The question concerning why human females experience menopause has plagued evolutionary biologists and anthropologists for a long time. After all, Darwinian evolutionary fitness is all about maximizing reproductive success; why might selection favour females living through a (at times) lengthy life history stage during which there is no possibility of contributing to their reproductive fitness? Or is it possible that selection has favoured females in some species contributing indirectly to their inclusive fitness via their offspring and grandoffspring? Is it possible that menopause in some female mammals is just a by-product of a long life history, which itself is a by-product of larger brains?
In this essay assignment you are to evaluate the various hypotheses that have been proposed in the above readings to explain the occurrence of menopause. In so doing you will also address the following questions:
- Is menopause really unique to humans?
- Are there other species of primates, or other mammals, that also clearly experience a postreproductive life-history stage?
- Are any hypotheses that have been proposed to explain the occurrence of menopause in other mammals applicable to the condition in humans?
- Evaluate the strength of evidence that does (or does not) support the various hypotheses about menopause. How might we accurately test these hypotheses in long-lived mammalian species?
One area of recent research that you should consider reviewing and incorporating into this essay assignment concerns the occurrence of postreproductive life spans in cetaceans (particularly the “toothed” whales, such as orcas and pilot whales). Use the AU Library or other search engines (such as Google Scholar) to find relevant articles on this topic in addition to the three presented here.
Required Readings
Peccei, Jocelyn Scott. “Menopause: Adaptation or Epiphenomenon?” Evolutionary Anthropology: Issues, News, and Reviews 10, no. 2 (2001): 43–57.
Kirchengast, Sylvia. “Menopause Female Reproductive Senescence from the Viewpoint of Evolutionary Anthropology.” In A Multidisciplinary Look at Menopause, edited by Juan Francisco Rodriguez-Landa and Jonathan Cueto-Escobedo. London: InTech, 2017.
Takahashi, Mike, Rama S. Singh, and John Stone. “A Theory for the Origin of Human Menopause.” Frontiers in Genetics 7, no. 222 (2017).