Forum:Spandrels

A spandrel is a term coined by S.J.Gould and R.Lewontin (1979a) for traits which confer no adaptive advantage to an organism, but are 'carried along' by an adaptive trait. Their example being the lengthening of a bone in the hind limb of the Giant Panda, as a result of the lengthening of the corresponding bone in the forelimb. The bone in the forelimb has adapted to perform a function similar to that of an opposable thumb. The change in the hind limb, arguably, confers no adaptive advantage, whereas the change in the forelimb certainly does. The important implication of this idea for Evolutionary Psychology being, that therefore not every trait can be accounted for in terms of adaptive advantage. For instance, Gould puts forward the hypothesis that language itself in humans came about as a spandrel: "Natural selection made the human brain big, but most of our mental properties and potentials may be spandrels - that is, nonadaptive side consequences of building a device with such structural complexity" (S.J.Gould. The Pleasures of Pluralism, p.11) But of course, once a trait confers an adaptive advantage, as arguably most of our "mental properties and potentials" do, it is no longer a spandrel, and thus opens the debate concerning the importance of the concept of spandrels.