Why did men evolve to be able to always have children, but women evolved to have menopause?
Tuesday, December 1st, 2009 at
11:37 pm
Shouldn’t evolution had eliminated menopause? The women with late or no menopause would reproduce more.
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Pregnancy and childbirth are tremendously taxing on the female body. This is precisely why in almost every culture–no matter their level of "development"–women have strategies for spacing and preventing pregnancies. It’s often in the health interests of women to end childbearing before it causes a) death, b) serious health concerns (tears, fistulas), or c) just plain exhaustion, and the longer it goes on, the higher the risks.
Furthermore, there are cultural elements of preference that override that abstract sense of "we want to reproduce as much as possible"; specifically, that most adults actually want to reproduce at a far lower rate than they are physically capable.
So, there’s not really a beneficial element to eliminating menopause, but a few good reasons to maintain it.
The older a female is when pregnant, the greater likelihood of birth defects and/or delivery being risky to the mother or child.
Well if you look at how humans evolved, you can see something called "The Grandmother Hypothesis" and it has to do with child rearing, and making it possible for young children to be taken care of while their mother’s are pregnant or giving birth.
To make this brief, women have menopause because it prevents them from having children, but it enables them to be caretakers. They are no longer burdened with reproduction and can help take care of babies and young animals/people, thus making the job of a woman who is reproducing, easier. Men used to have the tasks of providing food (women did produce food in gardens and also processed food but again, this is where menopausal women helped out by being able to care for children while other women worked in food production). Because child care was not the purpose for evolving man, it wasn’t necessary to limit their ability to reproduce.
The man be a male menopause.
"Since men do not go through a well-defined period referred to as menopause, some physicians refer to this problem as androgen (testosterone) decline in the aging male. Men do experience a decline in the production of the male hormone testosterone with aging, but this also occurs with some disease states such as diabetes. Along with the decline in testosterone, some men experience symptoms such as fatigue, weakness, depression, and sexual problems."
http://men.webmd.com/guide/male-menopause
It has been show the male still produces sperm but:
"The tubes that carry sperm may become less elastic (a process called sclerosis). The testes continue to produce sperm, but the rate of sperm cell production slows. The epididymis, seminal vesicles, and prostate gland lose some of their surface cells "
http://www.wellman.org.au/male.html
It’s also reported that the number of damaged sperm increases. This would effect conception and likely increase birth defects.
Actually female human beings are fertile for a far greater amount of time than most animals. This is because women do not have to be "in heat" to reproduce like many other animals such as horses, dogs, cats, etc.
Researchers believe that at some point on the evolutionary chain human women did have to wait to be in heat to reproduce but that since this was a disadvantage, those women slowly got weeded out and women with the genetic mutation to ovulate monthly in the current menstruation pattern were naturally selected to flourish. So if you think about it, evolution has already helped human production a great deal. Evolution may have even continued until it eradicated menopause as you suggested… but advances in medicine and current obstetrics practices have probably made this an unnecessary development.