Are We Smart Enough to Know How Smart Animals Are?(23)

This is not the case. Nature abounds with illustrations to the contrary. One that I know firsthand is a pair-bonding Amazonian cichlid, the discus fish, that has achieved the equivalent of mammalian nursing. Once the fry have absorbed the egg yolk, they gather along the flanks of Mom and Dad to nibble mucus off their bodies. The breeding pair secretes extra mucus for this purpose. The young enjoy both nutrition and protection for about a month until they are “weaned” by parents who now turn away each time they approach.13 No one would use these fish to make a point about the complexity or simplicity of mammalian nursing for the obvious reason that the mechanisms are radically different. All that they share is the function of feeding and raising the young. Mechanism and function are the eternal yin and yang of biology: they interact and intertwine, yet there is no greater sin than confusing the two.

To understand how evolution works its magic across the evolutionary tree, we often invoke the twin concepts of homology and analogy. Homology refers to shared traits derived from a common ancestor. Thus, the human hand is homologous with the wing of a bat, since both derive from an ancestral forelimb and carry the exact same number of bones to prove it. Analogies, on the other hand, arise when distant animals independently evolve in the same direction, known as convergent evolution. The parental care of the discus fish is analogous to mammalian nursing but certainly not homologous, since fish and mammals do not share an ancestor that did the same. Another example is how dolphins, ichthyosaurs (extinct marine reptiles), and fish all have strikingly similar shapes owing to an environment in which a streamlined body with fins serves speed and maneuverability. Since dolphins, ichthyosaurs, and fish did not share an aquatic ancestor, their shapes are analogous. We can apply the same line of thought to behavior. The sensitivity to faces in wasps and primates came about independently, as a striking analogy, based on the need to recognize individual group mates.

Convergent evolution is incredibly powerful. It has equipped both bats and whales with echolocation, both insects and birds with wings, and both primates and opossums with opposable thumbs. It has also produced spectacularly similar species in distant geographic regions, such as the armored bodies of armadillos and pangolins, the prickly defense of hedgehogs and porcupines, and the predatory weaponry of the Tasmanian tiger and the coyote. There is even a primate, the aye-aye of Madagascar, that looks like E.T. with an extremely elongated middle finger (to tap for hollow spots and extract grubs from wood), a trait that it shares with a small marsupial, the long-fingered triok of New Guinea. These species are genetically miles apart, yet they have evolved the same functional solution. We should not be surprised therefore to find similar cognitive and behavioral traits in species that are eons and continents apart. Cognitive rippling is common precisely because it isn’t bound by the evolutionary tree: the same capacity may pop up almost anywhere it is needed. Instead of taking this as an argument against cognitive evolution, as some have done, it perfectly fits the way evolution works through either common descent or adaptation to similar circumstances.

A prime example of convergent evolution is the use of tools.


Redefining Man

As soon as an ape sees something attractive yet out of reach, he starts to cast about for a bodily extension. An apple floats in the moat around the zoo island: the ape takes one glance at the fruit before racing around in search of a suitable stick or a few stones that he can throw behind it so that it will float toward him. He distances himself from his goal in order to reach it—an illogical thing to do—while carrying a search image of what tool might work best. He is in a hurry, because if he doesn’t return fast enough, someone else will beat him to the prize. If, on the other hand, his goal is to eat fresh green leaves from a tree, the required tool is quite different: something sturdy to climb on. He may work for half an hour to drag and roll a heavy loose tree stump in the direction of the one tree on the island that has a low side branch. The whole reason he needs a tool is to get across the electric wire around the tree. Before making the actual attempt, he has figured out that the low branch will come in handy. I have even seen apes check the hot wires with the hair on the back of their wrist, hand bent inward, barely touching it, but enough to know if the power is on. If it is off, obviously no tool will be needed, and the foliage is fair game.

Apes do not just search for tools for specific occasions; they actually fabricate them. When the British anthropologist Kenneth Oakley, in 1957, wrote Man the Toolmaker, which claimed that only humans make tools, he was well aware of K?hler’s observations of Sultan fitting sticks together. But Oakley refused to count this as tool manufacture, since it was done in reaction to a given situation rather than in anticipation of an imagined future. Even today some scholars dismiss ape tools by stressing how human technology is embedded in social roles, symbols, production, and education. A chimpanzee cracking nuts with rocks doesn’t qualify; nor, I suspect, does a farmer picking his teeth with a twig. One philosopher even felt that since chimpanzees don’t need their so-called tools, it remains a feeble comparison.14



One of the most complex tool skills is the cracking of tough nuts with rocks. A wild female chimpanzee selects an anvil stone and finds a hammer that fits her hand to open a nut, while her son watches and learns. Only by the age of six will he reach adult proficiency.

I feel like recalling my know-thy-animal rule here, according to which we can safely dismiss a philosopher who thinks that wild chimpanzees sit there pounding and pounding hard nuts with rocks, an average of thirty-three blows per consumed kernel, for generation after generation, for no good reason at all. During peak season, chimpanzees at some field sites spend close to 20 percent of their waking hours fishing with twigs for termites or cracking nuts between rocks. It is estimated that they gain nine times as many kilocalories of energy from this activity as they put into it.15 Moreover, the Japanese primatologist Gen Yamakoshi found that nuts serve as fallback foods when the apes’ main nutrition—seasonal fruits—is scarce.16 Another fallback is palm pith, which is obtained through “pestle pounding.” High up in a tree, a chimpanzee stands bipedally at the edge of the tree crown, pounding the top with a leaf stalk, thus creating a deep hole from which fiber and sap can be collected. In other words, the survival of chimpanzees is quite dependent on tools.