Smart Species
Because animals cannot read or speak, their aptitude is difficult to discern, much less measure. Thus, comparative psychologists have invented behavior-based tests to assess birds’ and mammals’ abilities to learn and remember, to comprehend numbers and to solve practical problems. Animals of various stripes-but especially nonhuman primates-often earn high marks on such action-oriented IQ tests.
During World War I, German psychologist Wolfgang, for example, showed that chimpanzees, when confronted with fruit hanging from a high ceiling, devised an ingenious way to get it: they stacked boxes to stand on to reach the fruit. They also constructed long sticks to reach food outside their enclosure. Researchers now know that great apes have a sophisticated understanding of tool use and construction.
Psychologists have used such behavioral tests to illuminate similar cognitive feats in other mammals as well as in birds. Pigeons can discriminate between male and female faces and among paintings by different artists; they can also group pictures into categories such as trees, selecting those belonging to a category by pecking with their beaks, an action that often brings a food reward. Crows have intellectual capacities that are overturning conventional wisdom about the brain.
Behavioral ecologists, on the other hand, prefer to judge animals on their street smarts that is, their ability to solve problems relevant to survival in their natural habitats-rather than on their test-taking talents. In this view, intelligence is a cluster of capabilities that evolved in response to particular environments.
Some scientists have further proposed that mental or behavioral flexibility, the ability to come up with novel solutions to problems, is another good measure of animal intellect. Among birds, green herons occasionally throw an object in the water to lure curious fish a trick that, ornithologists have observed, has been reinvented by groups of these animals living in distant locales. Even fish display remarkable practical intelligence, such as the use of tools, in the wild.
Cichlid fish, for instance, use leaves as “baby carriages” for their egg masses. Animals also can display human-like social intelligence. Monkeys engage in deception, for example; dolphins have been known to care for another injured pod member (displaying empathy), and a whale or porpoise may recognize itself in the mirror.