Towards an extended synthesis

‘Nothing in biology makes sense except in the light of evolution’, wrote Theodosius Dobzhansky, but while ‘[t]here are no alternatives to evolution as history that can withstand critical examination […] we are constantly learning new and important facts about evolutionary mechanisms’ (Dobzhansky 1973, 129). This is as true today as it was forty years ago and a number of biologists now seem to agree with Sahotra Sarkar that ‘much of the received framework of evolution makes no sense in light of molecular biology’ (Sarkar 2005, 5).

This chapter asks what implications the developments we analysed earlier in the book have for the mechanisms of evolution. These developments include distributed specificity, the idea that a large range of factors share sequence specificity with coding sequences through their role in the regulation of genes expression, and that many of these factors are designed to relay environmental information to the genome. The developments include the revival of notions of epigenesis and plasticity in developmental biology. They include exogenetic heredity, the idea that many non-genetic resources are passed on across the generations and are employed to reconstruct and modify the life cycle through their role in the regulation of gene expression. They include systems biology, which we have suggested has a distinctive style of genetic explanation. Do these developments necessitate an extension of the conventional, neo-Darwinian theory of evolution, the so-called ‘Modern Synthesis’?