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One morning in January 1961, following a breakfast of baby cereal, condensed milk, and half an egg, a male chimpanzee from Cameroon known to his handlers as Ham was strapped into a pressure-controlled capsule, loaded aboard a NASA rocket, and shot into space. No human had yet been where he was headed. At the time of Ham’s foray to the stars, physicians still feared that crucial bodily functions (including swallowing and cardiac activity) might not weather the weightlessness of astronautic flight. When Ham returned to Earth’s surface with only a bruised nose to show for the adventure, he entered history as the first hominoid to endure outer space.
Chimpanzees—along with their cousins the bonobos—are our closest living relatives. Little wonder we are prone to view them as human prototypes. At least 96 percent of our DNA is shared, and we have many anatomical traits in common, including some of the same blood groups and skeletal features such as delicate sinuses. Using a chimpanzee to aid in “human rating” a NASA space vehicle for astronauts was a test of our mutual fragility. It was also a symbolic gesture, marking space travel as the culmination of our evolutionary trajectory into social beings and tool-users sophisticated enough to leave Earth. One way to understand the moment when Ham was flung into that inhuman realm where the universe skims the planet would be to say that we were, as a species, looking to our ancestral past to forge the frontiers of our future.
The story of our evolutionary congruence with primates is perhaps our most powerful collective origin myth. It has a lineage that is scientific: The prehistoric ancestry of Homo sapiens shares a bough of the tree of life with several primates, including gorillas and orangutans, but most recently forked from that of the chimpanzees and bonobos, about 6 million to 8 million years ago. But that lineage isn’t purely a matter of science. The conjoined heritage of apes and humans has been put to political use, invoked by those seeking to explain aspects of human society as an intractable function of our inner ape. Others have been motivated by that very debate to assert fundamental differences between people and our primate kin.
Now in his 70s, Frans de Waal, the preeminent Dutch American primatologist, has a career’s worth of perspective on the major through lines of simian research, and an abiding interest in how his field’s findings have been drawn on to support narratives of intrinsic human tendencies. De Waal’s own work with chimpanzees in the 1980s loaned the term alpha male to the zeitgeist. He has decried its contemporary connotations of chest-beating chauvinism as a departure from the actual strategies of chimp leadership, which can include more generous and prosocial deeds than acts of bullying.
Issues of sex and gender have been on de Waal’s mind for decades. In Different: Gender Through the Eyes of a Primatologist, de Waal is concerned with the ways in which we look to primates for precedents of communal life and social cohesion, dynamics that are intimately tied up with movements for equality in our human world. Until surprisingly recently, the notion that the prehistory of patriarchy stretches back to a time before humans were human—that a zoology of patriarchy exists—was leveraged to perpetuate discriminatory aspects of culture, situating them as daunting or obdurate scripts of nature. To understand how primatology was partway captured by sexist ideologues, and how it is being freed from those strictures, Differentsuggests, we must look not just to scientists’ shifting mindsets, but also to social and political concerns that inevitably shape research and its reception.
When Ham arrived back at Cape Canaveral the next day, he was delivered to a scrum of reporters and photographers. He screamed with such ungoverned agitation that he soon had to be removed. However distressing Ham’s outbursts appeared, onlookers may not have been surprised to see him acting beastly. The earliest accounts of chimpanzee temperament portrayed the animals as placid, forest-dwelling frugivores, but their profile started to shiftduring the Cold War, based on observations of males in the wild vying ferociously with one another over territory and status. Scattered reports of infanticide among primates were later borne out by fieldwork.
After World War II, the brutality of apes had become an anthropological preoccupation that promised answers to the question: Does our capacity for depravity divide us from the animal kingdom, or does violence lie at the core of our nature, an upshot of our evolution? Such unease only intensified as the brinkmanship of nuclear powers threatened to tilt into even more catastrophic conflict. Against this backdrop, a corrosive vision of primate life grew more vivid: Front and center was a portrait of male tyranny, aggression, antagonism.
Fuel for this conviction can be traced back to the 1920s and the notorious carnage at Monkey Hill, a captive-primate colony at the London Zoo. The Monkey Hill enclosure had been designed with the latest thinking on animal welfare in mind. Rather than consigning apes to stuffy, shadowy cages where lung diseases ran rife, the open-air attraction featured artificial-rock monoliths furnished with heat and light. To this impressive diorama, the zoo sought to introduce an equally impressive animal. Amid a popular craze for all things Egyptian (King Tut’s tomb had lately been discovered), it settled on the hamadryas baboon, a creature that appears in hieroglyphics and, rendered as a deity, on pharaonic jewelry.
