Print

Print


http://www.nybooks.com/articles/22694
Volume 56, Number 9 · May 28,
2009<http://www.nybooks.com/contents/20090528> Why
Darwin? By Richard C. Lewontin <http://www.nybooks.com/authors/4463> Darwin's
Origin of Species: A Biography by Janet Browne

Grove, 174 pp., $13.00 (paper)
The Annotated Origin: A Facsimile of the First Edition of On the Origin of
Species by Charles Darwin, annotated by James T. Costa

Belknap Press/Harvard University Press, 537 pp., $35.00
Why Evolution Is True by Jerry A. Coyne

Viking, 282 pp., $27.95
It Takes a Genome: How a Clash Between Our Genes and Modern Life Is Making
Us Sick by Greg Gibson

FT Press, 187 pp., $24.99

When I was a student I was enjoined to reject the "Cleopatra's Nose" theory
of history, so called after Pascal's remark in the *Pensées* : "Cleopatra's
nose: if it had been shorter, everything in the world would have changed."
[1] <http://www.nybooks.com/articles/22694#fn1> The intent was not to
dismiss biography as a way into the structuring of a historical narrative,
but to reject the idea that the properties, ideas, or actions of some
particular person were the necessary conditions for the unfolding of events
in the world. If Josef Djugashvili had never been born, someone else could
have been Stalin.

Despite this injunction, a remarkable amount of the history of science has
been written through the medium of biographies of "great" scientists to
whose brilliant discoveries we owe our understanding of the material world,
and this historical methodology has reinforced the common notion that
history is made by outstanding individuals. No respectable historian would
claim that if Newton had never been born we would still be ignorant about
gravitation. Yet we still refer to the regularities of the behavior of
physical bodies as "Newton's Laws," the general regularities of simple
inheritance as "Mendelism," and the science of biological evolution as
"Darwinism." Even the famous history of science written by the Marxist J.D.
Bernal is a recounting of the discoveries and inventions of individuals.

It would be wrong to say that biography is the sole, or even principal,
present pathway into an understanding of the history of science. Certainly
since Robert Merton's founding of modern studies of the sociology of science
in his 1938 work on seventeenth-century English
science,[2]<http://www.nybooks.com/articles/22694#fn2>the social
milieu in which the problems of science arise and the
institutional structure of scientific investigation have been central to our
understanding of the history of scientific work. There are, however,
occasions on which there are orgies of idolatrous celebrations of the lives
of famous men, when the Suetonian ideal of history as biography overwhelms
us. For Darwinians, 2009 is such a year.

It is the two hundredth anniversary of Darwin's birth, and because, whether
by chance or design, Darwin published his famous work when he was fifty, it
is the 150th anniversary of the appearance of *On the Origin of Species*, It
is not clear at what intervals such commemorations might occur. I myself
have been a participant in international symposia on the one hundredth
anniversary of the appearance of the *Origin* in 1859 and the one hundredth
anniversary of Darwin's death in 1882, both of which were attended by
leading scientists of the time and resulted in commemorative volumes.

Neither of those occasions, however, was marked by the immense outpouring of
Darwinalia that has marked the current occasion. On my desk are fifteen
works that have just appeared, of which eleven are biographical, including
two selections of Darwin's letters, two books about the *Origin*, and two
books concerned with explicating and commenting on evolutionary biology and
its implications; but none deals either with the history of evolutionary
thought before Darwin, or in any detail with his contemporary, Alfred Russel
Wallace, the acknowledged independent inventor of the theory of evolution by
natural selection, or the socioeconomic milieu in which Darwin and Wallace
worked. Beyond these publications there are plans for two dozen
commemorative gatherings of scientists, historians, and philosophers, so
many indeed that some had to be put off until next year so that busy
evolutionists could fit them into their schedules.

Of the books that have appeared this year that are directly related to the
history of nineteenth-century evolutionary theory, two are clearly worth
attention. One is Janet Browne's *Darwin's Origin of Species*, which is an
excellent short excursion through the origin of Darwin's book, its argument,
its publication, and the controversies it engendered. It ends with an
all-too-brief summary of the history of modern evolutionary genetics and the
attempts to demonstrate natural selection in action in nature, as well as a
quick visit to modern creationism.

These subjects deserve a treatment in extenso while some of the participants
or their immediate students are still among the living, perhaps by a
collaboration of a sophisticated and knowledgeable historian like Browne
with someone in the thick of it. The other work of interest to the reader of
the *Origin* is an annotated text of the first edition, juxtaposing a
facsimile of Darwin's publication with an extensive page-by-page commentary
by James Costa. Costa makes use of his experience as a field naturalist and
his knowledge of the modern literature of evolutionary biology to illumine
many passages in Darwin's work.

