Log in

No account? Create an account
Steven Pinker is the man - Arvind Narayanan's journal [entries|archive|friends|userinfo]

Steven Pinker is the man [Oct. 1st, 2008|05:35 pm]
Arvind Narayanan
[Tags|, , ]

Watch Steven Pinker once again fearlessly tell it like it is, this time on the subject of nature vs. nurture. The talk is about his book "The Blank Slate" in which he demolishes said hypothesis.

My favorite part is when he makes fun of literary criticism and (some) modern art. Parts of his thesis are controversial, and while it's fun to see him take on his opponents, I'm not sure I agree fully with the view that parenting plays a negligible role in a child's development compared to genetics. This is also the main claim of the last chapter of Freakonomics, which I greatly enjoyed, and appears to be supported by a huge body of studies.

The studies in question look at twins reared apart, either fraternal or identical. By observing the correlations in their outcomes, one can indeed claim that many traits belong to the 'nature' side of the great nature vs. nurture debate. On any number of observables, perhaps the most controversial of which is intelligence, the correlation between identical twins is significantly higher than for fraternal twins, which is in turn much higher than for genetically unrelated (adoptive) children reared as siblings.

The problem, however, comes in claiming that the correlation is necessarily due to genetics, because this ignores the effect of prenatal nutrition. It is well known that early childhood nutrition is crucial to health; for instance, it is a very strong predictor of adult height. Common sense dicates that prenatal nutrition is at least as important, especially in the light of the fact that nutrient deficiency in the mother is known to cause a variety of disorders. Surprisingly, there appear to be virtually no studies study the correlation between prenatal nutrition and adult outcomes.

Assuming that prenatal nutrition does affects adult outcomes, of course you'd expect those correlations to show through in the case of twins reared apart, and genetics is not involved. (Or at least not to the extent claimed. The difference between identical and fraternal twins shows that there is some involvement.) Furthermore, adopted children are unwanted by the genetic mother, arguing strongly for poor prenatal nutrition and consequently reduced fitness.

I haven't seen a single discussion of heredity studies that address this issue. Ever. Therefore, I question the entire body of knowledge derived in this way, and my mind is not made up on the nature vs. nurture issue until I can find out more.

None of this changes the fact that Steven Pinker kicks ass, and you've got to give it to the guy for regularly championing politically incorrect but scientifically supported viewpoints.