Christopher Ryan received a BA in English and American literature from Saybrook University in San Francisco, California, in 1984 and returned twenty years later for an MA and PhD in psychology. The intervening decades, he writes, were spent “traveling around the world, living in unexpected places working at very odd jobs (e.g., gutting salmon in Alaska, teaching English to prostitutes in Bangkok and self-defense to land-reform activists in Mexico, managing commercial real-estate in New York’s Diamond District, and helping Spanish physicians publish their research).” Drawing upon his multi-cultural experience, Ryan’s research focuses on trying to distinguish the human from the cultural; his doctoral dissertation looked specifically at the prehistoric roots of human sexuality. Based in Barcelona since the mid-1990s, he has lectured at the University of Barcelona Medical School and consults at various local hospitals. He speaks about human sexuality to audiences around the world, and his work has appeared in major newspapers, magazines, and scholarly journals. He is also the author of a textbook used in medical schools and teaching hospitals throughout Spain and Latin America.

In December 2010 Ryan appeared on the radio program Equal Time for Freethought (ETFF) where he spoke about Sex at Dawn, coauthored with Cacilda Jetha and published by Harper in 2010—and also about just what the anthropological and psychological evidence says about humans’ “natural” state. The following excerpt is reprinted here with permission from the producers.

ETFF: Dr. Ryan, can you give us an overview of your work, as explored in your new book?

Christopher Ryan: Essentially, what we argue in Sex at Dawn is that there’s a great deal of data—evidence from primatology, from human anatomy, comparative primate anatomy, psychology, sexology, all sorts of anthropology—that all point to the fact that our sexual evolution was as a promiscuous species where most of our ancestors would have had several ongoing sexual relationships at any given point in their lives. And when I say promiscuous, I mean it in the original sense of the word, which is just “to mix”. I don’t mean any sort of moral judgment. And I certainly don’t mean to imply that these were casual, non-loving relationships.

Our ancestors spent their lives in groups, generally of under 150 people, where they would have known everyone very well, very intimately. So even if they had several ongoing sexual relationships, they would have been more intimate in many ways than the casual relationships that people experience these days. We evolved as sharing everything before the advent of agriculture, including sexual pleasure. Then with the agricultural revolution, which was only about 10,000 years ago (a period that’s only 5 percent of our existence as anatomically modern humans), we took a 90-degree turn off the path that we had been on for a very long time, and everything changed. And that’s when we became possessive about each other, about sexuality, and also about paternity and land and housing and animals and all these things that entered human life with the advent of agriculture.

ETFF: The traditional message we get about our sexuality is that we’ve always been this way, and always will be. Evolutionary psychologists sometimes tell us bizarre things about human history, for example that rape made us a more successful species evolutionarily speaking. Is it possible that if we look at the evidence carefully, we may find that reality is very different from what the traditional narrative tells us?

CR: Well, we tried to be very careful in Sex at Dawn not to romanticize pre-agricultural hunter-gatherer societies. So we’re not saying that sharing was so widespread because everyone was loving and sitting around the fire singing “Kumbaya” every night. The reason that sharing was so widespread—and continues to be in the remaining hunter-gatherer societies in existence—is because it’s simply the most efficient way of distributing risk among a group of people. So the conventional view, what we call the standard narrative in our book, is that males have always been obsessed with the sexual behavior of females because that’s the only way to assure paternity. A male doesn’t want to invest in children that aren’t his biological children, right? That’s the core of the standard narrative of human sexuality.

But if you really think about that, if you apply that to actual pre-agricultural society, what you see is that it makes no sense at all. Because it assumes that a man would go out hunting, let’s say he kills a deer. He comes back to the village, to the camp of people he lives with. He’s lived with them his whole life and is related to most of them—his brothers, cousins, parents, and so on—but he’s only going to share that deer with his wife and his children? It makes no sense at all, and we find no evidence for that. In fact, what we find in pre-agricultural societies that have been studied is that the worst possible thing you can do is hoard food. That sort of selfishness is not only bad form, but it puts the entire group in jeopardy. It causes conflict and it’s just plain stupid. Because you’re not going to get a deer every time you go hunting; nine times out of ten you’re going to come home empty-handed. So it simply makes sense to share what you get when you’re lucky, and other people share what they get when they’re lucky. That way everyone survives. Nobody starves to death. Without that understanding, the groups would fragment, obviously, because of the conflict.

