We still live in a world in which a significant fraction of people, including women, believe that a woman belongs and wants to belong exclusively in the home; that a woman should not aspire to achieve more than her male counterparts.
—Rosalyn Sussman Yalow, in her banquet speech on being awarded the Nobel Prize in Physiology or Medicine, December 1977
The long road to the sprawling home of Sarah Blaffer Hrdy, primatologist, anthropologist, and emeritus professor at the University of California, Davis, is flanked by dry fields. She and her husband carved their walnut farm here, near Sacramento, out of almost nothing. The trees are new, the pastures on which their lambs and goats are feeding are new, and they planted the spindly silver walnut groves themselves. She survives under the looming possibility that wildfires could come along to claim it all, as they’ve almost done in the past.
But then any fire would have to battle Hrdy herself, who, now seventy years of age, is a force of nature in her own right. Hrdy’s work into what primate behavior can tell us about human evolution, one scientist tells me, reduced her to tears. For Hrdy’s groundbreaking ideas on women, she’s been described as the original Darwinian feminist.
Primatology is today a female-dominated field, guided by early pioneers like Jane Goodall and Dian Fossey. But when Hrdy started her career in the 1970s, not only did men rule the roost, the accepted wisdom was that human evolution had been shaped largely by male behavior. Males were the ones under pressure to attract as many mates as possible to increase their odds of having more offspring, males were aggressive and competitive in their quest for dominance, and males needed to be creative and intelligent when they hunted for meat.
As our closest evolutionary cousins, primates were naturally expected to follow similar patterns. When male primatologists went into the field, they would often focus on aggression, dominance, and hunting, Hrdy tells me. Females were routinely overlooked. They were believed to be passive, sexually coy, and generally at the mercy of stronger, larger males. Indeed, early studies of chimpanzees—a species in which males happen to be particularly aggressive and dominant—reinforced this.
Things changed for Hrdy when she went out into the field for herself. She finally saw how this account of females might be wrong.
It began with a trip to Mount Abu, a region of Rajasthan, northwestern India, which is home to a species of monkey known as the Hanuman langur. Hanuman is the name of the Hindu monkey god, a symbol of strength and loyalty, while “the name langur is Sanskrit for having a very long tail,” she explains to me in her large office, which is decorated with framed drawings of primates. “They are the beautiful, elegant gray ones with the black gloves and faces.” Hrdy had heard that male langurs were killing infants of their own species. It was so strange a phenomenon that scientists assumed there must be something desperately wrong with them. Animals simply didn’t behave in ways that were bad for their group, they thought. The only possible cause must be that the male monkeys had gone mad. Overcrowding had created a pathological hotbed of aggression, perhaps.
The truth was stranger. When Hrdy watched closely, she began to realize the murders weren’t random acts of madness at all. In the everyday course of life, she noticed that male langurs were far from violent toward infants. “I would see young langurs jumping on a male langur reclining on the ground as if he were a trampoline. He was completely tolerant of the infants in his troop. There was nothing pathological about it,” she explains.
The rare infanticides turned out instead to be carefully calculated. And they were committed by males from outside the breeding group. “When I first did see infants missing, and then later I actually saw a male attack infants, it was very goal-directed stalking, as if by a shark. Day after day, hour after hour.” What was making a male commit this gruesome killing was the expectation that, without her baby, a mother would have to mate again. If he didn’t kill the infant, he would have to wait a year before she finished nursing and started ovulating. She couldn’t mate any sooner.
To scientists, the idea was shocking. Hrdy had shown that a monkey could choose to kill a healthy young member of his own species simply to perpetuate his bloodline. Infanticide went on to become a fruitful area for animal research. The behavioral patterns Hrdy saw, detailed in her 1977 book, The Langurs of Abu: Female and Male Strategies of Reproduction, have since been reported for more than fifty primate species as well as other animals.
But something else also fascinated her about these murders. It was the extraordinary way the female Hanuman langurs reacted. They weren’t passive. They didn’t carelessly allow their infants to be killed by aggressive males. Instead, they banded together and put up fights to fend them off. This observation, too, challenged long-standing ideas about natural primate behavior. It showed that females weren’t only fiercely protective of their children (which might have been expected), but that they could also be aggressive and cooperative.
Questioning assumptions can have a remarkable ripple effect. Further work by Hrdy showed that female langurs were promiscuous, too, contrary to popular wisdom about females being sexually coy. Male langurs, she noticed, attacked only those infants being carried by an unfamiliar female—never by a female with which they’d mated. By having as many mates as possible, Hrdy suggested that female langurs might be strategically lowering the odds of a male killing her infant.
It became impossible for primatologists to ignore females any longer.
Hrdy believes that being a woman in her field is one reason she noticed behavior that hadn’t been recognized before. She was driven to investigate what others may have chosen to overlook. “When a langur female would leave her group, or when she would solicit a male when she was pregnant, a male observer may say, ‘Well, that’s just freak,’ and not even follow her to find out where she was going or what she was doing. A woman observer might empathize more with the situation or be more curious.”
Her work didn’t just mark a sea change in how primates were beginning to be understood but was a personal revelation as well. Hrdy had been raised in a conservative, patriarchal family in south Texas. Noticing how competitive and sexually assertive females could be in the rest of the primate world prompted her to question why women in her own society should be thought of as any different. Primates, particularly great apes such as chimpanzees, bonobos, gorillas, and orangutans, have long been used by science as a way of understanding our own evolutionary origins. We share roughly 99 percent of our genomes with chimpanzees and bonobos. In genetic terms, we are so close that primatologists routinely refer to humans as another great ape. So if other female primates could show so much variation in their behavior, why did evolutionary biologists still characterize women as the naturally gentler, more passive, and submissive sex?
