Shadows of Forgotten Ancestors (58 page)

The chimp style of teaching nut cracking and termite fishing to the young is relaxed—by example and not by rote. The student fiddles with the tools and tries out various approaches, rather than slavishly copying every hand movement of the instructor. Gradually the technique improves. Chimps have for this reason been criticized
¹²
as not really having culture. (Ironically, one group of scientists denies chimps language because—as we described earlier—they are said to be too imitative, while another group of scientists denies chimps culture because they are said to be not imitative enough.)

The learning style of the great physicist Enrico Fermi was to ask colleagues to state the problems they had recently solved, but to withhold their answers: He could understand the problem only by working it through himself. Learning by doing is—in science and technology, as in many other human activities—much more effective than learning by rote. Knowing, as the chimps do, that a problem exists and can be solved with the tools at hand is most of the battle.

Baboons
in Gombe eat termites, but almost entirely during the two- or three-week period in which the insects migrate. Then the baboons can be seen gathering and slurping the insects, and leaping into the air to catch them on the wing. In less bountiful times, baboons will be shooed away from a termite mound by an arriving group of chimpanzees. Sometimes the displaced baboons sit a little distance away, morosely observing the chimps working away with their tools on the mound. When the chimps are done, they leave their modified stalks and reeds at the base of the mound. But no baboon has ever been observed trying to use an abandoned tool—even though it could extend their termite season from weeks to months. Apparently the baboons just don’t have it in them. They’re not smart enough. Probably their brains are too small.

As chimps are much better than baboons at collecting termites, so some preindustrial humans who routinely eat termites are much better
than chimps. They dig open the termite mounds, or fumigate them, or flood them with water. One of the more elegant practices is—with the tongue on the palate, or two pieces of wood gently touched to the mound’s surface—to imitate the sound of raindrops, which entices the termites out of their nest.
¹³
Chimps have never been observed to use these techniques.
*
Probably they’re not smart enough. Probably their brains are too small.

What we find most interesting is the overlap. Some chimps lack even probe technology, and are no better at catching termites than baboons are. Other chimps are armed with a well-developed if rudimentary technology, many steps having to be done correctly and in the right sequence for the method to work—as good as many human cultures, although nowhere near as good as some. There are human cultures barely up to the highest chimpanzee standards of termite catching, and others only on a par with the baboons.
¹⁵
No sharp boundaries are apparent here separating baboons from chimps, or chimps from humans.

Chimps also drop branches on intruders and sop up drinking water with leaves. While they cannot be described as fastidious or obsessively hygienic, chimps are known to use leaves as toilet paper and handkerchiefs, and twigs as toothbrushes. They employ sticks for digging up roots, for investigating animals in burrows and knotholes, and—like a croupier at a gaming table—for raking in otherwise inaccessible fruit. If they were able to manufacture more complex tools, they certainly would have the intelligence and dexterity to use them: In zoos, chimps try to steal the keys from the keeper’s pocket. When successful, they often manage to open the lock. Like us, they can sometimes use their intelligence to escape from bondage.

Male chimps like to throw missiles—whatever is handy, generally sticks and stones. (Like the inmates of college fraternity houses, they also occasionally throw food.) Females are much less interested in missiles. Chimps would throw stones at the visitors who gawk at them in the traditional kind of zoo—if they had stones. As it is, all they
have is feces. When wild chimps are presented with a fairly realistic mechanical leopard, after a reassurance frenzy of screams, hugs, and mutual mountings, they find appropriate clubs and beat the effigy to death—or at least until they knock the stuffing out. Or they’ll pelt it with stones. (In the same circumstance, baboons will furiously attack the leopard, but without a thought of using clubs. Baboons just don’t know about tools.)

Chimps have stunned or killed by throwing stones. The directionality of their throwing is good. Where they’re deficient is in range: In tense confrontations with prey or hostile peers, thrown rocks hit their targets only a few percent of the time. Adolescent boys don’t do much better under comparable conditions. But even when inaccurate, a hail of stones can be off-putting.

A distinction needs to be made between tool
using
and tool
making
. Many scientists have conceded tool use to other animals, and, following Benjamin Franklin, defined humans as the sole tool-making animal; where tools are manufactured, it is suggested, language cannot be far behind.
¹⁶
But the chimpanzee termite fishery industry makes it clear that chimps, with considerable forethought, both make and use tools. Chimps also have a rudimentary stone technology, although, as far as we know, they don’t manufacture stone tools in the wild. In captivity, though, Kanzi—the linguistically talented bonobo—has, imitating human models, hit stones together to produce sharp flakes, which he then uses to cut a string so he can open a box which is filled with food. (This is a causality sequence at least five steps long.) As long as it’s sharp enough to cut the string, Kanzi will generally settle for the first crude stone knife he flakes off. But the thicker the rope he must cut, the larger and sharper the knife he makes.
¹⁷

Evidence of chimpanzee talent to combine objects purposefully to make tools has actually been with us for decades:

It’s not hard to imagine an especially insightful chimp or bonobo wondering if there weren’t some way to make a stone flake cut better or a projectile go farther.

