Friday, April 13, 2007

Density dependent, group level benefits of ADHD types

Highly speculative, but interesting. Of course, as luck has it, I can't get access to the full text. I'd much appreciate the pdf if anyone has access to it. They invoke a group selection type mechanism favoring ADHD types of personalities. Groups with these kinds of people are more successful than groups without them: "Simulations of the Changing Food group task show that unpredictable behaviour by a minority optimizes results for the group" -- kind of a division of labor scenario, but within the group (i.e point guard, center, forward in basketball)

The evolution of hyperactivity, impulsivity and cognitive diversity

Jonathan Williams and Eric Taylor

Journal of The Royal Society Interface
Volume 3, Number 8 / June 22, 2006: 399 - 413

Abstract: The evolutionary status of attention deficit/hyperactivity disorder (ADHD) is central to assessments of whether modern society has created it, either physically or socially; and is potentially useful in understanding its neurobiological basis and treatment. The high prevalence of ADHD (5–10%) and its association with the seven-repeat allele of DRD4, which is positively selected in evolution, raise the possibility that ADHD increases the reproductive fitness of the individual, and/or the group. However, previous suggestions of evolutionary roles for ADHD have not accounted for its confinement to a substantial minority. Because one of the key features of ADHD is its diversity, and many benefits of population diversity are well recognized (as in immunity), we study the impact of groups' behavioural diversity on their fitness. Diversity occurs along many dimensions, and for simplicity we choose unpredictability (or variability), excess of which is a well-established characteristic of ADHD.Simulations of the Changing Food group task show that unpredictable behaviour by a minority optimizes results for the group. Characteristics of such group exploration tasks are risk-taking, in which costs are borne mainly by the individual; and information-sharing, in which benefits accrue to the entire group. Hence, this work is closely linked to previous studies of evolved altruism.We conclude that even individually impairing combinations of genes, such as ADHD, can carry specific benefits for society, which can be selected for at that level, rather than being merely genetic coincidences with effects confined to the individual. The social benefits conferred by diversity occur both inside and outside the ‘normal’ range, and these may be distinct. This view has the additional merit of offering explanations for the prevalence, sex and age distribution, severity distribution and heterogeneity of ADHD.

1 comment:

Anonymous said...

This is fascinating.


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