"Nature" 2001
The case of the missing carpaccio
JERRY A. COYNE
Jerry A. Coyne is in the Department of Ecology and Evolution, University
of Chicago, Chicago, Illinois 60637, USA.
The Evolution Explosion: How Humans Cause Rapid Evolutionary Change
by Stephen R. Palumbi
W. W. Norton: 2001. 277 pp. $24.95
Many students open The Origin of Species expecting intellectual
fireworks, but are disappointed to find a soporific discussion of sheep
and pigeons. Yet Darwin's tedious opening chapter on artificial
selection was a stroke of rhetorical genius: by recounting the familiar
triumphs of animal and plant breeders, he paved the way for his
infinitely more heretical evolutionary ideas. (This strategy nearly
misfired: one of the publisher's readers, noting that "everybody is
interested in pigeons", recommended that Darwin drop the messy stuff
about evolution and concentrate instead on birds.)
Although darwinism is now firmly established in scientific and
intellectual life, it is far from entrenched in the public
consciousness. This is due partly to the prevalence of creationism, but
also to the notion — familiar to anyone who teaches premedical students
— that evolution has nothing to do with everyday life. In The Evolution
Explosion, Stephen Palumbi, a biologist at Harvard University, tries to
dispel this view, using Darwin's own strategy of appealing to the
reader's experience and hoping that familiarity breeds consent.
Palumbi concentrates on cases in which humans have produced rapid
evolution in other species by changing their environments: his examples
include the evolution of antibiotic resistance in bacteria, herbicide
resistance in plants, pesticide resistance in insects, and changes in
the growth rate of fish caused by overfishing. Remarkably, many people
familiar with these phenomena have failed to see that they demonstrate
evolution driven by selection. There is, for example, a public
misconception that 'drug resistance' involves not evolutionary change in
pathogenic bacteria, but some process whereby a person becomes
acclimated to antibiotics.
Palumbi writes enthusiastically and clearly, and his stories are based
on extensive research documented in an appendix. His chapter on AIDS is
particularly useful, describing in detail how HIV evolves to avoid the
double depredations of our immune system and new generations of
antiviral drugs. Elsewhere, we learn that antibiotic resistance in
pathogenic bacteria has been caused both by the overprescription of
drugs (leading, for example, to the resurgence of drug-resistant
tuberculosis) and by the use of antibiotics that increase growth rates
in farm animals (producing chickens harbouring dangerous, drug-resistant
salmonellae and explaining the absence of carpaccio di pollo in Italian
restaurants).
Sadly, our understanding of these evolutionary responses seems to have
contributed little to solving the attendant medical and economic
problems. Combating drug or pesticide resistance usually involves
applying more drugs or poisons — solutions that hardly require a
sophisticated understanding of evolution. Moreover, new treatments are
eventually stymied by further evolution, so that human ingenuity seems
nearly impotent in the face of recurring mutation and selection.
By compiling and explaining these diverse cases of anthropogenic
evolution, Palumbi has made a useful contribution to the public
understanding of science. However, The Evolution Explosion suffers from
a few problems. Palumbi's narrative runs out of steam in a final chapter
about memes, the 'units of culture' (slogans, ideas and inventions, for
example) that serve as analogues to genes in theories of social
evolution. Despite much attention, 'memetics' has ultimately proved a
sterile metaphor, of little value in understanding history or society.
It is not clear why Palumbi chose to drag a perfectly straightforward
book about science into this pseudo-philosophical quagmire.
The book's style poses an equally serious problem. Straining mightily to
achieve what the dust-jacket calls "popular imagery", Palumbi produces
an incessant stream of exuberant metaphors and similes that can distract
rather than enlighten. In places the prose causes near-physical pain, as
in the discussion of memes: "Bad ideas, rejected like anchovy daiquiris,
live on only in a few people with fishy breath. Good ideas duplicate
quickly and spread far and wide, generating clutches of mental
ducklings, with some subsequently turning into brilliant swans and
others fated to remain only brain geese."
Finally, although the science is generally accurate, Palumbi's
discussion is occasionally confusing or incorrect. For example, he
repeats as truth the common belief that artificial selection has made
domestic turkeys so dim-witted that during storms they look up at the
rain, forget to look down, and drown. This is, in fact, an agro-urban
myth that has been branded an "unfounded turkey rumor" by Turkey Call,
the official organ of the National Wild Turkey Federation. (Turkeys
have, however, suffered greatly from domestication. Responding to human
fondness for breast meat, farmers have bred birds too buxom to bonk, and
new turkeys must be produced by artificial insemination.)
Nevertheless, The Evolution Explosion should help quash the eternal
student complaint that evolution is irrelevant. Alas, it is unlikely to
change the minds of creationists and advocates of 'intelligent design'.
Many who reject darwinism on religious grounds already accept
anthropogenic evolution as 'adaptation within a species', but argue that
such small changes cannot explain the evolution of new groups of plants
and animals. This argument defies common sense. When, after a Christmas
visit, we watch grandma leave on the train to Miami, we assume that the
rest of her journey will be an extrapolation of that first quarter-mile.
A creationist unwilling to extrapolate from micro- to macroevolution is
as irrational as an observer who assumes that, after grandma's train
disappears around the bend, it is seized by divine forces and instantly
transported to Florida. Those not besotted by the anchovy daiquiris of
creationism, however, will be convinced by Palumbi's book that evolution
is alive and well, if not always welcome.
Nature © Macmillan Publishers Ltd 2001 Registered No. 785998
England.
POWRÓT