Animal Intelligence and the Evolution of the Human Mind

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Subtle refinements in brain architecture, rather than large-scale alterations, make us smarter than other animals

By Ursula Dicke and Gerard Roth

• The human brain lacks conspicuous characteristics—such as relative or absolute size—that might account for humans' superior intellect.
• Researchers have found some clues to humanity's aptitude on a smaller scale, such as more neurons in our brain's outermost layer.
• Human intelligence may be best likened to an upgrade of the cognitive capacities of nonhuman primates rather than an exceptionally advanced form of cognition.

As far as we know, no dog can compose music, no dolphin can speak in rhymes, and no parrot can solve equations with two unknowns. Only humans can perform such intellectual feats, presumably because we are smarter than all other animal species—at least by our own definition of intelligence.

Of course, intelligence must emerge from the workings of the three-pound mass of wetware packed inside our skulls. Thus, researchers have tried to identify unique features of the human brain that could account for our superior intellectual abilities. But, anatomically, the human brain is very similar to that of other primates because humans and chimpanzees share an ancestor that walked the earth less than seven million years ago.

Accordingly, the human brain contains no highly conspicuous characteristics that might account for the species' cleverness. For instance, scientists have failed to find a correlation between absolute or relative brain size and acumen among humans and other animal species. Neither have they been able to discern a parallel between wits and the size or existence of specific regions of the brain, excepting perhaps Broca's area, which governs speech in people. The lack of an obvious structural correlate to human intellect jibes with the idea that our intelligence may not be wholly unique: studies are revealing that chimps, among various other species, possess a diversity of humanlike social and cognitive skills.

Nevertheless, researchers have found some microscopic clues to humanity's aptitude. We have more neurons in our brain's cerebral cortex (its outermost layer) than other mammals do. The insulation around nerves in the human brain is also thicker than that of other species, enabling the nerves to conduct signals more rapidly. Such biological subtleties, along with behavioral ones, suggest that human intelligence is best likened to an upgrade of the cognitive capacities of nonhuman primates rather than an exceptionally advanced form of cognition.

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 Köhler, 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.

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[MichelleN 0]

I actually watched a very interesting documentary a few months back on the intelligence of dogs. It was found that they were actually much smarter than we gave them credit for and were actually the only animals able to take cues from a human in the face of a 'puzzle'. A dog would be faced with three buckets and only one would have a treat. In the experiment, a human sat behind the buckets and would indicate which one held the prize with either her eyes or by pointing. Each time the dogs observed the human's actions before going to the correct bucket.