Why do we call the modern theory of organic evolution "Darwinism"? Charles
Darwin certainly did not invent the idea of evolution, that is, of the
continuous change in time of the state of some system as a fundamental
property of that system, or even the idea that a process of evolution had
occurred in the history of life. The study of the evolution of the cosmos
itself was founded in Kant's *Metaphysical Foundations of Natural
Science*in 1786 and Laplace's nebular hypothesis of 1796. Sadi
Carnot's second law
of thermodynamics, the principle that over time all differences in energy
between bits and pieces of the universe decrease, was published in 1824. The
idea that the various geological formations observed on earth were not the
result of a unique catastrophe or Great Flood, but the consequence of
repeated and continual geological processes still going on at present, was
postulated before the turn of the nineteenth century by James Hutton and
long since accepted by 1859.

By the time of the appearance of the *Origin*, the physical sciences had
become thoroughly evolutionary. Living beings were not seen as an exception.
In 1769, Diderot had his dreaming philosopher d'Alembert wonder what races
of animals had preceded us and what sorts would follow. He provided the
motto of evolutionism as a worldview: "Everything changes, everything
passes. Only the totality remains." Darwin's grandfather, Erasmus, in his
epic *The Temple of Nature* of 1803, invokes his Muse to tell "how rose from
elemental strife/Organic forms, and kindled into life," and the Muse
completes the evolutionary story by telling him that even "imperious man,
who rules the bestial crowd,/...Arose from rudiments of form and sense." By
the younger Darwin's time, the idea of organic evolution had become a common
currency of intellectual life. Two years before the publication of the *
Origin*, Herbert Spencer argued for a belief in organic evolution on the
basis of the agreed-upon universality of evolutionary processes:

It is now universally admitted by philologists that languages, instead of
being artificially or supernaturally formed, have been developed. And the
histories of religion, of philosophy, of science, of the fine arts, of the
industrial arts, show that these have passed through stages.... If, then,
the recognition of evolution as the law of many diverse orders of phenomena
has been spreading, may we not say that...evolution will presently be
recognized as the law of the phenomena we are considering?

If Darwin (and Wallace) did not invent the idea of evolution or its
application to the history of life, then at least it might be claimed that
they invented a natural historical theory of the cause of that evolution.
But they were not the first to do so. Jean-Baptiste Lamarck, in a succession
of works between 1801 and 1809, provided a biological theory of adaptive
organic evolution based on the supposed inheritance of changes acquired by
organisms in the course of their individual lives. The example often cited
is the roughly six-foot increase in the length of giraffes' necks from their
ancient origin as deer-like animals. If giraffes in any generation stretched
their necks, even slightly, to feed on leaves higher up in trees, and if
that slight increase in length were passed down to their offspring, then
over many generations the cumulative effect would be the extraordinary shape
of the modern giraffe.

Lest the sophisticated readers of *The**New York Review of Books* regard
this as a hopelessly outmoded nineteenth-century view of biology, it should
be pointed out that until about fifteen years ago a neo-Lamarckian
institution affiliated with the University of Paris, the Laboratoire
d'Évolution des Êtres Organisés, carried out scholarly research on evolution
that took seriously the possibility of the inheritance of acquired
characteristics.

The Darwin-Wallace explanation of evolution, the theory of natural
selection, is based on three principles:

1) Individuals in a population differ from each other in the form of
particular characteristics (the principle of variation).

2) Offspring resemble their parents more than they resemble unrelated
individuals (the principle of heritability).

3) The resources necessary for life and reproduction are limited.
Individuals with different characteristics differ in their ability to
acquire those resources and thus to survive and leave offspring in the next
generations (the principle of natural selection).

It seems amazing that two naturalists could independently arrive at the same
articulated theory of evolution from a consideration of the characteristics
of some species of organisms in nature, their geographic distribution, and
their similarities to other species. This amazement becomes considerably
tempered, however, when one considers the social consciousness and economic
milieu in which the theory arose, a milieu marked by the rise of competitive
industrial capitalism in which individuals rose in the social hierarchy
based, presumably, on their greater entrepreneurial fitness.

Darwin's maternal grandfather, Josiah Wedgwood, started life as a potter's
apprentice and rose to be a member of the circle of new Mid- land industrial
magnates along with James Watt, James Keir, and Matthew Boulton. While the
nineteenth-century theory that some rose and some fell in society depending
on their personal strengths and weaknesses is often referred to as "social
Darwinism," we would be much more in agreement with historical causation
were we to call Darwinism "Biological Competitive Capitalism." The perceived
structure of the competitive economy provided the metaphors on which
evolutionary theory was built.

