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Caroline Turner's avatar

I'm not ready to conclude that ADHD is adaptive, but I'm also not convinced a trait value being away from the mean is evidence against that trait being adaptive. In particular, I'm thinking about frequency-dependent selection. It could be, for example, that in a population of competitors that tend to explore less, a rare trait of exploring more would allow those individuals access to more resources that haven't been exploited by others and therefore that trait could be beneficial when rare.

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Randolph Nesse's avatar

Yes, negative frequency dependent selection is one of the main explanations for the persistence of trait diversity. But it requires that all the different morphs have equal fitness, and that the fitness increases as the prevalence of the trait decreases. Neither of these conditions seems to apply to mental disorders.

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Paul Goldsmith's avatar

I flitted to several other tasks logged in my memory banks before finishing reading this !

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Emiel de Jonge's avatar

Doesn't an adaptation nessecitate a stable definition of a stable phenotype? And considering how nothing in the DSM can be considered a stable definition, I cannot see how a syndrome, or collection of symptoms that changes a lot of over time and seems to have some cultural concept creep in it, can be linked to such concepts as an adaptation? Wouldn't it be better to first create the best possible definition of what is considered ADHD, which can reasonably stay stable over time and be internally and externally valid and accurate before trying to correlate such semi-vague concepts to biological concepts like adaptations? I think that the DSM has enough problems that needs solving before it can be useful to such a degree. Or do you consider ADHD stable and accurate enough for such research? I am interested in what your opinion is about such things.

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