Maybe we’ve been searching for the basis of intelligence in the wrong way. Rather than looking for the genetic regions responsible for a person’s high IQ, perhaps we should be looking for the opposite: the roots of stupidity. This is the provocative hypothesis put forth by a recent Wiring the Brain post by Kevin Mitchell:
On the one hand, mutations that arose during human evolution that conferred increased intelligence (through whatever mechanism) will have been positively selected for and fixed in the population.
Mutations that lower intelligence could be quite non-specific, diverse and far more idiosyncratic.
The idea is that, while we all carry hundreds of deleterious mutations, some of us carry more than others, or ones with more severe effects.
This means that the mutations affecting intelligence in one person may be totally different from those affecting it in another – there will be no genes “for intelligence”.
In other words, humanity has evolved a baseline intelligence, but random mutations can push an individual to one side or the other of the smartness bell curve.
We may all carry many mutations that affect intelligence, negatively and mostly non-specifically, with the total burden determining how far away we each are from our archetypal Homo platonis.
Following this logic, ‘What’s your IQ?’ could someday be rephrased to ‘What’s your mutation load?’ For now, however, Mitchell’s ideas remain the speculative musings of a mutation-free mind.
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