One can hardly imagine anything that would have better justified the
established social and economic theories of the Industrial Revolution than
the claim that our very biological natures are examples of basic laws of
political economy. How else are we to explain the immediate and continued
commercial success of Darwin's books? The entire first edition of 1,250
copies of the *Origin* was immediately snapped up by booksellers. The
expectation of public interest is revealed by the fact that a circulating
library took five hundred
copies.[3]<http://www.nybooks.com/articles/22694#fn3>The sixth
edition, only thirteen years later, sold 11,000 copies. One cannot
understand the origin and the immediate success of the *Origin* outside of
the social and economic setting in which it was conceived, nor have
historians of science ignored the question. The pages of the *Journal of the
History of Biology* have certainly not been devoid of papers on the subject.
Yet what we have been provided with in 2009 is biography and annotations on
the *Origin*, Perhaps it is time for a socioeconomic analysis of our own
preoccupations.

The parallel between the arguments for natural selection and
nineteenth-century economic and social theory, however, misses an extremely
important divergence between Darwin and political economy. The theory of
competitive socioeconomic success is a theory about the rise of individuals
and individual enterprises as a consequence of their superior fitness. But
even though the Industrial Revolution resulted eventually, at least in some
countries, in a general rise in material well-being, the number of immensely
successful entrepreneurs is evidently limited precisely because their
success depends on the existence of a large mass of less successful workers.
No population can consist largely of people like Henry Clay Frick.

The theory of evolution by natural selection, in contrast, is meant to
explain the adaptation and biological success of an entire species as a
consequence of the disappearance of the less fit. Provided that a species
does not become so numerous as to destroy the resources on which it depends,
there is no structural reason why every individual of that species cannot be
highly fit. If we seek a true originality in the understanding of Darwin and
Wallace, it is to be found in their ability to adapt a theory meant to
explain the success of a few to produce a theory of the success of the many,
even though the many may be competing for resources in short supply. Whether
they were conscious of this divergence of the theory of evolution by natural
selection from the reigning economic and social theory is a question.

Despite the intuitive appeal of the theory of evolution by natural
selection, there is a deep flaw in it as it was conceived in the nineteenth
century, a flaw that was potentially fatal: it lacked an understanding of
heredity. This problem was first pointed out in 1867 by a Scottish engineer,
Fleeming Jenkin, but it does not seem to have had any effective force. From
the observations that Darwin (and breeders) made about domesticated animals
and plants, the most likely basis for the inheritance of characteristics
seemed some sort of mixture of an internal fluid. If, for example, a
large-bodied variety was mated to a small-bodied one, the usual outcome was
offspring of intermediate size.

The problem is that if inheritance proceeds by a blending mechanism, then
new variants in a species would rapidly be lost by dilution through mating
with the common form. Suppose a variant individual appeared that was larger
than normal. That individual would necessarily mate with the normal type and
their offspring would be intermediate. When those few intermediate offspring
mated it would almost certainly be with the vastly more numerous normal form
so that the next generation of this family would be yet closer to the usual
type. After a few generations of this process of dilution by crossing, there
would be no detectable variation on which natural selection could operate,
even if a larger type would be of some selective advantage. The reduction of
variation by half with each generation is a vastly more powerful force than
any biologically reasonable countervailing difference in reproductive
fitness.

The Darwinian mechanism would, in fact, not work in a world of blending
inheritance. Unknown to Darwin, Wallace, or any of the enthusiasts for the
claim of evolution by natural selection, work by an obscure monk in the
Königenkloster at Brno in Moravia would turn out to save the theory.
Mendel's experiments on peas demonstrated that inheritance was not based on
the blending of some fluid-like material, but by the passage of particles
that maintained their individual properties even when mixed together in a
hybrid. Thus, in future generations, variant properties would reappear even
though what we now call the genes for those variants were temporarily mixed
with the normal gene forms in hybrids.

The journal of the Brünn Society of Natural Science in which Mendel's
research was published would never have been read by the English scientific
establishment, nor indeed by anyone in the major centers of
nineteenth-century natural science. It was not until 1900 that Mendel's work
was rediscovered as a consequence of the appearance of new scientific
results on crossing plants. In full historical justice, if we are to
personalize our modern explanation of evolution we should call it not
"Darwinism," nor even "Darwin-Wallacism," but "Darwin-Wallace-Mendelism."

