This week’s New Scientist magazine has an interesting article on human evolution and the spread of humans across the planet. It seems it might be to do with ADHD genes! Note: this isn’t the whole article, the ADHD bit was only mentioned at the end so we’ve cut out quite a bit for our ADHD readers (and editors). The full article on the NS web site is here. If you have trouble getting the full version let us know and we’ll see what we can do. Now read on…
Out-of-Africa migration selected novelty-seeking genes
AS HUMANS migrated out of Africa around 50,000 years ago and moved across the planet, evolution may have latched onto a gene linked to risk-taking and adventurousness.
The DRD4 gene codes for a dopamine receptor in the brain. It exists in several versions, or alleles, and studies have shown that people tend to have slightly different personality traits depending on which they have. The 4R allele, for instance, is associated with being even-tempered, reflective and prudent. The less common 7R and 2R versions have been linked to impulsive and exploratory behaviour, risk-taking and the ability to shrug off new situations. Matthews and Butler think that migrants with these versions were better able to deal with dangerous, fluctuating situations and more likely to survive and reproduce under those conditions.
Researchers are beginning to play with the idea that our culture could be influencing evolution, says Robert Moyzis of the University of California, Irvine. He has shown that 7R arose as a rare mutation 40,000 to 50,000 years ago, after we left Africa, then spread rapidly in human populations. The 2R allele is a modified version that arose in Asia less than 10,000 years ago.
He has also shown that people diagnosed with attention deficit hyperactivity disorder are twice as likely to have the 7R allele. He thinks some of what we consider ADHD symptoms, like rapidly shifting focus and quick movements, are actually survival traits that were selected for during our migration out of Africa.