Niche construction

Much of evolutionary biology is motivated by one basic question: what determines biological diversity? Traditional explanations emphasize the role of natural selection acting on variation among the individuals that make up a population, sorting them into fit and less fit versions, thereby creating adaptation and diversification across generations. However, recent advances in the study of host-associated microbes has complicated this understanding. The microbial symbionts now known to reside in and on virtually all eukaryotic organisms exert a vast array of influences on their hosts. Processes as diverse as early embryonic development, gut formation, digestion, and the regulation of some behaviors have now been shown to be influenced by the microbiota (see a previous blog post). Though this line of evidence is exciting, the degree to which microbes and hosts may influence each other’s evolution remains largely unexplored.

A consequence of the gene-centric view of evolution we call the Modern Synthesis (MS) is to foster a severe constriction in scientists’ understandings of Darwin. Despite Darwin’s original treatment of evolution being enormously rich, he becomes the purveyor of just one dangerous idea: evolution by natural selection – the idea which, when modified by the post-Darwinian discoveries of Mendelian and population genetics, underpins the MS. Hence we find Richard Dawkins catching the gist of a hundred biology textbooks by claiming both that ‘the selfish gene theory is Darwin’s theory expressed in a way that Darwin did not choose’ [1], and, that while Darwin believed in the ‘Lamarckian’ principle that acquired characters were heritable, this belief ‘was not a part of his theory of evolution’ [2]. Only in such an intellectual world, a world still sustained by MS assumptions, could the MS be said to capture the ‘central tenets’ of Darwin’s work [3].