With the benefit of hindsight, as de Waal tells it, the exhibit was doomed from the get-go. In their natural habitats in countries such as Somalia and Ethiopia, hamadryas baboons form polygynous groups. Marauding, virile males snatch juvenile females from their kin before they become reproductively mature and amass “harems.” But the zoo wanted only resplendent males, which can weigh nearly twice as much as females and sport a frost-gray ruff around a narrow, pumice-pink face. About 100 were ordered. When the baboons arrived, the zoo staff found that the batch included a handful of surplus females. On release, a bloody furor unfolded. The males grievously injured or killed one another; they butchered or maimed more than half the females, and some copulated with corpses. The event would be retold over the years as an archetypal narrative of male supremacy and barbarity and abject female subservience. This, some were quick to pronounce, was what the animal within us looked like: We’re naturally led to dominate and oppress, or to be oppressed.
Bonobos, rain-forest dwellers that live wild exclusively in the Democratic Republic of Congo, were distinguished from chimps only in 1929. Before that, they had been deemed pygmy chimpanzees, and were believed to mirror chimps in all ways save their diminutive size. Behaviorally, the species are poles apart. A bonobo troop is organized around ranking coalitions of females; power is stratified according to matriarchal authority, and so is access to food. High-up bonobo mothers make matches between their own sons and females to whom they are allied. They wield this control even though males are larger and stronger than females. What gels the community is not physical coercion, implicit or otherwise; it is sex. Bonobos are rightly famous for engaging in frequent sexual activity, much of it nonreproductive (occurring in same-sex pairings or during windows when females cannot conceive).
They kiss. They French kiss. Bonobos practice oral sex and frottage; on one occasion, a female bonobo was observed making use of a knobbled stick as a stimulatory toy for masturbation. Females are said to orgasm, which was once thought a rarity in the animal kingdom, though evidence now supports the theory that female chimps, orangutans, rhesus monkeys, stumptail and Japanese macaques, and even tiny tamarins also experience pleasure and possibly climax. Bonobo copulations are short, about 13 seconds, but the animals often position themselves face-to-face and hold eye contact throughout. This comparatively harmonious suite of behaviors proved so challenging to androcentric models of primate dominance that early researchers, seeking to integrate bonobos into their existing frameworks, were forced to rely on patently contrived explanations: They chalked up female preeminence, for example, to strategic male deference, or ape chivalry.
Had we learned of bonobos first, de Waal observed in 2006 in Scientific American, we would “most likely believe that early hominids lived in female-centered societies, in which sex served important social functions, and in which warfare was rare or absent.” Our picture of the monopolist alpha-male chimp might also have changed if a wider set of observations had colored it. Many of the data on wild-chimpanzee interactions come from East Africa, but troops living in the Taï forest, in Ivory Coast, clash less frequently; their conflicts are not so brutal and the females are subject to less of a power differential—a dynamic de Waal partially attributes to the greater vigilance and cooperation needed to fend off predatory leopards. Male chimps at West African sites have also been seen adopting the dependent young of a deceased or missing parent, a shouldering of fatherly duty at odds with newborn killings witnessed elsewhere.
A corrective is now under way, and if female dominance in the animal kingdom was once overlooked or quashed, in some quarters it is lauded with the language of empowerment. Yet, as de Waal observes, and as Cooke amplifies, there is something reductive in its own way about supposing that a matrilineal society will tend toward a cordial sorority of disseminated power, in which consensus is brokered by affinity. To hold that women are natural peacemakers given to placation is to neuter women’s rage, to turn “female” into a partial, defanged category, foreclosing on the full range of motivations available to males—including status seeking, resource hoarding, nepotism, and vanity. Intransigence, too, is human.
Female ascendancy in the animal kingdom does not, as a matter of course, result in nonviolence. Both books show that aggression exists in bonobo society, directed principally by females. Scuffles might end with fingers or toes bitten clean off, punctured testicles, and deep lacerations. Among western lowland gorillas, Cooke writes, females will sometimes harass silverback males and interrupt their copulations with subordinate females. In the late 1970s, Jane Goodall’s research on chimpanzees in Gombe, Tanzania, showed that infanticide wasn’t only a male prerogative: The mother-daughter pair Pom and Passion also attacked the young of others, and ate them.
The most striking example of female-to-female intimidation comes from savanna baboons. Cooke describes ascendant females tormenting their underlings, obstructing access to water and food, and snatching their babies away only to overhandle and then neglect the infants. This hierarchy has a physiological effect: Lower-ranked female baboons breed later in their development and ovulate less frequently. What’s more, because female baboons pass their status on to their daughters, subordinate ones are best served by having sons, who not only are spared the raids but are more able to climb the social ladder. And biology accommodates: Through an evolutionary mechanism yet to be fully explained, these baboons give birth to more males than females; their social position essentially sex-selects their fetuses.
