the limits of animal intelligence -- 5/18/16

Today's selection -- from Are We Smart Enough to Know How Smart Animals Are? by Frans de Waal. Scientists routinely make claims about the uniqueness of humans compared to other animal species. For example, in the past, scientists have claimed that "only humans can learn to use tools" and "only humans are self-aware," only to have these claims disproven. In truth, these erroneous conclusions have often stemmed from poor test design, and we are only beginning to understand the full extent of animal capabilities:

"We hear abundant claims along the lines of 'only humans can do this or that,' referring to anything from looking into the future (only humans think ahead) and being concerned for oth­ers (only humans care about the well-being of others) to taking a vacation (only humans know leisure time). ... In fact, I find the best and most enduring claims about human exceptionalism to be the funny ones, such as Mark Twain's 'Man is the only animal that blushes -- or needs to.' But, of course, most of these claims are deadly serious and self-congratulatory. The list goes on and on and changes every decade, yet must be treated with suspicion given how hard it is to prove a negative. The credo of experimental science remains that an absence of evidence is not evidence of absence. If we fail to find a capacity in a given species, our first thought ought to be 'Did we overlook something?' And the second should be 'Did our test fit the species?'

Happy from Joshua Plotnik's experiment

"A telling illustration involves gibbons, which were once consid­ered backward primates. Gibbons were presented with problems that required them to choose between various cups, strings, and sticks. In test after test, these primates fared poorly compared to other species. Tool use, for example, was tested by dropping a banana outside their cage and placing a stick nearby. All they had to do to get the banana was pick up the stick to move it closer. Chimpanzees will do so without hes­itation, as will many manipulative monkeys. But not gibbons. This was bizarre given that gibbons (also known as 'lesser apes') belong to the same large-brained family as humans and apes.

"In the 1960s an American primatologist, Benjamin Beck, took a fresh approach. Gibbons are exclusively arboreal. Known as brachiators, they propel themselves through trees by hanging by their arms and hands. Their hands, which have tiny thumbs and elongated fingers, are special­ized for this kind of locomotion: gibbon hands act more like hooks than like the versatile grasping and feeling organs of most other primates.

"Beck, realizing that the gibbon's Umwelt barely includes the ground level and that its hands make it impossible to pick up objects from a flat sur­face, redesigned a traditional string-pulling task. Instead of presenting strings lying on a surface, as had been done before, he elevated them to the animal's shoulder level, making them easier to grasp. Without going into detail -- the task required the animal to look carefully at how a string was attached to food -- the gibbons solved all the problems quickly and efficiently, demonstrating the same intelligence as other apes. Their earlier poor performance had had more to do with the way they were tested than with their mental powers. ...

"In one experiment researchers conducted a mirror test -- to evaluate whether an animal recognizes its own reflection. They placed a mirror on the floor outside an elephant cage. Measuring only 41 by 95 inches, it was angled up so that the elephant probably mostly saw its legs moving behind two layers of bars (since the mirror doubled them). When the elephant received a body mark that was visible only with assistance of the mirror, it failed to touch it. The verdict was that the species lacked self-awareness.

"But Joshua Plotnik, then a student of mine, modified the test. He gave elephants at the Bronx Zoo access to an eight-foot-square mir­ror placed directly inside their enclosure. They could feel it, smell it, and look behind it. Close-up exploration is a critical step, for apes and humans as well; that had been impossible in the earlier study. In fact, the elephants' curiosity worried us, as the mirror was mounted on a wooden wall that was not designed to support climbing pachyderms. Elephants normally don't stand up against structures, so having a four-ton animal lean on a flimsy wall in order to see and smell what was behind the mounted mirror scared us to death. Clearly, the animals were motivated to find out what the mirror was all about, but if the wall had collapsed, we might have ended up chasing elephants in New York traffic! Fortu­nately, the wall held, and the animals got used to the mirror.

"One Asian elephant, named Happy, recognized her reflection. Marked with a white cross on her forehead above her left eye, she repeat­edly rubbed the mark while standing in front of the mirror. She con­nected her reflection with her own body. By now, years later, Josh has tested many more animals at Think Elephants International, in Thai­land, and our conclusion holds: some Asian elephants recognize them­selves in the mirror. "



Frans de Waal


Are We Smart Enough to Know How Smart Animals Are?


W. W. Norton & Company


Copyright 2016 by Frans de Waal


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