Since Darwin, we’ve basically taken a nineteenth-, twentieth-, and now a twenty-first century view of contemporary society, and we’ve projected them onto the past. We’ve imagined that the distant past to be very much like the present, just with some modifications around the edges. In the book we refer to it as “Flintstonization,” because the Flintstones are the so-called modern Stone Age family. It’s a nuclear, suburban existence, but in prehistory. And that doesn’t cut it in terms of science. We need a bit more imagination and fealty to the facts as we find them.

ETFF: Does the traditional take on human nature lead then to our ideas on human sexuality and behavior in general, or is it the other way around? Where can we look to better understand all this?

CR: Well, it’s interesting. The two primates that are most closely related to human beings are chimps and bonobos. And they’re equidistant. So any time you read that chimps are our closest primate relatives, that’s false; they’re exactly the same distance from us genetically. And that’s significant for several reasons. First of all, we’re more closely related to them than an Indian elephant is to an African elephant, or a dog to a fox. We’re very, very closely related. And in fact, chimps and bonobos are closer to humans than they are to gorillas or any other ape.

When talking about human nature, discussions generally refer to chimpanzees. And in chimpanzees you find war, you find rape, you find murder, you find infanticide; you find all these nasty Machiavellian political calculations. Frans de Waal has written great books about chimpanzee politics and so on. But what’s often left unmentioned, not by de Waal but by other commentators, is the bonobos. And that’s significant. Because bonobos are the opposite of chimps in every one of those categories. In fact, in the thirty or forty years that bonobos have been studied in captivity and in the wild, not a single case of infanticide, murder, rape, or war between bonobo groups has been observed.

Bonobos are highly sexual, and in fact extremely similar to human beings in many important respects in terms of their sexual behavior. Bonobo society is dominated by females, whereas chimp society is dominated by the males, and what we propose in our book is that it seems likely that pre-agricultural human societies were much more aligned with the bonobo model, whereas post-agricultural society seems to have shifted over to the chimpanzee model. And so when we’re talking about human nature, it’s important to look at the economic conditions in which we existed.

When people ask me, “Are humans naturally violent or peaceful, generous or selfish?” I say that’s like asking, “What’s the natural state of H2O?” It depends. It depends on the temperature and on the context. If it’s cold, it’s solid. If it’s a moderate temperature, it’s liquid. If it’s hot, it becomes a vapor. I think that’s what human nature is. Human nature is extremely reactive. So if you put us in a scarcity-based environment where we’re in a zero-sum situation, a competitive situation with other individuals, then we tend to get more like chimps. But if you put us in a sharing, non-zero-sum-based environment where sharing makes more sense than hoarding, then we tend to go more toward the bonobo approach to life.

ETFF: Is there evidence that during our nomadic hunter-gatherer existence, there was anything like today’s nuclear family, pair bonding, and perhaps jealousy?

CR: I’m sure there was some level of jealousy, just because that’s sort of omnipresent, even in nonsexual issues. But there would have been rituals to minimize jealousy as there are in many societies now. Because there is no solid evidence for purely social relationships, we’re working from various types of physiological and anatomical evidence, anthropological and primatological, and so on. But essentially what we come to is a picture of groups of humans who took care of each other’s children, who considered the children of the group to be shared among all the adults. Children probably referred to all the men as “father” and all the women as “mother,” even if they knew who their biological mother was; they likely believed in what anthropologists called partible paternity, which is the belief that several different men can all be biological fathers of one child. And as so many things were shared (like food and grooming) as a way to strengthen the group, so sexuality would have been as well.

Now there’s no reason to think that there weren’t loving relationships and very special, even pair-bonded relationships between individuals who just really enjoyed each other’s company. But there’s no reason to think that those would necessarily have been sexually exclusive. That’s the connection we make between love and sexuality but we don’t find it expressed so much in pre-agricultural society. And sometimes not at all.

ETFF: You’ve said that near the dawn of agriculture and the domestication of animals there was a change, that at this point in human history, we entered a truly new era.

CR: Yes, there were many changes. Jared Diamond (Guns, Germs and Steel) wrote an essay in which he describes the advent of agriculture as the greatest disaster in the history of humankind. Which is shocking, because it’s the opposite of what so many of us were told in school, how it was the dawn of civilization and made everything wonderful. But we find that the evidence actually suggests that agriculture was a big step down for our ancestors in terms of health, diet, famine, infectious diseases, you name it. And in addition to all that sort of material stuff, it also changed the way we dealt with each other socially. Because it introduced this concept of property. When you’re a nomadic society, you’re walking ten to fifteen kilometers most days. You don’t want to carry a lot of stuff around, so you don’t acquire much property. And whatever property you’re taking, like cooking pots and knives and things like that, you want to be sure it’s not more than you absolutely need as a group. It makes more sense to share these things. But when you’ve got settled communities and people working the land, you’ve got a very different way of looking at things. Now you say, “This is my land. It makes sense for me to spend five or six years building a house here, because I’ll leave this house to my children even when I’m dead.” But then you have to know who your children are. And the only way to know who your children are is to control the sexuality of your wife, and to have a wife, to have this concept of a woman as your property.

