Sunday, September 11, 2005

The evolution of the human brain: ASPM, microcephalin and FOXP2

First the article summary, then the discussion.
The Globe and Mail: Is your mind changing? Scientists think so

In two papers published today in the journal Science, Dr. Lahn and his colleagues report that the specific gene mutations they have found appear to have swept across certain areas of the globe so quickly that they are practically the norm. With prevalence rates higher than 70 per cent in Europe, for example, the researchers argue that chance alone cannot explain the changes, which first sprung up at the same time that modern humans developed culture and language...

...Testing 1,184 DNA samples from around the world, the researchers found, for example, that the frequency in West and sub-Saharan Africa is less than 10 per cent...

...They found that a particular series of mutations in the microcephalin gene appears to have been passed on and is now, surprisingly, carried by large numbers of people from different ethnic backgrounds. They estimate this series first emerged about 37,000 years ago, around the time modern humans settled Europe and began producing art.

The changes they found in the ASPM gene are far more recent, springing up about 5,800 years ago, coinciding with the rise of cities and the first record of written language.
This is one in a series of fascinating findings over the past few years, but the research is only beginning. I've blogged previously on the ASPM gene (it's undergone many mutations compared to chimps) and the timing of language and alleged gene relationship (including FOXP2), most recently there was the Ashkenazi IQ article.

The timing of the most recent alleged ASPM mutation is new to me. The African/European gene frequency data is a wee bit controversial, in almost all genetic measures, however, there's a lot more variation in Africa than Europe (founder effect).

This is new science, and we know that about half of the conclusions of major studies are reversed within 5-10 years. It's premature to put too much weight on it. I do suspect, however, that science will tell us that potential IQ is related to only a handful of genes, that we'll learn that all human brains have an extremely high defect rate, and we'll learn that our notions of 'responsibility' are based on faith rather than evidence.

I also agree with the researchers that people will pay a great deal to increase the intellect of their offspring -- more than they'll pay to make them tall or pretty or long lived. I think deliberate manipulation rather than natural selection will drive further changes to these genes.

Update 9/15: The ASPM variant is about 5700 years old. Amerindians crossed into the Americas at least 10,000 years ago. It turns out that virtually no Amerindians had this gene.

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