The (non-) autapomorphic ramus of Neandertals02 May 2005
Wolpoff and Frayer (2005) pick up the question of whether the Neandertal mandibular ramus presents features absent in other humans, recent or archaic. Here's the abstract:
The ramus of Neandertal mandibles is said to show a suite of uniquely Neandertal character states that demonstrate the independent course of Neandertal evolution. This is the latest of numerous attempts to define cranial and mandibular autapomorphies for Neandertals. We examine variation in the four presumably autapomorphic ramal features and show they are neither monomorhic within Neandertals (to the contrary Neandertals are at least as variable as other human samples) nor unique to Neandertals, since they regularly appear in populations predating and postdating them. Neandertals differ from other human populations, both contemporary and recent, but the question of whether this fact reflects a divergent evolutionary trajectory must be addressed by the pattern of differences. In this case, as in the other attempts to establish Neandertal autapomorphies, rather than showing restricted variation and increased specialization, the Neandertal sample shows that the range of human variation in the recent past encompasses, and in some cases exceeds, human variation today, even in the very features claimed to be autapomorphic.
The four features examined are the position of the lowest point in the mandibular notch (posterior or central), the height of the coronoid process relative to the condyle, the position where the crest of the mandibular notch meets the condyle (central or lateral), and the depth of the mandibular notch (shallow in many Neandertals). They conclude:
The question we have addressed is not whether Neandertal ramal features differ from other samples; all populations vary and have their unique aspects, whether in unusual anatomies or in differing frequencies of anatomical variants. The question is whether Neandertals differ in a way that could be used to support the notion that they are a distinct clade, evolving for whatever reason in their own unique direction. Are there, in the words of Weidenreich (1943) cited above, "peculiarities which could be claimed as 'specialization,' thereby proving the deviating course this form has taken in evolution"? We believe the answer is no. The "distinctive" mandibular ramus features discussed here are not Neandertal autapomorphies. They are neither limited in their range of expression within Neandertals (to the contrary, Neandertals are at least as variable as other human samples) nor are they unique to Neandertals, since they appear in populations predating and postdating them (7).
I think if I could wrap up every paper with a Weidenreich quote I would.
Wolpoff MH and Frayer DW. 2005. Unique ramus anatomy for Neandertals? Am J Phys Anthropol Early View