Environmental Engineering Reference
In-Depth Information
48 km. Almost invariably, only herbivores were hunted:
hunting carnivores was energetically unprofitable given
their low numbers and higher risks of injury to the hunt-
ers. Where available, larger species were preferred and
Silberbauer (1981) noted that the G/wi generally
selected the prey with the greatest food reward for the
lowest expenditure of energy, and this approach was
undoubtedly ubiquitous.
Wild herbivore meat is an excellent source of protein
(20% of fresh weight) but a marginal source of fat. Pro-
viding only about 6 MJ/kg and less than 10% of lipids,
it left people feeling hungry and craving fat. A richer ratio
of fat to lean meat was particularly critical for survival in
the Arctic (Cachel 1997). Hayden (1981) argued that
the high regard for meat is actually a misconception pro-
moted by ethnographers, that the meat itself was valued
little but fat was the real prize. Studies of Basarwa groups
showed a preference for fat underground mammals (por-
cupines, antbears) as well as for hippopotamus and eland,
the fattiest of all antelopes (van der Post and Taylor
1984). But Wrangham et al. (1999) argued that in gen-
eral it was the cooking of plant foods that enlarged diets
and improved their quality much more than did addi-
tional intakes of meat. Cannibalism took place in many
preagricultural societies, but the reasons for it were not
solely energetic (starvation) and included also ancestor
worship and terrorism (Brown and Tuzin 1983).
The best estimates based on a few studies of actual en-
ergy expenditure indicate that the PAL for adults in for-
aging societies were mostly in moderate category (Jenike
2001), but in general the energetic explanations of for-
aging have clear limits. For !Kung Basarwa abundant,
energy-dense mongongo nuts provided the best energy
return and much of the diet, but /Aise, another Basarwa
group with access to the nuts, did not eat them because
they did not taste good to them (Hitchcock and Ebert
1984). Similarly, coastal groups in Southern Australia
supported their high densities by fishing, but across the
strait the Tasmanians did not eat fish at all. And among
the Yanomami, Lizot (1977) found, a group surrounded
by a particularly animal-rich forest consumed less than
half as much animal food energy and protein as its neigh-
bors did. His explanation: people of the first group were
simply lazier and hunted infrequently, preferring to eat
less well and to spend days taking hallucinogens.
In this and other instances energy supply may simply
have been a function of the attitude toward work. And
yet some foraging efforts were rather brief, just 2-5 h/
day in many tropical and subtropical environments, and
these relatively short workdays were perhaps the most
important argument in attempts to portray foragers as
the original affluent society, living comfortably in a kind
of material plenty, filled with leisure and sleep, never in
hurry, never worried (Sahlins 1972). Such theorizing
ignored evidence of much less comfortable subsistence
patterns as well as the frequency with which seasonal
food shortages and famines ravaged the foraging societies
(Rowley-Conwy 2001).
Our understanding, based on foraging groups that sur-
vived to the twentieth century, may not be representative
of foragers during the time of their preagricultural domi-
nance. Still, these studies make it possible to reconstruct
the approximate energy returns of individual foraging
activities. They are as high as 30-40-fold for gathering
some energy-dense roots, 10-20-fold for all gathering,
in the same range for hunting large ungulates, and mini-
mal energy gain or even net energy loss for hunting
smaller mammals. Much higher energy gains (up to 19-
fold) in hunting a large (280-kg) eland rather than a
smaller (70-80-kg) gemsbok (sixfold return) explain the
