It is time to set minds at ease by raising the "specter" of "genetic determinism" andbanishing it once and for all. According to Stephen Jay Gould, genetic determinists believe the following:
"If we are programmed to be what we are, then these [genetically inherited] traits are ineluctable.We may, at best, channel them, but we cannot change them either by will, education, or culture."
If this is genetic determinism, then we can all breathe a sigh of relief: There are no genetic determinists. Ihave never encountered anybody who claims that will, education, and culture cannot change many, if not all, ofour genetically inherited traits. My genetic tendency to myopia is canceled by the eyeglasses I wear (but I dohave to want to wear them); and many of those who would otherwise suffer from one genetic disease or anothercan have the symptoms postponed indefinitely by being educated about the importance of a particular diet, orby the culture-borne gift of one prescription medicine or another. If you have the gene for the diseasephenylketonuria, all you have to do to avoid its undesirable effects is stop eating food containingphenylalanine. What is inevitable doesn't depend on whether determinism reigns, but on whether on not thereare steps we can take, based on information we can get in time to take those steps, to avoid the foreseenharm.
There are two requirements for meaningful choice: information and a path for the information to guide. Withoutone, the other is useless or worse. In his excellent survey of contemporary genetics, Matt Ridley drives thepoint home with the poignant example of Huntington's disease, which is "pure fatalism, undiluted byenvironmental variability. Good living, good medicine, healthy food, loving families, or great riches can donothing about it." This is in sharp contrast to all the equally undesirable genetic predispositions thatwe can do something about. And it is for just this reason that many people who are likely, given their familytree, to have the Huntington's mutation choose not to take the simple test that would tell them with virtualcertainty whether they have it. But note that if and when a path opens up, as it may in the future, fortreating those who have Huntington's mutation, these same people will be first in line to take the test.
Gould and others have declared their firm opposition to "genetic determinism," but I doubt ifanybody thinks our genetic endowments are infinitely revisable. It is all but impossible that I will ever givebirth, thanks to my Y chromosome. I cannot change this by either will, education, or culture -- at leastnot in my lifetime (but who knows what another century of science will make possible?). So at least for theforeseeable future, some of my genes fix some parts of my destiny without any real prospect of exemption. Ifthat is genetic determinism, we are all genetic determinists, Gould included. Once the caricatures are setaside, what remains, at best, are honest differences of opinion about just how much intervention it would taketo counteract one genetic tendency or another and, more important, whether such intervention would bejustified.
These are important moral and political issues, but they often become next to impossible to discuss in a calmand reasonable way. Besides, what would be so specially bad about genetic determinism? Wouldn'tenvironmental determinism be just as dreadful? Consider a parallel definition of environmentaldeterminism:
"If we have been raised and educated in a particular cultural environment, then the traits imposed on usby that environment are ineluctable. We may at best channel them, but we cannot change them either by will,further education, or by adopting a different culture."
The Jesuits have often been quoted (I don't know how accurately) as saying: "Give me a child until he is7, and I will show you the man." An exaggeration for effect, surely, but there is little doubt that earlyeducation and other major events of childhood can have a profound effect on later life. There are studies, forinstance, that suggest that such dire events as being rejected by your mother in the first year of lifeincreases your likelihood of committing a violent crime. Again, we mustn't make the mistake of equatingdeterminism with inevitability. What we need to examine empirically -- and this can vary just asdramatically in environmental settings as in genetic settingsis whether the undesirable effects, howeverlarge, can be avoided by steps we can take.
Consider the affliction known as not knowing a word of Chinese. I suffer from it, thanks entirely toenvironmental influences early in my childhood (my genes had nothing -- nothing directly -- to dowith it). If I were to move to China, however, I could soon enough be "cured," with some effort onmy part, though I would no doubt bear deep and unalterable signs of my deprivation, readily detectable by anynative Chinese speaker, for the rest of my life. But I could certainly get good enough in Chinese to be heldresponsible for actions I might take under the influence of Chinese speakers I encountered.
Isn't it true that whatever isn't determined by our genes must be determined by our environment? What else isthere? There's Nature and there's Nurture. Is there also some X, some further contributor to what we are?There's Chance. Luck. This extra ingredient is important but doesn't have to come from the quantum bowels ofour atoms or from some distant star. It is all around us in the causeless coin-flipping of our noisy world,automatically filling in the gaps of specification left unfixed by our genes, and unfixed by salient causes inour environment. This is particularly evident in the way the trillions of connections between cells in ourbrains are formed. It has been recognized for years that the human genome, large as it is, is much too smallto specify (in its gene recipes) all the connections that are formed between neurons. What happens is that thegenes specify processes that set in motion huge population growth of neurons -- many times more neuronsthan our brains will eventually use -- and these neurons send out exploratory branches, at random (atpseudo-random, of course), and many of these happen to connect to other neurons in ways that are detectablyuseful (detectable by the mindless processes of brain-pruning).
These winning connections tend to survive, while the losing connections die, to be dismantled so that theirparts can be recycled in the next generation of hopeful neuron growth a few days later. This selectiveenvironment within the brain (especially within the brain of the fetus, long before it encounters the outsideenvironment) no more specifies the final connections than the genes do; saliencies in both genes anddevelopmental environment influence and prune the growth, but there is plenty that is left to chance.
