Is it time to rework evolutionary biology’s “modern synthesis”?
The July 11, 2008 edition of Science (available only to subscribers on line) includes an article entitled “Modernizing the Modern Synthesis,” by Elizabeth Pennisi, regarding a group of scientists who call themselves “The Altenberg 16.” They have gathered together to explore the need to revamp the modern synthesis. What is the “modern synthesis”? According to Wikipedia, the modern synthesis “bridged the gap between experimental geneticists and naturalists; and between both and palaeontologists, stating that”:
- 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).
- Selection is overwhelmingly 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.
- The primacy of population thinking: the genetic diversity carried in natural populations is a key factor in evolution. The strength of natural selection in the wild was greater than 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 micro to macro-evolution is proposed. Historical contingency means explanations at different levels may exist. Gradualism does