Human fist evolution: a critique.
[Letter]
We were eager to read the manuscript entitled ‘Protective buttressing of the human fist and the evolution of hominin hands’ (Morgan and Carrier, 2013), for it potentially offered insight into our own evolution. The human hand is a complex and utilitarian anatomic structure and we have little doubt that its form has been influenced by natural selection. Sadly, we feel the authors fall short in demonstrating that the strike power of the fist was a key evolutionary force driving of the shape of the human hand. Mutations provide the raw material for evolutionary forces to act upon, and the resulting evolutionary changes can generally be explained by either selection or genetic drift (Futuyma, 1998). However, the confounding effects that result from the presence of exaptations and the difficulty in selecting traits that are discrete attributes make it risky to attribute each and every human feature to natural selection. The perils of this kind of thinking were well illustrated in the 1970s by evolutionary biologists such as R. C. Lewontin, S. J. Gould and E. O. Wilson. Morgan and Carrier claim that the evolution of the well-buttressed fist was driven by sexual selection, but provide no compelling evidence to reject the null hypothesis that this fortuitous structure was the result of either random genetic drift or exaptation (Gould and Lewontin, 1979). Is ‘protective buttressing’ even a legitimate, isolated trait? Or is it simply a tangential consequence of natural selection on other structural features – one that our species has learned to use to its advantage?
