Sep 232008
 

Updates here at the Whiteboard may be slower over the next ten days or so… I don’t have an internet connection so much as an internet acquaintance.  (My suspicion is that relatively few people do a lot of online stuff while vacationing in Emerald Isle, North Carolina.)

Even so, I came across this post on Razib’s Gene Expression blog, linking in turn to an article by Carl Zimmer: Genes and Intelligence: My Anti-Story.

Zimmer has interesting news about the nature of intelligence:  “There is no news.”

The news about intelligence is that now scientists have new tools for probing intelligence, from brain scans to gene chips that can search for variations in half a million genetic markers at a time. But so far, those tools are yielding some pretty scant results. For example, just a handful of genes show much sign of influencing intelligence, and yet each one accounts at best for a fraction of one percent of the variation in test scores.

It may not be fashionable to write about the lack of breakthroughs, but in a case like that of intelligence, that’s what fascinates me most.

Zimmer includes this link to an article he published in Scientific American, “Searching for Intelligence in Our Genes.”  It’s worth a read, in part to convey the complexity of the search.  At one level, we all know something exists that we tend to call “intelligence.”  But defining it scientifically and testing for it — that’s very much a different matter.

Zimmer cites studies by Robert Plomin, who’s searching for genes that may be associated with intelligence (as measured by the performance of children on certain tests).  Plomin found certain areas in which twins did better than non-twin siblings, and siblings did better than unrelated children — a sign that genes play some role.

So far, thogh, Plomin hasn’t found any genes that seem to account for more than 1% of the variation.  What this means, he says, is that there may be hundreds (if not thousands) of genes that together produce “the full range of gene-based variation in intelligence.”

The Scientific American article is longer by far than the typical blog post, but includes differing points of view — the kind of thing that doesn’t make it into headlines (“Scientists at MIT Discover Gene for Liking Carrots”).

…one of the most puzzling patterns in twin studies on intelligence: how the influence of genes becomes stronger on test scores as people get older. Genes may affect how people mold their intellectual environment. Choosing to seek out new experiences, reading books and engaging in conversations may alter the brain. And as children grow up and take over control of their own lives, this effect may get stronger.

“Intelligence is kind of an emergent property of the brain,� [National Institutes of Mental Health psychiatrist Philip] Shaw says. “The idea that you’re born with 15 genes, and they set in stone how intelligent you’re going to be and how your brain is going to develop, is almost certainly wrong.�

Click this image to see some interesting graphics from the Scientific American article (click again to enlarge):


  2 Responses to “If you’re so smart, how come?”

  1. Glad you made it to the beach!

  2. Cammie, I’m always happy to be able to hear the surf — and I’ve always agreed with Daisy May Moses that a swimming pool is essentially a ce-ment pond.

    One gene I apparently do not have expresses itself in the ability to tan. My hypothesis: my Highland- and island-dwelling ancestors, feeling as they did so often “the kiss of sweet Scottish rain,” never got around to evolving melanin.

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