THE GENOME CHANGES EVERYTHING (p2)

(MATT RIDLEY:) For the first time in four billion years a species on this planet has read its own recipe, or is in the process of reading its own recipe. That seems to me to be an epochal moment, because we're going to get depths of insight into the nature of human nature that we never could have imagined, and that will dwarf anything that philosophers and indeed scientists have managed to produce in the last two millennia. That's not to denigrate what's gone before, but the genome changes everything. We know that just because the first one or two glimpses inside this box, the first lifting of the lid of the human genome, reveals to us enormous insights into what's going on, and just from the first few genes we're looking at.

What I've set out to do, both in Genome and in Nature via Nurture is to try to put these in historical context, because I think it is important not only to understand how the old debates are going to be refracted through the new genomics, but also to simply tell some of the stories that are coming out of the genomics labs and other psychology and evolution labs that are using genetic information. The sheer leverage that genomic science now has, compared with sciences that went before, is very striking. What I mean by that is that with a small amount of effort you can get really big results. You can get stuff that doesn't need statistics to prove that it's significant in molecular biology in a way that you can't, necessarily, in brain imaging or particle physics studies or something like that, which requires a lot more effort to get a small amount of data.

The substance of what I'm interested in is that it's the genes that are related to behavior, and how they work. The big insight is that genes are the agents of nurture as well as nature. Experience is a huge part of a developing human brain, the human mind, and a human organism. We need to develop in a social world and get things in from the outside. It's enormously important to the development of human nature. You can't describe human nature without it. But that process is itself genetic, in the sense that there are genes in there designed to get the experience out of the world and into the organism. In the human case you're going to have genes that set up systems for learning that are not going to be present in other animals, language being the classic example. Language is something that in every sense is a genetic instinct. There's no question that human beings, unless they're unlucky and have a genetic mutation, inherit a capacity for learning language. That capacity is simply not inherited in anything like the same degree by a chimpanzee or a dolphin or any other creature. But you don't inherit the language; you inherit the capacity for learning the language from the environment.

That's a good example, because for the first time we've now got a gene, the FOXP2 gene on chromosome 7, which looks like it may be an important cog in that machinery. It would be surprising, given it's the first gene that we've been able to look at, if it was the most important cog, but it's certainly one of them. What happens is that if that gene is broken you get, essentially, a human being with a great difficulty in generalizing grammatical rules and in developing fluent speech. You get a general language disorder. But what's interesting about that gene is that although you might say, "Well, here's the language gene, and humans have got it and nobody else has it," this is not so—it's present in mice; and chimpanzees, orangutans and every other mammal has this gene. Indeed, it's a very highly conserved gene with very little change over the past few million years.

So you might say, "How can it be important in language?" If you take Svante Pääbo's work on it and you look at what's been going on in it, it appears that it's had very little evolutionary change in it until you get to the human lineage. And then, since the common ancestor of the chimpanzee there have been two amino acid changes in the gene, which is as much in the whole of the rest of the mammalian pedigree. Those two sense-changing alterations in the gene have happened in the past 200,000 years. It was probably about 200,000 years ago they happened, and they've elbowed aside all other versions of the gene. There's been a selective sweep of these mutations through the species. So what we're looking at here is a gene that was under very strong selective pressure around 200,000 years ago, which is around the time that we think human beings first started using language in something like the form that it is today. How that genetic change changes the wiring of the brain in order to enable language learning I don't know, and nobody knows the answer. But the point is the word enable there. Genes are enablers and not constrainers. People tend to think about genes as being constraints on what human beings can do. In fact, that's a very misleading way of looking at it. What's happened is that genetic changes are necessary to enable kinds of learning, to enable kinds of nurture, and to enable kinds of experience to get into the organism. In that sense genes are just as important a part of the story of nurture as they are the story of nature. When you start to see it that way, you can resolve the old nature-versus-nurture debate, and you can instead start to talk about nature via nurture instead.