Most animals reproduce until they die, but in humans the majority of women live long after menopause. Research published in Nature (Vol. 628, No. 6979, pp. 178-181) may shed some light on this rare occurrence within the animal kingdom.
Using multi-generational data from Finland and Canada, Mirkka Lahdenperä and colleagues discovered that women with a longer post-reproductive lifespan have more grandchildren and so pass more of their genes on to future generations. Simply put, they help their children to breed earlier, more successfully and more frequently.
The results support the 'Grandmother hypothesis' - that women of a certain age are better off helping their children to raise offspring than having any more kids of their own. Consistent with this, the authors found that grandmothers become more likely to die at around the time when their own offspring reach menopause. This is discussed further in an accompanying News and Views article by Kristen Hawkes.
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