Trying to get her male colleagues to see primates from a female’s perspective, though, was a battle. When Hrdy returned from her fieldwork in Mount Abu in the 1970s, despite social change happening around her, including a resurgence in feminism, science was still very much a boys’ club. One time at a conference, when she was asked to define what feminism meant to her, Hrdy recalls saying, “A feminist is just someone who advocates equal opportunities for both sexes. In other words, it’s being democratic. And we’re all feminists, or you should be ashamed not to be.” But equal opportunities weren’t always encouraged, in her field at least. Her work, as well as that of many other women scientists, was sometimes treated differently from that of her male counterparts. Some people refused to acknowledge her research, let alone incorporate its ideas.
Hrdy used to get together with other female researchers at womenonly house parties to discuss the problems they faced. They euphemistically called them their “broad discussions.” And there was plenty to discuss. The influential evolutionary biologist Robert Trivers, a colleague of Hrdy’s, once told a reporter that Hrdy should concentrate on being a mother instead of on her work She forgives him now, she tells me. (Trivers, meanwhile, tells me that he intended the remark to be a secret, and admits he’s sorry it was made public.)
Exasperated, she even used her work on apes and monkeys to make covert remarks about her male colleagues. “I was writing about how male baboons were the basis of social organization. Males compete with males, and then the dominant males form alliances with each other so as to improve their access to females. And then I would make these very oblique parallels to what went on in American universities,” she remembers. “I was, of course, referring to male professors who, when called out for sleeping with academic subordinates, would back one another up. All through my career, these things were going on.”
Hrdy’s feminism and science met in the middle, not just because of the behavior of some men in her field but also because she recognized that scientific theories that ignored female behavior were incomplete. “In science, paying equal attention to selection pressure on both males and females, that’s just good science. That’s just good evolutionary theory,” she tells me. One of the most important frontiers, as she saw it, was understanding mothers and how they defined a woman’s role in human evolution. It was a question that would also lead her back again to the dark phenomenon of infanticide.
“Cooperative breeding in humans is becoming more and more important.”
I’m in the ape enclosure at San Diego Zoo, one of the biggest zoos in the world.
I’m transfixed by a fluffy two-year-old bonobo. She’s cheerfully hanging on to her mother’s fur as the ape leaps from branch to floor, letting go of her to playfully roll on the ground for a few seconds before quickly returning. I have a two-year-old as well. And the bonobos’ behavior reminds me of my own close relationship with my son. In the little bonobo I see a similar mischievousness and even the hint in her of his cheeky smile. They watch each other the same way that we do. The similarities between us are uncanny.
At close quarters like this, I start to understand why humans are sometimes regarded as another great ape, alongside bonobos, chimpanzees, gorillas, and orangutans. But as much as we have in common, there’s one important contrast between me and the bonobo mother. In the entire time I’m looking into the glass enclosure, I never see her lose contact with her infant. At no point does the little one fall out of her mother’s protectively tight orbit. My son, on the other hand, is already at the other end of the enormous zoo with his father.
Human motherhood is rarely the single-handed job that it is for chimpanzees and bonobos. Of course, this is something most of us know from our own experience as children or parents. When I’m at home in London, my son typically spends half the week being cared for by other people, including his father, grandmother, and nursery staff. Aunts, uncles, and friends step in too, sometimes. When I’m traveling for work, I go days without seeing him. This isn’t unusual. Few babies or toddlers get through their early years without ever leaving their mothers’ sides.
Primates are different. According to Sarah Hrdy, there are nearly three hundred primate species, and in about half of them you’ll rarely see a female ape or monkey out of contact with her child. The infants, in turn, stick close to their mothers, sometimes for years. “Under natural conditions, an orangutan, chimpanzee, or gorilla baby nurses for four to seven years and at the outset is inseparable from his mother, remaining in intimate front-to-front contact a hundred percent of the day and night. The earliest a wild chimpanzee mother has ever been observed to voluntarily let a baby out her grasp is three and a half months,” Hrdy notes in her 2009 book, Mothers and Others: The Evolutionary Origins of Mutual Understanding. She includes a picture she once took of a female langur who was so attached to her baby that she faithfully carried around its corpse after it died.
Others have made similar observations. “Mothers carrying dead infants is not uncommon in the primate world,” confirms Dawn Starin, a London-based anthropologist who has spent decades studying primates in Africa, Asia, and South America. In her research on red colobus monkeys in Gambia, one female “carried her maggot-riddled infant around with her for days, grooming it, sticking it in the crotches of trees so that she could feed without it slipping to the ground, and never letting any of the others touch it.” Encounters like these left her with the impression that an infant is treated like an extension of the mother’s body, a real part of her, and not a separate being.
For humans, the universal pattern seems to be that mothers are just as protective of their children but not so constantly attached. This isn’t something that’s true only of modern parents in big cities but everywhere across the world. It really does take a village to raise a child.
For anthropologists trying to get a grip on our evolutionary history, the best case studies are people who live the way our earliest ancestors might have, hunter-gatherers. Modern-day hunter-gatherers are rare and dwindling, drawing a subsistence living off the land, foraging for wild plants and honey, or hunting animals. They’re an imperfect window on our past, partly because each community is different from the next, depending on its environment, and also because other cultures have encroached on them over the years and distorted how they live. But by watching their lifestyles and behavior, we can still get some sense of how humans might have lived many thousands of years ago, before societies began domesticating animals and before agriculture.
Some of the most studied hunter-gatherer groups are in Africa, the continent from where all humans originally migrated. This makes them arguably the most reliable source of data for evolutionary researchers. They include the !Kung, bushmen and bushwomen living in the Kalahari desert in southern Africa, the Hadza who live in the Lake Eyasi region of northern Tanzania, and the Efé in the Ituri Rainforest in the Democratic Republic of the Congo. Anthropologist Sarah Hrdy notes that all three of these societies have people who play parental roles to other people’s children—known as “alloparents.”
