Monday, January 12, 2009

John Hawks - Steve Pinker's Hot Hot Legs Profiled in NY Times Magazine

John Hawks has something to say about Steven Pinker's genome article in the New York Times Magazine from this weekend.

Steve Pinker's Hot Hot Legs profiled in NY Times Magazine

Honestly, that was my first reaction to an article that includes relatively neutral grey-background shots of Pinker from several angles. Way to go, dude!

The article is Pinker's insider's account of the Personal Genome Project, and is larded with some ongoing results in human behavioral genetics. Both should interest those who have been following technology and human genetics. Earlier this week, I posted about Sharon Begley's reaction to Pinker's last Edge essay; I thought the short section cited probably didn't reflect the full nuance of Pinker's views (for instance, as expressed in The Blank Slate). Today's essay in the NY Times Magazine does a better job of describing the science, along with its possible benefits and risks:

Though the 20th century saw horrific genocides inspired by Nazi pseudoscience about genetics and race, it also saw horrific genocides inspired by Marxist pseudoscience about the malleability of human nature. The real threat to humanity comes from totalizing ideologies and the denial of human rights, rather than a curiosity about nature and nurture. Today it is the humane democracies of Scandinavia that are hotbeds of research in behavioral genetics, and two of the groups who were historically most victimized by racial pseudoscience — Jews and African-Americans — are among the most avid consumers of information about their genes.

Pinker describes the current state of what behavior geneticists know (most things are heritable, shared familial environment accounts for little variation) and what they don't know (which genes account for any of the heritable variation). Given this state of knowledge, the results from direct-to-consumer genetic testing seem to approach the trivial -- and are notable for their exceptions more than their rules:

Direct-to-consumer companies are sometimes accused of peddling “recreational genetics,” and there’s no denying the horoscopelike fascination of learning about genes that predict your traits. Who wouldn’t be flattered to learn that he has two genes associated with higher I.Q. and one linked to a taste for novelty? It is also strangely validating to learn that I have genes for traits that I already know I have, like light skin and blue eyes. Then there are the genes for traits that seem plausible enough but make the wrong prediction about how I live my life, like my genes for tasting the bitterness in broccoli, beer and brussels sprouts (I consume them all), for lactose-intolerance (I seem to tolerate ice cream just fine) and for fast-twitch muscle fibers (I prefer hiking and cycling to basketball and squash). I also have genes that are nothing to brag about (like average memory performance and lower efficiency at learning from errors), ones whose meanings are a bit baffling (like a gene that gives me “typical odds” for having red hair, which I don’t have), and ones whose predictions are flat-out wrong (like a high risk of baldness).

The second half of the essay focuses on Pinker's own experiences with gene testing and the constraints of behavior genetics. In particular, he discusses the observation that so far the genes found to be significantly correlated with behavioral traits like IQ explain only a very tiny fraction of the heritable variation in large populations -- he calls this "Geno's Paradox". We've plumbed the depths -- as noted here on other occasions -- and if there were any genes explaining large fractions of the variation, we would have found them by now. The observation is easily explained -- the heritable variation is explained by rare alleles or small effects across hundreds or thousands of genes. But this solution means that genome-wide tests will not be good predictors of such traits in the foreseeable future.

With that result prominently in mind, what is the point of all this genome sequencing? Pinker makes the point that the Personal Genome Project is not about predicting phenotypes, it's about research. The participants want to help find new pathways by which genes affect phenotypes. Recording the whole genomes of a well-studied set of people, whose phenotypes have been recorded in more-or-less excruciating detail, is the way to get data for this process. Conceivably, if influential alleles really are rare in the population, we will continue to get valuable data as we expand the set of such public genomes into the hundreds of thousands.

There are many good analogies in the essay. I especially like Pinker's distinction between an person's physical state and the mental state of other individuals who may know genetic information about that person. The conclusion of the essay conveys an important point: Even if the genome were destiny, it's pretty unlikely that any particular gene would explain it:

It’s our essentialist mind-set that makes the cheek swab feel as if it is somehow a deeper, truer, more authentic test of the child’s ability. It’s not that the mind-set is utterly misguided. Our genomes truly are a fundamental part of us. They are what make us human, including the distinctively human ability to learn and create culture. They account for at least half of what makes us different from our neighbors. And though we can change both inherited and acquired traits, changing the inherited ones is usually harder. It is a question of the most perspicuous level of analysis at which to understand a complex phenomenon. You can’t understand the stock market by studying a single trader, or a movie by putting a DVD under a microscope. The fallacy is not in thinking that the entire genome matters, but in thinking that an individual gene will matter, at least in a way that is large and intelligible enough for us to care about.

Well, I've pulled several quotes, but it's a very long essay -- 8000 words. So it's hard to give an impression of the whole thing. I think it will make great reading for the students of my course in genetics. Of course, the printed PDF doesn't include Pinker's legs...

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