Is monogamy unnatural? Is the nuclear family bad for people’s mental health? Can a child have more than one biological father? These are some of the provocative questions explored in the new book Sex at Dawn: The Prehistoric Origins of Modern Sexuality, by research psychologist Christopher Ryan and his psychiatrist wife, Dr. Cacilda Jetha. The authors argue, among other things, that human beings have evolved to desire sexual novelty — and that the current cultural conventions of marriage and monogamy, while not wrong, come at a cost to well-being — which would help explain why so many couples have problems with infidelity. I spoke with Ryan recently:
Do you think that early humans were promiscuous, rather than monogamous or polygamous?
I think it looked like casual sexual [behavior], with overlapping simultaneous sexual relationships between different people who had known each other for most of their lives. This is the difficulty of using words like promiscuous. For us, promiscuous means random, cheap, shallow, but these people grew up with each other in most cases. There was some shifting between bands of [hunter-gatherers] but they certainly knew each other very well and depended on each other for everything from child protection to sharing food, for support of every kind. There was a very deep sense of intimacy. (More on Time.com: 5 Little-Known Truths About American Sex Lives)
But if humans have evolved to be more polygamous than monogamous, why do we also have jealousy? In various cultures, people become very unhappy when their romantic partners sleep with someone else.
Depending on the cultural context, jealousy can be a major or minor issue. It varies between individuals to a great extent. I think we’re mistaken in generalizing our own sense of jealousy and assuming that what we see around us is an expression of human nature as opposed to perhaps something that is [just] part of human nature. [We all have] insecurity, fear of losing someone important — that’s been amplified by a culture that encourages a very immature sense of romantic love.
Are you saying that early humans didn’t fall in love — or pair-bond, as the researchers say — or didn’t mind when someone they were in love with cheated?
It’s like [with] jealousy. The pair-bond does appear to be an expression of some aspect of human nature but I think we make a mistake in assuming that the pair-bond included sexual exclusivity. I wouldn’t use the word cheat because it is so loaded.
The fact that these are the words we choose says something about the cultural forces trying to shape our experiences. There certainly is evidence that human beings form very deep, loving, long-term, unique relationships, often between a male-female couple, but not always. (More on Time.com: Can an iPhone App Save Your Marriage?)
So you don’t think early humans pair-bonded to raise children?
We’re arguing that the pair-bond was not the basis of the family unit and was not, as has been hypothesized, an evolutionary adaptation for raising children.
You are basically agreeing, then, with anthropologist Sarah Hrdy, who claims that parenting requires more than two people and that early human children were raised by extended families and friends.
We’re really challenging the whole notion of the traditional family being a mother, father and two kids. We agree with Sarah Hrdy that that’s not the nucleus of human organization. The nucleus is a band-level society in which there are many adults taking care of many children. Love flows between all the adults.
The nuclear family is detrimental to both child development and parental mental health. It’s too much. It’s like wearing shoes that don’t fit. Society can force you into [them] or you can force yourself and you’re going to suffer.
Are you suggesting that people should not be monogamous?
What we’re hoping is that the book will provoke people to reconsider their assumptions about the naturalness of long-term sexual monogamy. We’re not encouraging people to abandon the notion of long-term sexual monogamy, we’re just encouraging them to educate themselves and have a more realistic sense of what to expect if that’s the path they choose.
This is not an indictment of monogamy. Choosing a lifetime of a monogamous union is like choosing to be a vegetarian. It’s not necessarily a bad decision. It’s very healthy — it’s ethically wise, but that doesn’t mean that bacon isn’t going to smell good any more. (More on Time.com: The Roots of Empathy)
You wrote Sex at Dawn with your wife. I have to ask you, do you practice what you preach?
We have a stock answer for this. Our relationship is informed by our research but we don’t discuss the particulars publicly.
Some would argue that people tried having open marriages in the 1970s and it didn’t work out too well. There was a massive increase in the divorce rate.
We confront that in the book. First, where’s the proof that it didn’t work out so well? We don’t know, because discretion is such an important part of intimacy. We don’t know how many couples experimented and stayed together. We hear about the cases that don’t work, but we don’t really hear about the ones that did. Who is going to come out and say, “My wife and I were swingers for 20 years and I want to be your governor”? (More on Time.com: Is Altruism Sexy?)
Your book also discusses “partible paternity,” a belief common to some South American hunter-gatherers that a child can actually have multiple fathers, that all the men a woman sleeps with play a role in fathering her child.
Yes, it’s the notion that any individual child can have multiple fathers, in both the biological and the spiritual sense. [They believe that] the fetus is literally made of accumulated semen.
These cultures have names for the different fathers, things like: the “father who put it in, the “father who mixed it up,” the “father who gave the child its essence.” But how common is this idea really?
There are many different tribes down there who believe in it. And it’s not just in the Amazon, it’s found all over the world. It’s an idea that has arisen [independently] all over the world.
And because the child is — the fetus is literally made of these men’s semen — the woman who wants to have a child that combines the advantages of different fathers will have sex with the best hunter, the best looking [guy], the funniest, in order to get some essence of each of these men into her baby.
Where do you think this idea comes from?
It’s another indication that sperm competition was present in human evolutionary times, that we evolved in the presence of sperm competition. There are so many indications of that, so many anatomical and behavioral [signs], it’s just another nail in the coffin.
What other evidence is there for human sperm competition?
There’s testis size and penis morphology and the fact that the testicles are outside the body rather than inside. (More on Time.com: Forget Pain Pills, Fall in Love Instead)
Um, how does size matter? Smaller size of male organs means less sperm competition?
[Yes.] A gorilla has a penis the size of a human pinky; its testicles are the size of kidney beans. [Gorilla males have harems, and females in the harem do not have the opportunity to mate with other males.]
It always amazes me when people try to look for deep psychological explanations for why politicians cheat — as if biology has no influence at all.
Did you see the South Park episode with Tiger Woods? It also had Bill Clinton and Charlie Sheen — all the famous philanderers of recent American history. The underlying thesis of the episode was that they formed a commission in Washington to try to figure out what drives successful, powerful men to have sex with young women. [They proposed ridiculous explanations] like the Peter Pan complex or [that the men were] acting out of fear of their own homosexual urges. (More on Time.com: The Real Eliot Spitzer Question)
Do you think there are any models for a successful society that is centered less on the nuclear family or monogamy?
Every culture is sort of developing along its own path. One place to look would be Northern Europe. Marriage rates are very low, but the number of single-parent families is also low. There isn’t this economic pressure [to stay together] because the government takes care of mothers and children, so people don’t need to worry.
In the U.S., a single mother is thrown to the wolves, whereas in a more collectivist — dare I say, socialist — society, there isn’t that pressure. People seem to be much more forgiving and the relationships seem to be more durable, even if they are not official marriages.
This is very much a political issue. It’s really breaking down into American versus European notions of what society is. To what extent are we in this together? In America, it’s become so fractured. People end up being so lonely. It really comes down to whether or not we are sharing our lives with enough people.
Correction [Nov. 2]: The original version of this post misstated that gorillas’ testicles reside near their kidneys; in fact, they are the size of kidney beans.
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