Nature Invented Menopause to Keep Your Mother-In-Law From Hating YouS

My mother describes menopause as a mixture of pros and cons. Pros: no more bleeding! Cons: hot flashes, mood swings, and an unavoidable message from Mother Nature that you're getting really old. But it turns out that she may have another positive point to balance out that whole "mortality" bummer: according to a study 200 years in the making, the menopause evolved so that mothers and daughters-in-law wouldn't feel competitive about childbearing.

Scientists studied birth and death rates unfettered by modern contraception or heath care from 1700 to 1900 and found that women had more grandchildren if they stopped having babies around the age of 50. Grandmas that had kids later in life and around the same time as their daughters-in-law were way less likely to have healthy children that lived long enough to grow into adults. One reason for the findings may be because grandmothers could help raise their grandchildren if they didn't have to deal with little ones of their own, but also because of the "reduced competition" between women:

A child born to families with a mother-in-law and daughter-in-law reproducing simultaneously was twice as likely to die before reaching the age of 15. However, this was not the case in the instances when a mother and daughter had babies at the same time. This suggests that related women breed cooperatively and unrelated women breed conflictually.

There is a clear biological benefit to a woman cooperating with her daughter: the women share 50 per cent of the same genes so being in competition for food and other resources makes little sense. This is not the case for a mother-in-law and daughter-in-law: they are not related, so it is logical they should compete to maximise on their chances of spreading their genes.

The craziest part of the study is that data showed that it was better for the average woman to stop reproducing at the age of 51 if she risked breeding with her daughter-in-law, but not her daughter — which means that everything probably turned out fine for Annie and Nina Banks in Father of the Bride 2. Phew.

"We are so used to the fact that all women will experience menopause, that we forget it is seriously bizarre," Co-author Dr Andy Russell said in a statement. "Evolutionary theory expects animals to reproduce throughout their lifespan, and this is exactly what happens in almost every animal known, including human men. So why are women so different?"

Looks like the only real "con" is the missed potential for so many reality TV shows.


Menopause evolved to prevent competition between in-laws
[EurekAlert]

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