The long-standing challenge of interpreting brain changes in the fossil record: a brain-based parcellation method for interpreting brain organization from endocasts
Faculty of Science, Complex Traits Genetics, CNCR, VU Amsterdam, The Netherlands
Besides extracting very global properties like cranial capacity, inferring further brain structural properties from fossil endocasts is particularly challenging. Indeed, the classification of cerebral gyri and sulci from impressions on endocast is a taxing and often highly subjective undertaking. Ongoing debates surrounding the identification and interpretation of fossil hominin endocasts are thus numerous. Even if the endocast is not a brain per se, palaeoneurology may benefit from methodological developments in neurosciences. In particular, the introduction of digital brain atlases has offered the unique opportunity of developing automated methods for the recognition of gyri and sulci within the human brain.
Here we test a new protocol for the application of virtual human and chimpanzee brain atlases based on MRIs and histology (i.e., the Desikan-Killiany and von Bonin and Bailey atlases) to parcellate cortical regions identifiable in extant and fossil hominid virtual endocasts. More specifically, our sample includes the digital endocasts of one extant human individual, one extant chimpanzee individual, and the Australopithecus africanus specimen Sts 5 from Sterkfontein Member 4 (South Africa). We then compare the position and identification of cerebral imprints in endocasts to cerebral sulci. Through this methodology, we hope to propose an alternative to the traditional approach that relieson the visual inspection of endocasts.