Often the complaints of hunter-gathers were about the monotony of a carbohydrate staple, such as mongongo nuts, for every meal; when they spoke of shortages, or even hunger, they meant a shortage of meat, and a hunger for fat, and a distaste for periods of hunger. Their small amount of technology gave them sufficiency for most of the time, but not abundance.
The fine line between average sufficiency and abundance matters for health. When anthropologists measure the total fertility rate (the mean number of live births over the reproductive years) of women in modern hunter-gatherer tribes, they find it relatively lowâabout five to six children in totalâcompared to six to eight children in agricultural communities. There are several factors behind this depressed fertility. Perhaps because of uneven nutrition, puberty comes late to forager girls, at 16 or 17 years old. (Modern females start at 13.) This late menarche for women, combined with a shorter life span, delays and thus abbreviates the childbearing window. Breast-feeding usually lasts longer in foragers, which extends the interval between births. Most tribes nurse till children are 2 or 3 years old, while a few tribes keep children suckling for as long as 6 years. Also, many women are extremely lean and active and, like lean, active women athletes in the West, often have irregular or no menstruation. One theory suggests women need a âcritical fatnessâ to produce fertile eggs, a fatness many forager women lackâat least part of the yearâbecause of a fluctuating diet. And of course, people anywhere can practice deliberate abstinence to space children, and foragers have reasons to do so.
Child mortality in foraging tribes was severe. A survey of 25 hunter-gatherer tribes in historical times from various continents revealed that, on average, 25 percent of children died before they were 1, and 37 percent died before they were 15. In one traditional hunter-gatherer tribe, child mortality was found to be 60 percent. Most historical tribes had a population growth rate of approximately zero. This stagnation is evident, says Robert Kelly in his survey of hunting-gathering peoples, because âwhen formerly mobile people become sedentary, the rate of population growth increases.â All things being equal, the constancy of farmed food breeds more people.
While many children died young, older hunter-gatherers did not have it much better. It was a tough life. Based on an analysis of bone stress and cuts, one archaeologist said the distribution of injuries on the bodies of Neanderthals was similar to that found on rodeo professionalsâlots of head, trunk, and arm injuries like the ones you might get from close encounters with large, angry animals. There are no known remains of an early hominin who lived to be older than 40. Because extremely high child mortality rates depress average life expectancy, if the oldest outlier is only 40, the median age was almost certainly less than 20.
A typical tribe of hunters-gatherers had few very young children and no old people. This demographic may explain a common impression visitors had upon meeting intact historical hunter-gatherer tribes. They would remark that âeveryone looked extremely healthy and robust.â Thatâs in part because most everyone was in the prime of life, between 15 and 35. We might have the same reaction visiting a trendy urban neighborhood with the same youthful demographic. Tribal life was a lifestyle for and of young adults.
A major effect of this short forager life span was the crippling absence of grandparents. Given that women would only start bearing children at 17 or so and die by their thirties, it would be common for children to lose their parents before the children were teenagers. A short life span is rotten for the individual. But a short life span is also extremely detrimental for a society as well. Without grandparents, it becomes exceedingly difficult to
Learning to Kill: Stories