When you look at the Old Testament, we all know the line: “Thou shalt not covet thy neighbor’s wife,” and we generally assume that’s about jealousy, right? But if you read it in context, it says: “Thou shalt not covet thy neighbor’s wife, nor his house, nor his ox, nor his servants.” Basically you shouldn’t covet your neighbor’s stuff. And his wife is part of your neighbor’s stuff. So it’s really about property. And so that’s where everything changed. Then you start to get hierarchical societies, because somebody has to control the planting operations, and then the harvesting operations, and somebody’s got to store the food for the winter and deal with distribution, and you have to raise armies to defend your land against other agricultural societies, and so on. So it’s a very different life that started 10,000 years ago compared to what our ancestors experienced before then.

ETFF: Are there similarities concerning sexual and related attitudes between Americans and similar cultures in, say, Europe where you live now?

CR: I’ve been living in Spain for twenty years off and on now, and when I talk to my Spanish friends about the States, we all say the same thing: it’s like a country ruled by teenagers. They’re obsessed by sex, but they’re also afraid of it. They’re obsessed by violence. Non-Americans can’t understand things like NASCAR, which is obviously designed to appeal to the adolescent, testosterone-intoxicated male mentality. But let’s not forget the Islamic societies, which have a similar take as the conservative American right-wing on sexuality and so-called traditional values that seek to put the woman back in her place, and whereby anyone who’s not in the group is necessarily evil and to be oppressed or attacked in some way. So I think it’s not just the United States that has a puritanical vision, but a good bit of the world, unfortunately.

ETFF: What is meant by “natural?” Are we in this mess today because we’ve moved away from what is natural, or is everything natural because we are, after all, part of nature and thus our innovations are natural?

CR: That’s an excellent question and it’s the subject of my next book.

We’ve already established that human beings are extremely flexible, surpassed only by the cockroach, perhaps. We can eat anything, we can live in all sorts of different temperatures, we can live underground if we have to, and we’re extremely adept at that. But there are costs to be paid when the cultural adaptation runs counter to our predisposed state. I try to stay away from the word “natural” because it’s so charged, but we are evolved for certain environments. So if you look at something like diet or exercise, when we stray too far from certain marginal parameters within which we operate most efficiently, we end up with obesity and diabetes and circulatory diseases and so on. So we’re not infinitely malleable. We’re still apes, and we have bodies that are evolved for a certain kind of diet and certain kind of exercise and certain stress levels. So as I said earlier, we do have the bonobo, we do have the chimp within us, but it’s worth noting that nobody suffers from post-traumatic stress disorder from helping a stranger. Now when we kill other people and hurt other people we suffer from that, it hurts us. So that does indicate that we’re not neutral, that we are, I would say, closer to the bonobo than to the chimp in terms of our reaction to violence and our ability to tolerate high levels of stress. There’s an interesting story that when the Allies bombed Dresden, there were chimps and bonobos in a zoo nearby. And after the bombing, they found that none of the chimps had died. They weren’t hit by bombs, the zoo wasn’t hit by the bombs, but the explosion and the noise was incredible. None of the chimps had died, but all the bonobos were dead.

ETFF: Perhaps we’re just not very experienced at this society thing yet. After only 10,000 years, is it possible we’re still working the kinks out of having surplus (though capitalism does create a kind of false scarcity), and that with the notion of radical individuality we seem to be intoxicated with, perhaps we’re still immature as a species? Perhaps we’re still figuring all this out?

CR: Well, if that’s the case, we’re not nearly as smart as we think we are. Ten thousand years is plenty of time to figure things out. Agriculture seemed like a good idea at the time, and it probably was a good idea at the time, since climatological evidence from that period suggests people basically could either start irrigating and cultivating grain or they would die. The problem is that once you start cultivation, your population starts growing. And so you’re on a spinning wheel where you have to always cultivate more land in order to feed this ever-growing population. And you get into this Malthusian struggle. So until we find a way to radically reduce population levels, we’re always going to be chasing our tails. The problem is that the planet isn’t infinite, and we can’t play this game forever. And it certainly seems like we’re coming to the end of the road here, with systems completely collapsing and the rest of it. So I’m not real hopeful that we’ll have much more time to learn our lessons. I think it’s now or never.