The present understanding of natural selection of chance variants—variants
produced through mutations of genes—as the basis for adaptive evolution
obscures the historical fact that in the eighteenth and nineteenth centuries
evolution was accepted as a reality but other scientific explanations for it
existed and came into competition with "Darwinism." Lamarck's theory of the
inheritance of acquired characteristics was certainly coherent given the
ignorance of the basis of heredity, and was, in a sense, more nearly
complete than Darwin's precisely because it included and depended on a
definite theory of inheritance. A direct challenge to Darwin appeared in
1860 in an article in the prestigious journal *Edinburgh Review*, Although
unsigned, it is generally accepted that its author was Richard Owen, a
zoologist of considerable fame and prestige whose Hunterian Lectures on
zoology were attended by Queen Victoria and Darwin himself. Exhibiting a
typical hardworking professional's disdain for the amateur, Owen writes that
Darwin

has long been favourably known...by the charming style [of his]
observations.... Of independent means, he has full command of his time for
the prosecution of original research.... The same pleasing style which
marked Mr. Darwin's earliest work, and a certain artistic disposition...

have had the result that "several, and perhaps the majority, of our younger
naturalists have been seduced into the acceptance" of his
theory.[4]<http://www.nybooks.com/articles/22694#fn4>

Owen's personal attack aside, he points out, quite correctly, that neither
Darwin nor anyone else knows what the underlying phenomena of heredity and
development really are and that the transformation and divergence of
organisms over time might simply be the manifestation of some hidden laws of
development. Moreover, similar species that Darwin would claim as having
evolved from a common ancestor might simply be developmental variants
produced in response to different environments. I must confess that in
reading Owen's essay I found myself over and over nodding my head in
agreement. Given the state of ignorance of basic biological processes in
1860, Owen might well have been right.

How are we to explain the extraordinary activity surrounding the 150th
anniversary of the appearance of *On the Origin of Species* ? It seems
unlikely that an enthusiasm of equal magnitude will greet the 150th
anniversary, seven years from now, of Mendel's paper, if we can judge by the
moderate celebrations of its one hundredth in 1966. Yet genetics in its
present molecular stage pervades the public consciousness as more and more
genes are discovered that may be relevant to health and longevity.

The primary reason for the attention being paid to Darwin is the
rejuvenation in recent years of theories of the divine creation of the earth
and the organisms that inhabit it. In the years following the end of World
War II, natural science became a major preoccupation of the state and of
education. The sounds of the explosions over Hiroshima and Nagasaki were
heard in every American classroom and a dozen years later Sputnik had hardly
made its first orbit before Congress was pouring money into the institutions
of American science, both universities and government agencies like the
National Science Foundation and the National Institutes of Health. One
immediate consequence was the creation by the NSF of the Biological Sciences
Curriculum Study in 1958, which brought together university and high school
teachers to rewrite the biology curriculum for the schools.

The result was a major change in the teaching of biology, with a large
emphasis on evolution both in textbooks and in the classroom. Although we
may think that the Scopes trial legitimized the teaching of evolution, it
had little effect on public education. When I was a high school student in
the late 1940s, evolution was not part of the standard science curriculum
even in the New York public high schools, although teachers were at liberty
to introduce it. Sputnik changed all that.

There remains, nevertheless, a substantial population whose commitment to a
fundamentalist Christian belief in divine creation of the earth and its
inhabitants has driven them to political action. Having been convinced that
the separation of church and state is here to stay, they have adopted a
pseudo-scientific theory of intelligent design in which the designer is
unspecified, and attempted to introduce it into the school curricula in the
name of intellectual openness. The scientific community has the definite
sense of being embattled and one of its responses is to use the two
hundredth anniversary of the birth of its apostle of truth about the
material basis of evolution and the 150th anniversary of the appearance of
his gospel to carry on the struggle against obscurantism. Jerry Coyne's *Why
Evolution Is True* is intended as a weapon in that struggle.

Coyne is an evolutionary biologist who, like his former student H. Allen
Orr, has been a leader in our understanding of the genetic changes that
occur when species are formed. His primary object in writing this book is to
present the incontrovertible evidence that evolution is a physical fact of
the history of life on earth. In referring to the theory of evolution he
makes it clear that we do not mean the weak sense of "theory," an ingenious
tentative mental construct that might or might not be objectively true, but
the strong sense of a coherent set of true assertions about physical
reality. In this he is entirely successful.

Where he is less successful, as all other commentators have been, is in his
insistence that the evidence for natural selection as the driving force of
evolution is of the same inferential strength as the evidence that evolution
has occurred. So, for example, he gives the game away by writing that when
we examine a sequence of changes in the fossil record, we can

determine whether the sequences of changes at least conform to a
step-by-step adaptive process. And in every case, we can find at least a
feasible Darwinian explanation.

