Sex at Dawn: The Prehistoric Origins of Modern Sexuality (Book Review)

All group-living nonhuman primates, such as chimpanzees and the lesser known bonobos, are polygamous. Perhaps not coincidentally, researchers have documented infidelity in every human culture. Yet, most evolutionary biologists agree that monogamy is natural to humans and that it has evolved to assure the survival of our species through guaranteed paternal child support. In other words, without monogamy there is no guarantee a guy would stick around to invest in his offspring. Christopher Ryan and Cacilda Jethá, authors of Sex at Dawn,1 argue that a driving force behind this assured “male parental investment” is the certainty that it’s the particular male’s genes that are passed on to any offspring in which he invests. A monogamous bond insures a man will not accidentally support another man’s child, while it simultaneously assures the female that her male partner will not share resources with another woman’s offspring.

If monogamy is so natural, however, then why is it that cultures need to sanction monogamy?

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Hairless Skin and Romantic Love: The Naked Love Theory

A striking feature of human beings is our lack of a thick coat of body hair. Since all other primates have such fur this suggests the primate ancestors of human beings likewise had fur and that, for some evolutionary reason, lost their body hair. But what could this reason be? There are various theories but none is fully adequate.

In a new attempt to explain this loss of body hair I argue that human hairlessness had its origin in the ancestral mother-infant relationship. In the “naked love theory”, as I call it, this hairlessness is ultimately the result of bipedalism or the ability to walk on two feet.

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Do Nice Guys Really Finish Last?

We often hear tales of women forsaking the nice, kind, dependable man for the brooding, confident bad boy, but do women really prefer bad boys? New research from the University of British Columbia suggests that perhaps they do, at least in terms of sexual attractiveness.

Across two studies, women rated happy, smiling men as less attractive than proud, confident men. The opposite pattern emerged for men’s ratings of women; happy women were rated as more attractive than proud women.

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When Are Women Into Casual Sex?

Men are more interested and likely to engage in casual sex than women, right? Not so fast...New research published in the Journal of Personality and Social Psychology shows that when great pleasure is expected, women are just as likely as men to say "YES" to casual sex.

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Why Do Some People Date Multiple Partners at the Same Time?

A reader asked the following question: I'm interested in why some people like dating multiple people at a time and others only focus on one. Is it just for attention? Low self esteem? Or maybe it's survival of the fittest- don't stop on one until you're officially locked down?

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NPR interview with Dr. John Maner and Dr. Martie Haselton

If you enjoyed last week's post on John Tierney's write-up about Saul Miller and Jon Maner's work, you might be interested in the new interview on NPR's On Point with Dr. Maner (Florida State University) and Dr. Martie Haselton (UCLA). Click here to check it out at the NPR site.

Ovulating Women: Hot or Not?

We're big fans of John Tierney at the New York Times, and in a recent post he discusses new research by Saul Miller and Jon Maner at Florida State University.1 Their work indicates that single men are more attracted to women who are ovulating, but that men in committed relationships are actually less attracted to those same ovulating women. In short, it's adaptive for males to want to mate with fertile females, but the motivation to protect one's current long-term relationship can counteract this effect as committed men downplay the attractiveness of others as a means of protecting their current relationship.2

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