The Search for Intelligence

"The Search for Intelligence" by Carl Zimmer (Scientific American, October, 2008).

Much work has been done on twins to learn about intelligence in attempt to answer various nature vs. nurture questions. The studies done over the last 30 years looking for genetic influences on intelligence have been mostly disappointing. Of all the genetic markers shown to have statistically significant correlations with intelligence, the strongest was able to "explain" only 0.4% of intelligence variation.

Yet, as the article points out, we know that there is a meaningul concept of intelligence, which is more than just a personality trait, that helps us evaluate people that we meet every day.

One very interesting thing from this article was the research which showed that parts of the cerebral cortex were thinner in intelligent people at age 7, and then thicker than normal, in the same people, at ages 10-16.

But, on the whole, this article highlights (correctly, I think) that intelligence is primarily an emergent property. As the article mentions, some people may think "faster" about the same things. Some may think about a wider range of things, more slowly. Some may be better at recalling related facts during any given thought, others worse. The specifics are all very different, but when put together, create a system of "thought" that is somewhat unique to each thinker. "Smart" people are those with a system that has developed far enough to prove useful (at least, useful in a way that others can recognize).