ADHD Linked to Evolutionary Success in Ancient Humans

taylorvich writes:

https://newatlas.com/science/adhd-evolutionary-benefits-foraging-explore-exploit/

While current diagnostic definitions of attention-deficit hyperactivity disorder (ADHD) are relatively new, the general condition has been identified by clinicians under a variety of names for centuries. Recent genetic studies have revealed the condition to be highly heritable, meaning the majority of those with the condition have genetically inherited it from their parents.

Depending on diagnostic criteria, anywhere from two to 16% of children can be classified as having ADHD. In fact, increasing rates of diagnosis over recent years have led to some clinicians arguing the condition is overdiagnosed.

What is relatively clear, however, is that the behavioural characteristics that underpin ADHD have been genetically present in human populations for potentially quite a long time. And that has led some researchers to wonder what the condition's evolutionary benefits could be.

Imagine you are part of a wandering tribe of early humans. Your group comes across a field full of one kind of fruit and everyone is faced with a big question. Do you settle in the field and exploit the fruit stocks until they are all gone, or do you quickly take what you can and continue to explore for more varied foods?

This exploit or explore trade-off is fundamental to the survival of all animals. At what point is the risk of staying in one place greater than the risk of moving on to find out what is over the next hill?

In the early 2000s a team of scientists set out to study the genetics of a unique tribe of people in Northern Kenya. Known as the Ariaal, this population has traditionally been incredibly nomadic. Some members of the Ariaal settled down in one place over the 20th century and adopted modern methods of agriculture while other tribe members continued to live as nomadic pastoralists.

The scientists compared the genetic and health differences between these two cohorts of Ariaal and discovered something incredibly interesting. Generally, all of the Ariaal people carried a unique genetic mutation, dubbed DRD4/7R. This genetic trait had previously been identified commonly in people with ADHD.

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