Tuesday, 25 October 2011

The modern synthesis is toast

Eugene V. Koonin (2009) wrote:
In the post-genomic era, all the major tenets of the modern synthesis have been, if not outright overturned, replaced by a new and incomparably more complex vision of the key aspects of evolution.
Alex Mesoudi (2011) states that cultural evolution is Darwinian - but not neo-Darwinian.

I reviewed a couple of expressions of the modern synthesis - lifted from here and here:
  • All evolutionary phenomena can be explained in a way consistent with known genetic mechanisms and the observational evidence of naturalists.
  • Evolution is gradual: small genetic changes, recombination ordered by natural selection. Discontinuities amongst species (or other taxa) are explained as originating gradually through geographical separation and extinction (not saltation).
  • Natural selection is by far the main mechanism of change; even slight advantages are important when continued. The object of selection is the phenotype in its surrounding environment.
  • The role of genetic drift is equivocal. Though strongly supported initially by Dobzhansky, it was downgraded later as results from ecological genetics were obtained.
  • Thinking in terms of populations, rather than individuals, is primary: the genetic diversity existing in natural populations is a key factor in evolution. The strength of natural selection in the wild is greater than previously expected; the effect of ecological factors such as niche occupation and the significance of barriers to gene flow are all important.
  • In palaeontology, the ability to explain historical observations by extrapolation from microevolution to macroevolution is proposed. Historical contingency means explanations at different levels may exist. Gradualism does not mean constant rate of change.
- Wikipedia article on the modern evolutionary synthesis.
The major tenets of the evolutionary synthesis, then, were that populations contain genetic variation that arises by random (ie. not adaptively directed) mutation and recombination; that populations evolve by changes in gene frequency brought about by random genetic drift, gene flow, and especially natural selection; that most adaptive genetic variants have individually slight phenotypic effects so that phenotypic changes are gradual (although some alleles with discrete effects may be advantageous, as in certain color polymorphisms); that diversification comes about by speciation, which normally entails the gradual evolution of reproductive isolation among populations; and that these processes, continued for sufficiently long, give rise to changes of such great magnitude as to warrant the designation of higher taxonomic levels (genera, families, and so forth).
- Futuyma, D.J. in Evolutionary Biology, Sinauer Associates, 1986; p.12.

Looking at these, it does appear that the modern synthesis is toast.

The most obvious issues are merging/symbiosis, and directed mutations/cultural evolution.

So: the modern synthesis and neo-Darwinism are indeed dead.

References

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2 comments:

  1. Cameron McPherson Smith28 October 2011 at 20:52

    Hello, Tim, you might be interested in my recent paper:

    http://pdx.academia.edu/CameronMSmith/Papers/998973/What_Anthropologists_Should_Know_About_the_New_Evolutionary_Synthesis

    Here in the US, evolutionary models of culture remain largely shunned, for largely historical reasons. But, in Europe, an evoltionary approach to culture is taken almost for granted. Interesting!

    Cheers
    Cameron M Smith

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  2. Tim Tyler31 October 2011 at 14:31

    There are quite a few researchers in the UK - but still most biologists/anthropologists are essentially ignorant about the resurgence of a science of the evolution of culture. Your paper has pretty minimal coverage of the issue - while it is bigger than most of the other things you headline (except "NCT").

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