Chapter 4 Summary and Analysis

Chapter 4 explains why there are two sexes, male and female, rather than some other number and why the ratio, at least among humans, of male to female is around 1:1. Part of the reason involves logic similar to the familiar notion of a "tragedy of the commons." A tragedy of the commons occurs when what is individually rational leads to outcomes that are collectively irrational. For instance, it would be better for everyone if a certain stretch of ocean is not fished excessively. However, for an individual fisherman, assuming that his neighbors will fish as much as they can, it is in his best interest to get as much fish as he can before there are no more left. If everyone fishes the right amount, the fisherman will not have an incentive to overfish. However, since there is not reason for any...