Click here for Part Two: Sarah Blaffer Hrdy on the Evolutionary Lessons of Motherhood
In my cover article out this week in Times Higher Education I featured the life and work of famed primatologist and evolutionary theorist Sarah Blaffer Hrdy. While she never intended to be a radical, she has nevertheless had a radical influence on how primatology and evolutionary biology address female strategies as well as the evolutionary influences on infants. Hrdy graduated summa cum laude from Radcliffe College in Cambridge, Massachusetts and received her Ph.D. in anthropology from Harvard. She is a former Guggenheim fellow and a member of the National Academy of Sciences, the American Academy of Arts and Sciences, and the California Academy of Sciences. She is currently professor emeritus at the University of California, Davis.
In our discussion, Hrdy explores both her own life as well as how her personal experiences inspired her to ask different questions than many of her scientific colleagues. While it may not seem like a particularly dramatic idea to emphasize the evolutionary selection pressures on mothers and their offspring, it is a telling insight into the unconscious (and at times fully conscious) sexism that has long been a part of the scientific process. Through her work, in books such as The Woman that Never Evolved, selected by the New York Times as one of its Notable Books of 1981, Mother Nature: A History of Mothers, Infants and Natural Selection, chosen by both Publisher's Weekly and Library Journal as one of the "Best Books of 1999" and, her latest, Mothers and Others: The Evolutionary Origins of Mutual Understanding, Hrdy has challenged, and transcended, many of the flawed assumptions that biologists have held dating back to the Victorian era. It is a body of work that continues to provoke and inspire a new generation of scientists and was highly influential in my own scientific work.
Eric Michael Johnson: Why do you think it’s important to look at mothers and infants from an evolutionary perspective?
Sarah Blaffer Hrdy: If we really want to raise Darwin’s consciousness we need to expand evolutionary perspectives to include the Darwinian selection pressures on mothers and on infants. So much of our human narrative is about selection pressures but, when you stop to think and parse the hypotheses, they’re really about selection pressures on males: hunting hypotheses or lethal intergroup conflict hypotheses to explain human brains. Well, does that mean that females don’t have brains?
Johnson: In an autobiographical sketch published in the book Leaders in Animal Behavior you wrote that: “It was no accident that I would later become interested in the evolutionary and historical origins of patrilocal marriage, male-biased inheritance, female sexuality and peoples’ obsessive concerns with controlling it.” When did you start becoming interested in these topics and what were some of the leading motivations you had at the time?
Hrdy: You have to take into account where I grew up and when. It was in south Texas. I was born in 1946 so I was growing up in the 50s. This was a very segregated and really quite patriarchal society. Growing up in Houston was a lot like growing up in South Africa. Also within my family males had a very special role. The good news, in a way, is that I was the third daughter born in a family eventually of five. It was a very wealthy family and I was sort of the heiress to spare. So they didn’t pay too much attention to what I was doing, though they certainly had very set ideas about who I should marry and what sort of life I should lead. But once I was out of sight off at school, I was pretty much out of mind which was good for me. So I went off to school when I was 16 and that really was the beginning I think of my intellectual development.
Johnson: This was during the midst of what Betty Friedan later called "the feminine mystique." In what ways did you see this dissatisfaction at play in the women around you? How did you interpret this as a girl when looking to grownups for a model of womanhood?
Hrdy: Oh Eric, I was so clueless. I didn’t understand. I had no political awareness at all. I was really finding it out for myself. I still recall sitting in a simian seminar at Harvard and the discussion revolved around women being exchanged between groups as a way of connecting male brotherhoods and achieving alliances between groups. I remember thinking to myself, “This is what it must be like to be a black person listening to a lecture in support of the Ku Klux Klan.” I had no sense of the culture I’d grown up in and the way women were regarded within it. I had no sense of what this was really about and how it was working. I was learning from politically more aware people around me who, I think, often were stunned at my naivet. At that time primate behavior and the whole evolutionary endeavor was steeped in these very Victorian preconceptions. So I was reacting, at a very visceral level, even before I realized what was going on.