Were we to seek out a broader vantage on simian life, as Cooke suggests we must, we would find several other paradigms of sexual difference and interrelation. New World monkeys—tailed primates that inhabit the Americas—offer alternative snapshots of collaboration and cooperation. Male black-headed owl monkeys share equal, if not more, duties in rearing their offspring. During the pregnancy of his mate, a male cotton-top tamarin also puts on weight—he will shed it later, carrying their twins on his back. His levels of estrogen and prolactin (hormones associated with birth and bonding) rise in tandem with hers. Some lemurs, natives of Madagascar, have shared child-care arrangements that permit mothers to socialize, forage, and eat without distraction. They build nests for their young, where sentinel adults—typically unrelated, not only females—watch over them.
Cooke and de Waal are both invested in showcasing a range of animal behaviors—including mate choice and gender expression—that usefully redraw the boundaries of “natural” sex difference. In Differentwe meet Donna, a captive chimp that de Waal describes in our human parlance as asexual and gender-nonconforming. Whether identity markers like “butch” and “femme” have any currency for chimpanzees is clearly an inscrutable matter, but as de Waal is at pains to point out, the norms of gender are impressed upon young chimps by their elders. Sex-typical customs are not entirely a matter of biological destiny: Some are nurtured, some are learned; extraordinarily, there are gendered habits that resemble fashions. De Waal collects anecdotes of female-chimp self-adornment—grass blades tucked inside an ear and crushed fruit smeared over the upper body. Labor can be gendered, and can stem from expertise that is taught. Daughter chimps will pay keen attention to their mother’s efforts to extract termites from a mound using twigs selected for the task. Mothers share their favored grub-spearing tools with their female offspring and instruct them, but not so much their sons: Male chimps are less likely to master the skill, or even attempt it. If these can be said to be cultural phenomena, then they are not coercive; chimps that diverge from the settled habits of their sex are not fated to be pariahs.
De Waal’s accounts of chimpanzee interactions show some aspects of gender to be performative and communal in animal worlds, and he resists categorical absolutes when it comes to the sexes, eager to unpack the pronounced inequalities they have led to in the human world. At the same time, though, he emerges sure that, at root, biological sex and gender are linked—that sex difference is neither the pure product of upbringing and socialization nor a matter of choice. One lesson de Waal takes from his studies is that striving for a genderless society is more than anathema; he regards it as arrogant. In his view, sex and power can be decoupled, but to do away with difference altogether is to cut ties with nature and suppose ourselves to be beyond animality.
Cooke, too, argues that greater respect should be paid to difference—but where de Waal frames Homo sapiens as a tailless ape, she is motivated to find new ways for humans to see themselves reflected in nature. With a broader set of examples to pull from, she dedicates more attention to nonbinariness, sexual fluidity, and queerness in species of crustaceans, reptiles, birds, and fish. As it turns out, the planet’s wildlife abounds with varied examples of family-making, shape-shifting, and connectedness (or celibacy) that can help recalibrate pejorative and exclusionary understandings of who is entitled to see themselves reflected in nature.
As I read Different, and Bitch too, I was struck by the number of instances in which the traditionally gendered behavior and biological functions of humans mold the lives of primates in care or captivity. Women are brought into zoos to breastfeed their babies as a demo for naive apes with young who do not yet know how to nurse. Cooke does a stint as a stand-in mother for a juvenile monkey that nests in her hair as she sleeps—an experience that brings her to reflect on her own maternal urgings, or lack thereof. In Different, an orangutan male stalls in his development and fails to acquire the fleshy flanges (cheek pads) of maturity until after the retirement of a senior zookeeper, when the change is at last triggered—as it would be in the wild, following the decline or death of a dominant orangutan male.
I came to wonder whether primates of different species within audible and olfactory range—if not in visual contact, as at a zoo—also influence one another. If chimpanzees have a worldview inflected by what we call patriarchy, are they blind to the sisterhood of bonobos? If bonobos have a matriarchy, would they consider the sexual obstructions of female lowland gorillas to be traitorous? These triangulations are playful, of course, though they illuminate one thing apes could contribute to the development of human society: an expansion of empathy arising from our affinity with the animal kingdom.
Yet not all affinities are helpful; some are harmful. Having retired from the U.S. space program, Ham had difficulty settling into the life of a zoo animal, given how habituated he had become to people. And it’s perhaps worth noting that our evolutionary closeness with primates has changed human sex lives, in ways that have radically altered the course of history: We can’t forget that AIDS is a zoonosis, a disease that crossed species, from chimpanzees to human beings. At their core, Different and Bitch both pursue a question that does, in the end, set us apart from the animal kingdom. We are the sole primate to explore how much our self-knowledge owes to a history of science.