It turn out that what causes menopause in women is men. Men have a version of it too, but women are usually the ones with the annoying hot flashes. Although couples often have temperature disputes, for females menopause is part of the "third act" of life. Evolutionary geneticist Rama Singh thinks that menopause is actually an unintended outcome of natural selection. She theorizes that, over time, human males have shown a preference for younger women in selecting mates, stacking the Darwinian deck against continued fertility in older women. Singh says, "In a sense it is like aging, but it is different because it is an all-or-nothing process that has been accelerated because of preferential mating."
While conventional thinking has held that menopause prevents older women from continuing to reproduce, the new theory suggests that it is the lack of reproduction that has given rise to menopause, which is believed to be unique to humans, but no one had yet been able to offer a satisfactory explanation for why it occurs.
The "grandmother theory" holds that women have evolved to become infertile after a certain age to allow them to assist with rearing grandchildren, thus improving the survival of kin. Singh says that does not add up from an evolutionary perspective. "How do you evolve infertility? It is contrary to the whole notion of natural selection. Natural selection selects for fertility, for reproduction -not for stopping it," he says.
The new theory holds that, over time, competition among men of all ages for younger mates has left older females with much less chance of reproducing. The forces of natural selection, Singh says, are concerned only with the survival of the species through individual fitness, so they protect fertility in women while they are most likely to reproduce. After that period, natural selection ceases to quell the genetic mutations that ultimately bring on menopause, leaving women not only infertile, but also vulnerable to a host of health problems. "This theory says that natural selection doesn't have to do anything,” Singh says. "If women were reproducing all along, and there were no preference against older women, women would be reproducing like men are for their whole lives." The development of menopause, then, was not a change that improved the survival of the species, but one that merely recognized that fertility did not serve any ongoing purpose beyond a certain age.
Singh points out that if women had historically been the ones to select younger mates, the situation would have been reversed, with men losing fertility.
Historians of witchcraft have suggested that older, infertile women were exiled into the forests during times of famine, where they learned to use herbs and roots as medicines, then traded them to villagers for food. Ironically, most of the old formulas involve aphrodisiacs, especially those designed to induce male desire.
Essential oils are also a time-honored treatment for menopause.
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