Comments on Dobson (2005), body proportions in early hominins, and the joint and limb proportion differences between Stw 431 (A. africanus) and A.L. 288-1 (A. afarensis).

In his recent paper, Dobson (2005) concludes that, contrary to the work of McHenry and Berger (1998a,b), the pattern of differences in joint proportions between the partial skeleton Stw 431 and A.L. 288-1 ‘‘does not correspond to the pattern revealed from a comparison of large samples of unassociated postcranial material from Sterkfontein Member 4 and Hadar’’ (Dobson, 2005, p. 153). Using exact randomization, he further suggests that Stw 431 and A.L. 288-1 ‘‘are not significantly different from each other with regard to limb joint proportions’’ (Dobson, 2005, p. 153). In his study, Dobson (2005, p. 146) formulates and tests the null hypothesis: ‘‘Can the differences between A.L. 288-1 and Stw 431 be sampled from a single species?’’ In response to Dobson’s conclusions and interpretations of his results, this author would like to raise several additional points that are not adequately elaborated upon by Dobson (2005). These points may offer further insight into the important question of the mode and tempo of the evolution of hominin limb and body proportions, and more specifically on the potentially more ape-like body proportions of A. africanus. One of the principle points of our 1998 series of papers (McHenry and Berger, 1998a,b) was to illustrate that contrary to widely held opinion at the time (McHenry, 1992), we found that A. africanus appeared to possess limb joint and, by inference, limb length and body proportions which differed from those of A. afarensis, humans, and living apes. We further suggested that the evidence supported a hypothesis that these proportions in A. africanus were in fact more ape-like than those