Reconciling explanations for the evolution of evolvability

Evolution’s ability to find innovative phenotypes is an important ingredient in the emergence of complexity in nature. A key factor in this capability is evolvability, or the propensity towards phenotypic variation. Numerous explanations for the origins of evolvability have been proposed, often differing in the role that they attribute to adaptive processes. To provide a new perspective on these explanations, experiments in this paper simulate evolution in gene regulatory networks, revealing that the type of evolvability in question significantly impacts the dynamics that follow. In particular, while adaptive processes result in evolvable individuals, processes that are either neutral or that explicitly encourage divergence result in evolvable populations. Furthermore, evolvability at the population level proves the most critical factor in the production of evolutionary innovations, suggesting that nonadaptive mechanisms are the most promising avenue for investigating and understanding evolvability. These results reconcile a large body of work across biology and inform attempts to reproduce evolvability in artificial settings.