Menopause cause? It may well be men, scientists say

Study: Women go through menopause because men prefer younger women

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This must be the week for the release of gender controversial science. Yesterday it was a study that showed iPhone users found male voices more credible in apps like Siri.

 Today, the theory raising the hackles of the sexes -- men are to blame for menopause.

Women go through menopause because men have consistently preferred younger women in recent evolutionary history, according to a study published today in the journal PLOS Computational Biology.

"Our first assumption is that mating in humans is not random with respect to age, which means men of all ages prefer to mate with younger women," said study co-author Rama Singh, an evolutionary biologist at McMaster University in Canada. "If mating is with younger women, any deleterious mutations which affect women's reproduction later in life will accumulate because they are not being acted on by natural selection."

In his blog, Brian Alexander writes:

At first blush, menopause doesn't make much evolutionary sense. According to one widely accepted theory, the point of evolution is successful reproduction. After that, nature doesn't have much interest in keeping us alive, and so we die. Why, then, keep women kicking for decades after they can no longer make babies?

Rama Singh, a professor in the department of biology at McMaster University in Hamilton, Ontario, thinks he's figured it out. Menopause, the Canadian researcher argues, is men's fault.

In a paper published today in PLOS Computational Biology, Singh and two colleagues detail elaborate evolutionary computer models demonstrating that "male mating preference for younger females" leads to the development of a long menopausal period.

"I am saying what women have been saying all their lives," Singh told "Men are to blame."

Singh's argument relies on one key fact: "Sex is fun," he says.

In humans, sex isn't just about making babies, it's also about pleasure and bonding. Over time, he contends, men found that having that sex with younger women was more desirable than sex with older women, without regard to making babies.

As men began to prize younger women as sex partners, gene variants that led to infertility with advancing age were not eliminated. Menopause became built in, even as women lived longer and longer.

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