She describes this system as “cooperative breeding.” In her book Mothers and Others she writes, “!Kung infants were held by others some twenty-five percent of the time—a big difference from other apes, among whom new infants are never held by anyone other than their mother.” Among the Hadza, newborns are held by alloparents 31 percent of the time in the first days after birth. For children under four years of age, people other than their mothers hold them around 30 percent of the time. In central-African foraging nomadic communities, including the Efé, mothers share their babies with the group immediately after birth, and they continue this way. Efé babies average fourteen different caretakers in the first days of life, she adds, including their fathers.
One more difference between humans and apes is how we give birth. Chimpanzee females are known to move away and seek seclusion before they give birth, to hide from predators or others who might harm their newborns (chimps enjoy meat, and have been known to kill and eat infants of their own species). Humans, on the other hand, do exactly the opposite. Expectant mothers almost always have people to help them when their babies are due. In my case, it was an entire team, including my husband, sister, doctors, and a midwife. Anthropologists Wenda Trevathan at New Mexico State University and Karen Rosenberg at the University of Delaware have noted that childbirth is a lonely activity in few human cultures. Helpers are so important that women may even have evolved to expect them, they’ve argued. Their theory is that the awkward style of delivery of human births and the emotional need that mothers have to seek support during birth may be adaptations to the fact that our ancestors had people aiding them when they delivered their babies.
All this evidence suggests that cooperative breeding is an old and universal feature of human life, not a recent invention. And there are good reasons why. “One of the primary traits that we have is that we’re sort of the rabbits of the great ape world,” explains Richard Gutierrez Bribiescas, professor of anthropology at Yale University, who has studied the role of fathers in human evolution. “We have very high fertility compared to other great apes, compared to chimpanzees, gorillas, and orangutans. And we tend to produce these very large offspring that require a lot of long-term care,” he tells me.
Most primates, meanwhile, will generally wait until the first infant has matured before having the next. A female bonobo would struggle to feed herself and move lithely through the forest if she had to drag around a litter of baby bonobos clinging to her fur.
Two notable exceptions are titis and tamarins, both species of New World monkey in which fathers are extraordinarily involved in child care. Anthropologist Dawn Starin tells me, “When I studied a group of titi monkeys in Peru, the infant was usually carried by the father and spent most of its time with him. The father is completely involved with the rearing of the young. The mother was really just a dairy bar, a pair of milk-secreting nipples.” Like humans, titi monkeys are cooperative breeders. Some captive studies on this species, she says, have even suggested that the infant may be primarily attached to the father rather than the mother.
Tamarin monkeys also rely on the efforts of both parents, simply to cope. “With tamarin monkeys, for reasons we don’t understand, they twin, and the twins are very large,” explains Bribiescas. “So the only way that can be viable is. . .some kind of paternal care. Otherwise it is very unlikely that the mother would be able to support these two very large twins.” This support is so vital that tamarins are known to neglect their children if they don’t have the help anymore. Sarah Hrdy has noted, according to data from a colony living at the New England Primate Research Center, that when a tamarin mate dies, the infants’ survival odds plummet. “There was a twelve percent chance of maternal abandonment if the mother had older offspring to help her, but a fifty-seven percent chance if no help was available,” she writes.
Abandonment and neglect like this are rare. In the thousands of hours that scientists have watched monkeys and apes in the wild, very rarely has anyone seen one injure her infant deliberately. Primate mothers may be incompetent sometimes, especially with their first babies, but they hardly ever choose to let their offspring die. This, too—shocking though it may sound—is a feature in which humans again mark themselves out from their evolutionary cousins.
The maternal instinct in humans is not an automatic switch, which is flicked on the moment a baby is born.
This is Sarah Hrdy’s radical proposition. All over the world, mothers are known to admit that it takes time for them to fall in love with their babies, while some never do. In some unfortunate cases, mothers deliberately neglect and even kill their newborns. This may seem utterly unnatural. After all, we assume the maternal instinct is as strong and immediate in humans as it is in any other creature. It’s considered a fundamental part of being a woman. So much so that those who don’t want children or reject their own are sometimes considered odd. But the reality, observes Hrdy, is that it’s more common for mothers not to form an immediate attachment to their offspring than we like to believe.
Her argument is that this is a legacy of cooperative breeding. Like tamarin monkeys, humans often rely on help to cope with raising their children. Hormones released in pregnancy and childbirth help a mother bond to her baby. But this bond may also be affected by her circumstances. If her situation is particularly dire, she may feel she has no choice but to give up altogether.
In Britain, studies estimate that between thirty and forty-five babies are killed every year—about a quarter of these within the child’s first day of life. According to research in 2004 by Michael Craig, a lecturer in reproductive and developmental psychiatry at the Institute of Psychiatry at King’s College London, this is likely to be an underestimate, because these kinds of killings can easily go unreported. But even as the reported figures stand, infants are at a bigger risk of homicide than any other age group. For the babies killed soon after birth, the most common perpetrators are teenage mothers, especially those who are single and living at home with parents who might be disapproving of their pregnancies. Most of them aren’t killing their babies because they’re psychotic or mentally ill, says Craig, but because of the desperate positions they find themselves in.
To make her case, Sarah Hrdy has also investigated a particularly grisly historical example. In the eighteenth century in urban parts of France, as many as 95 percent of mothers sent their children away to be wet-nursed by strangers, sometimes in questionable conditions. Her research, outlined in a series of lectures she gave at the University of Utah in 2001, suggests that the mothers must have known this would dramatically lower their babies’ odds of survival. Culture dictated that they do it, so they did. The deadly practice was evidence, she argues, that not every human mother protects her newborn at all costs. Female infanticide in Asia today is sometimes also carried out with the complicity of mothers. Again, society influences how they respond to a birth.
