Natural Selection for Everyone
The Making of the Fittest: DNA and the Ultimate Forensic Record
of Evolution. Sean B. Carroll. 301 pp. W.W. Norton, 2006. $25.95.
Garry Trudeau recently composed a Doonesbury cartoon in which a
doctor asks a patient with tuberculosis whether he is a
creationist—saying that his answer will determine whether the
treatment will be streptomycin (effective only for the TB of
yesteryear) or a more modern antibiotic (one that would work on the
drug-resistant strain into which the TB bacterium had lately
evolved).Despite his religious convictions, the patient shows great
interest in the updated drug. Sean Carroll, an evolutionary
developmental biologist at the University of Wisconsin, opens his
new book with a similar conundrum: Why is it that so many Americans
are willing to use DNA to convict those accused of murder while
simultaneously refusing to accept the validity of the overwhelming
molecular evidence for evolution? Carroll has an interesting point,
for many Americans harbor creationist sentiments yet seem quite
happy to reap the fruits of modern research, such as nuclear power
(or nuclear weapons!), the beneficial products of agricultural
genetics, or forensic DNA, without acknowledging that the science
underlying these advances has revealed an abundance of information
(the radiometric dating of ancient rocks and the molecular
fingerprints of evolution, for example) that is contrary to their
Popular exposition about evolution has had difficulty conveying the
incredible power of natural selection. The late Stephen Jay Gould
perfected one approach, writing engaging essays about odd
peculiarities whose only explanation can be evolution. Other
approaches all too often get bogged down with such boring things as
changing allele frequencies in peppered moths, and let's face it, no
one, not even a population geneticist, has ever really enjoyed
rehashing that argument.
As a developmental biologist, Carroll has a far more engaging set of
examples to offer: the remarkable genetic and developmental evidence
for the evolution of antifreeze proteins in Antarctic fish, the
evolution of color vision through the duplication of opsin genes in
birds and primates, and the fossil evidence preserved in our own
genes for battles against malaria. In each case, he describes both
the basic natural history and the genetic changes involved.
Carroll does not shy away from the mathematics of natural selection,
but he presents quantitative aspects of evolutionary theory in a
deceptively simple manner (and yes, peppered moths make their
obligatory appearance). He also includes some math in his discussion
of Alberto Palleroni's investigation of falcon predation on pigeons
near Davis, California, where, it turns out, a white rump on a
pigeon evidently distracts falcons. Having conveyed the mathematical
essence of such examples of natural selection, he can turn back to
the compelling arguments that come from the work of his own lab and
from the labs of many colleagues.
Of course, one wonders whether books like this ever reach their
intended audience. Most readers of popular science books (and,
presumably, most readers of American Scientist) recognize
that there is not a scintilla of evidence for intelligent design or
its more antiquated progenitor, creationism. (Indeed, these systems
of belief are not just flawed, they are theologically bankrupt as
well, as many theologians have pointed out.) Carroll is not, I
think, so foolish as to think that his efforts will convert members
of the Discovery Institute or the Institute for Creation Research.
Rather, he aims at the middle ground: those sufficiently curious
about the world and how it works to want to understand, rather than
to rely on blind faith. In this he is, I think, quite successful.
Carroll does not shrink from confronting head-on the intellectual
poverty and often downright dishonesty of the purveyors of
"creationist science." In a chapter on creationists, he
begins with a review of Lysenkoism and the damage it did for several
decades to genetics (and to science in general) in the Soviet Union.
Chiropractors and their battles against immunization then serve as a
cautionary tale, demonstrating that such anti-scientific posturing
is not limited to other countries. Carroll then identifies in the
behavior of creationists several of the techniques of disinformation
characteristic of these two movements. It should go without saying,
but sadly cannot, that Carroll's complaint is not with religion as
such, but with those fundamentalists whose fear of intellectual
inquiry leads them to such discreditable ends.
I do wish that Carroll had shared more of his views about the future
directions of evolutionary theory, a topic he touched on near the
end of his previous book, Endless Forms Most Beautiful. He
is among those who feel that science is on the verge of a new
synthesis in evolutionary biology (a perspective I share). Yet he
missed an opportunity here to elaborate on what the future might
bring and to show how scientists deal with new data that challenge
Carroll is a devoted father, and his children make frequent
appearances during the course of family trips to satiate Dad's love
of natural history. As a field geologist, I get a sense that part of
Carroll wishes he had become a field biologist, tracking snakes
through the underbrush. But we are all fortunate that instead he has
become a vital contributor to the growth of evolutionary
developmental biology and is now an engaging author of popular books
on this and allied subjects. Conveying the excitement of current
research while also providing a firm foundation of why we know what
we know is a rare gift. In The Making of the Fittest,
Carroll offers a graceful and insightful view of the explanatory
power of evolution.
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