A Conversation With George C. Williams
by Frans Roes
am convinced that it is the light and the way." These are the final words in
Adaptation and Natural Selection,
George C.
William's 1966 book about evolution. In the decades since the publication
of this book, which became one of the most influential in its field, nothing
has altered Williams's conviction that evolutionary theory is not just of
intellectual interest but has much practical significance for human life.
A marine biologist by training, Williams took two
sabbaticals to conduct fish research in Iceland, but he is most widely known
as a theoretician. As early as 1957, he wrote a paper on senescence
considered by some to be a cornerstone of modern evolutionary theory.
Williams has also written passionately about the "moral unacceptability of
natural selection" and the necessity of using our intelliqence to triumph
over it. For a paper on evolutionary ethics, Williams came up with one of
the most eye-catching titles in scientific literature: "Mother Nature Is a
Wicked Old Witch."
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Despite
his strongly held convictions, Williams says that for him, controversy is what
makes biology interesting. In years past, he defended reductionism (the idea
that organisms can be adequately understood in terms of physics, chemistry, and
the history of evolutionary change) when it was not fashionable to do so. More
recently, he has explored the insights to be gained by applying evolutionary
theory to medicine. His 1996 book, Evolution and Healing: The New Science of
Darwinian Medicine (coauthored with Randolph Nesse, of the University of
Michigan Medical School), stresses the importance of understanding the adaptive
significance of symptoms such as fever rather than merely seeking immediate
relief. |
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George C. Williams | |
George Williams taught biology for thirty years at the
State University of New York at Stony Brook, where he is now professor
emerittis. He is also editor of the Quarterly Review of Biology,
which has been publishing thoughtful articles and book reviews about the
life sciences for nearly three-quarters of century. Williams's latest book,
The Pony Fishes Glow and Other Clues to Plan and Purpose in Nature,
was published by BasicBooks as part of its Science Masters Series.
Frans Roes: Thirty years ago, in
Adaptation and Natural Selection, you criticized some ideas in
biology.
George Williams: I think that my main
criticism in the book was directed at the general assumption that adaptation
characterizes populations and species, rather than simply the individuals in
the populations and species. What I did was take the position that natural
selection works most effectively at the individual level, and adaptatious
that are produced are adaptive for those individuals, in competition with
other individuals of the same population, rather than for any collective
well-being.
Frans Roes: Individual selection would mean
that living organisms are not adapted to prevent the extinction of their owm
species.
George Williams: That is right. Most
evolving lineages, human or otherwise, when threatened with extinction,
don't do anything special to avoid it. I presume that the last pair of
passenger pigeons, once a very abundant bird in North America, now extinct,
reproduced the same old way. Once the species had gotten extremely rare, it
did nothing new and did not take any special measures, the way an individual
would if threatened with death. On other hand, we humans in fact have not
gone extinct as yet; all our closest relatives have, so I would presume that
to some extent the current human biology may be biased in favor of
attributes that make us less vulnerable to extinction.
Just what features raise or lower vulnerability to
extinction is a generally neglected problem, but it is widely recognized
that sexual reproduction helps to keep a population going. Sexual
reproduction is a complicated process that is occasionally lost, thereby
simplifying the reproductive process. As a general rule, though, in both
plants and animals, once a line of descent loses the sexual process, nothing
new ever comes of it. It won't branch into several new species the way a
sexual species might. So asexual reproduction exclusively in any line of
descent appears to be a dead end. If there has ever been a mammal that
reproduced asexually, it is not around any more and has no descendants.
Frans Roes: If selection works at the
individual level, why don't individuals live forever? Why do we grow
old?
George Williams: Well, no matter how fit
you keep yourself, sooner or later something will get you: an accident, a
new epidemic, an attack by terrorists, or whatever. Even if you had eternal
youth, this would obviously not assure that you live forever. So the
interesting question is, once we attain our full youthful adulthood, why
don't we just stay that way?
Suppose we could do that: let's wave a magic wand, and
suddenly we have eternal youth. In evolution that would not be stable,
because eternal youth does not abolish mortality. Let's say that half of us
with this eternal youth managed to live to 100, a quarter to age 200,
one-eighth to 300, and so on. A mutation that would confer some slight
advantage in our twenties and thirties might well be favored, even if it
causes us to drop dead at age 300. Most people are going to be alive in
their twenties and thirties and thus get the benefits of whatever that
mutation does, but since only one-eighth of the population is going to
reach age 300, dropping dead then would be worth an advantage earlier in
life. So the evaluation by natural selection of new genetic variability
would be biased in favor of the earlier part of life histories and against
the later part, until we had reevolved to something like the senescence we
have now.
Frans Roes: But I read that sea anemones
may live forever. How is this possible?
