poly: Why Demographic Transition?

I've been puzzling over the demographic transition for a while.
Over the last few centuries, we have seen a robust phenomena where
as people get richer and more educated, they have smaller families.
It has gotten to real extremes in Europe in the last decade.
I think the average # kids per couple in Bolgna, Italy is 0.8!
This seems evolutionarily unstable, suggesting that DNA or culturally
encoded preferences which where once evolutionarily adaptive have
lost this feature upon translation to a very different world.

One question to ask would be: in a tribal context, what reproductive
advantage would there be to a strategy of having fewer kids
as one got richer?

An obvious answer occurred to me yesterday. A standard explanation
for risk-taking among young men is that they are in more of a
"winner take all" contest. The local male perceived to be the most
fit, or having the most resources, gets to do a big chunk of the local
mating.

When a parent cares about their boy's mating changes, they also care
how rich each of their boys is. With a strong enough effect, a rich
parent may prefer to concentrate their resources on a few rich kids,
rather than more poorer kids.

Robin Hanson
hanson@econ.berkeley.edu http://hanson.berkeley.edu/
RWJF Health Policy Scholar, Sch. of Public Health 510-643-1884
140 Warren Hall, UC Berkeley, CA 94720-7360 FAX: 510-643-2627
Received on Tue Jul 28 19:13:16 1998