The movie Amadeus sees the precocious Mozart through the eyes of his rival, Salieri. For their first proper meeting, when Mozart arrives at the Court, Salieri has composed a little piece of music. Mozart thanks him, plays back the thing from memory, and then, having commented that a particular chord change “doesn’t really work”, proceeds to improvise on the theme, vastly improving Salieri’s original. Salieri turns to the audience and tells us: “I think it was then that I first decided to kill him.”
It would be hard to dispute that the difference in talent between Mozart and Salieri was genuine, and something they were respectively born with. Mozart didn’t “learn” to be the genius Salieri could never hope to be. And this difference goes to the heart of the long-standing debate between theories of “nature” and “nurture” explaining human behaviours and capacities. After World War Two, and reacting to the horrors of Nazi biological approaches to human beings, a dominant view held that human nature is entirely, or mainly, determined by “environment”, or “culture”. More recently, modern genetics has challenged this, in numerous ways.
So the announcement by the different teams working on the human genome that human beings are made up of far fewer genes than previously thought has thrown new light on this debate. Against previous guesses of 100,000 genes in the human genome, scientists now say there are between 30,000 and 40,000. This is upsetting, on one reading, because there are, in that case, only a bit more than twice as many genes making up a human being as making up a fruit fly. The complexities of human behaviour would seem not to be automatically shaped by our genes.
What, then, of Mozart and Salieri?
Of course there is much about human beings which is genetically shaped. We are organisms — same as any other — and what makes us human organisms rather than, say, fruit flies, or chimpanzees, is, biologically speaking, our “genome”, the sum total of the bits of DNA called “genes”. Raise even a very intelligent chimp in a human community and it will still be a chimp.
Where the argument has always been controversial is in reference to human behaviour. As genetics has matured as a science, wide-ranging claims have been made for the power of genes to explain behaviour, in a number of different ways, and with differing degrees of emphasis. “Behaviour genetics” has looked to find genetic influence on, for instance, sexual preference, alcoholism and other addictions, aggressiveness and propensity to violence, obesity, risk-taking, intelligence, and so on. Sometimes this has been simply through studies of related people (best of all identical twins), where a statistically significant correlation of such relatives sharing a “trait” is shown to declare a hereditary, and therefore genetic, influence. Sometimes it has gone on from there to try to identify the specific gene or “genetic marker” (bit of a chromosome) responsible.
Evolutionary biology, under a number of pseudonyms (the most famous is “sociobiology”), has focused not on differences between individuals in this way, but on common human characteristics which are claimed to have been shaped by evolution.
From whichever point of view, none of the scientists (or journalistic popularisers) of such theories would describe themselves as “genetic” or “biological” determinists, though their critics often do. But their studies have been presented as a challenge to what is sometimes called the “Standard Social Science Model”, supposedly favoured by sociologists, social anthroplogists, Marxists and feminists, in which biology is allowed no part in explaining what human beings think, feel and do. Thirty thousand genes might be only a third of the number previously hoped for, but it’s not few enough seriously to undermine the approaches these schools have outlined.
As the extreme example of Mozart shows, it’s plainly common-sense plausible that elements of an individual’s behaviour and ability are inherited. But there are methodological, or philosophical, problems with the ways in which behaviour genetics has approached its subject.
Take the famous “gay gene” discovered by Dean Hamer and his team in the early nineties. (In fact Hamer claimed only to find a genetic marker for male homosexuality, but I’ll say “gay gene” for short because this is how it’s popularly known). Whatever the reliability of Hamer’s results, which have been contested, those results can only ever show a correlation between two phenomena.
Hamer showed that a statistically high number of male homosexuals share the “gay gene” (Xq28), suggesting their sexual preference is inherited through their mothers. He did not show either that Xq28 caused their sexuality (it might be a gene for something else completely with sexual orientation as a side-effect). Nor did he show that most men with this gene are gay. It was never part of the claim that Xq28 alone makes a man gay, or that you can’t be gay without it. A statistically high correlation is only that. Sometimes scientists and their popularisers mistake correlation for cause. But even if they don’t, a theory — in this case of sexuality, needs to integrate these results into an overall picture.
This is true of all the areas where such “high” (very rarely more than 50%) influence for identified or putative genes has been claimed.
Perhaps more important that that, though, the qualities or types of behaviour subjected to such analysis are usually treated as more or less obvious, unproblematic. What is “homosexuality”? Ask a tribesperson in Papua New Guinea, assuming you could translate it, and he or she would have no idea what you are talking about.
Stephen Jay Gould, in his book The Mismeasure of Man, which chronicles the frequently racist assumptions of intelligence testing through history, criticises even modern, state-of-the-art research into intelligence on these grounds, which he calls “reification” (making something into a “thing”, although it is not one). Different types of intelligence are tested for, which are then averaged into “g” or “general intelligence”. “G” is then treated as if it is measurable, and can be inherited. But “g” isn’t a real thing, it’s a statistical convenience, an average.
This problem runs through most behaviour genetics. It’s true that if you read both behaviour geneticists and their critics carefully, on one level they often seem to say the same thing about how much we know. Yet is there is often a dramatic difference in emphasis. Writers like Hamer, or Matt Ridley (in his book Genome, for instance) enthuse about the discoveries of modern genetics. Gould, or his colleague, Harvard geneticist Richard Lewontin, put great stress on the limits of our knowledge and the dangers of “reductionist” (concentrating on “ultimate” causes without looking at complex interaction) or “atomist” (looking only at ‘bits’) reasoning.
On the evolutionary front, “sociobiology”, or as it’s often called now “evolutionary psychology”, has become extremely popular, infiltrating pop culture with television documentaries called things like Why Men Don’t Iron. Since as a species we evolved in our modern form in stone age Africa, the argument runs, human beings are, basically, stone age hunter-gatherers. One typical assertion which follows is that men hunt and women gather, which explains differences between the sexes (men don’t iron because the palaeolithic savannah didn’t require them to… well, iron).
There are more and less sophisticated versions of such theories (for an unbelievably crass and offensive one, see Thornhill and Palmer’s A Natural History of Rape). The fundamental objection, put forward by scientists and others, is that it doesn’t take account of the complexity of human culture, transmitted as it is through language and social practices, giving instead tendentious and ideological justifications for inequalities.
The relatively small size of the human genome does not spell death either for behaviour genetics or Darwinian narratives. It throws into sharp relief a point made by many scientists, on both sides of the debate, that genes operate in extremely complex ways, interacting with each other and with other biological — and in the case of human beings at least, social and cultural — processes. “Nature” and “nurture” is a simplistic distinction. The question, for an account of human nature, is to explain how nature and nurture interrelate.
Genes, and inherited characteristics, clearly play a role: human beings aren’t “blank slates” purely shaped by “environment”. There are common features of what makes human beings human, and many of these are probably to do with evolutionary history. Which, though? And to what extent?
There is no doubt that there remains, both in genetics and evolutionary biology, a way of looking at life, and at human beings in particular, which suffers from the “reductionist” and “atomistic” methods of reasoning condemned by Stephen Jay Gould and others. “Genetic determinism” in its full-blown sense is largely to be found only in the media, or in popular crudifications of these approaches. But in a softer sense, they remain.
That we only have two and a half times as many genes in our genome as a fruit fly is not the end of the story. (It still makes us a lot more complex.) But it demands of us a recognition that it is, indeed, a complex and subtle thing to be human, and that “the environment” plays a part at all sorts of levels.
We are not merely the outer expression of a genome; our biology is not simply destiny. We are, as human beings, free to make and remake our world.
Clive Bradley
