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For Women, Biological Clock Is an Aphrodisiac

• June 28, 2010 • 11:54 AM

New research suggests women think more about sex, and engage in intercourse more frequently, as their fertility declines.

According to conventional wisdom, men have sex on the brain from puberty until, roughly, death. The Kinsey Institute, which uses somewhat more refined measurements, reports 54 percent of men think about sex every day or several times a day. It adds this is true of only 19 percent of women, making for quite a gender gap.

However, new research suggests that for females, the answer to that question may vary considerably depending upon one’s age.

According to a new study published in the journal Personality and Individual Differences, women’s interest in sex peaks between age 27 and 45. A research team led by psychologist Judith Easton of the University of Texas at Austin concludes this is an unconscious reaction to declining fertility.

A total of 827 women, recruited from the UT community and from Craigslist.com, completed a detailed online survey that included questions about their sexual desires and behaviors. They were grouped into three age categories: 18-26 (high fertility); 27-45 (reduced fertility); and 45 plus (menopausal and post-menopausal).

Those in the middle group were dubbed “RE women,” which stands for “reproduction expediting.” (One can only hope that shorthand term seeps into the culture. “See those two over there?” one man drinking at a bar asks another. “They’re RE. I know it.”)

The study reveals these 27- to 45-year-old females “think more about sex, have more frequent and intense sexual fantasies, are more willing to engage in sexual intercourse, and report actually engaging in sexual intercourse more frequently than women of other age groups,” the researchers report.

Compared to older or younger women, RE women are more willing to engage in sex after knowing a partner for either one month, one week or one evening. Controlling for the number of children the women had, or whether they consciously desired to have a child, did not change the results.

And where does this urge to, er, expedite arise from? “We hypothesized women evolved a psychological mechanism — a reproduction expedition adaptation — that motivated them to capitalize on their remaining fertility before likelihood of conception between less probable,” the researchers write.

“Modern women’s sexual psychology is a consequence of such evolved mechanisms,” they add. “One key design feature of this adaptation is an increased desire and willingness to engage in sexual activity during the period of declining fertility.”

The researchers concede their findings may simply reflect the fact older women tend to have more sexual experience, and this leads to their “increasing comfort with sexuality.” But they add that “this alternative explanation cannot account for why, in the present study, menopausal women consistently displayed decreased sexual motivations and behaviors.”

So according to Easton and her colleagues, the ticking of the biological clock is loud and clear even in women who have no desire for children (or additional children). They conclude that, while it may never penetrate the conscious mind, women feel an urge to “facilitate conception before the window of opportunity closes.” Men: You have been notified.

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Tom Jacobs
Staff writer Tom Jacobs is a veteran journalist with more than 20 years experience at daily newspapers. He has served as a staff writer for The Los Angeles Daily News and the Santa Barbara News-Press. His work has also appeared in The Los Angeles Times, Chicago Tribune, and Ventura County Star.

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