Since the progress of human technology is a continuum, to pick a particular milestone—the domestication of fire, say, or the invention of the bow and arrow, agriculture, canals, metallurgy, cities, books, steam, electricity, nuclear weapons, or spaceflight—as the criterion of our humanity would be not just arbitrary, but would exclude from humanity every one of our ancestors who lived before the selected invention or discovery was made. There is no
particular
technology that makes us human; at best it could only be technology in general, or a propensity for technology. But that we share with others.

Like us, nonhuman primates are not all the same. They vary in focus from individual to individual and group to group. Some, like Imo, are technological geniuses. Others, like the hierarchy-besotted macaque males, are hopelessly old-fashioned and stuck in their ways. One chimp population pounds nuts, another does not. Some probe for termites, others only for ants. Some use grass stalks and vines to coax the insects out, others sticks and twigs. Females preferentially use hammers and anvils, males preferentially throw stones. None of them, so far as we know, has ever used a stick to dig out a nutritious root or tuber, although it ought to be possible and adaptive. Some individuals find technology uncongenial or intellectually too taxing and never use it, despite the obvious advantages accruing to other members of their group who are comfortable with technology. Some
large groups have no technology at all. “I’m embarrassed to say,” says an observer of a community of Ugandan chimps, “that the Kibale chimpanzees appear as the country bumpkins of the chimp world.” He goes on to speculate that life is too easy and food too plentiful at Kibale for the challenge of deprivation to elicit the response of technology.
¹⁹

Chimps are smart. They carry accurate mental maps of their territory in their heads. They seem to know the seasonal availability of plant foods and will congregate in some peripheral province of their territory to harvest a small stand of ripening fruits or vegetables. They have rudimentary culture, medicine, and technology. They have a startling capacity for simple language. They can plan for the future. Think again of the sensory and cognitive skills necessary to succeed in chimpanzee social life. You must recognize dozens of faces and their expressions. You must remember what each of these individuals has done to you or for you in the past. You must understand the foibles, weaknesses, ambitions of potential allies and rivals. You must be quick on your feet. You must be very flexible. But if you have all this, there’s probably a great deal else about the world that, sooner or later, you can figure out and change.

——

How thoroughly the chimps and bonobos have erased the list of purported human distinctions!—self-awareness, language, ideas and their association, reason, trade, play, choice, courage, love and altruism, laughter, concealed ovulation, kissing, face-to-face sex, female orgasm, division of labor, cannibalism, art, music, politics, and featherless bipedalism, besides tool using, tool making, and much else. Philosophers and scientists confidently offer up traits said to be uniquely human, and the apes casually knock them down—toppling the pretension that humans constitute some sort of biological aristocracy among the beings of Earth. Instead, we are more like the nouveau riche, incompletely accommodated to our recent exalted state, insecure about who we are, and trying to put as much distance as possible between us and our humble origins. It’s as if our nearest relatives, by their very existence, refute all our explanations and justifications. So as counterweights to human arrogance and pride, it is good for us that there are still apes on Earth.

Much of this chimp and bonobo behavior was discovered only recently.
Doubtless they have other talents that have so far eluded us. We humans are biased observers, with a vested interest in the answer. The cure for this disease is more data. But the study of primate behavior, both in the laboratory and in the wild, is by and large poorly and grudgingly funded.

If we insist on absolute rather than relative differences, we do not, so far at least, discover any distinguishing characteristic of our species. Shouldn’t we expect, especially with our close relatives, that the differences will be of degree and not of kind? Isn’t this the lesson of evolution? If we require that we uniquely possess tools, culture, language, trade, art, dance, music, religion, or conceptual intelligence, we will not understand who we are. If, on the other hand, we are willing to admit that what distinguishes us from the other animals is more of one propensity and less of another, then we may make some progress. Then, if we wish, we can take pride in the fuller flowering of primate aptitudes that has taken place in our species.

The more an animal weighs, the more of it there is that its brain must control, and so—within certain limits—the bigger its brain needs to be. This is true between species, although not between individual members of a given species. A species with a much bigger brain for its body weight—especially in its higher brain centers—has a good chance of being, on some level, smarter. Indeed, for comparable body weights, humans tend to have bigger brains than other primates; primates than other mammals; mammals than birds; birds than fish; and fish than reptiles.
²⁰
There is some scatter in the data, but the correlation is clear. It corresponds pretty well to the commonly accepted (by humans, of course) rank order of animal intelligence. The earliest mammals had significantly larger brains than their reptilian contemporaries of comparable body weight; and the earliest primates were similiarly well-endowed compared to other mammals. We come from big-brained stock.

Adult humans, who weigh only a little more than adult chimps, nevertheless have brains three to four times more massive. A human infant a few months old already has a larger brain than a grown-up chimpanzee.
²¹
It seems very likely that we’re significantly smarter than the chimps because we have a significantly larger brain—despite the comparable body weights. For a factor of three to four increase in brain weight, the brain
size
(its circumference, say) must increase by
about 50%. But the human brain isn’t entirely a proportional scaling up of a chimp brain. Despite what Huxley found, there
is
a little bit of brain architecture—not much, but some—that humans have and the other primates at least mainly don’t. Significantly, some of it seems to be related to speech.