(...) High status has almost always translated into reproductive success, not just in the animal world, but for humans, too. This phenomenon started back in our hunter-gatherer days, when the men who brought home the most meat won the most mates, and it has continued up through the likes of J. Paul Getty and Donald Trump. Betzig's research piled up historical examples, including extreme cases such as the Aztec strongman Montezuma, said to have kept 4,000 concubines, and a Chinese emperor whose harem numbered in the tens of thousands. On a lesser scale, the big houses of the British countryside before World War I often accommodated 10 to 20 servants, who were typically young, female and single. "Housemaid Heights," Betzig argues, functioned as a de facto harem for upper-class males. Thus an 1883 investigation in Scotland found that domestic servants accounted for almost half of out-of-wedlock births (...)