the argument almost beyond recognition, within a
short article as the present one. Others have
attempted to use short quotations, often parts of
sentences, which I shall show can obscure and even
completely reverse the overall meaning Darwin
intended. One might almost believe that Mayr delib-
erately selected unfair Darwinian text about species
(e.g. in Mayr, 1982; and see below) in order to make
out that Darwin was wrong-headed. But I do not
accept this; if Mayr had been thinking of deliberately
obfuscating Darwin’s thoughts, he must also have
known that he could not have got away with it. We
would only have to read Darwin ourselves, and he
would have been found out. Instead, I think Mayr
took from Darwin’s book what he genuinely thought
he had read in it. I think he probably just copied out
fragments of sentences or paragraphs for brevity, and
then did not often check back to the original text to
make sure he had not misconstrued Darwin’s precise
meaning. Having formed a very different interpreta-
tion of species from Darwin’s, indeed one which has
now become the standard today, Mayr found it hard to
see the logic in these fragmentary statements about
species and speciation. Although I cannot lay out
Darwin’s whole argument, I here attempt to avoid the
problem of short quotations by quoting extensive pas-
sages from the first edition of The Origin. These are
more extended sections of text than used by Mayr,
and are those that I consider especially relevant to
the argument that Darwin was confused about or did
not properly deal with species and speciation.
D
ARWIN ON ARTIFICIAL SELECTION AND
THE NATURE OF SPECIES
In Chapter I, ‘Variation under Domestication’, after a
brief introduction explaining the history and back-
ground of evolutionary ideas, and also the scope of
the book, Darwin introduces the ideas of variability
within species, and of artificial selection. A major
argument in this chapter is that breeds of domesti-
cated animals are much more divergent in form than
varieties of the same species in nature, and often
more divergent even than separate species in nature.
Darwin is not just making an argument that animal
and plant breeds are similar to species, and that
artificial selection by humans is analogous to natural
selection; he is making a much more radical argu-
ment: that domesticated animal and plant breeds are
in a sense separate species.
Of course, pigeon breeds such as pouters and tum-
blers are not reproductively isolated in the classical
sense, but Darwin clearly rejects hybrid sterility and
inviability as a useful species definition in the chapter
on ‘Hybridism’ (see below). The different breeds of
pigeons, dogs, or sheep remain separate because they
have adapted to different ecological niches, niches
which are determined by their symbiosis with
humans. Their divergence into these separate niches,
and their ability to maintain themselves distinct is of
course due to human-aided selective breeding, but
this is in practice the same as the way in which
natural selection for nonhuman ecological niches can
keep species separate in nature. The only difference
is that the ecological niches of domesticated breeds
depend on human preferences or uses, rather than on
survival or ability to reproduce in natural environ-
ments. Today, we are entrained by our education, due
in no small part to Mayr’s own influence, to place
species in nature on the one hand, and breeds of
domesticated animals on the other, in separate
mental boxes. We can no longer appreciate the radical
vision that Darwin was outlining. In particular, we
think of natural selection (and artificial selection) as
an essentially within-species process that affects the
whole population identically, rather than as a process
which may include divergent selection into separate
niches. For me, it still took several years after my
initial conversion before I really understood the full
power of the uniformitatian, Darwinian view of the
nature of species. A simple question from an under-
graduate after a lecture on species and speciation
finally made the penny drop. She asked: ‘if what you
say about species is true, why aren’t breeds of dogs
considered separate species as well?’ When I recov-
ered from the question, I had to reply that breeds of
dogs were indeed exactly what Darwin, and indeed I,
in my lecture, had meant by separate species.
The argument then moves on to Chapter II, ‘Varia-
tion in Nature’. At this point, Darwin raises the
problem of a species definition, and it is his solution
here that has led so many to criticise him since, and
often to argue that his book was not really about
speciation at all. Darwin came from a world where
most people believed that species were separate,
created kinds, each with a ‘true’ Aristotelian essence.
At that time, educated and literary people in Europe
had classical educations that would have encom-
passed Latin and Greek, and Ancient philosophy
including arch-essentialists such as Aristotle and
Plato. Consciously, or unconsciously, pre-Darwinian
thinkers applied the essentialist terms ‘genus’ and
‘species’ to taxonomic categories in biology, as well as
in other philosophical activities. Varieties within each
species, on the other hand, were simply the imperfect
expression of the species essence. Darwin had to
overturn this view, because in any theory of evolution,
varieties must evolve into species, and probably do
so gradually, which means that species and varieties
must be very much the same kind of thing: the
boundary should be a continuum, and a clear defini-
tion of species can no longer be made. To make the
WAS DARWIN WRONG?
5
© The Author
Journal compilation © 2008 The Linnean Society of London,
Biological Journal of the Linnean Society, 2008,
95, 3–16