Earlier this year, Eugene Koonin published a masterly analysis of the impact of genomics on evolutionary thinking. This proved to be too meaty a study for a concise blog, and my initial draft was abandoned. Happily, a shorter overview has now been published, and this abstracts salient points from the research paper. Koonin notes that the 1959 Origin centennial was "marked by the consolidation of the modern synthesis" but subsequent years have witnessed great changes which have undermined its credibility.
"The edifice of the modern synthesis has crumbled, apparently, beyond repair."
It is time for a paradigm change - but neoDarwinists are stuck because they have so much philosophical baggage holding them down (Image credit: Shaun Curry/AFP/Getty Images, Source here)
Koonin uses the metaphor of "the landscape of evolutionary biology". There are three distinct revolutions have occurred over the past half-century: the molecular, the microbiological and the genomic revolutions.
"[T]his year is the perfect time to ask some crucial questions: how has evolutionary biology changed in the 50 years since the hardening of the modern synthesis? Is it still a viable conceptual framework for evolutionary thinking and research?"
The molecular revolution culminated, says Koonin, in the neutral theory, which means that purifying selection is more common than positive selection. The microbiological revolution brought the world of prokaryotes into the domain of evolutionary biology, but it then became apparent that the concepts of Darwinism and the modern synthesis "applied only to multicellular organisms". The genomic revolution revealed that the living world was "a far cry from the orderly, rather simple picture envisioned by Darwin and the creators of the modern synthesis". In particular, it is now interpreted as an "extremely dynamic world where horizontal gene transfer (HGT) is not a rarity but the regular way of existence, and mobile genetic elements that are vehicles of HGT are ubiquitous".
"The discovery of pervasive HGT and the overall dynamics of the genetic universe destroys not only the tree of life as we knew it but also another central tenet of the modern synthesis inherited from Darwin, namely gradualism. In a world dominated by HGT, gene duplication, gene loss and such momentous events as endosymbiosis, the idea of evolution being driven primarily by infinitesimal heritable changes in the Darwinian tradition has become untenable."
Koonin is serious in saying that all the concepts of the modern synthesis are in need of a fundamental overhaul.
"Moreover, with pan-adaptationism gone forever, so is the notion of evolutionary progress that is undoubtedly central to traditional evolutionary thinking, even if this is not always made explicit.
The summary of the state of affairs on the 150th anniversary of the Origin is somewhat shocking. In the postgenomic era, all 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. So, not to mince words, the modern synthesis is gone."
Koonin tentatively identifies two candidates to fill the vacuum left by the discarded modern synthesis. The first of these appears to emphasis the role of chance; the second appears to emphasise law.
"The first is the population-genetic theory of the evolution of genomic architecture, according to which evolving complexity is a side product of non-adaptive evolutionary processes occurring in small populations where the constraints of purifying selection are weak. The second area with a potential for major unification could be the study of universal patterns of evolution such as the distribution of evolutionary rates of orthologous genes, which is nearly the same in organisms from bacteria to mammals or the equally universal anticorrelation between the rate of evolution and the expression level of a gene. The existence of these universals suggests that simple theory of the kind used in statistical physics might explain some crucial aspects of evolution."
It is not difficult to predict that Koonin's analysis will not be received quietly by the very vocal leaders of evolutionary biology. They are still entrenched in neoDarwinism and show no signs of conceding any ground to anyone. From a design perspective, Koonin's analysis of the changing landscape of evolutionary biology is spot on. His two candidates for moving forward the theoretical framework are interesting - but lack any recognition of purposeful design in nature. Dembski's design filter concept is relevant here: there are features in the biological world that are best understood in terms of stochastic processes; there are other features that are best understood in terms of natural law; but there are also features that require a design perspective in order to understand them. It is the latter element, prominent in the thinking of design-orientated scientists, which needs to be part of any discussion of where evolutionary biology is heading.
The Origin at 150: is a new evolutionary synthesis in sight?
Eugene V. Koonin
Trends in Genetics, 25(11), November 2009, 473-475.
Abstract: The 200th anniversary of Charles Darwin and the 150th jubilee of the On the Origin of Species could prompt a new look at evolutionary biology. The 1959 Origin centennial was marked by the consolidation of the modern synthesis. The edifice of the modern synthesis has crumbled, apparently, beyond repair. The hallmark of the Darwinian discourse of 2009 is the plurality of evolutionary processes and patterns. Nevertheless, glimpses of a new synthesis might be discernible in emerging universals of evolution.
Darwinian evolution in the light of genomics
Eugene V. Koonin
Nucleic Acids Research, 2009, 37(4), 1011-1034 | doi:10.1093/nar/gkp089
ABSTRACT: Comparative genomics and systems biology offer unprecedented opportunities for testing central tenets of evolutionary biology formulated by Darwin in the Origin of Species in 1859 and expanded in the Modern Synthesis 100 years later. Evolutionary-genomic studies show that natural selection is only one of the forces that shape genome evolution and is not quantitatively dominant, whereas non-adaptive processes are much more prominent than previously suspected. Major contributions of horizontal gene transfer and diverse selfish genetic elements to genome evolution undermine the Tree of Life concept. An adequate depiction of evolution requires the more complex concept of a network or 'forest' of life. There is no consistent tendency of evolution towards increased genomic complexity, and when complexity increases, this appears to be a nonadaptive consequence of evolution under weak purifying selection rather than an adaptation. Several universals of genome evolution were discovered including the invariant distributions of evolutionary rates among orthologous genes from diverse genomes and of paralogous gene family sizes, and the negative correlation between gene expression level and sequence evolution rate. Simple, non-adaptive models of evolution explain some of these universals, suggesting that a new synthesis of evolutionary biology might become feasible in a not so remote future.
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