From the issue dated January 31,
2003
http://chronicle.com/weekly/v49/i21/21b00701.htm
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The Mythical Threat of Genetic DeterminismBy DANIEL C.
DENNETT
It is time to set minds at ease
by raising the "specter" of "genetic determinism" and banishing 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 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. I have never
encountered anybody who claims that will, education, and culture cannot change
many, if not all, of our genetically inherited traits. My genetic tendency to
myopia is canceled by the eyeglasses I wear (but I do have to want to wear
them); and many of those who would otherwise suffer from one genetic disease or
another can have the symptoms postponed indefinitely by being educated about the
importance of a particular diet, or by the culture-borne gift of one
prescription medicine or another. If you have the gene for the disease
phenylketonuria, all you have to do to avoid its undesirable effects is stop
eating food containing phenylalanine. What is inevitable doesn't depend on
whether determinism reigns, but on whether on not there are steps we can take,
based on information we can get in time to take those steps, to avoid the
foreseen harm.
There are two requirements for meaningful choice:
information and a path for the information to guide. Without one, the other is
useless or worse. In his excellent survey of contemporary genetics, Matt Ridley
drives the point home with the poignant example of Huntington's disease, which
is "pure fatalism, undiluted by environmental variability. Good living, good
medicine, healthy food, loving families, or great riches can do nothing about
it." This is in sharp contrast to all the equally undesirable genetic
predispositions that we can do something about. And it is for just this reason
that many people who are likely, given their family tree, to have the
Huntington's mutation choose not to take the simple test that would tell them
with virtual certainty whether they have it. But note that if and when a path
opens up, as it may in the future, for treating 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 if anybody thinks our genetic endowments are
infinitely revisable. It is all but impossible that I will ever give birth,
thanks to my Y chromosome. I cannot change this by either will, education, or
culture -- at least not in my lifetime (but who knows what another century
of science will make possible?). So at least for the foreseeable future, some of
my genes fix some parts of my destiny without any real prospect of exemption. If
that is genetic determinism, we are all genetic determinists, Gould included.
Once the caricatures are set aside, what remains, at best, are honest
differences of opinion about just how much intervention it would take to
counteract one genetic tendency or another and, more important, whether such
intervention would be justified.
These are important moral and political
issues, but they often become next to impossible to discuss in a calm and
reasonable way. Besides, what would be so specially bad about genetic
determinism? Wouldn't environmental determinism be just as dreadful? Consider a
parallel definition of environmental determinism:
"If we have been
raised and educated in a particular cultural environment, then the traits
imposed on us by 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 is 7, and I will show you the
man." An exaggeration for effect, surely, but there is little doubt that early
education and other major events of childhood can have a profound effect on
later life. There are studies, for instance, that suggest that such dire events
as being rejected by your mother in the first year of life increases your
likelihood of committing a violent crime. Again, we mustn't make the mistake of
equating determinism with inevitability. What we need to examine empirically
-- and this can vary just as dramatically in environmental settings as in
genetic settingsis whether the undesirable effects, however large, 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 to environmental
influences early in my childhood (my genes had nothing -- nothing directly
-- to do with it). If I were to move to China, however, I could soon enough
be "cured," with some effort on my part, though I would no doubt bear deep and
unalterable signs of my deprivation, readily detectable by any native Chinese
speaker, for the rest of my life. But I could certainly get good enough in
Chinese to be held responsible 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 is
there? 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 of our 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 in our environment. This is
particularly evident in the way the trillions of connections between cells in
our brains are formed. It has been recognized for years that the human genome,
large as it is, is much too small to specify (in its gene recipes) all the
connections that are formed between neurons. What happens is that the genes
specify processes that set in motion huge population growth of neurons
-- many times more neurons than our brains will eventually use -- and
these neurons send out exploratory branches, at random (at pseudo-random, of
course), and many of these happen to connect to other neurons in ways that are
detectably useful (detectable by the mindless processes of brain-pruning).
