Please read: age-old-question Still Pondering an Age-Old Question. Flatt T and Promislow EL. 2007. Science (318) 1255-1256.

2. Kirkwood and Shanley The connections between general and reproductive senescence and the evolutionary basis of menopause

Optional readings:

1) News article describing the grandmother hypothesis of menopause and 2) economist article

Writing project: Why do women cease to reproduce in middle age? How did menopause evolve in humans?

Some suggest that menopause evolved because grandmothers are more successful at passing on their genes by investing in grandchildren than in more babies of their own. Others argue that menopause is a consequence of modern medicine prolonging the lifespan of women past 60 when most pre-historic women would be dead. So in the past reproductive aging would have been in sync with aging of the rest of the body. In this view menopause reflects the early mortality in pre-history and is a gene-environment mismatch.

The artificial lifespan prolongation hypothesis espoused by Steven Austad is described here by Paul Sherman:

[Menopause] may simply be a cultural artefact. According to this ‘blessings of modern life’ theory’, menopause occurs because women live longer now than in the past. Most animals reproduce as long as they live, but zoo specimens and pets (whose lifespans have been artificially lengthened) often stop reproducing before they die. Menopause may similarly result from medically increasing the lifespan of a primate that is born with a fixed total number of gametes. (from Sherman 1998 Nature 392, 759-761)

Argue for either the “grandmother hypothesis” or the “artificial lifespan prolongation” hypothesis.

Lecture from today is here: Aging

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Joe Alcock

Emergency Physician, Educator, Researcher, interested in the microbiome, evolution, and medicine