In today's society, impulsivity and continuous need for novelty are traits likely to be associated with little more than job loss. However, in other eras of human existence, such traits might have been an individual's key to survival: Research published in BMC Evolutionary Biology has found real-world evidence supporting the theory that attention deficit hyperactivity disorder (ADHD) may in fact be an evolutionary adaptation necessary for survival in nomadic environments.
Northwestern University graduate student Dan Eisenberg and associates studied the Aarial, a Kenyan tribe which has recently split into a nomadic and a settled group. Adult males from the tribe were tested for genetic variations in the DRD4 gene, which is associated with impulsivity and addiction. In particular, researchers looked for allele 7, a version of the gene associated with both ADHD and food cravings. The team also assessed the body mass indices (BMIs) of the Aarials.
Results showed that men with allele 7 were better nourished in the nomadic division of the tribe, but less well-nourished among settled members of the tribe.
The results suggest traits affected by this genetic variation can have positive or negative implications depending on the environment. As Eisenberg notes:
Increased impulsivity, ADHD-like traits, novelty-seeking like traits aggression, violence and/or activity levels may help nomads obtain food resources, or exhibit a degree of behavioural unpredictability that is protective against interpersonal violence or robberies. Increased activity levels, if not resulting in increased food access, likely would decrease nutritional stores.
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