Food And Evolution: Toward a Theory of Human Food Habits

13. How Much Food Do Foragers Need?

KRISTEN HAWKES How Much Food Do Foragers Need? i\N INTERESTING EMPIRICAL PUZZLE IS POSED BY RECENT OBSERvations on foraging effort among hunter-gatherers. In the mid-1960s, the Dobe ~Kung of Botswana reportedly spent no more than 20 hours per week collecting resources that yielded an average of 2,100 kilocalories per consumer day (Lee 1968, 1969). Many anthropologists take these figures to be typical of hunter-gatherers. They expect that work effort is set to meet some general and specifiable consumption need, so that when this need is easily met, foragers work little. When it takes more effort to reach the same goal, workloads increase. Yet, in contrast to Lee's reports on the !Kung, the Ache of eastern Paraguay have recently been observed to work, averaging male and female foragers, at least 35 hours per week for a mean return of 3,800 kilocalories per consumer day (Hill et aI., 1984). They procure more food than Lee reports for the! Kung, and they work longer hours to get it. The Ache data are inconsistent with what has become the received wisdom on hunter-gatherer foraging, and they raise an obvious and important theoretical question: what determines the amount of time hunter-gatherers devote to foraging and the quantity of food they consume? The Problem Largely because of the rich ethnographic descriptions (e. g., Lee 1968, 1979; Marshall 1976; Thomas 1959; and films by John Marshall), the !Kung are often identified as prototypical hunter-gatherers-well-nourished foragers who work relatively short hours, rely on the widely available plant foods collected by women for the bulk of their diet, and maintain low birthrates, which prevent population growth from threatening local resources. Though this characterization has been challenged, as applied both to the! Kung themselves and to other hunter-gatherers (e.g., Ember 1978; Lee and DeVore 1968; Truswell and 341 IV. Pre-State Foadways Hansen 1979; Wilmsen 1978), it remains remarkably persistent. When anthropologists write about hunter-gatherers, more often than not they write about the !Kung (e.g., Cohen 1977; Harris 1977, 1983; Leakey and Lewin 1978). The Ache are very different. The per capita daily consumption rates they sustain while foraging are quite high, averaging 2,600 to 5,400 kilocalories, depending on the season (Hill et al. 1984). More than half this total comes in the form of meat. This is especially surprising in view of generalizations about tropical hunter-gatherers (Lee 1968), particularly those of the South American lowlands (Lathrap 1968). These figures are not the result of unusually high local capture rates. Hourly returns for Ache hunters average only 10 to 15 percent higher than those calculated for the !Kung (Hawkes, Hill, and O'Connell 1982; Hill and Hawkes 1983). The difference in return is almost entirely a function of the time Ache men devote to hunting-nearly 50 hours per week per hunter while on foraging trips, more than twice the figure reported by Lee (1969) for !Kung men. The contrast becomes even more striking when one considers the difference in women's work effort. !Kung women spend about 12 to 19 hours per week collecting food (Lee 1968; but see recalculation by Hawkes and O'Connell 1981); yet for Ache women, the figure seldom exceeds 10 hours per week. Stimulated by Lee's description of the !Kung, Sahlins characterized huntergatherers as "the original affluent society" (1968, 1972). Wanting little, they could work little to have all their needs met. Yet neither the differences in overall time investment in foraging between the !Kung and the Ache nor the differences in relative time investment between men and women show the pattern that might be expected if some fixed food total were the goal. The !Kung and Ache are both of small stature. They are of about the same height. Vet the Ache eat a great deal more, and they are almost 20 percent heavier (Hill et al. 1984; Howell 1979). If needs were a function of some standard nutritional goal, patterns of caloric intake should be more similar than they apparently are. Moreover, the Ache are not an isolated case, an oddity among huntergatherers with respect to foraging. Other groups described within the past few years (Harako 1981; Hawkes and O'Connell 1981; Tanaka 1980), including the !Kung themselves (Yellen 1977), display patterns of work effort and food consumption quite different from those reported by Lee. These data underline the problem of interest here: how much food will hunter-gatherers eat, and how...