"The evolution of reproductive restraint through social communication"
The debate about group selection has traditionally focused on individual reproductive restraint. We demonstrate the evolution of conditional reproductive restraint based on an explicitly social mechanism, modulated by intra-population communication comprising signal and evolved response, in a spatially distributed predatory/parasitic/pathogenic model system. The predatory species consistently comes to exploit a signal implying overcrowding, individuals constraining their reproduction in response, with a corresponding increase in equilibrium reproduction rate in the absence of signal. This signaled restraint arises in a robust way for a range of model spatial systems; it outcompetes non-signal-based restraint, and is not vulnerable to subversion by non-cooperating variants. These results demonstrate a social system where communication is used to evaluate population density and regulate reproduction accordingly, consistent with central ideas of Wynne-Edwards, whose claims about the evolutionary importance of group selection helped ignite decades of controversy. Further, the simulations support the hypothesis that intercellular communication, and ultimately multicellularity, may have originated via the co-opting of an unrelated metabolite as a signal carrier. This quantitative simulational model accounts for a key evolutionary transition, the advent of cooperation through communication, relevant to intercellular communication as well as to organismal social organization.