Hrdy’s hypothesis about the profound importance of cooperative breeding is a difficult one to prove, especially given the myriad pressures that pregnant women experience in the modern world. But it also has the power to release women of the guilt they may feel when they’re unable to cope alone. If we are natural cooperative breeders—a species in which alloparents are part of the fabric of families—it’s unreasonable to expect women to manage without any help. For Hrdy, a feminist, this line of research also has obvious political implications. It reinforces why lawmakers shouldn’t outlaw abortion and force women to have babies they feel they cannot raise or do not want. It also highlights how important it is that governments provide better welfare and child care for mothers, especially those who don’t have support at home.
The weight of evidence does at least seem to be in favor of the idea that humans didn’t evolve to raise their children single-handedly. Child care was not the sole responsibility of mothers. “What we’re finding is that cooperative breeding in humans is becoming more and more important in terms of our thinking,” agrees anthropologist Richard Bribiescas. As evidence builds around this and what it means, it’s becoming clearer just how important alloparents are in the human story. And it also raises an interesting question: If mothers didn’t evolve to parent alone, who else around them would have been providing the most support?
“We see a huge range of plasticity in how much engagement there is in human males.”
Sarah Hrdy tells me that when she welcomed her first grandchild last year, she took the opportunity to run a small experiment on her family. Arriving at her daughter’s house, she took saliva samples from herself and her husband. She took another set of samples after spending time with the new baby. Tests revealed that they had both experienced a rise in oxytocin, the hormone associated with love and maternal attachment.
Our bodies betray how strong the emotional connections can be between children and people who aren’t their parents. Physical contact with a baby, scientists have long known, can have dramatic effects on a mother’s hormone levels. These hormones in turn influence how she bonds with her child. Others who aren’t mothers, we now know, can experience these hormonal changes, too.
Evolutionary biologists have often assumed in the past that, of all the people providing support to mothers, fathers would have been front and center. In his 2006 book, Men: Evolutionary and Life History, Richard Bribiescas suggests exactly this. And from the perspective of how we’ve lived for centuries, often in monogamous marriages and nuclear families, this seems to make sense. Even if they weren’t directly involved in child care, the material help that fathers brought to families, such as food, must have been crucial to keeping children alive and thriving.
Some recent studies, however, don’t agree. In a 2011 paper in Population and Development Review, Rebecca Sear at the London School of Hygiene and Tropical Medicine and David Coall at Edith Cowan University in Australia pulled together all the published studies they could find on how the presence of fathers, grandparents, and siblings affect a child’s survival. They found that other family members were so valuable that, once a child passed the age of two, they could even cushion the impact of an absent mother. Where this help came from, though, was more of a surprise. Older siblings had a more positive effect than anyone besides the mother. After this came grandmothers, then fathers, followed far behind them all by grandfathers.
“Fathers were rather less important: in just over a third of all cases did they improve child survival,” Sear and Coall note in their paper.
This doesn’t mean that hands-on fathering isn’t important. Just that it isn’t always there. In 2009 anthropologist Martin Muller at the University of New Mexico and his colleagues studied how much effort men in two neighboring but different East African communities put into parenting. In one, the Hadza hunter-gatherers, they found that fathers were involved in everything from cleaning to feeding infants, spending more than a fifth of their time interacting with children under three if they were in the camp at the same time, and also sleeping close to them. In the other, a pastoralist and warrior society called the Datoga, they found a strong cultural belief that looking after children was women’s work, with men eating and sleeping separately and not interacting much with infants. Their hormone levels reflected the difference in parenting styles. The more involved fathers—the Hadza—produced less testosterone than Datoga fathers.
“We see a huge range of plasticity in how much engagement there is in human males,” admits Richard Bribiescas, from “the most doting and caring father, and everything is great and lovely, to a father that’s sort of engaged and maybe just brings food and resources home, to the ultimate, very horrific cases of things like infanticide.” If society expects men to be involved in child care, they are, and they can do it well. If society expects them to be hands-off, they can do that, too.
This plasticity is unique to humans. “In other great apes and other primates you simply don’t see that. They’re locked into one strategy,” he adds.
If in our evolutionary history, caring for children is something that would have been done not just by mothers but also by fathers, siblings, grandmothers, and others, the traditional portrait we have of family life starts to crack. A nuclear family with one hands-on father certainly isn’t the norm everywhere. In a few societies, for example, children even have more than one “father.” In Amazonian South America, there are communities that accept affairs outside marriage and hold a belief that when a woman has sex with more than one man in the run-up to her pregnancy, all their sperm help build the fetus. This is known by academics as “partible paternity.” Anthropologists Robert Walker and Mark Flinn at the University of Missouri and Kim Hill at Arizona State University, who have confirmed how common partible paternity is in the region, claim that children benefit from these family arrangements. With more fathers, their odds of survival go up. They have more resources and better protection from violence.
This all points to the possibility that living arrangements among early humans could have taken any number of permutations. Monogamy may not have been the rule. Women, if they weren’t tied to their children all the time, would have been free to go out to get food and perhaps even hunt. The Victorian ideal that Charles Darwin based his understanding of women upon—mother at home, taking care of the children, hungrily waiting for father to bring home the bacon—is left out in the cold.
“A theory that leaves out half of the human species is unbalanced.”
It was April 1966.
Some of the most important names in anthropology had come together at the University of Chicago to debate what was then a fast-growing body of research about the world’s hunter-gatherers. The symposium they were all a part of was headlined “Man the Hunter.” And they would help shape the way a generation of scientists thought about human evolution.
The gathering was appropriately titled. The “man” in the title, as anyone attending would have guessed, really did refer to men, not to all humans. In almost no hunter-gatherer communities were women known to routinely hunt. Even so, this one activity was believed to be the most important in human evolutionary history. Hunting made men band together in groups and work cooperatively, so they could target their prey more effectively. It forced men to be inventive and create stone tools. Hunting may also have been what prompted men to develop language so they could communicate more effectively. By bringing home meat, followed the logic, men were able to provide themselves, women, and their hungry children with the densely packed nourishment they needed to develop bigger brains and become the smart species we are today.
