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Friday, August 21, 2009

The overthrow of Darwinism - in real life, forget the pop science media

In "The collectivist challenge to Darwinism" British physicist David Tyler observes,

... it is horizontal gene transfer that is perceived to be ushering in the overthrow of Darwinism. This is because all the mechanisms that are being seriously discussed to account for the data invoke environmental influences/drivers. Buchanan argues that the phenomenon can be regarded as confirmed, even though our understanding of mechanisms is in its infancy. "The clear impact of horizontal gene transfer on bacterial evolution has been established only fairly recently using large-scale genome sequencing, and in the context of a small number of bacteria. Biologists have only begun exploring the various environmental factors that promote or limit horizontal gene transfer, and know almost nothing of how this mechanism of genetic sharing influences the overall logic of the evolutionary process itself."

Why does this take us beyond Darwinism? It is because the mechanisms of Darwinian evolution are inherently reductionistic, with individual life forms struggling for survival in competition with other individuals. Within Darwinian theory, the environment acts as a filter, allowing the fit to live on. Horizontal gene transfer (HGT) moves us away from individuals and towards breeding populations, and the environment becomes a driver of genetic change rather than a passive filter. The tree of life now looks like an unstructured bush (for more, see here). "[T]he apparent ubiquity of horizontal gene transfer implies that microorganisms have an impressive capacity to actively alter their genomes in response to environmental stresses or opportunities, and this capability is intimately linked to their involvement in a larger community in which the diversity of genetic material resides. Consequently, [. . .] the basic concept of an organism as an isolated biological entity with a unique genetic make-up makes little sense in the bacterial world, as the genetic repertoire of an entire population, as well as foreign species, is available to any individual within it."
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