Why is attention deficit hyperactivity disorder so common? is there an evolutionary reason why these traits are found in as many as 1 in 20 American youngsters? Such questions have prompted intriguing speculation. Harvard psychiatrist John Ratey finds no mystery in the prevalence of ADHD in the U.S. It is a nation of immigrants who, he notes, "risked it all and left their homelands." Characteristics like impulsiveness, high energy and risk taking are therefore highly represented in the U.S. gene pool. "We have more Nobel laureates and more criminals than anywhere else in the world. We have more people who absolutely push the envelope."
But why would adhd have evolved in the first place? Perhaps, like the sickle-cell trait, which can help thwart malaria, attention deficit confers an advantage in certain circumstances. In Attention Deficit Disorder: A Different Perception, author Thom Hartmann has laid out a controversial but appealing theory that the characteristics known today as adhd were vitally important in early hunting societies. They became a mixed blessing only when human societies turned agrarian, Hartmann suggests. "If you are walking in the night and see a little flash, distractibility would be a tremendous asset. Snap decision making, which we call impulsiveness, is a survival skill if you are a hunter." For a farmer, however, such traits can be disastrous. "If this is the perfect day to plant the crops, you can't suddenly decide to wander off into the woods."
Modern society, Hartmann contends, generally favors the farmer mentality, rewarding those who develop plans, meet deadlines and plod through schedules. But there's still a place for hunters, says the author, who counts himself as one: they can be found in large numbers among entrepreneurs, police detectives, emergency-room personnel, race-car drivers and, of course, those who stalk the high-stakes jungle known as Wall Street.