Are there genes for practically everything? For being gay? For being mean? For being a philosopher? Does modern science show that we are largely the product of our genes --- or not?
Do genes make the person? If you listen to popular press reports of new genetic discoveries coming out at fairly rapid pace, you certainly might think so. Lung Cancer Gene! Gay Gene! Genius Gene! Little wonder that many people believe -- or should I say fear? -- that genes somehow directly and invariably determine who we are. One has visions of being able to choose the IQ, personality, and physical attributes of one's offspring with the ease and reliability with which one chooses a meal at a good Chinese restaurant. As Stephen Jay Gould once put it, "If we are programmed to be what we are, then these traits are ineluctable. We may, at best, channel them, but we cannot change them either by will, education, or culture." But even a brief perusal of the scientific and/or philosophical literature about the role of genes in determining who we are reveals that at least in this strong form, genetic determinism has little or no basis in either scientific fact or theory. Genes clearly play an important causal role in the development of a phenotype. And according to one standard, but by no means universally endorsed conception of evolution, genes are the units on which natural selection operates. But none of that entails rigid and direct genetic determinism. So what, really, is the big fuss?
That's precisely the question we hope to get clear about in this episode. Our guest John Dupre thinks the power of genes to make the person has been vastly oversold. Here's how he puts it in his book, Human Nature and the Limits of Science in the context of discussing the idea that genes build brains:
We can now see how massively simplistic is the assumption that genes build brains. Obviously genes can do nothing, let alone build a brain, on their own. To build a human brain the genes must be properly located in a cell complete with all the properly functioning extranuclear machinery; the cell must be properly positioned in the uterus of a human female; and the child must be born into a social setting that will provide an extremely complex set of stimuli to the human organism in which the brain is located. So is there really any sense in which genes build brains in which it is not equally true to say that wombs build brains, or even schools build brains?
For Dupre the answer to this last question is clearly no. And there is surely a sense in which he is right. I think probably everyone who has thought much about it would concede his central point, since everyone agrees that genes are not, to coin a phrase, self-developing. To get from a gene to a phenotype often takes a lot of steps. And all sorts of things -- things in which the gene may have no direct role -- have to go right along the way. So again, it's fair to ask, exactly what the fuss is all about.
One thing that may be at the source of at least the popular understanding of the ways genes help to make the person is the very idea of a genetic code. One imagines that there is something like a "Language of the Gene" (LOG) in which certain biological imperatives on the developing organism are explicitly laid down. "You will have a heart!" "You will have two kidneys." "You will have an IQ of 129!" "You will be disposed to criminality!" "You will suffer from Alzheimer's Disease!" and on and on. Although it might be conceded that genes need help translating their directives into phenotypic traits in the organism, still they are the ultimate sources of those traits, since they "explicitly encode" for them. Just as you can't make a program run on a computer unless you compile it or interpret it, so you can't translate a genetic program into a phenotype until you compile or interpret it. If that's right, maybe we shouldn't take so much comfort in Dupre's remarks that genes don't build brains any more than wombs or schools do. Wombs and Schools are just part of the machinery for interpreting or compiling of the genetic program.
I don't think this is right. Moreover, I'm sure we'll get Dupre to say a lot more about why this is not the right way to think about the distinctive role of genes in causing a phenotype. If there is such a thing as LOG -- the Language of the Genes -- then LOG is, in a matter of speaking, written in a pretty impoverished vocabulary. To a first approximation, LOG is probably only rich enough to express "statements" about amino acid sequences. This can't be quite the whole story, because something has to determine in which order the various amino acid sequences get laid down and there do seem to be genes that have that role. In any case, it's a very very long and complex journey from even the orchestrated laying down of amino acid sequences to constructing anything so complex as a human brain. Of course, there are normal and relatively stable developmental pathways that mediate between the genes, with their encoded instructions for building amino acids, and any large scale phenotypic trait. And for some explanatory purposes, it might be useful to construe the mediating developmental pathways as "black boxes" into which we need not look. As I understand it, that's precisely what "genetic selectionists" about the so-called units of natural selection tend to do. But granting even this much is a very far from endorsing genetic determinism or elevating the genes into uniquely privileged sources of what we are. Even the genetic selectionist, who claims that only genes are selected for, has to concede that development is not the business of the gene alone.
There's a lot more to say here. I'm sure we'll say lots of it on the air today. And I'm sure both John and I and hopefully you too will learn a lot from our conversation with John Dupre. But I'm tempted to conclude already, that the whole boogieman of genetic determinism is based mostly on misunderstanding. Dan Dennett is probably right to say that no one, at least no serious scientist, seriously endorses genetic determinism. It certainly is hard to find anyone who admits to being a genetic determinist. S0 exactly how does a view that has no hold in the scientific community take on such a life of its own in the popular imagination?
It doesn't follow, though, there are no remaining controversial issues about genes and their role in making us who we are. Dupre, for example, holds pretty dismissive views about the explanatory promise of Evolutionary Psychology, a discipline that I myself find rather intriguing. His dismissal is partly based on his rejection of what he thinks is their misappropriation of genetic explanation. I'm not sure he's right about that and I'm not sure that evolutionary theory has as little to teach us about universals of human nature as he apparently believes. But we'll see.