George Williams: The general rule is that
anything that is passed on in reproduction does not undergo senescence. So
things that can divide in two, with both halves going on, would ordinarily
not deteriorate with increasing age. They wouldn't have the kind of
trade-off that you have when there is something you can discard. We humans
may discard our bodies, but our germ cells do not necessarily come to an
end. We can pass them on in reproduction to people who in turn can pass them
on. Asexually reproducing organisms such as sea anemones retain eternal
youth for the same reason that our germ cells retain eternal youth. I think
it is the British biologist Tom Kirkwood who invented the term "disposable
soma." If you have a disposable soma, that soma will undergo senescence. If
you don't, it won't.
Frans Roes: There are all sorts of
wonderful adaptations, yet you write that natural selection never designs
new machinery. Why did you write this?
George Williams: Because there is nothing
in natural selection that looks ahead and plans ahead. All it can do is make
use of variation that is present. Some things work better than others, and
the ones that work better are the ones that tend to be preserved. And these
are always preserved in relation to immediate circumstances, never in order
to facilitate anything in the future.
Frans Roes: You also wrote that every
organism shows features that are functionally arbitrary or even
maladaptive.
George Williams: The human body is just
full of illustrations of what are really either arbitrary or in many cases
quite unfortunate legacies from prior history. Our respiratory system, for
instance. Way back, half a billion years ago at least, some early vertebrate
didn't have a respiratory system, but it had a digestive system with a way
of taking in water at the front end and running it through a filter. That
machinery turned out to be easily modified to facilitate respiration, to
arrange some special mechanisms for exchanging gases with the environment
when the organism got big enough to actually need that.
Ever since then, all descendant vertebrates have had the
forward end of the digestive system and the forward end of the respiratory
system very much involved with each other. This manifests itself in the
human body with a crossing of the two systems in the throat. So there can
be, and frequently are, traffic problems there, the extreme being that you
choke to death because you are trying to eat something. If you could
redesign it, you would have two completely separated systems, or they would
be connected in a way that doesn't require any crossing of the two
systems.
Frans Roes: Another seemingly maladaptive
phenomenon: Why would a vital organ like the human male testis be outside
the body, where it is quite vulnerable?
George Williams: For some reason, sperm
development has to be at a lower temperature than the rest of the body. This
is accomplished by the somewhat external scrotal structure. This certainly
makes the testicles vulnerable, and I think an indication of this is that
whenever mammals reproduce seasonally and don't need to be producing sperm
for much of the year, the testicles are retracted into the body and only go
back into the scrotum during the breeding season.
Frans Roes: But this sounds like an excuse:
We don't know why testicles are outside the body, so it must be
temperature.
George Williams: Oh no, I think it quite
obviously is temperature because any time the testicular temperature is
abnormally elevated, for instance by a high fever, sterility or defective
sperm results.
Frans Roes: Still, I think this sounds like
making the theory irrefutable.
George Williams: If you are talking about
the general theory, it is not likely to be refutable by any one study. No
single observation like this is going to make users of some major
theoretical set of ideas abandon these ideas. What does happen is that you
use evolutionary theory to make certain predictions and check on those
predictions. More often than not, they turn out not to work. So you go back
to the drawing board and try something else. You don't find the wrong ones
being published in biological journals.
Frans Roes: But aren't people justified in
saying, hey, there is a conspiracy going on of biologists who don't publish
anything that is unfavorable to evolutionary theory?
George Williams: The same bias affects
engineers. They calculate that if they did something a certain way, they
would produce a better engine. They do it and try it out, and it turns out
not to be better at all. So they go back and try something else. They do not
claim to have refuted the laws of thermodynamics. These are not things that
get published in the engineering journals. It is only the improvements that
get published. Evolutionary theory works the same way: Use it to generate
expectations and then check on them. If the expectations turn out as
expected, then you have made a discovery that may be something important.
Darwin based his theory on generalizations that were
strictly empirical. You can go out and see that organisms do vary, that
variations are inherited, and that every organism is capable of increasing
its numbers in sufficiently favorable circumstances. These are basic
premises that can be checked directly. By contrast, physical theories, such
as those that describe invisible atoms, are often not directly testable.
Frans Roes: In your latest book, you
describe the biological creation process as being both "evil" and
"abysmally stupid." What do you mean when you say this?
George Williams: Natural selection
maximizes shortsighted selfishness, no matter how much pain or loss it
produces. There are far more losers than winners, and great losses often
arise from trivial gains. The killing of monkey infants for minor male
reproductive gain is the example that most persuasively led me to use words
like evil.
As to its stupidity, natural selection produces what seem
to be ingenious devices, like eyes and hands and the human capacity for
language, but a close examination shows these devices to be just the sorts
of things that can arise from trial and error, with no modifications that
would arise from any real understanding of the problems to be solved. As a
result, all organisms are burdened with maladaptive historical legacies,
such as the many problems that arise from the close association of the
human reproductive and excretory systems.