Johnson: And when you entered college?
Hrdy: The year I graduated [from Radcliffe in 1969] there was not a single woman professor at Harvard and I was my professor’s first woman graduate student. Female role models, especially in the sciences, were almost nonexistent. Moving closer to biology was a different thing for me than being an undergraduate in cultural anthropology. The dominant narrative about primate social lives was the savannah baboon where males are very political and dominant and they would support each other so they could control females. Are you familiar with those stories?
Johnson: Of course, that was one of the dominant paradigms for human evolution at the time.
Hrdy: And it was. That’s what I was hearing and that’s what I was responding to. There was really no consideration of how much variation existed among females. Remember, the models back then held that there was variance in male's reproductive success and no variance in female's. It was assumed every female would be a mother and would breed to the maximum of her capacity so that females would be producing about the same number of offspring each whereas, with males, they could do tremendously well or be a complete zero -- what was referred to as "the Bateman paradigm". Supposedly, because the ovary was bigger and more resource rich than the sperm, it meant there were many tiny sperm actively competing for a large, resource rich ovum. This was the basis for the assumption that there was stronger selection pressure on males than on females.
Johnson: What led you to question this paradigm?
Hrdy: It was after I started studying langur monkeys that it began to dawn on me how many sources of variation in female reproductive success there were. It brought the old paradigm into question. For so long it had been assumed that males were basically polygynous [many sexual partners] while females were monandrous [one sexual partner]. Watching langurs convinced me that this was not true. When I examined the wider literature I realized just how common polyandrous mating by females actually was across primates. Now we realize it’s not just primates, it’s across the animal kingdom.
This was all starting to emerge at the time and it really gelled for me in a paper I prepared for the first (and really only) overtly feminist conference I ever attended organized by Ruth Bleier in 1985. Almost none of my colleagues from biology read that essay -- “Empathy, Polyandry, and the Myth of the Coy Female” at the time, but it was recently republished in Elliot Sober’s Conceptual Issues in Evolutionary Biology [pp. 131-160]. The essay was about how inapplicable, or wrongly applied, the Bateman paradigm was. There was so much more selection on females to mate with multiple males for a variety of reasons, from genetic reasons to extracting more investment, or confusing the issue of paternity. By the 1970s, I recognized that paternity confusion was what was going on with langurs. But this was heresy back then. Now I think it’s widely accepted. I think the history and the feminist provenance of this idea has been forgotten which, in a way, is too bad because we know what happens when you forget history, old mistakes get repeated, old biases reinserted. I see no reason why some of these same biases couldn’t come back in other forms just as appears to be happening in our political sphere today.
Johnson: Earlier I interviewed you about patrilocal residence patterns and how that alters women’s sexual choices. In contrast, matrilocal societies are more likely to be egalitarian. What are the factors that lead to the differences between these two systems?
Hrdy: I think in societies where women have more say, and that does tend to be in societies that are matrilocal and with matrilineal descent or where, as it is among many small scale hunter-gatherers, you have porous social boundaries and flexible residence patterns. If I had to say what kind of residence patterns our ancestors had it would have been very flexible, what Frank Marlowe calls multilocal. This means they were sometimes matrilocal and living with a woman’s family, or sometimes patrilocal and living with a man’s family. Or sometimes they weren’t living with either family because they could vote with their feet and move away if someone was being oppressive. I think these porous boundaries and flexible residence patterns were very important for our ancestors. But, over time, as populations built up and property became much more important—and it also becomes important to defend property—that’s when it became much harder to move between groups. The boundaries became less porous but also men would tend to stay together. Sons would stay near where their brothers and fathers were because they made the best allies for defending a particular resource.
