TY - JOUR
T1 - Evidence for independent brain and neurocranial reorganization during hominin evolution
AU - Warren, José Luis Alatorre
AU - De León, Marcia S.Ponce
AU - Hopkins, William D.
AU - Zollikofer, Christoph P.E.
N1 - Funding Information:
ACKNOWLEDGMENTS. We thank W. Coudyzer, W. Develter, C. Kellenberger, S. Kollias, and L. Michels for access to clinical data, as well as the reviewers for providing constructive comments that helped improve the manuscript. This research was funded by the Swiss National Science Foundation Grant #31003A_135470 (to C.P.E.Z.).
Publisher Copyright:
© 2019 National Academy of Sciences. All rights reserved.
PY - 2019/10/29
Y1 - 2019/10/29
N2 - Throughout hominin evolution, the brain of our ancestors underwent a 3-fold increase in size and substantial structural reorganization. However, inferring brain reorganization from fossil hominin neurocrania (=braincases) remains a challenge, above all because comparative data relating brain to neurocranial structures in living humans and great apes are still scarce. Here we use MRI and samesubject spatially aligned computed tomography (CT) and MRI data of humans and chimpanzees to quantify the spatial relationships between these structures, both within and across species. Results indicate that evolutionary changes in brain and neurocranial structures are largely independent of each other. The brains of humans compared to chimpanzees exhibit a characteristic posterior shift of the inferior pre- and postcentral gyri, indicative of reorganization of the frontal opercular region. Changes in human neurocranial structure do not reflect cortical reorganization. Rather, they reflect constraints related to increased encephalization and obligate bipedalism, resulting in relative enlargement of the parietal bones and anterior displacement of the cerebellar fossa. This implies that the relative position and size of neurocranial bones, as well as overall endocranial shape (e.g., globularity), should not be used to make inferences about evolutionary changes in the relative size or reorganization of adjacent cortical regions of fossil hominins.
AB - Throughout hominin evolution, the brain of our ancestors underwent a 3-fold increase in size and substantial structural reorganization. However, inferring brain reorganization from fossil hominin neurocrania (=braincases) remains a challenge, above all because comparative data relating brain to neurocranial structures in living humans and great apes are still scarce. Here we use MRI and samesubject spatially aligned computed tomography (CT) and MRI data of humans and chimpanzees to quantify the spatial relationships between these structures, both within and across species. Results indicate that evolutionary changes in brain and neurocranial structures are largely independent of each other. The brains of humans compared to chimpanzees exhibit a characteristic posterior shift of the inferior pre- and postcentral gyri, indicative of reorganization of the frontal opercular region. Changes in human neurocranial structure do not reflect cortical reorganization. Rather, they reflect constraints related to increased encephalization and obligate bipedalism, resulting in relative enlargement of the parietal bones and anterior displacement of the cerebellar fossa. This implies that the relative position and size of neurocranial bones, as well as overall endocranial shape (e.g., globularity), should not be used to make inferences about evolutionary changes in the relative size or reorganization of adjacent cortical regions of fossil hominins.
KW - Biomedical imaging
KW - Brain reorganization
KW - Human evolution
KW - Morphological integration
KW - Neurocranium
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U2 - 10.1073/pnas.1905071116
DO - 10.1073/pnas.1905071116
M3 - Article
C2 - 31611399
AN - SCOPUS:85074302713
SN - 0027-8424
VL - 116
SP - 22115
EP - 22121
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 44
ER -