The Wall Street Journal has a fascinating article on Bruce Lahn today. Last September, Lahn announced in Science that he had isolated two brain genes in humans which had undergone recent evolution, but only in certain populations. His paper contained maps which showed that the genetic changes had taken hold and spread widely in Europe, Asia and the Americas, but weren’t common in sub-Saharan Africa. Needless to say, the data sparked an uproar. Now, nine months later, Lahn is leaving the field. “It’s getting too controversial,” he told the Journal.
This is a tough issue. On the one hand, scientists have a responsibility to society. We often hold politicians, talk show hosts, historians and artists responsible for the reactions their ideas provoke, and I think it’s appropriate to do the same for scientists. Truth is a lofty goal, but the data, especially on controversial issues like this, is rarely just data. As William James once remarked, “Objective evidence and certitude are doubtless very fine ideals to play with, but where on this moonlit and dream-visited planet are they found?”
On the other hand, Lahn is a good scientist, and I’m sure he had absolutely no ulterior motives in asking these sensitive questions. (Besides, Asians don’t have very high frequencies of the brain-gene mutations in question.) Science can’t shirk away from difficult areas just because it might offend our sense of political correctness. The fact is, most great scientific truths – like evolution – make us very queasy.
But I’m not convinced that Lahn’s retreat is simply a result of attacks from the politically correct side of science. I think his data had some serious flaws, which are only now becoming apparent. For one thing, his papers were very suggestive, and used historical analogies – which may actually be irrelevant – to make these minor brain mutations appear extremely important. Here is the Journal:
One mutation, which according to his estimates arose some 40,000 years ago, coincided with the first art found in caves, Lahn’s paper observed. The other mutation, present mostly in people from the Middle East and Europe, and estimated to be 5,800 years old, coincided with the “development of cities and written language.”
I think Lahn should have known better. He let his grandiose theories infect his facts. And now even his facts are being questioned:
Scientists at the Broad Institute, a top genetics center in Cambridge, Mass., have been reanalyzing some of the data and say they may challenge Dr. Lahn’s finding that evolution acted on ASPM, one of the genes. Broad’s influential chief, Eric Lander, says scientists probing recent evolution run the risk of “seeing a difference, and saying there is a story to fit it.”
A team at the University of California, Los Angeles, recently tested whether the gene variants actually affect brain size. They studied DNA from 120 people whose brain volumes they had already measured using magnetic-resonance imaging. They didn’t find any difference. “It certainly makes you want to look at other explanations” of what the variations mean, says Roger P. Woods, a UCLA brain-mapping expert who reported the results in May.
What’s the moral? The brain is an impossibly complicated organ, and its cells can justify a wide range of imaginative hypotheses. The history of science should make us wary of any ideas which try to draw too neat a connection between brain size, race and civilization. There are no easy answers, and that’s what makes us interesting.