What explains the dogmatism and persistence of neo-darwinism?
When the history of
neo-Darwinism gets written it will need to answer this
question. I am not a historian. The answers I give here are
tentative. They could be leads for serious historians of
science to follow up. I also highlight two brilliant
scientists, Waddington and McClintock, whose work should not
have been neglected.
Despite the great
influence of Popper, single contrary observations rarely
destroy a strongly established theory. The tendency is to
fix theories, extend them, even to redefine their entities,
in ways that allow the contrary observations to be absorbed.
This is what happened to Waddington’s work. If they can’t be
absorbed in this way, they are sidelined as anomalies. This
nearly happened to McClintock until she was awarded the
Nobel Prize for discovering mobile genetic elements (jumping
genes). It is more often the accumulation of many forms and
examples of contrary evidence that persuades people to
change. I think we are at that point now in the case of
neo-Darwinism. There are exceptions to all the central
assumptions, and in the case of the inheritance of acquired
characteristics the exceptions are becoming a flood of
evidence. Moreover, the central element of the theory, the
gene, is no longer easy to define. All those functional RNAs
also act as ‘genes’. The marking of the genome and chromatin
also play a role in inheritance. That is the reason why a
growing number of scientists admit that a major rethink is
already happening.
Conrad Waddington in 1946 (left, from The Royal Society
picture library) and his diagram of the epigenetic landscape
(right, from The
Strategy of the Genes, 1957). Genes (solid pegs at the
bottom) are viewed as parts of complex networks so that many
gene products interact to produce the phenotypic landscape
(top) through which development occurs. Waddington’s insight
was that new forms could arise through new combinations to
produce new landscapes in response to environmental
pressure, and that these could then be assimilated into the
genome. Waddington was a systems biologist in the full sense
of the word. If we had followed his lead many of the more
naïve 20th century popularizations of genetics
and evolutionary biology could have been avoided.
Left: Barbara McClintock in her laboratory in 1947
(Smithsonian Institute Archives).
“In
the future attention undoubtedly will be centered on the
genome, and with greater appreciation of its significance as
a highly sensitive organ of the cell, monitoring genomic
activities and correcting common errors, sensing the unusual
and unexpected events, and responding to them, often by
restructuring the genome. We know about the components of
genomes that could be made available for such restructuring.
We know nothing, however, about how the cell senses danger
and instigates responses to it that often are truly
remarkable.” (McClintock, Barbara. 1984 The significance of
responses of the genome to challenge.
Science
226, 792-801.)
McClintock clearly
understood the correct direction of causality in relation to
the genome. Characterising the genome as “a highly sensitive
organ of the cell” was her great insight. It is as foolish
to regard the genome as the active cause of the organism as
it would be to say that the pipes of an organ play the
music!
Cold War
Theories of evolution
became an issue during the Cold War. Those, like Waddington,
who found evidence for the inheritance of acquired
characteristics were thought in some way to be associated
with Lysenkoism, a Soviet era school that denied Mendelian
inheritance. Waddington was not even allowed to visit the
USA. His work was virtually ignored in the USA, and was
eventually sidelined in the UK. He saw himself as a
Darwinist, but not as a neo-Darwinist. I think it is
shameful that such a brilliant scientist was side-lined,
just as I think it is shameful that Lamarck was virulently
denigrated. Anyone who thinks that science is neutral, and
is not influenced by politics, should answer the question:
how did these injustices happen?
See also
http://musicoflife.website/pdfs/LetterfromLamarck.pdf
Religious fundamentalism
It is said that
nearly 50% of the population of the USA do not accept the
theory of evolution. Some are called creationists since they
believe in various forms of creation, either literally as
described in Genesis,
or in a variety of more modern ideas of creationism. Some
also espouse the ideas of Intelligent Design (ID). Both the
creationists and the supporters of ID tend to take every
example of a break with neo-Darwinism as a vindication of
their views. Some have done the same with my article,
despite the fact that I make it clear that I am arguing for
a return to a “more nuanced, less dogmatic view of
evolutionary theory (see also Muller, 2007; Mesoudi ¨ et
al.2013), which is much more in keeping with the spirit of
Darwin’s own ideas than is the Neo-Darwinist view.”
Muller GB (2007). Evo–devo: extending the evolutionary
synthesis. Nat Rev
Genet 8,
943–949
http://www.ncbi.nlm.nih.gov/pubmed/17984972
Mesoudi A, Blanchet S, Charmentier A, Danchin E, Fogarty L,
Jablonka E, Laland KN, Morgan TJH, Mueller GB, Odling-Smee
FJ & Pojol B. (2013). Is non-genetic inheritance just a
proximate mechanism? A corroboration of the extended
evolutionary synthesis.
Biological Theory
7, 189–195.
http://link.springer.com/article/10.1007/s13752-013-0091-5
One way to view the
dogmatic nature of neo-darwinism as it is often presented in
public is to see it as a reaction to the dogmatism of the
creationists. The ‘uncertain’ (in the sense of lacking
reason) faith in creationism is replaced by the
‘certainties’ of science. But there is a conflation here of
very different degrees of certainty in science. There can’t
be much doubt about the fact that life on earth has evolved.
There is much less certainty about the mechanisms. Unlike
Darwinism (Darwin knew nothing of mechanisms, genes were not
known), neo-darwinism proposes the exclusion of many
mechanisms that have in fact now been found to occur in
nature. Adopting the ‘certainty’ of evolution to clothe the
‘uncertainty’ of particular theories about mechanisms has
been the cause of many problems in public debate on
evolution. It is perfectly possible to defend the virtual
certainty that life has evolved while debating in the usual
argumentative scientific way the uncertainties surrounding
the question of mechanisms. The truth is that amongst the
many mechanisms now known we know very little about which
were prevalent in evolution. The answer is likely to be that
different mechanisms were dominant at different stages.
Evolution itself evolves.
See also the item on
The Language
of Neo-darwinism
where the discourse of neo-darwinism is analysed.
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The MUSIC of Life: Biology Beyond the Genome ©Denis Noble |