Hunting was everything.
“In a very real sense our intellect, interests, emotions and basic social life—all are evolutionary products of the success of the hunting adaptation,” wrote leading anthropologists Sherwood Washburn and Chet Lancaster in their chapter of a 1968 book about the symposium, also titled Man the Hunter. The importance of the kill, dramatic as it was, would later be popularized for a wider audience in a 1976 book by Robert Ardrey, a Hollywood screenwriter who changed career to focus on anthropology. “It is because we were hunters, because we killed for a living, because we matched wits against the whole of the animal world, that we have the wit to survive even in a world of our own creation,” he wrote in The Hunting Hypothesis.
But for some anthropologists, this way of characterizing the past struck a bum note. For one thing, it utterly diminished the role of women. This wasn’t even a time when sexism could go easily unchecked. Universities were starting to offer courses in women’s studies and gender studies, and female life scientists and social scientists were becoming famous in their fields. Primatology was on its way to becoming a female-dominated discipline. How could anthropologists now claim that women were the sidekicks in human history? By the end of the conference a growing cadre of scientists—many of them women, but some men too—were outraged. Already marginalized for decades, the hunting hypothesis was threatening to airbrush women out of the evolutionary story altogether.
Capturing their feelings, in 1970 anthropologist Sally Linton (later publishing under the name Sally Slocum) presented a provocative retort at the American Anthropological Association’s annual meeting. It was titled “Woman the Gatherer: Male Bias in Anthropology.” Her words echoed those of suffragist Eliza Burt Gamble, whose critique of Charles Darwin and his contemporaries had been published around eighty years earlier. Linton passionately condemned her field as one that had been “developed primarily by white Western males, during a specific period in history.” Given this bias, she said, it wasn’t surprising that anthropologists had failed to ask just what it was females were doing while the males were out hunting.
“A theory that leaves out half of the human species is unbalanced,” Linton announced. “While this reconstruction is certainly ingenious, it gives one the decided impression that only half the species—the male half—did any evolving.”
The focus of her complaint was the notion that women were somehow not equal providers for their families. Experts at the 1966 “Man the Hunter” conference already knew this wasn’t true. In fact, one organizer, Richard Lee, had been the very anthropologist to establish the immense importance of women in sourcing food. His fieldwork had shown that, while often not hunters of big animals, women were responsible for getting hold of every other kind of food, including plants, roots, and tubers, as well as small animals and fish. Men were the hunters, but women were the gatherers.
Gathering was arguably a more important source of calories than hunting. In 1979 Lee noted that among the !Kung hunter-gatherers in Africa, women’s gathering provided as much as two-thirds of food in the group’s diet. As well as feeding their families, women were often also responsible for cooking, setting up shelter, and helping with hunts. And they did all this at the same time as being pregnant and raising children.
By elevating hunting, anthropologists were willfully ignoring women, according to Sally Linton. She reasoned that the hunting hypothesis couldn’t possibly explain as much about human evolution as it claimed to. If hunting by men was what drove communication, cooperation, and language in our species, then why were there so few psychological differences between men and women? The original social bond in any human society would clearly have been between a mother and her child, she added, not between hunters. And what about the intellectual challenges of raising children? “Caring for a curious, energetic, but still dependent human infant is difficult and demanding. Not only must the infant be watched, it must be taught the customs, dangers and knowledge of its group,” she added.
The title of Linton’s passionate talk, “Woman the Gatherer,” was seen as the female counterpoint to “Man the Hunter.” And it became a rallying cry for other researchers who were determined to bring women to the heart of the human evolutionary story.
Adrienne Zihlman, now a prominent anthropologist at the University of California, Santa Cruz, had been teaching for a few years by the time Sally Linton addressed the American Anthropological Association in 1970. “It really struck a note,” Zihlman tells me. We are sitting in her home in San Francisco, a stack of papers and books in front us on the table. One book, which she wrote a chapter for in 1981, is titled Woman the Gatherer.
“Women were invisible. It’s hard for you to imagine what that was like. It was making women visible for the first time,” Zihlman continues. She was deeply inspired by Linton and decided to follow up on her ideas and build hard data around them, digging up evidence from observations of hunter-gatherers, primates, and fossils. Through detailed research like this, living with hunter-gatherers, and dissecting their lives, anthropologists and ethnologists like her now finally understand just how mobile, active, and hard working women really are.
One important myth to be cracked was that males were always the main inventors and tool users in our past. Zihlman is convinced this is wrong. While chimpanzees tend to pick and eat their food alone and on the spot, at some point in history humans began to gather and bring it back home to share. They would have needed containers to hold all this food, as well as slings to carry their babies while they gathered—and both probably before anyone created stone hunting tools. These are likely to have been the earliest human inventions, she says, and they would have been used by women. One of the earliest tools, meanwhile, would have been the “digging stick.” She tells me that female gatherers to this day use digging sticks to uncover roots and tubers and kill small animals. They’re as multifunctional as Swiss army knives.
What digging sticks, slings, and food bags all have in common, though, is that they’re wooden or made of skin or fiber, which means they break down and disappear over time. They leave no trace in the fossil record, unlike hardwearing stone tools that archaeologists have assumed are used for hunting. This is one reason, adds Zihlman, that women’s inventions, and consequently women themselves, may have been neglected by evolutionary researchers.
Other species provide clues, too, that suggest hunting and toolmaking are not exclusively male domains. The primatologist Jane Goodall has shown through her intimate observations of chimpanzees that females are more skilled at using simple tools and cracking nuts with hard shells than males are. This is partly because they spend more time doing it. Zihlman points out in a paper in the journal Evolutionary Anthropology in 2012 that young chimpanzees learn from their mothers to “fish” for termites and that their daughters spend more time watching them than their sons. Some chimpanzees have even been spotted hunting for small animals, such as squirrels, using sticks that they bite off into sharp points. “It is predominantly females, particularly adolescent females, that hunt this way, doing so almost three times as often as males,” she writes.
