View Full Version : The evolution of modern human brain shape (Neubauer et. al 2017)

01-25-2018, 02:45 PM
The Evolution of Modern Human Brain Shape (full article) (http://advances.sciencemag.org/content/4/1/eaao5961.full)

Modern humans have large and globular brains that distinguish them from their extinct Homo relatives. The characteristic globularity develops during a prenatal and early postnatal period of rapid brain growth critical for neural wiring and cognitive development. However, it remains unknown when and how brain globularity evolved and how it relates to evolutionary brain size increase. On the basis of computed tomographic scans and geometric morphometric analyses, we analyzed endocranial casts of Homo sapiens fossils (N = 20) from different time periods. Our data show that, 300,000 years ago, brain size in early H. sapiens already fell within the range of present-day humans. Brain shape, however, evolved gradually within the H. sapiens lineage, reaching present-day human variation between about 100,000 and 35,000 years ago. This process started only after other key features of craniofacial morphology appeared modern and paralleled the emergence of behavioral modernity as seen from the archeological record. Our findings are consistent with important genetic changes affecting early brain development within the H. sapiens lineage since the origin of the species and before the transition to the Later Stone Age and the Upper Paleolithic that mark full behavioral modernity.

PCA of cranial shape:

These are the fossils in each of the H. Sapiens clusters (non-modern) from left to right:
Geological age group 1
Jebel Irhoud 1315 ky1.375 ± 6 ml
Jebel Irhoud 2315 ky1.467 ± 6 ml
Omo 2195 ky1.491 ± 4 ml
Geological age group 2
L.H. 18120 ky1.237 ± 5 ml
Skhul V115 ky1.363 ± 1 ml
Qafzeh 6115 ky1.524 ± 8 ml
Qafzeh 9115 ky1.497 ± 5 ml
Geological age group 3
Hofmeyr36 ky1.498 ± 13 ml
Mladeč 135 ky1.606 ml
Cro-Magnon 131 ky1.574 ± 1 ml
Cro-Magnon 331 ky1.813 ± 32 ml
Dolní Věstonice 1630 ky1.542 ± 4 ml
Dolní Věstonice 1329 ky1.590 ± 2 ml
Dolní Věstonice 1429 ky1.663 ± 5 ml
Dolní Věstonice 1529 ky1.385 ± 3 ml
Abri Pataud27 ky1.323 ml
Ohalo II H222 ky1.475 ± 1 ml
Oberkassel D99914 ky1.330 ± 2 ml
Oberkassel D99813 ky1.492 ml
Combe Capelle8 ky1.457 ± 2 ml