Besides changing our diets, the adoption of agriculture brought about a host of new challenges: crowding, the accumulation of garbage, difficulties with human waste disposal, and increased numbers of rats and mice as well as livestock near places of human habitation. All of these led to infectious diseases, some newly common, others new altogether. These diseases acted as a selective pressure to produce genetic changes. The authors list nine separate mutations, for example, which protect against falciparum malaria (the most common and dangerous form of malaria); different mutations are common in different regions.
The most interesting genetic changes, as the authors say, are those that change minds rather than bodies. Agriculture selects for personality traits that make men successful rather than colorful: traits such as patience, self-control, and the ability to defer gratification: “Food is often shortest just before sowing, and those earlier farmers had to abstain from eating the seed grain when they and their families were hungriest. This is something that classic hunter-gatherers just didn’t do. Efforts to teach Bushmen to become herders frequently fail when they eat all their goats”.
For similar reasons, “conventional solutions to the problem of slow modernization among peoples with shallow experience of farming are highly problematic.” The cause of differences between “developed” and “undeveloped” societies may well be “biological changes that are the product of natural selection acting over millennia”.
Agriculture also leads to private property and stinginess. Huntergatherers usually shared resources with the tribe, largely because there wasn’t much else to do with them: “Try eating a whole giraffe before the meat goes bad”. But farmers could increase their reproductive success by being miserly.
Hunters are often lazy as long as their stomachs are full, and this makes sense since it conserves their energy. But farmers can almost always find things to do to increase their fitness: piling up enduring assets, building barns or irrigation works, trading for more land or livestock. Evolution seems to be selecting for men who enjoy keeping busy.
(The Occidental Quarterly, Vol. IX, No. 2, Summer 2009).