Other scientists have also tallied how many calories hunter-gatherers bring home to their families and how this breaks down by sex. They’ve reinforced earlier observations that the food brought home by women is vital to keeping everyone alive.
Men’s contribution to calories from hunting varies hugely, depending both on the society and the environment they’re in, explains Richard Bribiescas at Yale University, who has done fieldwork with the !Kung in East Africa and the Aché hunter-gatherers in eastern Paraguay. “For example, in the group that I worked with years ago, the Aché, they were bringing in 60 percent of the calories. In groups like the !Kung, men were bringing in 30 percent of the calories. It also makes a difference in the type of game they’re going after. In the !Kung, for example, they were going after very large, high-risk game like giraffe. It was boom or bust. Whereas with the Aché in Paraguay, the largest thing they would hunt would be the tapir, which is about the size of the small pig. They were getting a lot of small animals, which are a lot more reliable. So it really varies with the environment,” says Bribiescas.
In a 2002 paper in the Journal of Human Evolution, anthropology professors at the University of Utah James O’Connell and Kristen Hawkes confirmed that hunting is rarely a reliable source of food. Observing more than two thousand days of hunting and scavenging, they estimated that the Hadza in northern Tanzania, for instance, successfully brought home a large animal carcass only one hunting day in thirty. In none of the societies that have been studied do men bring home all the food. At worst, they bring in far less than half. This means that relying on male hunting, in many places, would leave families hungry.
“Something beyond family provisioning was needed to explain men’s work,” Hawkes and her colleagues have written. They’ve argued that the reason male hunter-gatherers persist with hunting big animals rather than gathering or chasing smaller prey, like women tend to do, is that it offers them an arena to show off to others, boosting their status and attracting mates.
But the question of who does more for the survival of their families remains a bone of contention. Hawkes’s observations have been challenged by anthropology professors Michael Gurven at the University of California, Santa Barbara, and Kim Hill at Arizona State University. In a 2009 paper they published in the journal Current Anthropology, titled “Why Do Men Hunt?,” they revisit the hunting hypothesis. Gathering plants, done mainly by women, can be a risky source of food, they argue. Plants are often seasonal, for instance. And men in some societies, including the Aché hunter-gatherers in Paraguay, do target small, more reliable game, suggesting that they aren’t just looking to display their hunting prowess.
Rebecca Bliege Bird, a professor of anthropology at Pennsylvania State University’s College of the Liberal Arts, meanwhile believes that researchers such as Gurven and Hill cling to the hunting hypothesis because of the communities they’ve happened to study, in particular, the Aché. “Some people’s ideas about what hunting and gathering were like in the past tend to be shaped by the society they’ve spent most of their time in,” she explains. “In Oceania, Southeast Asia, and sub-Saharan Africa, women contribute a lot to production. And in other places, like South America, women contribute less to production.”
She adds that the evidence to date makes the hunting hypothesis nothing less than “old-fashioned and ridiculous.”
The other myth around the hunting hypothesis is the question of language and intelligence. Were anthropologists right in thinking that male hunters drove forward the development of human communication and brain size? Sarah Hrdy’s work on infants and mothers has supported Sally Linton’s suggestion that language probably evolved, not through hunting, but more likely through the complex and subtle interactions between babies and their caregivers. Over generations, Hrdy explains, babies that were just a little better at gauging what others were thinking and feeling were the ones most likely to be cared for. “They have to engage and appeal to others. They have to understand what someone else is going to like,” she adds. This quest for engagement could have provided the original urge to communicate, pushing our ancestors beyond simple chimp-like calls toward sophisticated language.
More recent research has bolstered this idea. In the summer of 2016, Steven Piantadosi and Celeste Kidd in the Department of Brain and Cognitive Sciences at the University of Rochester, New York, published evidence in Proceedings of the National Academy of Sciences that child care may have been one major factor in driving up human intelligence. Human babies are particularly immature and helpless when they’re born, compared to other mammals. One reason for this is that their heads are so big—to make room for their large human brains—that if they were born much later, they simply wouldn’t fit through their mothers’ birth canals. “Caring for these children, in turn, requires more intelligence—thus even larger brains,” write Piantadosi and Kidd.
A runaway evolutionary process, in which brains got even bigger and babies were born even earlier, could explain why humans eventually became as smart as they are now.
The picture all this leaves us with is very different from that of the sedentary, weak, and dependent woman that some evolutionary biologists have painted in the past.
“When you see pictures of what these women can do, they’re pretty strong,” Adrienne Zihlman tells me. In her chapter in the 1981 book Woman the Gatherer, she includes a striking image, shot by anthropologist Richard Lee, showing a seven-month pregnant !Kung woman striding through the Kalahari like an athlete. She’s supporting a three-year-old child on her shoulders, brandishing a digging stick in one hand, and hauling the food she’s gathered on her back to take home.
Seen from an evolutionary context, strength like this makes sense. Our sedentary lifestyles and beauty ideals that prize skinniness and fragility in women over size and strength can blind us to what women’s bodies are capable of. But if the lives of modern-day hunter-gatherers are anything to go by, our female ancestors would have done plenty of hard physical work. Subsistence living, which is the way humans survived for several million years before they settled into food production of their own around ten thousand years ago, is so tough that they wouldn’t have had any other choice. Millions of women around the world now still have no option but to do hard, heavy work to survive.
Women are also known to be particularly good at endurance running, notes Marlene Zuk, who runs a lab focusing on evolutionary biology at the University of Minnesota. In her 2013 book Paleofantasy, she writes that women’s running abilities decline extremely slowly into old age. They’ve been known to go long distances even while pregnant. One example is Amber Miller, an experienced runner who in 2011 ran the Chicago marathon before giving birth seven hours later. English runner and world record holder Paula Radcliffe has also trained through two pregnancies.
