Environmental Engineering Reference
In-Depth Information
while bonobos eat small antelopes (duikers), l ying squirrels, and other small pri-
mates (Hohmann and Fruth 2008). Chimpanzee hunts are sometime cooperative
and meat is often shared, either to reinforce social bonds within a group or, more
often, to attract females (Teleki 1973; Boesch 1994; Stanford 1999).
The evolution of cooperative hunting (and subsequent meat sharing) is perhaps
best explained by the fact that it maximizes an individual's chance to get high-quality
protein and essential micronutrients in meat (Tennie, Gilby, and Mundry 2009). And
the exchange of meat for sex is not an infrequent occurrence, but is done on a long-
term basis (Gomes and Boesch 2009). These i ndings led anthropologists to expect
a similar importance of skilled and cooperative hunting to derive the nutritional
benei ts of meat and improve the probabilities of reproductive success in the evolu-
tion of our species. More frequent meat eating helps explain signii cant differences
in height and body mass (a roughly 40%-50% gain) between
Homo habilis
and
Homo erectus
(McHenry and Cofi ng 2000), and lower meat consumption in sed-
entary agricultural societies was a factor in their common health problems.
Moreover, Aiello and Wheeler (1995) argue that the only way humans could
support a larger brain size without increasing total metabolic rate was to reduce
the size of another internal organ. This would have been difi cult to accomplish with
liver, heart, or kidneys, but the size of a metabolically expensive gastrointestinal
tract could be reduced with a better, more meaty diet and would free more food
energy to support larger brains. Meat consumption remained limited in all tradi-
tional agricultural societies, but higher meat consumption has been a universal
marker of rising incomes; meat eating is still widely seen as a sign of afl uence, and
meat sharing is still used to create personal bonds in most cultures.
Lean meat is, of course, a virtually pure protein of the highest quality (unlike all
plant proteins, it has the correct proportions of all essential amino acids needed for
human growth), and as such, it has a rather low energy density. The meat of wild
herbivores, be they small lagomorphs (rabbits, hares) or large ungulates (antelopes,
elks, bison), is very lean: fresh carcasses are more than 70% water, 20%-23%
protein, and less than 10%(some species less than 1%) fat (subcutaneous and intes-
tinal), resulting in an overall food energy density of only 4.8-6.0 MJ/kg (compared
to 15 MJ/kg for grains and more than 16 MJ/kg for fatty meat). That is why even
a relative abundance of this lean meat could leave people feeling hungry and craving
high-energy-density, satiety-inducing fat. Moreover, prolonged eating of nothing but
lean meat causes acute malnutrition known as rabbit starvation (
mal de caribou
of
the early French explorers in Canada) that brings nausea, diarrhea and eventual
death (Speth and Spielmann 1983). This helps to explain why Hayden (1981)
