ADHD-like traits could offer humans an advantage in foraging
Traits associated with attention-deficit/hyperactivity disorder (ADHD) such as impulsivity and distractibility are known to make many everyday modern tasks more challenging.
But they may also offer humans an advantage by helping them to forage more effectively – a key technique used by hunter gatherers and nomadic tribes to survive, a new study published Wednesday suggests.
According to the study in the Proceedings of the Royal Society B, people with ADHD-like traits are less likely to dwell among depleting food resources and more likely to explore other options instead – which can give them a foraging advantage in some environments.
The findings challenge some of the negative associations of ADHD, described by the Centers for Disease Control and Prevention as “one of the most common neurodevelopmental disorders of childhood.” And they appear to support the “evolutionary mismatch” theory of neurodivergence, which posits that such traits are disadvantages only in certain environments.
Using an online berry-picking game informed by algorithms derived from optimal foraging theory, researchers from the University of Pennsylvania analyzed the decisions of 457 participants who were told to collect as many berries as possible under time pressure. Players chose between continuing to harvest from the same bushes – depleting them of berries and decreasing their yields – and traveling to different bushes, which were more abundant in fruit but cost players precious time.
After the game, the participants completed an online screening assessment on ADHD symptoms developed by the World Health Organization. Those who self-reported ADHDlike symptoms moved between patches more frequently and collected more berries overall, the researchers found.
“The increased foraging proficiency of participants with ADHD-like behavior observed here suggests that the prevalence and persistence of ADHD in human populations may serve an adaptive function in some environments,” they concluded.
The study had several limitations. The analysis compared 206 participants who reported more ADHD attributes with those who did not, but there was no clinical assessment of the participants, and just 24 participants reported a previous ADHD diagnosis. It’s not clear how well the virtual foraging task aligns with real-life foraging behavior, rather than other skills like computer gaming, and the study’s participants were recruited through an opt-in online sample, rather than a random sample of the population.
Nonetheless, health experts say the study has important implications for how we understand and view conditions like ADHD.
Annie Swanepoel, a child and adolescent psychiatrist who studies neurodivergent conditions from an evolutionary perspective and was not involved in the study, said it offered an evolutionary explanation for why ADHD-like traits are common.
“ADHD is not a disorder, it is a variation which gives an advantage in certain environments where a willingness to take risks and having lots of energy are advantageous,” Swanepoel, based in England, said in an email Wednesday.
“People often wrongly think that ‘survival of the fittest’ means that those who are strongest or fastest or most intelligent survive. This is not the case – it is not about being “fit” but rather about the “goodness of fit” between the individual and the environment. That is why there are tortoises and slugs as well as cheetahs and elephants.”
For years, researchers have theorized that hyperstimulated modern environments are uniquely ill-suited to people with ADHD – suggesting that internet usage in particular could exacerbate symptoms.
Since the first national survey on childhood ADHD was conducted in 1997, diagnoses of ADHD among children have grown steadily in the United States. Today, the CDC estimates that about 1 in 10 U.S. children have a diagnosis. They “may have trouble paying attention, controlling impulsive behaviors (may act without thinking about what the result will be), or be overly active,” according to CDC guidance.
For Swanepoel, those symptoms are negative only because of the way we organize our societies – creating an “evolutionary mismatch” between certain human attributes and the demands of modern life.
“Our modern environments are WEIRD (Western, Industrialised, Educated, Rich, Democratic) and nothing like the environment our ancestors lived in as hunter-gatherers for 95% of our history,” she wrote.
“The strengths of children with ADHD (hyperactivity, impulsivity and inattention) are seen as problematic as they do not fit in our modern school environment where children are expected to sit still and listen – whereas they may have been strengths in our ancestral environments,” she added. Children with ADHD symptoms are more likely to flourish in environments with higher activity levels and greater hands-on learning, Swanepoel argues.
The study shows how crucial a person’s environment is to the way potential neurodivergent traits like ADHD manifest themselves, said Graham Music, a child and adolescent psychotherapist at London’s Tavistock Clinic. “There might be a mismatch between the environments that we expect people to live in and the psychological traits they have.”
Instead of treating ADHD as a problem that needs solving in a child, Music suggests asking a different question: “What environment might they flourish in?”