of pure instinct in human nature. In one of the most interesting passages of his discussion of nonhuman mental powers, he quotes Alexander von Humboldt’s Personal Narrative: “The muleteers in S. America say, ‘I will not give you the mule whose step is easiest, but la mas racional,—the one that reasons best’; and Humboldt adds, ‘this popular expression, dictated by long experience, combats the system of animated machines, better perhaps than all the arguments of speculative philosophy.’”30 If mules are smart, then nonhuman primates are smarter. A century before Jane Goodall’s revelations about the lives of chimpanzees, Darwin found in his wide reading and research evidence of apes and monkeys using tools, building nests, passing on “culinary” skills such as the best way to eat an egg, and teaching botanical knowledge to the young.
Darwin was not a primatologist but a generalist, and all the evidence he draws from the nonhuman primate world supports his contention that humans are descended from an ape-like ancestor, through the mechanisms of the struggle for existence, natural selection, and sexual selection, which work just the same in human evolution as they do in the evolution of dogs or deer mice, cucumbers or cockatoos. He concludes the analysis of human descent by noting that embryology, physiological vestiges, and homological structures point to one conclusion about our ancestry:
that man is descended from a hairy quadruped, furnished with a tail and pointed ears, probably arboreal in its habits, and an inhabitant of the Old World. This creature, if its whole structure had been examined by a naturalist, would have been classed amongst the Quadrumana, as surely as would the common and still more ancient progenitor of the Old and New World monkeys. The Quadrumana and all the higher mammals are probably derived from an ancient marsupial animal, and this through a long line of diversified forms, either from some reptile-like or amphibian-like creature, and this again from some fish-like animal. 31
Further back, our ancestors were gilled hermaphrodites, and further still, we were similar to the larvae of ascidians—simple, sack-shaped water critters such as the sea squirt. But in Darwin’s view, physiology made no sense apart from the mental and emotional attributes that humans share with other mammals; morphological and physiological evolution could not be separated from the evolution of behavior.
Although he was horrified by slavery and by the brutal decimation of Indian tribes that he witnessed on his travels in South America, Darwin was not a “liberal” in the sense that we now use the term. On the voyage of the Beagle thirty-five years before the publication of The Descent of Man, he had studied the human inhabitants of Tierra del Fuego. Like Thomas Malthus, who contemplated the poor of the industrialized European nations, Darwin found the existence of the Fuegans “nasty, brutish, and short.” He preferred claiming kin with the animals, and, recalling his friend Huxley’s encounter with Bishop Wilberforce, he comments at the very end of Descent that “for my own part I would as soon be descended from that heroic little monkey, who braved his dreaded enemy in order to save the life of his keeper; or from that old baboon, who, descending from the mountains, carried away in triumph his young comrade from a crowd of astonished dogs—as from a savage who delights to torture his enemies . . . and is haunted by the grossest superstitions.”32 Darwin had so much to say about mind, emotion, culture, and society that he had to write another volume, published a year after Descent as The Expression of the Emotions in Man and Animals. According to Darwin’s biographers Adrian Desmond and James Moore, this smaller book amounted to “the amputated head of the Descent that had assumed a life of its own.”33 It was a best seller; readers could test every assertion, comparing each of the many illustrations to the faces of people they knew, to the body language of their pets, and to the monkeys they saw in the zoo. Unlike the history of life on earth, which had to be extrapolated by experts from geological strata and an imperfect fossil record, expressions of emotion were evident for all to see.
No less an authority than Konrad Lorenz, often considered the originator of the discipline of ethology, credits Darwin with originating ethology, for it was Darwin who articulated the notion that “behavior patterns are just as . . . reliably characters of species as are the forms of bones, teeth, or any other bodily structures.”34 However, while Darwin himself was willing to set aside the Enlightenment dictum that mules and monkeys were animated machines, most twentieth-century scientists found it difficult to give up the view that animal minds are simply bundles of inherited or conditioned impulses without true consciousness. And most scientists today, trained in the language of behaviorism, continue to guard carefully against the appearance of the sin of anthropomorphism. Many have felt that attributing an inner life to nonhuman animals is, in itself, anthropomorphic.
It may be “scientific” to avoid speaking of other primates as if we share vast tracts of psychological experience, but avoiding “anthropomorthic” language is difficult, because most people feel that we are psychologically kin to other primates as well as morphologically similar. In English, even the language used to describe groups of apes and monkeys reflects this difficulty. There are parliaments of owls, prides of lions, and gaggles of geese, but (at least in common parlance) troops of monkeys—as of soldiers, actors, or circus performers. Snakes, weasels, and cockroaches are “it,” but most English speakers readily grant grammatical gender when speaking of simians; they are “he” and “she.” Cats have kittens and dogs have puppies, but our fellow primates have babies, sons, daughters, grandmothers, and so on. The English language contains no other words for genetic relationships in primate families. Although popular accounts of primatologists’ lives and the lives of their study subjects admit social and psychological kinship with other primates, the technical literature persists in endeavoring to appear objective by censoring this kind of language. I have noticed this difference even when comparing the published abstracts of oral presentations at scientific primatology meetings with the oral presentations themselves. In the abstract, the typical presenter rigorously avoids humanizing language—even sometimes grammatical gender. The result is stiff and occasionally awkward phrasing. But in the oral delivery, that same presenter’s language is natural, humanized, and even humorous, though sometimes apologetically so.
Darwin had no such reservations. His conclusions about the expression of emotion are based on careful and detailed studies of facial anatomy and physiological investigations of many species. Contrary to the contemporary practice of primatology in the West, he cultivated anthropomorphism—in animal studies, we would now call it “critical anthropomorphism.” Although one may be skeptical of animal intelligence, and although one must set aside entirely any speculations about the spirituality of animals, Darwin argued, it is beyond question that humans share with them emotions and mutually understandable expressions. In The Expression of the Emotions in Man and Animals, Darwin recycled the field studies he had used in his previous works, but he relied even more on direct observation. He studied his dogs and the family cats, his favorite horse Tommy, farm fowl and other neighborhood birds, the cattle in nearby fields, and, in the same spirit, the antics and expressions of his children. He went back to the London Zoo, where he spoke with the primate keepers charged with the care of chimpanzees, orangutans, gibbons, baboons, Barbary apes, macaques, and several species of New World monkeys. “Some of the expressive actions of monkeys,” he explains, “are interesting . . . from being closely analogous to those of man.”35
In the monkeys and apes Darwin was able to observe, he saw little difference between the expression of affection and that of pleasure and joy. Monkeys laugh and smile when they are pleased, and Darwin notes that when chimps and orangutans are pleased, their eyes sparkle—especially when they are tickled. Like humans, monkeys also crinkle their eyelids when happy or amused. Attention, games, food treats, and reconciliation after quarrels can all be sources of pleasure for these primates. Some primate expressions of joy, such as grinning and baring the teeth, can be confused with expressions of pain or anger, but with a little practice, an observer can almost always distinguish subtle differences.
Not surprisingly, Darwin notes that nonhuman primates are equally expressive when they are in pain or otherwise unhappy. All of them express pain or unhappiness by crying, and a few even