These winning connections tend to survive, while the losing connections
die, to be dismantled so that their parts can be recycled in the next generation
of hopeful neuron growth a few days later. This selective environment within the
brain (especially within the brain of the fetus, long before it encounters the
outside environment) no more specifies the final connections than the genes do;
saliencies in both genes and developmental 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 30,000
genes (by today's assumptions about how to identify and count genes), not the
100,000 genes that some experts had surmised, there was an amusing sigh of
relief in the press. Whew! "We" are not just the products of our genes; "we" get
to contribute all the specifications that those 70,000 genes would otherwise
have "fixed" in us! And how, one might ask, are "we" to do this? Aren't we under
just as much 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 more benign source of determination since, after all, "we can
change the environment." That is true, but we can't change a person's
past environment any more than we can change her parents, and
environmental adjustments in the future can be just as vigorously addressed to
undoing prior genetic constraints as prior environmental constraints. And we are
now on the verge of being able to adjust the genetic future almost as readily as
the environmental future.
Suppose you know that any child of yours will
have a problem that can be alleviated by either an adjustment to its genes or an
adjustment to its environment. There can be many valid reasons for favoring one
treatment policy over another, but it is certainly not obvious that one of these
options should be ruled out on moral or metaphysical grounds. Suppose, to make
up an imaginary case that will probably soon be outrun by reality, you are a
committed Inuit who believes life above the Arctic Circle is the only life worth
living, and suppose you are told that your children will be genetically
ill-equipped for living in such an environment. You can move to the tropics,
where they will be fine -- at the cost of giving up their environmental
heritage -- or you can adjust their genomes, permitting them to continue
living in the Arctic world, at the cost (if it is one) 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 what we can change whether or not our world is deterministic. A
fascinating perspective on the misguided issue of 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 or Eurasians) have conquered, colonized, and
otherwise dominated "Third World" people instead of vice versa. Why didn't the
human populations of the Americas or Africa, for instance, create worldwide
empires by invading, killing, and enslaving Europeans? Is the answer ...
genetic? Is science showing us that the ultimate source of Western dominance is
in our genes? On first encountering this question, many people -- even
highly sophisticated scientists -- jump to the conclusion that Diamond, by
merely addressing this question, must be entertaining some awful racist
hypothesis about European genetic superiority. So rattled are they by this
suspicion that they have a hard time taking in the fact (which he must labor
mightily to drive home) that he is saying just about the opposite: The secret
explanation lies not in our genes, not in human genes, but it does lie to a very
large extent in genes -- the genes of the plants and animals that were the
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 in security, any ineffective
prohibition or surveillance or weakness in the barriers, will soon enough be
found and exploited to the full by the prisoners. Why? The intentional stance
makes it clear: The prisoners are intentional systems who are smart,
resourceful, and frustrated; as such they amount to a huge supply of informed
desire with lots of free time in which to explore their worlds. Their search
procedure will be as good as exhaustive, and they will be able to tell the best
moves from the second-best. Count on them to find whatever is there to be found.
Diamond exploits the same rule of thumb, assuming that people anywhere
in the world have always been just about as smart, as thrifty, as opportunistic,
as disciplined, as foresighted, as people anywhere else, and then 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 on technology is because they got a head
start on agriculture, and they got that because among the wild plants and
animals in their vicinity 10,000 years ago were ideal candidates for
domestication. There were grasses that were genetically close to superplants
that could be arrived at more or less by accident, just a few mutations away
from big-head, nutritious grains, and animals that because of their social
nature were genetically close to herdable animals that bred easily in captivity.
(Maize in the Western Hemisphere took longer to domesticate in part because it
had a greater genetic distance to travel away from its wild
precursor.)
And, of course, the key portion of the selection events that
covered this ground, before modern agronomy, was what Darwin called "unconscious
selection'' -- the largely unwitting and certainly uninformed bias implicit
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 their
many varieties of domesticated animals, Eurasians developed immunity to the
various disease pathogens that jumped from their animal hosts to human hosts
-- here is a profound role played by human genes, and one confirmed beyond
a shadow of a doubt -- and when thanks to their technology, they were able
to travel long distances and encounter other peoples, their germs did many times
the damage that their guns and steel did.
What are we to say about
Diamond and his thesis? Is he a dread genetic determinist, or a dread
environmental determinist? He is neither, of course, for both these species of
bogeyman are as mythical as werewolves. By increasing the information we have
about the various causes of the constraints that limit our current
opportunities, 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 human freedom, but one
of its best friends.
Daniel C. Dennett is a university professor and
director of the Center for Cognitive Studies at Tufts University. This essay is
adapted from Freedom Evolves, to be published in February by Viking.
Copyright © 2003 by Daniel C.
Dennett.
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Section: The Chronicle
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Volume 49, Issue 21, Page B7
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Copyright ©
2003 by The Chronicle of Higher Education