The evolution and development of cranial form in Homo sapiens

The evolution and development of cranial form in Homo sapiens
Daniel E. Lieberman,*† Brandeis M. McBratney,* and Gail Krovitz‡

Despite much data, there is no unanimity over how to define Homo sapiens in the fossil record. Here, we examine cranial variation among Pleistocene and recent human fossils by using a model of cranial growth to identify unique derived features (autapomorphies) that reliably distinguish fossils attributed to “anatomically modern” H. sapiens (AMHS) from those attributed to various taxa of “archaic” Homo spp. (AH) and to test hypotheses about the changes in cranial development that underlie the origin of modern human cranial form. In terms of pattern, AMHS crania are uniquely characterized by two general structural autapomorphies: facial retraction and neurocranial globularity. Morphometric analysis of the ontogeny of these autapomorphies indicates that the developmental changes that led to modern human cranial form derive from a combination of shifts in cranial base angle, cranial fossae length and width, and facial length. These morphological changes, some of which may have occurred because of relative size increases in the temporal and possibly the frontal lobes, occur early in ontogeny, and their effects on facial retraction and neurocranial globularity discriminate AMHS from AH crania. The existence of these autapomorphies supports the hypothesis that AMHS is a distinct species from taxa of “archaic” Homo (e.g., Homo neanderthalensis).

Just one for the record.

 

One response to “The evolution and development of cranial form in Homo sapiens

  1. These morphological changes, some of which may have occurred because of relative size increases in the temporal and possibly the frontal lobes, occur early in ontogeny, and their effects on facial retraction and neurocranial globularity discriminate AMHS from AH crania.

    For me this is not “just for the record”. The mentioned changes are precisely those that Leakey (for instance) emphasizes when comparing chimpanzee and human brains: he says that most of the human gain in brain size is located precisely in these two areas, related respectively to communication and logical thought.

    If Neanderthals were equal or even superior to us in total cranial size but inferior in these two “strategic” areas, that may mean that they did not think exactly as we do, no matter how brainy they were. If the main difference is in the temporal lobes, it may well mean that they were not as good communicators as we are – with all the implications for social cooperation this has.

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