Early hunter-gatherers who faced food shortages may have benefited from the hyperactivity that comes with ADHD.

John Sebak/Science Photo Library

Attention deficit hyperactivity disorder (ADHD) may have evolved in hunter-gatherer societies because it was beneficial for foragers, according to the results of a new study. Traits commonly associated with the condition, such as anxiety, may have encouraged some grazers to move from low-resource areas to crops more quickly than those without the condition.

ADHD Affects people’s behavior, causing them to act impulsively or have difficulty concentrating. The exact cause is not fully understood, but the condition runs in families.

Its origins are similarly unclear, say. Arjun Ramakrishnan “Is this the legacy of a hunter-gatherer world?” at the Indian Institute of Technology Kanpur.

To explore this, Ramakrishnan, David Brock at the University of Pennsylvania and colleagues recruited 506 people in the US to play an online bait game. Players were instructed to collect as many berries as possible by moving their cursor over the bushes in 8 minutes.

They were given the option of either staying at one bush or leaving to try their luck at another, which might have more or less berries. Moving to a new bush also took a short time, so players had to balance the benefits of potentially getting more berries with the time lost due to moving.

Before playing the game, participants completed a survey assessing whether they had symptoms of ADHD, such as difficulty concentrating and restlessness.

Individuals with ADHD symptoms spent about 4 seconds less hovering over any bush than those without symptoms of the condition, resulting in an average of 602 berries collected compared to 521 for the former group.

The results suggest that the selective pressures faced by early hunter-gatherer communities, including lack of food and other resources, may have driven ADHD. Evolution. Brock says that there may have been foraging situations where it was better to stay than move on, but in some situations it may be beneficial to abandon the trend.

“Humans and other apes are pretty sophisticated foragers, but like almost every other animal, we tend to stay in one patch too long and harvest the field,” he says. “So moving on early is beneficial because it reduces over-pruning, which is where the affective features of ADHD come into play.”

Many people around the world no longer forage for food, but there are still contexts where the decision-making process would be similar. If someone is studying for an exam, they can start by looking at a resource. If it doesn’t help them understand the topic, they can quickly move on to other resources, which may be more effective and helpful, says Brock.

“Determining exactly how behaviors associated with ADHD may have been adaptive in past environments, and these findings are compelling because of the implications of coping strategies used by individuals with and without ADHD. show measurable differences in strategies,” says Dan Eisenberg at the University of Washington in Seattle.

But Annie Swanpole The NHS Foundation Trust in North East London says that berries were abundant in foraging and therefore did not reflect resource scarcity by many early hunter-gatherers.