Beyond Spandrels: Stephen J. Gould, EvoDevo, and the Extended Synthesis

Abstract

In evolutionary biology, the term ‘‘spandrel’’ infallibly elicits the mem- ory of Steve Gould. It has become a standard in referring to constructional byproducts and developmental constraints. More often than not, these were regarded as lesser facets of evolutionary change, with priority given to population dynamics and the workings of natural selection. But the fundamental criticism, in the spandrels paper and other works of Gould, of the absence of organism level factors in the standard Modern Synthesis account, also helped trigger the EvoDevo revolution and important reconceptualizations of evolutionary theory. Recent versions of theory expansion include many of Gould’s propositions but also theoretical changes emerging from other fields, such as genomics, non-genetic inheritance, niche con- struction, and others. These amount not merely to a numerical addition of factors to be taken into account, but also initiate major shifts in theory structure. As a con- sequence, today’s extended frameworks of evolutionary theory entail a significant increase in explanatory capacity and predictive power.