For a large chunk of early human history, when humans migrated out of Africa to the rest of the world, women would have traveled hundreds or thousands of miles, sometimes under extreme environmental conditions. If they were pregnant or carrying infants, the daily physical pressures on them would have been far greater than those faced by men. “Just reproducing and surviving in these conditions, talk about natural selection!” says Zihlman. “Women have to reproduce. That means being pregnant for nine months. They’ve got to lactate. They’ve got to carry these kids. There’s something about being a human female that was shaped by evolution. There’s a lot of mortality along the way that really can account for it.”
This may even explain the mystery of why women are on average biologically better survivors than men are. “There is something about the female form, the female psyche, just the whole package, that was honed over thousands and thousands, even millions of years to survive and spread around the world,” says Zihlman.
The harsh realities of subsistence living would also have forced women and men to be flexible and share workloads. “The thing about hunter-gatherer societies is that there is less rigid division of human labor because everybody learns everything,” she explains. In our ancient past, thousands of years ago, it’s even possible that men would have been far more involved in child care and gathering while women would have been hunters.
“Being a woman hunter is a matter of choice.”
“I was up the river, and I saw a couple of women with bows and arrows. That was 1972,” recounts anthropologist Bion Griffin, an emeritus professor at the University of Hawaii at Manoa. He and fellow anthropologist Agnes Estioko-Griffin (they are married) are speaking to me over an unreliable line from the Philippines, where they both live.
Bion describes his first eye-opening trip to the island of Luzon in the Philippines. It’s home to a tiny hunter-gatherer community known as the Nanadukan Agta. Today, logging, farming, and migration have changed the Agta way of life utterly, drawing them away from subsistence living and integrating them into the farms around them. They share this fate with many of the other remaining hunter-gatherers around the world. But forty years ago the Griffins were lucky enough to catch the tail end of the Agta’s old way of life. The Nanadukan Agta were then known to fish and hunt regularly for wild game such as pigs and deer, using bows, arrows, and the help of dogs.
What made them unusual, though, was that Agta women hunted and fished.
Women hunters are not unheard of. In the 1970s the scientific literature included a few references to female hunters scattered across the globe, all the way from the Tiwi people in hot Australia to the Inuit in the cold Arctic north. But Nanadukan Agta women were perhaps the most enthusiastic and regular female hunters of all. “We found first of all that within this particular group, a considerable number of women hunted,” Bion tells me. “A lot of women don’t carry bows but will use knives, or knives strapped onto a sapling that’s been cut down, in order to finish off a cornered deer or a pig that the dogs are holding. . . . And we found that there were a few women that loved to hunt. We found out that they were very successful in hunting.”
Women hunted even when they had alternative ways of feeding themselves, adds Agnes. She recounts one time when the men of the group went off for several days on a hunt. Rather than gathering roots or fruits or trading with local farmers, a group of women went out on their own and killed a pig. “It was their choice to go off hunting,” she explains. Bion adds, “It varies from women opportunistically hunting and killing when traveling in the forest, including when they’re carrying their babies and kids with them, to young grandmothers or very mature women who had a long history of hunting but who have no real demands on child care, except the usual grandmothers always helping out and taking care.”
Agnes Estioko-Griffin published some of these findings in a paper in 1985. She noted that every able-bodied Agta, male or female, knew how to spearfish. Of twenty-one women above the age of fourteen in the group, fifteen were hunters, four had hunted in the past, and only two didn’t know how to hunt. In half of all the hunting trips she observed, men and women hunted together. If there were differences, they were in the way women tended to hunt. For instance, a woman never went alone, to avoid the risk of people suspecting that she was having a secret tryst with a lover. Women hunters were also more likely to use dogs to help with the kill.
“Being a woman hunter is a matter of choice. To keep an individual from performing certain tasks due to biological reasons is unthinkable to the Agta,” she described. “Lactation may temporarily cause a decrease in a woman’s active participation in hunting, but it certainly does not preclude her involvement in this activity.”
The key to making this possible was cooperative breeding, she adds. Women would take nursing infants with them on the hunt and leave older children in the care of other family members back home. Or a woman might nurse her sister’s baby while she was out hunting. “Even young adults could do the babysitting or keep an eye on the smaller children, cousins or siblings, left behind at the camp. Cooperative breeding is, I think, a very important component,” she explains.
The more the couple explored, the more they found that the women and men of the Nanadukan Agta were able and expected to do the same jobs. “By and large, people did whatever they wanted to do,” says Bion Griffin. No sphere of work was exclusively male or female, except perhaps killing other people. Women would stay back when groups of men went out on warlike enemy raids. “Some men did all sorts of child care, cooking, and so on. Others didn’t bother much with, say, cooking. I think everybody did everything. The only thing I can recall, I don’t recall men ever weaving baskets. But then, no one weaves baskets much. Men built houses with the women, men attended babies, they gathered firewood, they cooked, they pounded rice when there was rice to pound.”
Even as their old way of life disappears, the Nanadukan Agta have shown that, beyond the biological fact that women give birth and lactate, culture can dictate almost every aspect of what women and men do. The way lives are divided when it comes to child care, cooking, getting food, hunting, and other work is a moveable feast. There’s no biological commandment that says women are natural homemakers and unnatural hunters or that hand-son fathers are breaking some eternal code of the sexes.
The dilemma they pose for evolutionary biologists, though, is why they are the exception rather than the rule. Why don’t women hunter-gatherers everywhere hunt? And why aren’t all human societies just as egalitarian?
We sometimes imagine sexual equality to be a modern invention, a product of our enlightened, liberal societies. In actual fact, anthropologists have long known that the way women are treated throughout the world wasn’t always like this.
