On Love

'Sex at Dawn' authors say humans aren't naturally monogamous

By Ellen McCarthy
Washington Post Staff Writer
Sunday, May 30, 2010

It was Bill Clinton who first got Christopher Ryan thinking about monogamy.

As a doctoral student in psychology in the late 1990s, he kept wondering: "How is it that the most powerful man in the world is getting publicly humiliated for having a casual sexual relationship with someone?"

And it wasn't just Clinton, of course. Again and again, leaders were putting themselves in a position where "they could lose everything" for the sake of an affair.

Ryan devoted his dissertation to an examination of the roots of human sexual behavior and suggests, in new a book co-written with his wife, psychiatrist Cacilda Jethá, that we reevaluate the idea that monogamy comes naturally to men and women -- and look at whether it should even be something we require of our spouses.

In "Sex at Dawn: The Prehistoric Origins of Modern Sexuality," to be published this summer by HarperCollins, Ryan and Jethá point to anthropological and biological evidence that humans are designed to seek variety in sexual experiences.

The myth, says Ryan, who writes a blog at PsychologyToday.com, is that "you should be completely happy, completely fulfilled with one partner for 50 years. But that's not the design of the human organism."

"In fact," he says from their home in Barcelona, "the human organism is designed for the exact opposite of that."

"Adultery has been documented in every human culture studied," Ryan and Jethá write in the book. If monogamy is such a natural state, the authors ask, why are so many people driven to cheat?

Ryan and Jethá trace many of our modern ideas about matrimony and monogamy back to Darwin and a Victorian understanding of sexuality. To support their theory that the story is much more complex, they examine early human cultures and those of remote tribes that don't place a high value on monogamy. Some peoples believed babies could receive genetic material from multiple fathers, so women were encouraged to have sex with men who could pass on different positive characteristics.

Ryan's hope is that the book will prompt readers to question their beliefs about monogamy, though he knows many will be incredulous at the suggestion that adultery comes naturally.

The authors, who are married, are actually in favor of matrimony -- especially, Ryan says, when "it provides an emotionally and economically stable environment for a kid to grow up in."

The problem, as he sees it, comes when an expectation of absolute fidelity is placed on marriage. "There's a lot of suffering -- and what I would say is unnecessary suffering -- between couples who have unnecessary expectations of what life is going to be like," he says.

The authors draw a sharp distinction between love and lust -- in their view, an act of sex outside of marriage doesn't necessarily diminish the love one has for a spouse. "When it's just sex," they write, "that's all it is."

In their own 11-year relationship they've "had a similar understanding from the get-go," says Ryan, 48.

Americans in particular, he adds, see adultery as grounds for divorce, while many Europeans are inclined toward a more laissez-faire attitude when it comes to marital transgressions.

Their hope, he says, is that the book will spark honest conversations between couples, and incite them "to have a more tolerant attitude toward themselves, and their relationships."

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