Frans Roes: I found in your work several
references to Buddhism. Do you have a special liking for Buddhism?
George Williams: My reading on this sort of
thing is extremely limited, but as a doctrine I think Buddhism is more
compatible with the spirit of scientific inquiry than what you get in the
Old Testament. I think it is because of the explicit recognition in Buddhism
that things are not naturally good. There is a lot of pain and suffering in
the world, and that is because that's just the way the world is. And the way
to overcome this is to live a certain way and to be resigned to the
inevitable imperfections of life.
This is opposed to some Christian and Jewish traditions,
in which everything is for the best to some extent, because it is God's will
that things be this way. And if they don't seem right—well, that is
because we don't really understand. In the Book of Job, for instance, no
matter how many evils befall, you accept them and really don't admit that
they are evil because they must have come from God. And opposing what God
does is stupid because God is so powerful. Job's avoidance of rebellion
against God has nothing to do with God being good or wise or anything like
that; it's strictly because God is so powerful, and you don't fight
something when you are so much weaker than that which you would fight.
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Life and Death Fallacies
From The Pony Fish's Glow and Other Clues to Plan and Purpose in
Nature, by George C. Williams. Copyright 1997 by George C. Williams.
Reprinted by arrangement with BasicBooks.
Many traditional religions foster attitudes that ought to
have disappeared as biological understanding accumulated over the last century.
One of these might be termed the holy-corpse fallacy. When people die, their
relatives and friends behave as if there were some moral significance in the
dead body. They ignore the fact that the "last remains" are just that, material
that happened, at the time of death, to provide the medium of expression for a
human life. However long this complex human message was expressed is the
duration of time in which the materials were coming and going. The tons of
matter that at one time or another were part of a dead senior citizen are
already dispersed throughout the terrestrial ecosystem. A small minority of the
dead person's molecules are in orbit around the earth or sun. Cremation of the
matter that happened to be there at the last minute merely hastens an inevitable
process.
The holy-corpse fallacy once had support from the biological
concept of protoplasm, the special living matter of an organism. Other matter
may be entering and leaving a living cell, but it's protoplasm was presumably a
stable entity that regulated this material flux. A dead person may have dead
protoplasm, but it was presumably that person's very own protoplasm, and had
been throughout his or her life. Protoplasm was often discussed in the biology
courses I took in the 1940s. It is a term almost never heard today.
Another error is the moment-of-conception fallacy. The
joining of a human egg and sperm defines a new and unique human genotype. It
does not produce any human hopes and fears and memories or anything else of
moral importance implied by the term human. The newly fertilized egg may have
the potential for a fully human existence, but that potential was there even
before fertilization. The same can be said of all the fertilizations that might
have been. The penetration of that egg by one sperm meant an early death for
millions of competing sperm. It destroyed all hope for those millions of other
unique human genotypes.
The moment-of-conception fallacy implies that fertilization
is a simple process with never a doubt as to whether it has or has not happened.
In reality, the "moment" is a matter of some hours of complex activity. There
are elaborate biochemical interactions between the sperm and various layers of
the egg membrane. The sperm gradually breaks up, and only its nucleus is
established in the egg. Then both egg and sperm nuclei initiate radical changes
before the fusion of the two nuclei. Many of the developmental events following
this fusion were predetermined during the production of the egg. Genes provided
by the sperm do not have discernible effects until embryonic development is well
under way. A strictly biological definition of humanity would have to specify
some point in this elaborate program at which the egg and sperm have suddenly
been endowed with a single human life.
There are other difficulties with defining humanity this way.
If that single human life develops for a while and then divides to produce
identical twins or triplets, are they to be considered one human being? This
would be contrary to almost everyone's moral sensibilities. Recent observations
have raised additional questions about the connection between biological and
moral individuality. Early in development, fraternal twins from two separate,
fertilized eggs may fuse and develop into what, at birth, is physically a single
baby. Molecular techniques available today may show that such an individual is
genetically different in various parts of its body. An apparently normal woman
may have some genetically male tissues from what originated as her twin brother,
or vice versa. The only realistic view is that a human life arises gradually,
which is not much help in making personal decisions or devising public
policy. |
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Trained as a sociologist, Amsterdam native Frans Roes has for much of the
last decade written about evolutionary theory. His second book,
The Naked
Mole Rat: On Humans, Animals, and Evolution, was published (in Holland) in
1993. Roes is now working as an environmental adviser, consulting with firms on
their fossil energy consumption, chemical use, and waste production.
[ Frans Roes, "A Conversation With George C. Williams,"
Nat. Hist. 107 (May): 10-13. ]
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