Ecological Equilibrium
Marvin Harris (1974), based on his study of highland New Guinea tribes, suggests that war maintains “ecological equilibrium” in primitive cultures. That is, war brings population back into line with resources even if the participants do not understand that is the cause of the fighting.
War breaks out whenever population size reaches the carrying capacity of the land. It both reduces the population and allows the land to lie fallow long enough to recover. Diamond (2005) suggests a similarly Malthusian cause for the genocide in Rwanda in the 1990s.Harris asserts that primitive war is adaptive, although he does not extend the claim to modern war. That is, ecological equilibrium may explain the origin of war, but not its continuance. Harris (1980) further suggests that Freud may have had it backwards: that the Oedipus complex, if it exists at all, is not human nature but a predictable outcome of training males to be combative.
The low casualty rates in the brief battles Harris describes compared to the time for the land to recover its fertility and the existence of war in primitive societies with no shortage of resources suggest that Harris’s theory is at best incomplete and at worst invalid. While most anthropologists argue that primitive war was ritualistic and characterized by low casualties, others provide evidence that most fatalities in primitive war come not from battles but from raids and ambushes over an extended period that can extinguish entire tribes (Chapter 14).