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.
Of course! It’s all men’s fault!!!!
This is one of the most ridiculous things I’ve heard lately.
Heeheeeeeee, let me take it a step further.....Bush is a man, therefore, it's Bush's fault!
Chicken, meet egg...
I have observed that women who continue to have children , continue to have children, even to 50 years old.
Correct me if I’m wrong, but I thought women exited puberty with a set number of eggs and when they are gone, they are gone. And they lose a few every month or so.
“Of course! Its all mens fault!!!!”
That’s right ‘cause what we want is:
George Bush is a man, so it’s really his fault.
I need a shovel on this one. Can’t leave that laying in the yard. I have to mow the lawn later.
I’d think that “menopause” is a mammalian thing, and without having researched it yet, I’d bet a lot of other mammals go through something similar.
So they suggest we needed extra grandma’s to help raise the kids...
Next they will tell us there was also a need for some extra childless uncles to help raise the kids...
The gay gene explained!
I’m still trying to figure out the key question: what is the ADVANTAGE of women running out of eggs sooner? What disadvantage might there be to having surplus eggs? The article appears not to provide even a hypothests for this.
And, the sun rising in the east might be an unintended effect of God's design of the universe!
"Researchers" and "scientists" are becoming politically correct terms for "idiots" and "morons"!
Women didn’t live to see menopause for most of human history. I believe the human body is simply not yet adapted to live as long as we do today
The article appears not to provide even a hypothests for this.
What a complete load of horse sh*t.
Suggestion: Premenopausal women hang around bars at closing time.
Oh, wait...never mind.
So, women stop being able to reproduce after a certain age (the age is variable) how is this not menopause? If they stop generating eggs then why continue all the other processes that go into egg production like the uterine lining etc... Isn't the hormones that control reproduction so doesn't it make sense that the production of estrogen goes down then leading to infertility which makes it sound like their research is backwards.
I get it, it's all men's fault.
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.
Of course ... they call it "MEN"opause, don't they? ;-)
Other primates mature much more quickly than homo sapiens.
A female gorilla will begin ovulating at 6 years old. Female Homo sapiens begin ovulating at about 12. This is a significant difference.
The point being that there is necessarily a great deal more time invested in bringing the young to maturity in humans. There for an older woman may stop being able to bare children because her chances of bringing that child to maturity (independent survivability) significantly decreases as age advances. Also as age advances the chances of a woman surviving pregnancy decreases.
It could be the excessively long childhood of humans caused the evolution of menopause.
Women have enough eggs in their ovaries to continue ovulation well in to their second century.
The eggs simply stop maturing after menopause.
I am 54—and have four children from 30 to 11—and have concluded that menopause is one of the Almighty’s complex deals (NOT covenants , as there’s no record the understanding was ever inked by both parties). As with all of God’s deals (and covenants), mankind, here womankind, gets the overly generous deal (thank you, Lord). No threat of pregnancy once one is tuckered out; in turn, one is older (but that was coming down the pike, as men of the same age would attest). All is well, and if a given woman or man has had enough sense to have children (understanding, of course, that not all can, regardless of hope), then their futurity is assured.
My theory would be this: the older the woman is, the higher the risk of genetic defects (we see that now with Down’s Syndrome). The more genetically defective babies that are born (not all defects result in lack of reproduction) the more the genetic viability of the entire tribe is reduced, and thus the less likely that the tribe will survive. For those tribes where women got sterile around the age of the onset of high risk for birth defects, the gene pool is protected and elevated. That tribe then has a genetic advantage over other tribes, and thus would be become the dominant gene pool.
I think they are grasping at straws (or ovariea).
Growing old, functions slowing down, functions losing their vitality seems to be part of the human condition, so why would it not apply to our reproductive system?
Maybe, with equal evidence I would think, that “growing old” in every other sense triggered the evolution to menopause and its infertility, as pregnancy & childbirth have been known for ages to be more of a difficulty for the woman as she ages.
But no, let’s blame men. It’s like blaming Bush I think.
How many women have you observed doing this? (curious)
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