期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：32
DOI：10.1073/pnas.2123553119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Fossils of early
Homo sapiens from Herto, Ethiopia, show that populations living in Africa 160,000 years ago had already evolved brains broadly equivalent in size to those of humans living today. However, these early human braincases were shaped differently than ours, raising the question of whether the actual brains they housed were also structurally different. We used high-resolution computed tomography to perform accurate digital restorations of the fossil remains. These data allowed direct comparisons between endocranial shape development from childhood to adulthood in both fossil and living humans. Our results suggest that the peculiar shape of early
Homo sapiens adult braincases was likely due to dietary and lifestyle differences rather than different brain anatomy.
Fossils and artifacts from Herto, Ethiopia, include the most complete child and adult crania of early
Homo sapiens. The endocranial cavities of the Herto individuals show that by 160,000 y ago, brain size, inferred from endocranial size, was similar to that seen in modern human populations. However, endocranial shape differed from ours. This gave rise to the hypothesis that the brain itself evolved substantially during the past ∼200,000 y, possibly in tandem with the transition from Middle to Upper Paleolithic techno-cultures. However, it remains unclear whether evolutionary changes in endocranial shape mostly reflect changes in brain morphology rather than changes related to interaction with maxillofacial morphology. To discriminate between these effects, we make use of the ontogenetic fact that brain growth nearly ceases by the time the first permanent molars fully erupt, but the face and cranial base continue to grow until adulthood. Here we use morphometric data derived from digitally restored immature and adult
H. sapiens fossils from Herto, Qafzeh, and Skhul (HQS) to track endocranial development in early
H. sapiens. Until the completion of brain growth, endocasts of HQS children were similar in shape to those of modern human children. The similarly shaped endocasts of fossil and modern children indicate that our brains did not evolve substantially over the past 200,000 y. Differences between the endocranial shapes of modern and fossil
H. sapiens adults developed only with continuing facial and basicranial growth, possibly reflecting substantial differences in masticatory and/or respiratory function.
