Yep, it’s agriculture again:
Hunter-gatherers have little or no stored food, and no concentrated food sources, like an orchard or a herd of cows: they live off the wild plants and animals they obtain each day. Therefore, there can be no kings, no class of social parasites who grow fat on food seized from others. Only in a farming population could a healthy, non-producing élite set itself above the disease-ridden masses. Skeletons from Greek tombs at Mycenae c. 1500 B. C. suggest that royals enjoyed a better diet than commoners, since the royal skeletons were two or three inches taller and had better teeth (on the average, one instead of six cavities or missing teeth). Among Chilean mummies from c. A. D. 1000, the élite were distinguished not only by ornaments and gold hair clips but also by a fourfold lower rate of bone lesions caused by disease. Similar contrasts in nutrition and health persist on a global scale today. To people in rich countries like the U. S., it sounds ridiculous to extol the virtues of hunting and gathering. But Americans are an élite, dependent on oil and minerals that must often be imported from countries with poorer health and nutrition. If one could choose between being a peasant farmer in Ethiopia or a bushman gatherer in the Kalahari, which do you think would be the better choice?
Farming may have encouraged inequality between the sexes, as well. Freed from the need to transport their babies during a nomadic existence, and under pressure to produce more hands to till the fields, farming women tended to have more frequent pregnancies than their hunter-gatherer counterparts–with consequent drains on their health. Among the Chilean mummies for example, more women than men had bone lesions from infectious disease. Women in agricultural societies were sometimes made beasts of burden. In New Guinea farming communities today I often see women staggering under loads of vegetables and firewood while the men walk empty-handed. Once while on a field trip there studying birds, I offered to pay some villagers to carry supplies from an airstrip to my mountain camp. The heaviest item was a 110-pound bag of rice, which I lashed to a pole and assigned to a team of four men to shoulder together. When I eventually caught up with the villagers, the men were carrying light loads, while one small woman weighing less than the bag of rice was bent under it, supporting its weight by a cord across her temples.
So how did agriculture win out?
One answer boils down to the adage “Might makes right.” Farming could support many more people than hunting, albeit with a poorer quality of life. (Population densities of hunter-gatherers are rarely over on[e] person per ten square miles, while farmers average 100 times that.) Partly, this is because a field planted entirely in edible crops lets one feed far more mouths than a forest with scattered edible plants. Partly, too, it’s because nomadic hunter-gatherers have to keep their children spaced at four-year intervals by infanticide and other means, since a mother must carry her toddler until it’s old enough to keep up with the adults. Because farm women don’t have that burden, they can and often do bear a child every two years.
As population densities of hunter-gatherers slowly rose at the end of the ice ages, bands had to choose between feeding more mouths by taking the first steps toward agriculture, or else finding ways to limit growth. Some bands chose the former solution, unable to anticipate the evils of farming, and seduced by the transient abundance they enjoyed until population growth caught up with increased food production. Such bands outbred and then drove off or killed the bands that chose to remain hunter-gatherers, because a hundred malnourished farmers can still outfight one healthy hunter. It’s not that hunter-gatherers abandoned their life style, but that those sensible enough not to abandon it were forced out of all areas except the ones farmers didn’t want.