As you report, Tim Clutton-Brock of Cambridge University and Kavita Isvaran of the Indian Institute of Science in Bengalooru have shown that species in which females live longer than males tend to be polygynous, where a male monopolizes a number of females (“Live Fast, Love Hard, Die Young,” October 20, 2007). The stresses of competition for a harem, as well as its maintenance, reduce the lifespan of males. Applying this result to the human species, they surmise that polygyny was the rule in humanity’s evolutionary past. As polygyny is on the way out around the world, this result leads to an appealing corollary: men and women will eventually have the same lifespan. The only trouble is that it may take a long, long time to get there. After all, our evolutionary past goes at least a hundred-thousand years back.