Thursday, June 29

The Subject is Taboo: On the Importance of Genetic Research

I have a clear memory of the moment I learned the word “taboo.” I was 7 or 8, and I had just spent the day walking around a golf course with a great friend of my mother’s (and later, of mine), a man called Tim, and his opponent, a woman called Nora. They had not played each other before. Nora, it transpired, was an excellent golfer. Tim was not. She trounced him. Worse, she didn’t do it from what I learned were called the “ladies’ tees.” She didn’t do it from the “gentlemen’s tees.” She did it from the hardest of all, the “tiger tees.”

I was chatting happily about this, not knowing that women were supposed to lose to men, not knowing that Nora’s tigerish defeat of him was, in Tim’s mind, an exasperating humiliation. I soon found out. As I relived Nora’s victory yet again, Tim leaned over to me and said, “Olivia. The subject is taboo. Do you know what that means?” And he explained.

Looking back, it seems somehow fitting that I learned this word in the context of male versus female performance. For certain subjects in science are taboo — and research into genetic differences in ability or behavior between different groups of people is one of the biggest of all.

The reasons for this are obvious. Some of the most ghastly atrocities of the 20th century were carried out under the banner of the “master race” and nasty pseudoscientific notions about genetic superiority. Sexual and racial discrimination still persist. One legacy of all this is that no one dares look at whether, in humans, differences in anything other than the risk of disease might be influenced by genes. Many geneticists I know are scared — really scared, and with reason — of having their careers ruined if they ask any other questions. Look no further than Lawrence Summers, former president of Harvard University, who was pilloried last year for wondering if mathematical ability in men and women might have some genetic underpinning. A sign has been hung on the door that says “Area Closed to Research.”

Until recently. Research into the genetics behind certain sorts of group differences — skin color, the ability to digest milk, the underpinnings of autism and the like — is now starting to be published. But other subjects remain ferociously contentious. Let me tell you a tale of three papers.

Last September, the journal Science published two papers that claimed natural selection had acted recently and strongly on two human genes involved in brain development. Let’s look at what this claim means.

As you’d expect, a whole slew of genes affect aspects of brain structure in humans. The two featured in the Science papers are among those thought to affect brain growth. People who have two mutant copies of either one of the genes have a condition known as microcephaly — tiny heads and brains. Mental retardation is a consequence.

What do we know about these genes, besides the fact that everyone needs at least one functioning version of each gene for their brain to grow properly? Not much. We may need them for other things as well — both appear to be involved in cell division, for example — but no one knows what exactly. We also know that functioning versions of these genes come in several subtly different forms. Whether these subtle differences matter is unknown. In short, we know (some) of what these genes do when they go wrong, but not much about what they do when they’re normal.

Now, what does it mean to say that natural selection has acted on these genes? As I’ve been discussing over the last 10 days, natural selection happens when organisms carrying particular sets of genes are more successful than those with other sets of genes at surviving and reproducing. Sometimes, natural selection will stop genes from changing — mutant forms of a given gene appear, but fail to spread because they are not helpful. Sometimes, natural selection promotes rapid change: a mutant form of a gene appears and spreads quickly — within a few hundred generations, say. Evidence of a rapid spread — within the last several thousand years — of a new version of each of the two genes is what the Science papers announced.

The papers caused a stir. For the papers also claimed that the new versions of the genes, although present in various populations around the world, were more rare in sub-Saharan Africa than elsewhere. All this means is that, in populations outside Africa, the new forms of the genes may have conferred some sort of advantage — perhaps related to head size, perhaps not — while in Africa, they didn’t. But it didn’t take long for the whisperings to start that the new forms of the genes must be involved in intelligence.

The whispering has no basis: there is no evidence whatsoever that the variants have anything to do with intelligence. The Science papers are, in any case, a first foray into the area; the findings may, or may not, be borne out. But brains, genes and race form an explosive mixture. So much so that — according to a report in The Wall Street Journal last week — the lead scientist on the papers, Bruce Lahn, will now be retiring from working on brain genes.

Meanwhile, another paper has appeared, this time in the March issue of the online journal Public Library of Science Biology. This paper failed to confirm the earlier result. However, the authors found that versions of other genes, also thought to be involved in brain function or structure, have been under recent natural selection in a certain population — and this time, the population is not outside Africa, but in it. (Only one African population was looked at — the Yoruba people of Nigeria. Whether other African populations show the same pattern is unknown.) Again, we have no idea what this means. But strangely, these results have received almost no attention: there has been no whispering this time.

I offer this story as a kind of parable — an illustration of some of the grave difficulties in this field of research. And indeed, the difficulties are myriad. On the scientific side, there’s the problem of trying to figure out what different genes do, how they interact with the environment (this is crucial), and what we can say about our evolutionary past. Then there’s the usual job of interpreting results and of revising the picture as we learn more.

But that’s the least of it. As you can imagine, it is virtually impossible to work in an area as poisonously political as this one. On one side, you have neo-fascist groups twisting the most innocuous data out of shape; on the other, well-intentioned anti-racists who don’t even want the questions asked. Worse still, as the popular success of the “intelligent design” movement shows, it is not always easy to make sure that science is discussed rationally. Result: most geneticists are totally unnerved — and who can blame them?

Perhaps, if open debate is impossible, declaring the area taboo is the best way to proceed. I don’t pretend to have a solution. But here are some thoughts.

First, we know almost nothing about our brains. (Indeed, my bet is that in 100 years, people will look back and laugh about the extent of our ignorance.) If we declare brain genetics out of bounds, it will make it harder to understand how our brains are built. It may make it harder to understand and treat the diseases that affect people’s brains, especially in old age.

Second, the study of human genetics has already illuminated a lot that is interesting and important about our evolutionary past, and how we have come to be. Handled well, this is a tremendously exciting area for research. Do we want to limit it? (Sadly for our vanity, the genes that seem to differ most between humans and chimpanzees are not brain genes, but genes of the immune system and those for making sperm.)

Third, genetic information is pouring in. Questions about the genetics of human differences are not going to go away. On the contrary, they will become more pressing. Scientists have an essential role to play in mediating understanding. Do we really want to scare good scientists from this field? Then the only people left researching it could be those whose agendas genuinely are sinister.

Now that is a frightening thought.