Abstract
From intragenomic conflicts to mutualistic symbioses, biological interactions invite us to question the foundations of a rarely-explained concept that is nonetheless essential to Darwinian reasoning : the individual. The individual as " level of selection ", i.e. as the relevant scale for analyzing " heritable variance in fitness ", the source of adaptive evolution. The conceptual framework of " major transitions " offers us the possibility of conceiving the emergence of new scales of individuality through the assembly and more or less harmonious cooperation of individuals on a lower scale : the eukaryotic cell, the multicellular organism, the ant colony, etc. This framework also leaves open the possibility of developing new scales of individuality through the assembly and more or less harmonious cooperation of individuals on a lower scale : the eukaryotic cell, the multicellular organism, the ant colony, etc. This framework also leaves open the possibility of a multiplicity of scales of individuality, as illustrated by " selfish genetic elements " such as the Wolbachia bacterium or transposable elements. But is it capable of explaining the initial emergence of individuality ? At the origins of life, i.e., by definition, without individuals, how could evolution have operated ? More generally, how can we conceive of the emergence of Darwinian processes without relying, paradoxically, on pre-formed individuals ? My main aim is to demonstrate the importance and difficulty of this problem, and then to share the hope, if not the possibility, of solving it from a meta-evolutionary perspective.
