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 ... 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)
Learn how English works.
Thanks for the informative answer.
|GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach|
I have always thought that too until about a year ago.
Although it has long been assumed that women are born with all the eggs they will ever have in a lifetime, recent research has hinted that that might not be the case. Now researchers report the strongest evidence yet that women may be able to replenish their supply of eggs after they are born and perhaps after age or disease might have normally hindered their fertility.
I've had the chance to speak with 'scientists' about their subjects and consistently the biologists seem dumb as rocks. They 'study' things, but if you ask them their procedure, baselines and how they test they clam up or get defensive. Why is that?
I suspect they are less than scientists and more like parrots. As long as they parrot the party line, which may be government or professor or institution driven, but is most certainly a political process, they get funding and gigs. Any real science would end all that.
When confronted by well informed amateurs who won't toe the party line, they get frustrated. It's why it's so great to be a conservitive in America's North Korea. You're constantly challenged to come up with solid, irrefutable evidence for your theories. Something few scientists face today.
Or maybe Darwinism isn't tracking true. Today's scientist says, "If reality isn't tracking the model, go with the model that funds you."
He conflates natural selection with evolution. He can't be that smart to start with.
By definition, evolution theory consists of two main elements: 1) descent with modifications and 2) natural selection.
"Descent with modifications" is normally just another way of expressing Murphy's Law that "anything which can go wrong eventually will".
So various forms of infertility are frequent "modifications".
"Natural selection" simply means such "modifications" don't get passed on to future generations, unless they somehow help individuals to survive and reproduce.
In the example of menopause, the old "grandma theory" seems perfectly reasonable to me, since even though it's highly exaggerated to say "it takes a village," it certainly does take a family to raise children, and traditionally, the bigger the family, with more support for youngsters, the better.
And nobody loves children more than grandparents, since once you're done playing with them, you get to give them back.
So, call it "natural selection" or call it "God's will", it's still just a little gift, to make grandma's life happier, and give children a better chance to grow up... ;-)
You really don’t know, do you?
"I'm still fertile! Come and get it boys!"
I don’t want to hit the little red x.