The evolution of ADHD helped our ancient ancestors survive as hunter-gatherers, according to a new study.
Attention Deficit Hyperactivity Disorder is a neurodevelopmental condition that affects roughly 4 percent of adults and 11 percent of children, according to estimates from the National Institute of Mental Health. Its symptoms include distractibility, restlessness, forgetfulness, and impulsivity. But while many people today consider ADHD to be a condition that needs treating, it may have actually given our ancestors a survival advantage.
Foraging requires balancing the trade-off between exploiting known food sources and searching for new ones. While many hunter-gatherers may have chosen to stick to their known food patches, individuals with ADHD may have been more likely to engage in more exploratory behaviors. Indeed, modern-day nomadic populations, such as the Ariaal tribe in Africa, have been shown to have higher levels of certain genetic mutations associated with ADHD, according to a 2008 study.
Together, this information suggests that the evolution of ADHD may have helped our ancestors survive through exploratory foraging behavior.
In a recent study, published in the journal Proceedings of the Royal Society B, researchers from the University of Pennsylvania and the Indian Institute of Technology recruited a sample of 457 American individuals to participate in a foraging computer task. In the task, participants were asked to collect as many berries as they could in a given length of time. During this period, the participants could choose to stay at a known foraging site or explore other patch options. Participants were then assessed for ADHD.
Nearly half of the participants screened positive for ADHD, which is significantly higher than what would be expected from the general population. However, this was not a medical diagnosis but simply the score of a self-assessment. Even so, those who screened positive for ADHD collected significantly more berries on average than those who screened negative.
The researchers put this down to their tendency to move on to the next patch—that is, go exploring—sooner than those who screened negative, to tended to spend longer focusing on a single patch.
"In competitive environments where foragers must keep track of other foragers, impulsively leaving patches could yield a competitive advantage by enabling learning about competitors and capturing newly renewed resources first," the authors write.
"The increased foraging proficiency of participants with ADHD-like behavior observed here suggests the prevalence and persistence of ADHD in human populations may serve an adaptive function in some environments."
Uncommon Knowledge
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Pandora Dewan is a Senior Science Reporter at Newsweek based in London, UK. Her focus is reporting on science, health ... Read more
