Darwinism misleads again, this time about aging and fertility in chimps and humans
|January 23, 2014||Posted by News under Human evolution, Intelligent Design, Natural selection, News|
Further to “Chimpanzees, we learn, can use gestures to communicate when hunting for food,” some claim that women undergo menopause but chimpanzees do not, that “menopause is not a part of the life cycle of living apes but has been uniquely derived in the human lineage.”
Darwinian explanations for that are, of course, on offer. For example, men triggered menopause (by preferring younger women).Or women’s selfish genes cause them to forego future breeding in order to invest in the survival of their existing selfish genes (children), sometimes called the grandmother hypothesis. That thesis assumes, of course, that older women are an asset to a group. Sometimes they are. But typical human groups don’t act on that assumption. And they are wise not to.
Anyway, chimpanzees do undergo menopause. Consider this 2012 paper, which argues that menopause occurs, but late in life in the captive chimpanzee. Read the abstract carefully:
Menopause in women occurs at mid-life. Chimpanzees, in contrast, continue to display cycles of menstrual bleeding and genital swelling, suggestive of ovulation, until near their maximum life span of about 60 years. Because ovulation was not confirmed hormonally, however, the age at which chimpanzees experience menopause has remained uncertain. In the present study, we provide hormonal data from urine samples collected from 30 female chimpanzees, of which 9 were old (>30 years), including 2 above the age of 50 years. Eight old chimpanzees showed clear endocrine evidence of ovulation, as well as cycles of genital swelling that correlated closely with measured endocrine changes. Endocrine evidence thus confirms prior observations (cyclic anogenital swelling) that menopause is a late-life event in the chimpanzee. We also unexpectedly discovered an idiopathic anovulation in some young and middle-aged chimpanzees; this merits further study. Because our results on old chimpanzees validate the use of anogenital swelling as a surrogate index of ovulation, we were able to combine data on swelling and urinary hormones to provide the first estimates of age-specific rates of menopause in chimpanzees. We conclude that menopause occurs near 50 years of age in chimpanzees as it does in women. Our finding identifies a basic difference between the human and chimpanzee aging processes: female chimpanzees can remain reproductively viable for a greater proportion of their life span than women. Thus, while menopause marks the end of the chimpanzee’s life span, women may thrive for decades more.
Hey, wait a minute. If this holds up, she-chimps and women both cease to ovulate around fifty years of age. But in general, in modern societies with high standards of living, women live much longer after that than captive she-chimps, in a surprising variety of medical conditions. Can anyone think of possible reasons why that might be? 😉 Put another way, what if aged captive chimps were able to demand and get the same treatment?
Better still, what if we just left “evolution” and “natural selection” out of the discussion, and factored in the fact that humans don’t like aging and dying and try to put it off as long as we can. And can be surprisingly successful.
Chimps might not like it either, but for them it’s tough bananas. And the captive ones probably live much longer than the wild ones because humans make the decisions for them. (See Cheetah, below)
The relationship between aging and fertility is, in general, another subject where Darwinism has been a blight to the nations and a clamp of thought. This from a recent article in Nature:
Evolution drives, and is driven by, demography. A genotype moulds its phenotype’s age patterns of mortality and fertility in an environment; these two patterns in turn determine the genotype’s fitness in that environment. Hence, to understand the evolution of ageing, age patterns of mortality and reproduction need to be compared for species across the tree of life. However, few studies have done so and only for a limited range of taxa. Here we contrast standardized patterns over age for 11 mammals, 12 other vertebrates, 10 invertebrates, 12 vascular plants and a green alga. Although it has been predicted that evolution should inevitably lead to increasing mortality and declining fertility with age after maturity, there is great variation among these species, including increasing, constant, decreasing, humped and bowed trajectories for both long- and short-lived species. This diversity challenges theoreticians to develop broader perspectives on the evolution of ageing and empiricists to study the demography of more species.
The obvious message is that current evolution theory provides no basis whatever for any form of interpretation of the relationship between longevity and fertility. But no one is allowed to put it that way.
See also: So now it’s the “creationists’” fault that Darwin’s followers can’t face facts?
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