From genetics to biochemistry

A few months ago, I pointed out a paper identifying variants near the FTO gene as being involved in obesity. I noted how strikingly little was known about this gene, concluding:

So essentially, nothing is known about this gene. Thanks to this study, this is unlikely to be the case for long.

Little did I know it would only take a few months to get the ball rolling! From this week’s Science:

Variants in the FTO (fat mass and obesity associated) gene are associated with increased body mass index in humans. Here, we show by bioinformatics analysis that FTO shares sequence motifs with Fe(II)- and 2-oxoglutarate–dependent oxygenases. We find that recombinant murine Fto catalyzes the Fe(II)- and 2OG-dependent demethylation of 3-methylthymine in single-stranded DNA, with concomitant production of succinate, formaldehyde, and carbon dioxide. Consistent with a potential role in nucleic acid demethylation, Fto localizes to the nucleus in transfected cells. Studies of wild-type mice indicate that Fto messenger RNA (mRNA) is most abundant in the brain, particularly in hypothalamic nuclei governing energy balance…

This is an absolutely beautiful example of the hypothesis-generating power of genome-wide association studies. Studying the genetic variation underlying a trait is simply a great way to get at the mechanism by which the trait works. This point is lost on many people–even if the “environment”, however you want to define it, plays the most important role in a trait (like it may in obesity, for example), there are an infinite number of hypotheses about which environmental variables might be relevant, and once you find a correlation, it’s both difficult to establish causality and you get very little information about the mechanism by which the trait works (yes, eating a lot leads to increased weight in most people, but how?). In genetics, there is a finite number of hypotheses (there are many millions of genetic variants in humans, and all of them will eventually be testable), the road to establishing causality is much clearer (ie. this genetic variant leads to increased probability of obesity–it would be difficult to argue the inverse), and you immediately have your foot in the door to study the molecules involved in the trait. Again, this is a wonderful example of all of these points.

Education and Ethnic Groups in Britain

I have previously reported on the annual education statistics in Britain (e.g. here), so I will give an update for 2006-07. Figures have just been published for performance at the GCSE examinations, taken by most children at age 16. An official press release is here. Performance by children of all ethnic groups continues to improve (as measured by examination grades). The press release highlights the fact that the gap between ethnic groups is narrowing. Actually, this is not strictly true. The ‘narrowing’ is specifically between children of Black (Caribbean or African) origin and the (mainly White) average. Other ‘gaps’ are constant or widening. Children of Pakistani origin have the lowest rate of improvement, and have now been overtaken by Black Africans.

I won’t discuss the vexed question whether improvement in examination results actually indicates any improvement in education. But I guess (unless anyone knows reasons to the contrary) that the changes in differentials between ethnic groups are real and not artificial; for example, I can’t see any reason why the testing system should be biased against Pakistanis but not Bangladeshis.

Added on 1 December: In comments the point has been made that a general rising trend will tend to suppress differentials. In general this is a good point, but as I mentioned in my original post, not all of the gaps are narrowing. The pattern is more complex. Also, the (mainly White) average is still nowhere near the ceiling. It has also been suggested that the narrowing gap between Black African and Black Caribbean and White children could be due to increasing proportions of mixed-race children. This should not be the case. The statistics classify the various mixed-race groups separately, so provided the children are correctly classified this should not be a problem. Finally, I should warn against taking these results as indicators of IQ. No doubt there is some correlation with IQ, but it can hardly be very close, as girls have much better GCSE results than boys despite similar IQ.

I would suggest that before making further comments readers should consult the original statistics. Go here, click on the link marked ‘EXCEL’, then go to Table 8 for the GCSE figures. (If you don’t have an Excel reader there are free downloads on the web.)

Liberman responds

Mark Liberman has updated his post on race and IQ in response to my post. I actually wrote out a long response and deleted it–believe it or not, I have about as much of a desire to get sucked into this conversation as he does. But I strongly, strongly disagree with his claim that showing two populations have different distributions of IQ and claiming genetics plays a role is, in itself, a “racist theory”. My point in the post was that the basic premises of Saletan’s article (ie. that there are aspects of “intelligence” that are socially relevant, probably have a genetic component, and differ in distribution across populations) are entirely accepted by Shalizi (ok, he “might agree” with them). This is because they’re obvious in the light of evolutionary theory (allele frequencies evolve by natural selection and genetic drift. This includes alleles involved in socially awkward phenotypes like IQ). I’m not opposed to people holding out for more evidence, but imputing nefarious motives to writers for talking about the evidence that exists I do find questionable.

Mixed-race but homogeneous appearance?

tiger-woods-picture-1.jpgSeveral years ago Oprah Winfrey asked Tiger Woods what he would say to people who say that when they look him they see a black man. The issue was that some African Americans objected to Woods’ contention that he was multiracial, Cablinasian, which reflected the fact that he was ancestrally 1/2 Asian, 1/4 African, 1/8 European and 1/8 Native American. Woods is also a Therevada Buddhist by religion, taking after his Thai nationality (though mixed-race) mother, so one can argue he is quite Asian culturally. I know many people who frankly disagree with Winfrey’s assessment, that is, that Woods looks “like a black man.” Some Asian Americans have stated that “from the eyes down” he looks Asian, and frankly I can see that. Tiger Woods’ hair reflects his mixed ancestry, and it is neither straight nor kinky, but curly (he cuts it short enough that this doesn’t manifest normally, but I know people who played golf with him when he was a teenager and they attest to this). Some of my friends in college who were Asian American activists quite loudly would proclaim that Tiger Woods “looks Asian” when the topic came up.
Does Tiger Woods look Asian? Does he look like a “black man”? I am posting on this because of some responses below which asked how it was that mixed-race children can so favor one race. But to start out with I need to offer that perceptions of race are as much a matter of psychology and culture as they are of genetics. I bring up Tiger Woods because black Americans and Asian Americans might have radically different viewpoints about what race he looks like, showing that where you start from shapes where you end up at.

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This is faith!

Rock of Ages, Ages of Rock:

. To the young-earth creationists, this is both unscientific and dubiously religious. “We don’t subscribe to this idea of the ‘God of gaps,’ meaning if you can’t explain something, then blame God,” Whitmore told me before describing a method that hardly seemed more scientific. “Instead, we think: ‘Here’s what the Bible says. Now let’s go to the rocks and see if we find the evidence for it.’ ”

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Evolution: What the Fossils Say and Why It Matters

is an expansive new book authored by vertebrate paleontologist Donald Prothero and lushly illustrated by Carl Buell. The quality of the plates and illustrations, the binding as well as the texture of the pages, screams out “Coffee Table Book.” That’s not an insult, but it just reinforces that this isn’t a monograph aimed at specialists, rather, it is in large part a manifesto aimed toward the general public. And its high production quality testifies to the fact that it wants to be taken seriously by marrying style with substance.
Though the subtitle places the emphasis on fossils, Prothero covers a lot of ground early on in the book which examines evolution from various angles outside of his core field of expertise. There is a quick overview of the ideas of evolution before Charles Darwin, as well as the necessary geological context which made an evolutionary model of biology plausible. Biogeography, Mendelian genetics and molecular biology are all brought into the discussion and shown to converge upon the validity of evolutionary theory and its assumptions of common descent with modification. Additionally, the book also tackles the topic of abiogenesis, since it often gets thrown in with the arguments about the validity of evolutionary theory by Creationists and other assorted skeptics. The number of topics which the author addresses before moving onto the paleontological meat of the book is rather mind-boggling, and the economy of the prose is impressive.

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