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Thinking positively: The genetics of high intelligence

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136 points gwern | 3 comments | 01 Nov 15 23:33 UTC | HN request time: 0.719s | source
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danieltillett ◴[02 Nov 15 09:50 UTC] No.10490915[source]▶
I would be very surprised if high intelligence was anything other than the extreme edge of a normal distribution of the human population. For it to be anything other than this it would require people of high intelligence to be a sub-population that did not breed with the rest of humanity.
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yummyfajitas ◴[02 Nov 15 10:07 UTC] No.10490953[source]▶
You could make this argument for any trait. However, some traits are the result of a single gene - e.g., sickle cell anemia and the accompanying malaria resistance. Yet some of these traits occur in large populations that are not strongly inbred.
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danieltillett ◴[02 Nov 15 11:01 UTC] No.10491151[source]▶
Only single gene traits. Intelligence (however defined) is multi-genetic - there are thousands of genes that contribute to intelligence. Given this the only way that individuals with high intelligence could be anything other than edge of a normal distribution is if they were part of a human sub-population.

Edit. I should add that the humans are not completely one population because of genetic isolation and differential selection (especially over the last 10,000 years), but we are almost a single population. Like everything in genetics it gets fuzzy at the edges.

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arethuza ◴[02 Nov 15 12:09 UTC] No.10491417[source]▶
"there are thousands of genes that contribute to intelligence"

And the very definition of "intelligence" is incredibly complex and slippery, which is one of the reasons why I've always found trying to summarise such a complex property into a single numerical value such a silly exercise.

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sanxiyn ◴[02 Nov 15 14:33 UTC] No.10491960[source]▶
Summarizing a complex property into a single numerical value is very useful and not silly. For example, temperature is a numerical summary of huge number of molecular motions.

More on this here: http://slatestarcodex.com/2014/08/11/does-the-glasgow-coma-s...

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arethuza ◴[02 Nov 15 14:43 UTC] No.10492003[source]▶
I didn't say that all attempts to summarise a complex system in a single number are silly - just that intelligence is such a multi-faceted and ill-understood area that, in my opinion, evaluating people based on a single number is silly.

NB I say that as someone who got a very high IQ test result - which didn't exactly convince me that IQ tests are a good idea....

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1. themetrician ◴[02 Nov 15 15:46 UTC] No.10492420[source]▶
What is the name of the IQ test you took?

Intelligence really isn't "multi-faceted" (read Gardner's own admission that his theory never panned out) and it isn't ill-understood (refer to the Nature or Nurture interview with Nancy Segal on YouTube).

There's two reasons people say that. One is, they fared badly on a test and want to dismiss it, and the other is, they fared well on a test and are bashful about it.

Also, IQ tests are meant to measure a person's intelligence, not to convince them that IQ tests are "a good idea" - for that you would have to study Psychometrics.

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2. arethuza ◴[02 Nov 15 21:37 UTC] No.10495462[source]▶
"it isn't ill-understood"

I worked on AI research for a number of years and my strong opinion is that our understanding of general intelligence is, as some wit put it, "pre-Newtonian".

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3. Mz ◴[02 Nov 15 21:45 UTC] No.10495514[source]▶
IQ tests are somewhat ridiculous to begin with. The first tests that eventually became IQ tests were not intended to measure intelligence. They were intended to measure school readiness of rural children whose birthdates were often not known with certainty. The lack of clear birthdates meant an age cut off could not be used and rural children faced cultural differences from kids in the big city (namely: Paris) that created inherent challenges to them fitting in and doing well in school.

Intelligence is neither well defined nor well understood. It is fairly controversial stuff.

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