Skip to comments.Study: Men Caused Menopause by Selecting Younger Mates
Posted on 06/14/2013 11:10:52 AM PDT by nickcarraway
Menopause has bewildered evolutionary biologists, as females in virtually every other species remain fertile until they die. Now a team of Canadian researchers has shown that human menopause might be an unintended effect of men preferring to mate with younger women.
While conventional thinking has held that menopause prevents older women from continuing to reproduce, in fact, the researchers' new theory says it is the lack of reproduction that gave rise to menopause.
The prevailing "grandmother theory" held that women evolved to become infertile after a certain age to allow them to assist with rearing grandchildren, thus improving the survival of kin.
But Rama Singh, Richard Morton, and Jonathan Stone of McMaster University in Hamilton, Ontario, say that theory 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," Singh said.
Computer models suggest that competition among men of all ages for younger women left older females with a diminished chance of reproducing. Over time, human males stacked the Darwinian deck against continued fertility in older women.
"This theory 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," Singh said.
Menopause, however, is not only lost fertility, but an increased risk of illness and death that arises with the hormonal changes. Singh says the new research, published in the journal PLOS Computational Biology, suggests that if menopause developed over time, it could also be reversed.
The models aren't necessarily conclusive, however, as they assume male-driven sexual selection and an overwhelming male preference for younger women. The study also doesn't account for the dangers of pregnancy and childbirth in older women. Further, it isn't known if the only other species to undergo menopause -- captive chimps and certain whales -- lost their fertility due to male-driven selection.
They should change the name, to be fair, that is.. to..
Twilight’sHeat .. BalmyDaze .. or sumthin’ .. chemicals are strange things, how they interact, and .. uhh .. mess with Mother Nature and her cycles.
My theory is that people simply didn’t live as long until very recently. The number of eggs women have were more than adequate for most of human history.
Creating extra eggs and never using them is a waste of resources so over time the number of eggs matched the average lifetime.
My genes made me do it!!!!!
They are really stupid. NO ONE lived past 40 in primitive times! There was no need for the reproductive system to work!
BTW, the reason why men choose younger women should be obvious - because they are MORE fertile. In other words, it’s just the opposite of what these low-IQ “scientists” think.
Menopause is just one of a long list of things men invented to annoy women. Here are a few others:
** two-position toilet seat
** manual transmission
** TV remote
Maybe older women had such a high probability of giving birth to babies that had a low probability of surviving that evolution selected for women whose ability to get pregnant cutoff at a certain time.
It is men’s fault no matter what we do.
And older women had a low probability of living long enough to raise their children to an age at which they could fend for themselves.
Yes it is.
I'm not a biologist, but I have three good challenges to this theory:
1. Why doesn't male fertility have an age limit? A 20 year old honey will get tired of her 60 year old sugar daddy well before he turns 80.
2. Out of all mammals, human pregnancy is the hardest because we are bipedal. I theorize that menopause is for survival ... pregnancy is relatively harder on human females. Ending the ability to become pregnant when strength begins to wane allows females to live longer.
3. Until very recently, the human lifespan was about 35 years. Did menopause exist 5000 years ago? I am guessing that the limit on the number of eggs in the ovary is related to the rapid increase in the human lifespan and evolution hasn't caught up.
Because clearly evolution is pushing us in the direction of a bunch of single moms with kids whose dads are all dead. /sarc
Another more plausible interpretation: nagging older women drove men to younger companions thus obviating the older women’s reproductive functions.
No, it’s just because the body wears out. For a long time, they were blaming older mothers for things like Down syndrome, but now it appears to be that older fathers are a main contributor, no matter how young their wives.
The body does that. Men, because their body does to have to bear the hardship of childbirth, may be able to fertilize an egg longer, and the biological reason for this is actually that a lot of younger men would have been killed in combat or in accidents. This is something that no longer happens because most young men now are conflict-averse and will simply surrender.
Specious, considering that childbirth has been the traditional early killer of women throughout history, especially before the rise of medical science.
TOO LATE! ..sorry!
Women were originally the tougher sex, mean ugly b!tches who always demanded and got their own way. To demonstrate their superiority, they fought off all potential male suitors. Men were afraid to challenge or even approach them. The women who managed to get pregnant killed their offspring in order to pursue their own selfish goals.
These types of women died off after a generation, lonely, bitter and cold.
Somehow, a few of the more docile, cooperative, family-friendly females managed to survive, reproduce, and nurture their offspring to adulthood. Their legacy and progeny survives to this day, and society owes everything to them.
History has a way of repeating itself. The combative, family-hating females have made a comeback in modern times. Their genes probably won't be here in the next generation, but their anti-family philosophy could prove devastating in the short run.
When it’s based on evolution - garbage in, garbage out.
Menopause actually lines up pretty well with life expectancy 200 to 300 years ago.