How Many Of Our Ancestors Were Women?

Get Lucky: same-same but different

Roy F. Baumeister (2010) - It’s not a trick question, and it’s not 50%. True, about half the people who ever lived were women, but that’s not the question. We’re asking about all the people who ever lived who have a descendant living today […] Recent research using DNA analysis answered this question […] Today’s human population is descended from twice as many women as men. I think this difference is the single most under-appreciated fact about gender. To get that kind of difference, you had to have something like maybe 80% of women but only 40% of men reproduced.

[…] For women throughout history the odds of reproducing have been pretty good […] Why was it so rare for a hundred women to get together and build a ship and sail off to explore unknown regions, whereas men have fairly regularly done such things? But taking chances like that would be stupid, from the perspective of a biological organism seeking to reproduce. They might drown or be killed by savages or catch a disease. For women, the optimal thing to do is go along with the crowd, be nice, play it safe. The odds are good that men will come along and offer sex and you’ll be able to have babies. All that matters is choosing the best offer. We’re descended from women who played it safe.

For men, the outlook was radically different. If you go along with the crowd and play it safe, the odds are you won’t have children. Most men who ever lived did not have descendants who are alive today. Their lines were dead ends. Hence it was necessary to take chances, try new things, be creative, explore other possibilities. Sailing off into the unknown may be risky, and you might drown or be killed or whatever, but then again if you stay home you won’t reproduce anyway. We’re most descended from the type of men who made the risky voyage and managed to come back rich. We’re descended from men who took chances (and were lucky).

[…] Most women have only a few children, and hardly any have more than a dozen — but many fathers have had more than a few, and some men have actually had several dozen, even hundreds of kids. In terms of the biological competition to produce offspring, then, men outnumbered women both among the losers and among the biggest winners […] Experts estimate Genghis Khan had several hundred and perhaps more than a thousand children. He took big risks and eventually conquered most of the known world. For him, the big risks led to huge payoffs in offspring. My point is that no woman, even if she conquered twice as much territory as Genghis Khan, could have had a thousand children. Striving for greatness in that sense offered the human female no such biological payoff. For the man, the possibility was there, and so the blood of Genghis Khan runs through a large segment of today’s human population. By definition, only a few men can achieve greatness, but for the few men who do, the gains have been real. And we are descended from those great men much more than from other men. Remember, most of the mediocre men left no descendants at all.