Did Men Cause Menopause?

It has evolved because of men’s preference to breed with younger women

What causes menopause in women? Over the years, various hypotheses have been proposed to explain it. According to one hypothesis, often termed the ‘grandmother theory’, menopause evolved in women so that older women can cooperate and help their daughter rear children, thus improving the survival of their kin.

However, a new study questions this theory and posits a new one. Rama S Singh, head of Department of Biology, McMaster University, who led the new study says that the ‘grandmother theory’ does not add up. “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 authors of the new study, published in PLOS Computational Biology, claim that the reason why menopause has evolved is because of the preference among men to breed with younger women. This phenomenon would have stacked against continued fertility in older women, and when genetic mutations that finally brought on menopause started appearing, it persisted and became more prevalent over time.

Researchers used a computational model and computer simulation to show that male mating preference for younger females in humans could have led to the ‘accumulation of mutations deleterious to female fertility and thereby produced menopause’.

The authors write in the journal, ‘The origin and evolution of menopause is understood poorly and explanations remain contentious. Virtually ignored among explanations is the effect that mate choice can exert on an evolving population… Our model demonstrates for the first time that neither an assumption of pre-existing diminished fertility in older women nor a requirement of benefits derived from older, non-reproducing women assisting younger women in rearing children is necessary to explain the origin of menopause.’

According to the study, if menopause developed over time in the way they think it did, this also means that it can be reversed.

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