZZY MATH

Chimps are natural accountants, says Michael Beran of Georgia StateUniversity in Atlanta. They can roughly track how a group of objectschanges as objects are added and subtracted, like in a bank account. Andin a new test, Elizabeth Brannon of Duke University and her colleaguesfound that rhesus monkeys and college students do about equally well ona test of adding without being allowed to explicitly count objects. Whenshe and a colleague gave both kinds of primates mere glimpses of twosets of dots--not visible long enough for the humans to actually countthem--both did pretty well at selecting a picture that represented thesum of glimpsed sets. This shared ability to do approximate arithmeticin a flash probably reflects the evolution of cognitive abilities in theanimal family tree, Brannon says.

----------

Please note: Illustration(s) are not available due to copyrightrestrictions.