Grandmother Hypothesis - Evidence Against

Evidence Against

Such historical studies are, however, unable to quantify grandmotherly assistance; they are merely correlations between infant mortality and the existence of a grandparent. One study that calculated grandmaternal assistance to both offspring and grandchildren did not find appreciable effects to warrant termination of fertility as early as 50.

Another problem concerning the grandmother hypothesis is that it requires a history of female philopatry. Though some studies suggest that hunter-gatherer societies are patriarchal, mounting evidence shows that residence is fluid among hunter-gatherers and that married women in at least one patrilineal society visit their kin during times when kin-based support can be especially beneficial to a woman's reproductive success.

Others dispute the hypothesis, arguing that the grandmother herself will use up resources that could be used for new young.

In addition, all variations on the mother, or grandmother effect, fail to explain longevity with continued spermatogenesis in males. It also fails to explain the detrimental effects of losing ovarian follicular activity, such as osteoporosis, osteoarthritis, Alzheimer’s disease and coronary artery disease.

Alternatively, the debilitating symptoms that usually accompany menopause in Western cultures could be seen as a natural cull of non-reproductive members of a species. Hot flashes, loss of short term memory, decreased ability to concentrate and difficulty in the learning of new tasks would, in the wild, leave the sufferer at greater risk from predators and topographical dangers such as falls from a height. This natural cull would leave more food, usually in relatively short supply, for the reproductive members of a species whose youth could mean that they are less experienced at finding it. However, cross-cultural studies of menopause have found that menopausal symptoms are quite variable among different populations, and that some populations of females do not recognize, and may not even experience, these "symptoms". This high level of variability in menopausal symptoms across populations brings into question the plausibility of menopause as a sort of "culling agent" to eliminate non-reproductive females from competition with younger, fertile members of the species.