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 shed tears, as humans do. As far as Darwin was able to observe, other primates don’t frown, but they do express rage as emphatically as any human being—by striking the ground with a fist, yawning, screaming, staring, pouting, raising their eyebrows, reddening with passion, sucking their teeth, and throwing tantrums. Pain and astonishment could be read clearly on the countenances of the zoo animals Darwin studied. He recounts the almost comic cognitive dissonance of a multispecies group of monkeys who encountered a turtle in their cage for the first time. Curiosity enticed them to come close, and some of them stood up for a better view before reconsidering and running away. Some made jabbering noises, which Darwin interprets as attempts to conciliate the turtle. On other occasions, he observed monkeys raising their eyebrows in wonder before tasting a new food or when listening to a strange sound. When terrified, some monkeys raise their eyebrows, some scream, and some lose control of their bowels. Sometimes, the hair of a frightened monkey stands on end. And once Darwin watched a monkey “almost faint from an excess of terror” when caught.36
Humans are equipped to interpret most animal emotions, Darwin concludes at the end of a long section on animals, because, like our own feelings, animal emotions can be ex-plained according to three principles. The first is the principle of “serviceable associated habits,” which have evolved in mammals, especially, as surely as protective coloration or canine teeth for hunting, because the outward expression derives from a physiological process. An open mouth denoting astonishment, for instance, is the outward expression of a sudden intake of breath, which might be needed for a quick escape.37 The second principle is “antithesis”: in some situations, there is an involuntary tendency to express an opposite emotion, such as smiling in a conciliatory way to mask fear.38 The third Darwin calls the principle of “direct action of the nervous system,” such as trembling in fear.39 Darwin is clearly fascinated by the expression of emotions in different kinds of animals, who are treated in discrete sections of the book and constantly brought into the more general discussions of anatomy and physiology. But the point of this study is that humans and other mammals express emotions in the same ways and for the same reasons. So much for animated machines.
These were Darwin’s lifelong convictions, not so much drawn from his research as motivating it. In a private notebook, he remarked to himself, “Animals—whom we have made our slaves we do not like to consider our equals.—Do not slave holders wish to make the black man other kind? Animals with affections, imitation, fear. pain. sorrow for the dead.”40
IV
It would be almost impossible to exaggerate Darwin’s influence on science and society. His work in what are now an array of separate scientific disciplines has been formative. The effect of his famous books on the scientific literature of his time, not to mention fiction, poetry, and drama, was substantial. Darwin’s contributions to the modernist worldview are almost incalculable; the figure of Darwin continues to be omnipresent not only in science but in cultural forms of all kinds.
Aside from his theories of natural selection, sexual selection, and the struggle for existence, Darwin’s greatest contributions to science and culture have been to help us identify the important questions and to inspire debate—even when this means mounting challenges to the great scientist himself. Built on Darwinian foundations but departing from them are developments in evolutionary biology such as cladistics, the neutral allele theory, and the notion of punctuated equilibrium. Mendelian genetics