Migration and mobility of "early modern humans". How the first modern humans reached Eurasia

The researchers found that our direct ancestors – "early modern humans" – were the most variable group of all humans that lived within the last 1.8 million years. They appeared in the highly unstable environments of the Late Pleistocene between 200,000 to 100,000 years ago in Africa. Weber and his colleagues compared the fossil skulls with those from recent people, Neanderthals, the group of Homo erectus, and others. The results show that the shape variability of "early modern humans" is largest and that they are indeed closest to geographically dispersed recent people while no links to Neanderthals and other archaic groups could be found. This suggests that more than one population of “early modern humans” from Africa could be founder population of recent people. "Rather than a single exodus from Africa via western Asia" Weber says, "we think that there were several complex waves of migration. 'Early modern humans' were split into numerous, temporarily isolated populations before they migrated into Eurasia and probably back. Not unlikely they also took more than one route, for instance also the Strait of Gibraltar which is within sight distance to Europe".

The results are influential for the debate on the origins of modern humans and population genetic studies connected with it. Instead of assuming a single event of dispersal from Africa, the study suggests a much more dynamic scenario and raises the question what were the conditions emerging with "early modern humans" that supported these dynamics. "Migrating faster and farther is boosting genetic exchange. We thus infer that greater population mobility might have been an essential factor for that large shape variation", Weber concludes.

Advanced Techniques
The scientists implement advanced techniques for their research. As genetic data does not exist from the time when "early modern humans" appeared, morphology is the only access available to study them. The team applied virtual reconstruction techniques for fossil skulls and sophisticated mathematical methods to compare roughly 500 measuring points from each of the 200 skulls on the computer. "Such a complex analysis is only feasible with a numeric approach", says Philipp Gunz who performed the computations.

University of Vienna: Center of Virtual Anthropology
Gerhard Weber’s workgroup "Virtual Anthropology" at University of Vienna is one of the few centres where such kind of reconstructions of fossil specimens can be undertaken. After scanning the fossils with computer tomography the digital copies can be handled and measured electronically. Weber leads the largest anthropology network in Europe (European Virtual Anthropology Network – EVAN) which is funded by the EU. The network aims to spread this kind of technology and to train young researchers. Several graduate students from University of Vienna got research posts elsewhere, among it the Max Planck Institute for Evolutionary Anthropology and the Konrad Lorenz Institute for Evolution and Cognition Research. Applications of Virtual Anthropology meanwhile reached as well the medical sector where diagnosis and implant planning exploit the same methods as those used for investigating fossils.

Publication:
Early modern human diversity suggests subdivided population structure and a complex out of Africa scenario.
1,2 Philipp Gunz, 1,3 Fred L. Bookstein, 1,4 Philipp Mitteroecker, 1 Andrea Stadlmayr, 1 Horst Seidler, and 1 Gerhard W. Weber.
1 Dept. of Anthropology, University of Vienna, Althanstr. 14, A-1090 Vienna, Austria
2 Dept. of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany
3 Dept. of Statistics, University of Washington, Seattle, USA
4 Konrad Lorenz Institute for Evolution and Cognition Research, Adolf Lorenz Gasse 2, A-3422 Altenberg, Austria

Corresponding author:
Gerhard W. Weber
Department of Anthropology
University of Vienna
Althanstr. 14, A-1090 Vienna, Austria
M +43-664-817 49 26
gerhard.weber(at)univie.ac.at
www.evan.at
www.virtual-anthropology.com

Press office University of Vienna:
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Graphic (PNAS), Figure legend:
The shape of each skull is measured by several hundred points (as shown in the example in the lower right corner for a fossil skull) and then compared with the others using a method called "Geometric Morphometrics". Each of the 200 individuals in this shape plot is represented by one small sphere. The colors represent different groups of humans. The graph shows that archaic humans (orange) and Neanderthals (green) are much less variable (compare the size of the ellipsoids) than "early modern humans" (red, each individuals marked separately), ancestors from the Upper Paleolithic (blue), and recent humans (light brown). Moreover, archaic and modern groups are widely separated.
Copyrights: Proceedings of the National Academy of Sciences (PNAS).

Gerhard Weber (photo privat)
Gerhard Weber/field (photo privat)