barriomulas.com - Hunter-Gatherers with ADD

Fascinating article from The Economist. Those of you interested in things like primitivism and hunter-gatherism, enjoy:

ABOUT one in 20 children (those under 18) have a group of symptoms that has come to be known as attention-deficit hyperactivity disorder (ADHD). About 60% of them carry those symptoms into adulthood. For what is, at root, a genetic phenomenon, that is a lot--yet many studies have shown that ADHD is indeed genetic and not, as was once suspected, the result of poor parenting...

One hypothesis is that the behaviour associated with ADHD helps people, such as hunter-gatherers and pastoral nomads, who lead a peripatetic life. Since today's sedentary city dwellers are recently descended from such people, natural selection may not have had time to purge the genes that cause it...

As they report in this week's BMC Evolutionary Biology, they found that about a fifth of the population of both groups had the 7R version of DRD4... Among the nomads, who wander around northern Kenya herding cattle, camels, sheep and goats, those with 7R were better nourished than those without. The opposite was true of their settled relations: those with 7R were worse nourished than those without it...

One possibility is that its effects are beneficial only when they are not universal, and some sort of equilibrium between variants emerges.