When the human genome was recently published, and it was announced that we have "only" about 30,000genes (by today's assumptions about how to identify and count genes), not the 100,000 genes that some expertshad surmised, there was an amusing sigh of relief in the press. Whew! "We" are not just the productsof our genes; "we" get to contribute all the specifications that those 70,000 genes would otherwisehave "fixed" in us! And how, one might ask, are "we" to do this? Aren't we under just asmuch of a threat from the dread environment, nasty old Nurture with its insidious indoctrination techniques?When Nature and Nurture have done their work, will there be anything left over to be me?
Does it matter what the trade-off is if, one way or another, our genes and our environment (including chance)divide up the spoils and "fix" our characters? Perhaps it seems that the environment is a morebenign source of determination since, after all, "we can change the environment." That is true, butwe can't change a person's past environment any more than we can change her parents, and environmentaladjustments in the future can be just as vigorously addressed to undoing prior genetic constraints as priorenvironmental constraints. And we are now on the verge of being able to adjust the genetic future almost asreadily as the environmental future.
Suppose you know that any child of yours will have a problem that can be alleviated by either an adjustment toits genes or an adjustment to its environment. There can be many valid reasons for favoring one treatmentpolicy over another, but it is certainly not obvious that one of these options should be ruled out on moral ormetaphysical grounds. Suppose, to make up an imaginary case that will probably soon be outrun by reality, youare a committed Inuit who believes life above the Arctic Circle is the only life worth living, and suppose youare told that your children will be genetically ill-equipped for living in such an environment. You can moveto the tropics, where they will be fine -- at the cost of giving up their environmental heritage -- oryou can adjust their genomes, permitting them to continue living in the Arctic world, at the cost (if it isone) of the loss of some aspect of their "natural" genetic heritage.
The issue is not about determinism, either genetic or environmental or both together; the issue is about whatwe can change whether or not our world is deterministic. A fascinating perspective on the misguided issueof genetic determinism is provided by Jared Diamond in his magnificent book Guns, Germs, and Steel (1997).The question Diamond poses, and largely answers, is why it is that "Western" people (Europeans orEurasians) have conquered, colonized, and otherwise dominated "Third World" people instead of viceversa. Why didn't the human populations of the Americas or Africa, for instance, create worldwide empires byinvading, killing, and enslaving Europeans? Is the answer ... genetic? Is science showing us that the ultimatesource of Western dominance is in our genes? On first encountering this question, many people -- evenhighly sophisticated scientists -- jump to the conclusion that Diamond, by merely addressing thisquestion, must be entertaining some awful racist hypothesis about European genetic superiority. So rattled arethey by this suspicion that they have a hard time taking in the fact (which he must labor mightily to drivehome) that he is saying just about the opposite: The secret explanation lies not in our genes, not in humangenes, but it does lie to a very large extent in genes -- the genes of the plants and animals that werethe wild ancestors of all the domesticated species of human agriculture.
Prison wardens have a rule of thumb: If it can happen, it will happen. What they mean is that any gap insecurity, any ineffective prohibition or surveillance or weakness in the barriers, will soon enough be foundand exploited to the full by the prisoners. Why? The intentional stance makes it clear: The prisoners areintentional systems who are smart, resourceful, and frustrated; as such they amount to a huge supply ofinformed desire with lots of free time in which to explore their worlds. Their search procedure will be asgood as exhaustive, and they will be able to tell the best moves from the second-best. Count on them to findwhatever is there to be found.
Diamond exploits the same rule of thumb, assuming that people anywhere in the world have always been justabout as smart, as thrifty, as opportunistic, as disciplined, as foresighted, as people anywhere else, andthen showing that indeed people have always found what was there to be found. To a good first approximation,all the domesticable wild species have been domesticated. The reason the Eurasians got a head start ontechnology is because they got a head start on agriculture, and they got that because among the wild plantsand animals in their vicinity 10,000 years ago were ideal candidates for domestication. There were grassesthat were genetically close to superplants that could be arrived at more or less by accident, just a fewmutations away from big-head, nutritious grains, and animals that because of their social nature weregenetically close to herdable animals that bred easily in captivity. (Maize in the Western Hemisphere tooklonger to domesticate in part because it had a greater genetic distance to travel away from its wildprecursor.)
And, of course, the key portion of the selection events that covered this ground, before modern agronomy, waswhat Darwin called "unconscious selection'' -- the largely unwitting and certainly uninformed biasimplicit in the behavior patterns of people who had only the narrowest vision of what they were doing and why.Accidents of biogeography, and hence of environment, were the major causes, the constraints that "fixed''the opportunities of people wherever they lived. Thanks to living for millennia in close proximity to theirmany varieties of domesticated animals, Eurasians developed immunity to the various disease pathogens thatjumped from their animal hosts to human hosts -- here is a profound role played by human genes, and oneconfirmed beyond a shadow of a doubt -- and when thanks to their technology, they were able to travellong distances and encounter other peoples, their germs did many times the damage that their guns and steeldid.
What are we to say about Diamond and his thesis? Is he a dread genetic determinist, or a dread environmentaldeterminist? He is neither, of course, for both these species of bogeyman are as mythical as werewolves. Byincreasing the information we have about the various causes of the constraints that limit our currentopportunities, he has increased our powers to avoid what we want to avoid, prevent what we want to prevent.Knowledge of the roles of our genes, and the genes of the other species around us, is not the enemy of humanfreedom, but one of its best friends.
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Daniel C. Dennett is a university professorand director of the Center for Cognitive Studies at Tufts University and author, inter alia, of Darwin'sDangerous Idea. This essay is adapted from Freedom Evolves -- with permission of the author -- tobe published in February by Viking.
Copyright © 2003 by Daniel C. Dennett.