Anthropologist Mark Dyble, based at University College London, has studied another Agta community in the Philippines, known as the Palanan Agta, and analyzed this data together with that from a more distant group of hunter-gatherers in the Congo, a subgroup of the BaYaka, known as the Mbendjele. His research reveals a connection between the social structure of hunter-gatherer communities and high levels of sexual equality. It’s evidence, he suggests, that equality was a feature of early human society before the advent of agriculture and farming.
Published in 2015 in the journal Science, Dyble’s work built up detailed genealogies of hundreds of adults in these two communities. “We know as much as they know about their family histories. We even know if someone is second cousin with someone,” he tells me. These genealogies reveal that people living together are generally unrelated to each other. Women don’t always live with or near their husbands’ families and the same is true of men and their wives’ families. Sometimes they will switch between families, and sometimes they won’t live with close family at all.
Given the choice, people usually prefer to live with their own relatives all the time, because of the support and protection they can give them. “It’s not that individuals don’t want to live with kin,” Dyble explains. “It’s just that if everyone tried to live with as many kin as possible, this places a constraint on how closely related communities can be.” And this in turn means that neither men nor women have greater control over whom they live with. There must be sexual equality in decision making. “It has this transformative effect on social organization,” he says.
If this arrangement was normal in our evolutionary history, Dyble believes it could explain some aspects of human development. “We have the ability to cooperate with unrelated individuals, which is different from what we see in primates, which are very wary of interacting with individuals they haven’t met before,” he says. This is crucial to complex society. If people couldn’t cooperate with people they weren’t related to, civilization as we know it simply couldn’t exist. A study by anthropologist Kim Hill and his colleagues, published in the journal PLOS ONE in 2014, confirms that hunter-gatherers do interact widely with others. Their own data from the Aché in eastern Paraguay and Hadza in Tanzania suggest a person’s social universe can include as many as a thousand people over a lifetime. A male chimpanzee, by contrast, will only ever interact with around twenty other males.
This all points to the possibility that the way the Palanan Agta used to live may have been usual in our past. Historical investigations have always failed to uncover good evidence for matriarchal societies, in which women hold the reins of power. But that doesn’t mean humans weren’t egalitarian.
“There’s a general consensus now that hunting-gathering societies, while not perfectly egalitarian, were less unequal, particularly with regard to gender equality,” agrees Melvin Konner, a professor of anthropology at Emory University in Atlanta, who has spent many years doing fieldwork with hunter-gatherers in Africa. The communities he has studied have very little specialization of roles, he explains. There are no merchants or priests or government. “Because of the scale of the group dynamics, it would be impossible for men to exclude women. . . . Men and women participated, if not equally, women contributed at least 30 to 40 percent of the time.”
If the women of the Nanadukan Agta persisted with hunting for so long while others abandoned it earlier, one reason might have been their environment. The tropical forests in Luzon have fewer large and dangerous animals than in other parts of the world, such as South America, says Bion Griffin. Michael Gurven and Kim Hill, who have catalogued the reasons women don’t hunt, suggest that women avoid hunting as the risk of death rises. This is important to a group’s overall survival, because losing a mother is far more dangerous for a child than losing a father. In some societies and environments, hunting isn’t just dangerous; it can also take women far away from their home base for days at a time. If the culture does not provide enough support for women in terms of child care or other work, a woman may simply be unable to put in as many hours as a man to perfect her skills, making her a less useful killer.
Bion Griffin tells me that much of the resistance to the idea of women hunters comes from evolutionary theorists who can’t accept that hunting and motherhood are compatible. But among the Agta, hunting didn’t seem to put children at greater risk, as far as he and Agnes Estioko-Griffin could tell. It only brought in more food for everyone in a community in which food would otherwise have been desperately scarce.
Anthropologist Rebecca Bliege Bird, who has studied women hunter-gatherers in Australia, agrees. “There’s no reason why women wouldn’t hunt where hunting is an economically productive and predictable thing to do,” she says. One example she gives is that of the Meriam, an indigenous Australian society living in the Torres Strait Islands. They are skilled seafarers. On the beach, men spend more time line fishing, in the hope of bringing home a large, prized catch, while women choose to go after resident reef and shellfish where the odds of success are higher. As a result, women’s fishing harvests are more consistent and sometimes even more productive than men’s. “In most circumstances, hunting of large animals is not a very productive thing to do. I would guess that the majority of subsistence for most hunter-gatherers in most environments is the small animals. And women are going to be the major procurers of small animals,” she says.
Another example from the same continent is the Martu, an aboriginal tribe in Western Australia for whom hunting is a sport. Outrunning animals is a skill perfected by women in particular. “When Martu women hunt, one of their favorite prey are feral cats. It’s not a very productive activity, but it’s a chance for women to show off their skill acquisition. Women gain huge notoriety going after these cats,” Bliege Bird tells me. The hunting is done in scorching summer heat. “Women chase after these cats. They run to tire them out. It’s just tremendous the amount of effort that goes into it.”
Even among the Aché in eastern Paraguay—a community in which women don’t hunt—there is evidence that women are still able to hunt if they want to. Ana Magdalena Hurtado, an evolutionary anthropologist at Arizona State University, has documented how Aché women act as “eyes and ears” for male hunters. She and her colleagues once saw an Aché woman hunting while carrying an infant. They concluded, “Aché women are capable of hunting but avoid doing so most of the time.” Their focus, instead, must be on other work.
When it comes to family and working life, the biological rule seems to be that there were never any rules. While the realities of childbirth and lactation are fixed, culture and environment can dictate how women live just as much as their bodies do.
For those who have spent their careers on the outside looking in, documenting these rare human societies whose ways challenge our stereotypes, this can be personally life changing. At the end of our interview, Bion Griffin and Agnes Estioko-Griffin tell me that there’s no sexual division of labor in their own household, just like there was none among the Nanadukan Agta they studied for so many years. “And so, I’m off to cook dinner now!” Bion laughs before he hangs up the phone.
At home in London, I realize with disappointment, I’m the one cooking dinner that night.