"Synergistic selection": a Darwinian frame for the evolution of complexity.

Non-Darwinian theories about the emergence and evolution of complexity date back at least to Lamarck, and include those of Herbert Spencer and the "emergent evolution" theorists of the later nineteenth and early twentieth centuries. In recent decades, this approach has mostly been espoused by various practitioners in biophysics and complexity theory. However, there is a Darwinian alternative - in essence, an economic theory of complexity - proposing that synergistic effects of various kinds have played an important causal role in the evolution of complexity, especially in the "major transitions". This theory is called the "synergism hypothesis". We posit that otherwise unattainable functional advantages arising from various cooperative phenomena have been favored over time in a dynamic that the late John Maynard Smith characterized and modeled as "synergistic selection". The term highlights the fact that synergistic "wholes" may become interdependent "units" of selection. We provide some historical perspective on this issue, as well as a brief explication of the underlying theory and the concept of synergistic selection, and we describe two relevant models.