In the Seventies, the evolutionary-­biological approach to the study of human behavior grew even more popular. Its leading exponents were Hamilton’s Oxford colleague Richard Dawkins—­who has called Hamilton “the greatest Darwinian of my lifetime”—­and the Harvard entomologist E. O. Wilson, who recalled his imagination being “captured” by Lorenz at a pivotal point in his graduate studies.

W. D. Hamilton, one of the most influential evolutionary biologists of the second half of the twentieth century. Hamilton helped develop new theoretical tools that allowed scientists to postulate a genetic basis for a range of complex social behaviors. Among these behaviors, in Hamilton’s view, was genocide, which was a natural if morally regrettable response to population growth among a competing “tribe.”