The left-wing genes

Paul Raven @ 13-10-2010

Which genes are left-wing? All of them! At least that’s the interpretation Oliver James puts forward in this piece at The Guardian, as he points out that the mapping of the human genome hasn’t delivered evidence for the genetic determinism of mental health and social status that conservative politics – not to mention the pharmacology industries – hoped it would:

This result had been predicted by Craig Venter, one of the key researchers on the project. When the map was published, he said that because we only have about 25,000 genes psychological differences could not be much determined by them. “Our environments are critical,” he concluded. And, after only a few years of extensive genome searching, even the most convinced geneticists began to publicly admit that there are no individual genes for the vast majority of mental health problems. In 2009 Professor Robert Plomin, a leading behavioural geneticist, wrote that the evidence had proved that “genetic effects are much smaller than previously considered: the largest effects account for only 1% of quantitative traits”. However, he believed that all was not lost. Complex combinations of genes might hold the key. So far, this has not been shown, nor is it likely to be.

[…]

Another theory was that genes create vulnerabilities. For example, it was thought that people with a particular gene variant were more likely to become depressed if they were maltreated as children. This also now looks unlikely. An analysis of 14,250 people showed that those with the variant were not at greater risk of depression. Nor were they more likely to be depressed when the variant was combined with childhood maltreatment.

In developed nations, women and those on a low income are twice as likely to be depressed as men and the wealthy. When DNA is tested in large samples, neither women nor the poor are more likely to have the variant. Worldwide, depression is least common in south-east Asia. Yet a study of 29 nations found the variant to be commonest there – the degree to which a society is collectivist rather than individualistic partly explains depression rates, not genes.

Politics may be the reason why the media has so far failed to report the small role of genes. The political right believes that genes largely explain why the poor are poor, as well as twice as likely as the rich to be mentally ill. To them, the poor are genetic mud, sinking to the bottom of the genetic pool.

It’s a rather generalised and sweeping statement, but I think there’s a core of truth to it. Is this why there’s been such a right-wing push-back against genetic science in recent years, perhaps?

[ That said, James is narrativising genetic science in a very similar way, albeit on behalf of the other side of the debating chamber. The political polarisation of science worries me regardless of who’s doing it, because it puts the primacy onto agenda-driven interpretation rather than evidence; nowhere is this more clear than in climate science, where progressive/left-wing attempts to counter the right’s conspiracy theories with their own rhetoric have obscured the facts of the matter even further. ]


Culture is carried by DNA?

Paul Raven @ 05-05-2009

pair of Australian zebra finchesIt sometimes feels like you can’t go two weeks without some new aspect of human life or behaviour being declared as being related to our DNA. The latest attempted conquest of genetic determinism? Why, our very culture itself!

You see, male zebra finches usually learn their courtship song patterns from their fathers, but it turns out they can generate the same songs spontaneously after a few generations without influence:

“It’s the classic ‘chicken and the egg’ puzzle,” Mitra said. “Learning may explain how the son copies its father’s song, but it doesn’t explain the origin of the father’s song.”

Mitra’s team wanted to find out what would happen if an isolated bird raised his own colony. As expected, birds raised in soundproof boxes grew up to sing cacophonous songs.

But then scientists let the isolated birds give voice lessons to a new round of hatchlings. They found that the young males imitated the songs — but they tweaked them slightly, bringing the structure closer to that of songs sung in the wild. When these birds grew up and became tutors, their pupils’ song continue to conform, with tweaks.

After three to four generations, the teachers were producing strapping young finches that belted out normal-sounding songs.

Uhm. Well, if you’re thinking that seems a little tenuous, you’re not alone:

Mitra admits that the analogies between bird culture and human culture are tenuous. “But there are resemblances. Culture is just learned behaviors. The motivating scenario is, if you isolate human babies from culture, put them on an island and come back after a few generations, what would their culture be like? What sort of language would they have? What sort of politics would evolve?”

That experiment probably won’t take place in the near future. In the meantime, Fitch says we can learn valuable lessons about human culture from songbirds, both at theoretical and mechanistic levels.

“Social learning is shared between the two, and songbirds are a well-understood and experimentally tractable system,” he said. “These biologically-grounded studies will lead us beyond the tired ‘nature versus nurture’ or ‘biology versus culture’ dichotomies which dominate the social sciences today.”

With the caveat that I’m not a geneticist or behavioural scientist, I don’t really see how birdsong and human politics are supposed to be different expressions of the same thing; the former is a biological imperative, while the latter is an emergent phenomenon. As Brian Eno once said, “culture is everything we don’t have to do”; a zebra finch that doesn’t sing sweetly won’t pass on its DNA, making its songcraft a matter of reproductive necessity, but I don’t think you can declare the same thing about, say, a great human painter or poet or politician.

That said, I’m all for getting beyond the nature/nurture dichotomy – knowing how culture emerges from biology is one of the most tempting grails of knowledge I can imagine. But in the same way that everything from alcoholism to sexuality seems to be blithely written off as being primarily a function of our genetic code, declaring such a nebulous and complex phenomenon as human culture to be passed along by DNA on the basis of some songbird studies seems… well, it seems pretty daft, really.

If there’s someone in the audience who can set me straight on this subject, I’d be very glad for them to speak up and tell me where my reasoning is wrong, but this story seems to me like just another instalment in our ongoing fetish with genetics as the key to all unsolved mysteries. [image by Lip Kee]