As I suspect you know, I am convinced that until fairly recently in human history–-and of course, for me, recent means 10-20,000 years ago–-people weren’t defending resources. The ranging areas were so large that is very difficult to imagine anyone defending them. There was also no property, so they weren’t defending that either. Some people have argued that they were defending women because men are always going to be looking for extra wives and extra women to mate with. But the thing is, among hunter-gatherers, the way to breed successfully is having alloparental help and provisioning help from others. Anybody who goes around killing off his wife’s relatives and stealing women is going to have a lower chance of rearing offspring. These warring bands of brothers didn’t emerge until fairly recently, after people started to become more sedentary. For these reasons, I think our hunter-gatherer ancestors had a flexible residence pattern and that group boundaries were porous.
Johnson: As you argue in your latest book, Mothers and Others, humans evolved as cooperative breeders. However, most psychology studies (and nearly all parenting advice books) assume that the nuclear family is integral to human nature. How does this assumption influence the kind of advice parents receive?
Hrdy: By the time I was finishing Mother Nature I had realized that there was simply no way an ape with the life history traits observed in humans could have evolved unless our ancestors had been cooperative breeders. By this I mean a species where alloparents, individuals other than the parents, had helped to care for and also provision the youngsters. That’s the best explanation for the life history traits that you have in humans, these very long periods of dependency that anthropologists studying hunter-gatherers have documented. In other apes, once youngsters are weaned they’re basically nutritionally independent. But in humans offspring are going to be between 18-20 years old before they are producing as many calories as they’re consuming. So the dependency is lasting a very long time. Hillard Kaplan’s work has been very important to me. He estimates that it takes 13 million calories to rear a human from birth to nutritional independence and this is far more than a woman could provide by herself. Furthermore, the work of anthropologists like Kristen Hawkes and James O’Connell have shown that it would take more than both the mother and the father could have provided.
Johnson: So who was helping?
Hrdy: That’s where different emphases are being proposed and I take the view that it’s very opportunistic and mothers are getting help wherever they can. It can come from grandmothers, as Kristen Hawkes has stressed, and post-reproductive females. It can also come from fathers and males that might be the fathers, from patrilineal relatives, matrilineal relatives, older siblings, aunts, uncles, and even sometimes nonrelatives who happen to be in the group who are earning their keep by helping to rear the youngsters. It would be a varied assortment of helpers, albeit group members very familiar to the child.
Johnson: How could this human past help us today to design more compatible childrearing systems that are more geared to the needs of children?
Hrdy: What we learned from Bowlby, who’s been so important to me with attachment theory, is that children need this sense of security that comes from having close relationships from people around them. But where I depart from Bowlby is in assuming that the mother is the sole attachment figure. Of course, later, Bowlby did correct himself somewhat under the influence of Mary Ainsworth, so I want to give Bowlby credit for changing his views over the course of his career. But, for the most part, he was convinced that the mother was more than the primary caretaker, she was the one that mattered most. As a consequence, most studies of attachment theory focused on the infant's relationship with the mother. Yet a handful of studies that actually looked, noted that children with multiple attachment figures are better able to integrate the perspectives of multiple people. Marinus von IJzendoorn and Avi Sagi-Schwartz’s work has been especially important to me in this regards. Perspective taking is one of the key differences between humans and some of our closest ape relatives. We don’t really know whether a child who has, for example, equal amounts of care from the mother and the grandmother or more caretaking from the father can’t be just as secure with that person as with the mother. However, I predict that they would.
Johnson: How does the assumption of the standard nuclear family affect the kinds of approaches that humans have towards parenting? If, as you say, we have evolved as cooperative breeders?
Hrdy: I don’t think it can be separated from patriarchal traditions. A woman living in a patrilocal setting is surrounded by her husband’s people. She’s a fairly isolated figure and her role is going to be, essentially, a breeding machine for the patriline. She won’t have social support within her husband’s community. Out of that long tradition there emerges this view of the mother as an all-giving, totally dedicated creature who turns herself over to her children. I went back and read some of the early stereotypical views of motherhood in Western Europe and all of them were conflated with notions of charity and a woman giving of herself as the model for what a woman should be. If you stop to think about this you realize that these are all from the perspective of the patriline and the male’s perspective. It’s really not taking into account the woman’s perspective.
Click here for Part Two: Sarah Blaffer Hrdy on the Evolutionary Lessons of Motherhood