The two "out of Africas"18 Mar 2008
Another of the craniometric stories going around this week (Discovery News) proposes that early Levantine modern humans (Skhul-Qafzeh) and Pleistocene Australians come from an early out-of-Africa dispersal that was later mostly replaced by true modern humans (represented by Upper Paleolithic Europeans and living people everywhere). The study is by Michael Schillaci; here's the abstract:
This study examines the genetic affinities of various modern human groupings using a multivariate analysis of morphometric data. Phylogenetic relationships among these groupings are also explored using neighbor-joining analysis of the metric data. Results indicate that the terminal Pleistocene/early Holocene fossils from Australasia exhibit a close genetic affinity with early modern humans from the Levant. Furthermore, recent human populations and Upper Paleolithic Europeans share a most recent common ancestor not shared with either the early Australasians or the early Levantine humans. This pattern of genetic and phylogenetic relationships suggests that the early modern humans from the Levant either contributed directly to the ancestry of an early lineage of Australasians, or that they share a recent common ancestor with them. The principal findings of the study, therefore, lend support to the notion of an early dispersal from Africa by a more ancient lineage of modern human prior to 50 ka, perhaps as early as OIS 5 times (76-100 ka).
But the Skhul-Qafzeh sample and the Pleistocene Australia + Wadjak sample used in the paper (a subset of all the actual specimens) are all males, and the Upper Paleolithic Europeans and recent skeletal samples are (as you might expect) half female.
Seems like a problem....
Schillaci MA. 2008. Human cranial diversity and evidence for an ancient lineage of modern humans. J Hum Evol (in press) doi:10.1016/j.jhevol.2007.10.010