Free Why is Sex Fun?: the evolution of human sexuality by Jared Mason Diamond

predictions have been little tested. Perhaps unsurprisingly, the lead in testing them has been taken by a woman anthropologist, Kristen Hawkes of the University of Utah. Hawkes's tests have been based especially on quantitative measurements of foraging yields for Paraguay's Northern Ache Indians, carried out jointly with Kim Hill, A. Magdalena Hurtado, and H. Kaplan. Hawkes performed other tests on Tanzania's Hadza people in collaboration with Nicholas Blurton Jones and James O'Connell. Let's consider first the evidence for the Ache.
    The Northern Ache used to be full-time hunter-gatherers and continued to spend much time foraging in the forest even after they began to settle at mission agricultural settlements in the 1970s. In accord with the usual human pattern, Ache men specialize in hunting large mammals, such as peccaries and deer, and they also collect masses of honey from bees' nests. Women pound starch from palm trees, gather fruits and insect larvae, and care for children. An Ache man's hunting bag varies greatly from day to day: he brings home food enough for many people if he kills a peccary or finds a beehive, but he gets nothing at all on one-quarter of the days he spends hunting. In contrast, women's returns are predictable and vary little from day to day because palms are abundant; how much starch a woman gets is mainly a function of just how much time she spends pounding it. A woman can always count on getting enough for herself and her children, but she can never reap a bonanza big enough to feed many others.
    The first surprising result from the studies by Hawkes and her colleagues concerned the difference between the returns achieved by men's and women's strategies. Peak yields were, of course, much higher for men than for women, since a man's daily bag topped 40,000 calories when he was lucky enough to kill a peccary. However, a man's average daily return of 9,634 calories proved to be lower than that of a woman (10,356), and a man's median return (4,663 calories per day) was much lower. The reason for this paradoxical result is that the glorious days when a man bagged a peccary were greatly outnumbered by the humiliating days when he returned empty-handed.
    Thus, Ache men would do better in the long run by sticking to the unheroic “woman's job” of pounding palms than by their devotion to the excitement of the chase. Since men are stronger than women, they could pound even more daily calories of palm starch than can women, if they chose to do so. In going for high but very unpredictable stakes, Ache men can be compared to gamblers who aim for the jackpot: in the long run, gamblers would do much better by putting their money in the bank and collecting the boringly predictable interest.
    The other surprise was that successful Ache hunters do not bring meat home mainly for their wives and kids but share it widely with anyone around. The same is true for men's finds of honey. As a result of this widespread sharing, three-quarters of all the food that an Ache consumes is acquired by someone outside his or her nuclear family.
    It's easy to understand why Ache women aren't big-game hunters: they can't spend the time away from their children, and they can't afford the risk of going even a day with an empty bag, which would jeopardize lactation and pregnancy. But why does a man eschew palm starch, settle for the lower average return from hunting, and not bring home his catch to his wife and kids, as the traditional view of anthropologists predicts?
    This paradox suggests that something other than the best interests of his wife and children lie behind an Ache man's preference for big-game hunting. As Kristen Hawkes described these paradoxes to me, I developed an awful foreboding that the true explanation might prove less noble than the male's mystique of bringing home the bacon. I be-gan to feel defensive on behalf of my fellow men and to search for explanations that might restore my faith in the nobility of the