10.01 Structure vs. Function (Again!) – Beyond Networks: The Evolution of Living Systems

Module 10 of "Beyond Networks" returns from the true complexity of evolution to have a look at different simplified perspectives on the basic process of adaptation by natural selection. This first lecture revisits Lewontin's minimal conditions for evolution by natural selection and shows how we can gain broad and profound insights into its workings by looking at it from different perspectives, as proposed by philosopher James Griesemer. The first perspective covered is Lewontin's own structural account of the units of selection. It aims at identifying the levels of organisation at which selection can occur. The second perspective is the functional replicator-interactor perspective pioneered by Richard Dawkins and David Hull. It reduces the relevant levels of selection to the genetic one in a clear and simple manner. I argue that even such a minimalist and reductionist approach is useful given the proper conditions. Unfortunately, it has been massively overextended outside its safe boundaries of application. I conclude the lecture by comparing both the advantages and blind spots of both perspectives. The main problem is that neither of them can account for the different levels of organisation they take for granted. We will see in the next lecture that process perspectives on evolution can provide an alternative approach, which can help us overcome these limitations.

The first three lectures of this module closely follow an argument made by James Griesemer in 2006 (published as a chapter in a book called Genes in Development, edited by Eva Neumann-Held and Christoph Rehman-Sutter). This piece of work is massively underrated. It should be read by every evolutionary biologist on the planet!

Lewontin's 1970 discussion of the units of selection is still well worth reading (Annual Reviews in Ecology and Systematics, Vol. 1, p. 1). His famous diagram of the laws governing evolutionary transformations between genotype and phenotype space is from his 1974 texbook The Genetic Basis for Evolutionary Change.

Despite my reservations about their account, I do recommend Richard Dawkins' The Extended Phenotype (1982), and David Hull's Science as a Process (1988) for their clarity and force of argument. I have mentioned before that a clear exposition of wrong ideas can be extremely inspirational. The diagram I use in the lecture is taken from John Maynard Smith's 1972 book On Evolution.