But to say that some example is not falsification of a theory because we can
always "find" (invent) a feasible explanation says more about the
flexibility of the theory and the ingenuity of its supporters than it says
about physical nature. Indeed in his later discussion of theories of
behavioral evolution he becomes appropriately skeptical when he writes that

imaginative reconstructions of how things might have evolved are not
science; they are stories.

While this is a perfectly good argument against those who claim that there
are things that are so complex that evolutionary biology cannot explain
them, it allows evolutionary "theory" to fall back into the category of
being reasonable but not an incontrovertible material fact.

There is, of course, nothing that Coyne can do about the situation. There
are different modes of "knowing," and we "know" that evolution has, in fact,
occurred in a stronger sense than we "know" that some sequence of
evolutionary change has been the result of natural selection. Despite these
misgivings, it is the case that Coyne's book is the best general explication
of evolution that I know of and deserves its success as a best seller.

An important property of adaptive evolution is that it is usually a slow
process. Certainly there are cases where a single genetic change can mean
the difference between life and death in a hostile environment. The classic
cases are the mutations that give pathogenic microorganisms the ability to
resist antibiotics or mutations that allow crops to resist pathogens, for
example insects or herbicides. But these are not representative models for
how species adapt, by accumulation of mutations of small effect, to changes
in food availability, temperature modifications, and the thousand shocks
that flesh is heir to. The usual small differences in fitness among
genotypes are therefore manifest as detectable evolutionary change only
after thousands of generations.

This deliberate tempo has presented the human species with a problem of
adaptation. With a human generation of about twenty-five years, there have
been roughly only one hundred generations since the founding of the Roman
Republic. Yet the changes in the human environment caused by changes in
human activity have been enormous. Changes in diet, habitation, working
conditions, the pollution of air and water, and especially the considerable
increase of lifespan that result in major alterations and breakdowns in the
bodily machinery have all been too rapid for genetic adaptation.

Indeed for environmental changes that have their effect after the age of
reproduction, it is not clear that natural selection can operate at all. The
constant exposure to high doses of solar radiation that is experienced by
surfers on the California beaches might induce an eventually fatal skin
cancer, but the cancer death almost always occurs well after reproductive
age, so there is no opportunity for selection to act. The general result is
that parts of the human genome are out of correspondence with the conditions
of modern life.

Greg Gibson, a prominent student of the human genome and of the genetics of
development, brings together in *It Takes a Genome* typical cases of this
mismatch between the human physiology that is an inheritance from the past
and modern environmental challenges. As a consequence of his past work on
genetics and development, Gibson does not fall into the error of that
genomania that supposes that every difference between individuals is a
consequence of having different genes. He is careful to insist that there be
very good evidence for the conclusion that some disease conditions reveal a
genetic defect.

Nevertheless he makes a good case that the current state of the human
genotype makes us susceptible to physiological and developmental challenges
that did not exist for our remote ancestors. The major changes from the
usually minimal hunter-gatherer animal and plant diets to high-calorie sugar
intakes cause great stress to our carbohydrate metabolism. In a curious
contradiction of modern life, while in many human populations, for example
in Africa, people are dying young from overwork and undernourishment, people
in technologically advanced societies are dying at a greater age from
overeating and too little physical activity. We cannot count on natural
selection to deal with the problem.

It seems that Cleopatra's is not the only nose in question. In his brief *
Autobiography* Darwin writes of his successful visit to Captain FitzRoy to
arrange for his trip on the *Beagle* :

Afterwards, on becoming very intimate with Fitz-Roy, I heard that I had run
a very narrow risk of being rejected on account of the shape of my nose! He
was an ardent disciple of Lavater, and was convinced that he could judge of
a man's character by the outline of his features; and he doubted that anyone
with my nose should possess sufficient energy and determination for the
voyage. But I think he was afterwards well satisfied that my nose had spoken
falsely.

But what if it had been bigger?
Notes

[1] <http://www.nybooks.com/articles/22694#fnr1>*"Le nez de Cléopâtre, s'il
eût été plus court, toute la face de la terre aurait changé*," See
*Pensées*(Paris: Gallimard, 1977), fragment 392, p. 243.

[2] <http://www.nybooks.com/articles/22694#fnr2>*Science, Technology and
Society in Seventeenth-Century England* (H. Fertig, 1938).

[3] <http://www.nybooks.com/articles/22694#fnr3>I am indebted to Janet
Browne for telling me about the circulating library.

[4] <http://www.nybooks.com/articles/22694#fnr4>*The Edinburgh Review*,
April 1860.