Implications for evolutionary theory
Of course, there is no single theory of evolution. First,
the word “evolution” has many meanings, including simple
change over time, the history of the cosmos, or (in biology)
the transformation of one species into another. Second, even in
biology there are several theories of evolution. I will focus on
one of these, which I will call Neo-Darwinism.
Like evolution itself, Neo-Darwinism has had many
meanings. The term was first used by Samuel Butler in 1880 to
distinguish Charles Darwin’s theory from that of his grandfather,
Erasmus Darwin. Butler used “Darwinism” to refer approvingly
to Erasmus’s theory that new variations arise “due to the wants
and endeavours of the living forms in which they appear,”
while Butler used “Neo-Darwinism” to refer disparagingly to
Charles’s ascription of new variations “to chance, or, in other
words, to unknown causes” [415,416].
In 1895, Georges Romanes used “Neo-Darwinian” to describe
the view (which he attributed to August Weismann and Alfred
Russel Wallace) that “natural selection is the only possible cause
of adaptive modification;” Romanes used “Neo-Lamarckian” to
describe the view (which he attributed mainly to Americans)
that “much greater importance ought to be assigned to the
inherited effects of use and disuse than was assigned to these
agencies by Darwin.” According to Romanes, Charles Darwin’s
view (which he called “Darwinism”) stood “between these two
When Charles Darwin’s theory of evolution was combined in
the 1930s with Gregor Mendel’s theory of genetics, the resulting
“modern synthesis” attributed new variations to genetic
mutations and excluded the inherited effects of use and disuse
[418,419]. Since then, many people have used the term NeoDarwinism
to refer to the modern synthesis, as supplemented
by molecular genetics.
I use Neo-Darwinism here to mean the view that all living
things are descendants of one or a few ancestral organisms
that have been modified principally (though not exclusively)
by the natural selection of advantageous variations, and that
new variations originate from changes in DNA sequences. This
was Jacques Monod’s view, though he called it Darwinism .
Eric Davidson distances himself from what he calls the “neoDarwinian
concept” that evolution occurs by “small continuous
changes in primary protein sequence,” and he attributes
evolution instead to system level changes in developmental
gene regulatory networks (dGRNs) . But I would argue
that in so far as he attributes control of ontogeny to a program
in DNA, Davidson’s view is still a variant of Neo-Darwinism.
As we have seen, however, the idea that embryo development
is controlled by a genetic program is inconsistent with the
biological evidence. Embryo development requires far more
ontogenetic information than is carried by DNA sequences.
Thus Neo-Darwinism is false.
A recent advocate of the centrality of population genetics is
Michael Lynch, who wrote in 2006 that “evolution is a
population genetic process governed by four fundamental forces.”
One force is selection,
“whose central role in the evolution of complex phenotypic
traits is universally accepted, and for which an elaborate formal
theory in terms of genotypic frequencies now exists.” The other
three forces are mutation (including DNA insertions, deletions
and duplications), recombination, and random genetic drift.
“Given the century of empirical and theoretical work devoted
to the study of evolution,” Lynch wrote, “the only logical
conclusion is that these four broad classes of mechanisms are, in
fact, the only fundamental forces of evolution.” Thus “nothing
in evolution makes sense except in the light of population
genetics” .Of course, no one denies that DNA is essential for ontogeny,
and that DNA mutations can affect phenotypic traits.
Furthermore, population genetics may be useful for tracing
lineages within existing species. But since the ontogenetic
information in an embryo far exceeds that in its DNA,
evolution must necessarily involve far more than changes in