An Elder's View of a Young Theory
What Makes Biology Unique? Ernst Mayr. xiv + 232 pp.
Cambridge University Press, 2004. $30.
Evolution is a young theory. As someone who received his Ph.D. in
1975, I have been professionally active for 20 percent of the era
that comprises the history of the subject (taking Darwin's
Origin as the starting point). Yet I am a newcomer compared
with Ernst Mayr, who will celebrate his 101st birthday this year and
has been professionally active for more than 50 percent of that
history. He has now published his 25th book, What Makes Biology
Unique? It is a collection of essays on a wide range of topics,
including the nature of biology as a scientific discipline, the
problem of defining just what it means to be a species (the subject
for which he is perhaps best known), human evolution and the
possibility of life elsewhere in the universe.
Mayr has a lean prose style that assumes no special knowledge and
gets directly to the point. His acuity would be remarkable at any
age. His essays reflect the recent literature as much as can be
expected, given their broad scope, but their greatest virtue is
their historical and conceptual depth. Not only has Mayr been a
major force for much of the history of evolutionary theory, but he
is also a philosopher and a scholar of the old school who believes
in tracing ideas to their roots. Thus he cites Aristotle and Kant as
frequently as the newest discoveries in molecular biology or human origins.
In my experience, contemporary scientists and their students tend to
lack historical depth and philosophical curiosity; they could thus
benefit greatly from the expansiveness of Mayr's view. His major
theme is that the concept of science was originally based on
mathematics and physics and that biology does not fit that
conception, which has caused many to regard it as
"immature" or "soft" in some sense, whereas in
reality it is the concept of science that needs to be changed to
accommodate differences between biological and physical systems. For
example, experiments cannot be conducted on historical claims about
evolution, but alternative historical narratives can be constructed
and tested against evidence (the same goes for the physical sciences
of astronomy and geology). Evolutionary processes are less
deterministic and lawlike than are physical processes, but there is
still a notion of "concepts" that can be tested
experimentally. Above all, everything that evolves has two
explanations—proximate and ultimate—only one of which
can be reduced to physical processes.
Readers will also benefit from Mayr's long view of the history of
biology. He considers revolutionary developments that took place
before Darwin, the fact that Darwin's theory is a constellation of
what were then fundamentally new (and largely independent) claims,
and the many subsequent developments that led to the theory as we
know it today.
Mayr's philosophical bent is combined with a pragmatism that can be
refreshingly blunt. In the essay "Do Thomas Kuhn's Scientific
Revolutions Take Place?," Mayr shows (rather convincingly,
given the brevity of the piece) that scientific progress in biology
bears little resemblance to the notion of paradigms developed by
Kuhn. In "Are We Alone in This Vast Universe?" Mayr
regards the origin of life on other planets with suitable conditions
as probable, but he considers the likelihood that such life could
communicate with us electronically to be vanishingly remote, and he
deems the search for it a waste of time and money. He even views
efforts to find out whether primitive life evolved elsewhere in the
solar system as wrongheaded—arguing, for example, that the
money spent looking for hints of life on Mars is exorbitant:
The money could have been spent far more effectively in
researching the rapidly dwindling diversity of the tropical
rainforests on earth. But that urgent task is neglected in favor of
possibly finding some fossil bacteria on Mars. Should we perhaps
organize a search for terrestrial intelligence?
It is possible to take issue with Mayr on numerous details. His
critique of reductionism is valid in some respects but also takes
too literally the familiar holistic adage that "the whole is
more than the sum of its parts"—as if reductionists
ignore nonadditive interactions. He misrepresents the problem of
group selection as one of reductionism versus holism. In the
standard model of altruism that evolves by group selection, all the
effects are additive. The reason that group selection is required is
because the altruistic trait is selectively disadvantageous within
groups; to evolve, it requires the ingredients of natural selection
at the group level (a population of groups with variation,
heritability and fitness differences). However, specific issues such
as these do not seriously detract from the main virtue of the book
on a broader scale.
Readers who are already familiar with Mayr's contributions to biology
and philosophy will find primarily summaries and updates on the same
themes, although he is also refreshingly candid about changing his mind
on such subjects as the importance of sympatric speciation (the process
whereby evolutionary lines diverge without having been geographically
isolated). What Makes Biology Unique?
offers newcomers an entertaining way to expand their horizons. We are
lucky that someone who has experienced so much remains forever young in
his thinking.—David Sloan Wilson, Biology and Anthropology,
Binghamton University, Binghamton, New York
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