The evolutionary origins of modularity
This addresses a central biological problem of evolvability for researchers in fields like neuroscience and genetics, though it is incremental in building on existing hypotheses.
The study tackled the evolutionary origins of modularity in biological networks by showing that direct selection to minimize connection costs leads to the emergence of modular and evolvable networks, with experiments yielding significantly more modular networks than controls.
A central biological question is how natural organisms are so evolvable (capable of quickly adapting to new environments). A key driver of evolvability is the widespread modularity of biological networks--their organization as functional, sparsely connected subunits--but there is no consensus regarding why modularity itself evolved. While most hypotheses assume indirect selection for evolvability, here we demonstrate that the ubiquitous, direct selection pressure to reduce the cost of connections between network nodes causes the emergence of modular networks. Experiments with selection pressures to maximize network performance and minimize connection costs yield networks that are significantly more modular and more evolvable than control experiments that only select for performance. These results will catalyze research in numerous disciplines, including neuroscience, genetics and harnessing evolution for engineering purposes.