bit off a kitten’s claws himself to prove that it could be done by primate teeth.) Although some of these claims have not been verified in modern behavioral observations, they are still good evidence of Darwin’s views. In his opinion, then, the primate maternal instinct is so strong that it can operate independently of parturition or genetic kinship. Maternal instincts are allied to and perhaps the origin of other forms of altruism, including, Darwin suggests, the moral instincts developed by archaic humans.
Following his discussion of the maternal instinct, Darwin develops a more general description of the social instincts. “I fully subscribe to the judgment of those writers who maintain that of all the differences between man and the lower animals, the moral sense or conscience is by far the most important,” he remarks.24 But he also observes that “any animal whatever, endowed with well-marked social instincts, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well developed, or nearly as well developed, as in man.”25 In addition to the nurturing activities that can be associated with mothering, Darwin argues that warning cries, social grooming, mutual defense, cooperative hunting, obedience to a leader, and defense of the weak by the strong can be interpreted as protomoral behaviors. Even vengeance and jealousy, if not moral in themselves, reveal a mental capacity that can be channeled into moral behavior, as Darwin illustrates through an anecdote added in the second edition:
Sir Andrew Smith, a zoologist whose scrupulous accuracy was known to many persons, told me the following story of which he was himself an eye-witness; at the Cape of Good Hope an officer had often plagued a certain baboon, and the animal, seeing him approaching one Sunday for parade, poured water into a hole and hastily made some thick mud, which he skilfully dashed over the officer as he passed by, to the amusement of many bystanders. For long afterwards the baboon rejoiced and triumphed whenever he saw his victim. 26
Two additional anecdotes, first given in volume 1 and later repeated in the “Summary and Concluding Remarks” at the end of volume 2, exemplify Darwin’s thinking about the moral or protomoral instinct in primates. In the first anecdote, he writes,
I will give [an] instance of sympathetic and heroic conduct in a little American monkey. Several years ago a keeper at the Zoological Gardens, showed me some deep and scarcely healed wounds on the nape of his neck, inflicted on him whilst kneeling on the floor by a fierce baboon. The little American monkey, who was a warm friend of this keeper, lived in the same large compartment, and was dreadfully afraid of the great baboon. Nevertheless, as soon as he saw his friend the keeper in peril, he rushed to the rescue, and by screams and bites so distracted the baboon that the man was able to escape, after running great risk, as the surgeon who attended him thought, of his life. 27
A baboon is the hero of the second anecdote, from Alfred Edmund Brehm, like Rengger one of Darwin’s most reliable and complete sources of information on primate behavior. Brehm observed that when a troop of baboons fled from a pack of dogs, the dominant males managed to hustle all of the adolescents out of the way except one, who got stranded on a boulder. When one old patriarch, “a true hero,” returned to the boulder, “coaxed him, and triumphantly led him away,” the dogs were so “astonished” that they did not attack.28 Darwin notes that many mammals, including and especially dogs, have instincts for the “more complex emotions” of loyalty and fellow feeling, but the focus in this part of his argument remains on primates.29
Since there were no behavioral science labs in Victorian England, the only people able to give detailed accounts of animal cognition were zookeepers and the impresarios of animal shows and menageries. In fact, since their livelihood depended on intelligent, reliable animals, impresarios and animal trainers developed strategies not only for training their animals but also for identifying those with the most potential. One of Darwin’s sources was a Mr. Bartlett, whose approach was based on his observations of attention span: the longer a monkey was able to pay attention without being distracted, the greater its potential as an actor, and the more Mr. Bartlett was willing to pay for the animal. Since, in Darwin’s analysis, moral or protomoral behavior is allied to intelligence, the discussion of morality in The Descent of Man is bound up with the discussion of primate intelligence, which (in a parallel to Kant’s explanation of the human mind) is a function of both inherited capacities and learning. For René Descartes, whose 1637 treatise Discourse on Method initiated the European cultural emphasis on reason, humans were the apex of organic life, qualitatively different from the lower animals in their capacity for reason, which was expressed in human language and only human language. In contrast to the human, animals were always on automatic pilot, according to Descartes and the mainstream of Enlightenment philosophy that developed from his work. Although a century later the Utilitarian philosopher Jeremy Bentham pointed out that this analysis of animal nature did not excuse the mistreatment of any creature that could feel pain, the idea of “organic machines” was the default position in science and philosophy until Darwin returned to it.
Darwin saw traces of reason in the animals he studied, just as he saw traces 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