The ADHD children of the world may have their wandering ancestors to blame. A genetic variant associated with impulsivity, novelty seeking, and attention deficit hyperactivity disorder (ADHD) might have actually been adaptive in nomadic populations, according to a a recent study by Dan Eisenberg at Northwestern University. Kenyan nomads with this variant, he says, may have been better at searching for food and defending their resources, giving them a survival advantage. But the study shows that the nomads’ settled descendants who carried this gene were more often malnourished than those without the gene. “Just because we don’t see a trait as being currently advantageous,” Eisenberg says, “does not preclude the trait from having had a function in the past.” Geneticists continue to unravel our ancestral evolution in hopes of better understanding how formerly advantageous genes have led to modern-day health problems.
High Blood PressureHigh blood pressure may be caused by a gene that was key to nomadic survival. The ability to retain salt—controlled in part by a gene called CYP3A5—varies by latitude, according to scientists at the University of Chicago. The closer a population lives to the equator, the better individuals are at retaining salt. “Since hunter-gatherers weren’t assured of getting sodium every day, they needed to be sure not to lose what they did acquire,” says Alan Weder, a hypertension specialist. But bring this gene to a modern setting—with couch lounging and salty snacking—and it is easy to retain more salt than is needed, which can lead to medical problems like high blood pressure.
3 Diseases We May Be Able to Blame on Our Ancient Ancestors
Obesity, lactose intolerance, and high blood pressure may all be traceable to hunter-gatherer survival. by Emily Anthes. Source: Discover Science,Technology and the Future. 8/1/09