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Author Notes:

Corresponding author: Emiliano Bruner, Centro Nacional de Investigación sobre la Evolución Humana, Paseo Sierra de Atapuerca 3, 09002 Burgos (Spain). Phone: +34.947.040.800. Fax: +34.947.040.810. emiliano.bruner@ceneih.es

The authors declare no conflict of interest.

Subjects:

Research Funding:

This work was supported by National Institutes of Health Grants P01AG026423 and National Center for Research Resources P51RR165 (superceded by the Office of Research Infrastructure Programs/OD P51OD11132).

ASPP is funded by the Atapuerca Foundation. EB is funded by the Spanish Government (CGL2015-65387-C3-3-P) and by the Italian Institute of Anthropology.

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Behavioral Sciences
  • Neurosciences
  • Zoology
  • Neurosciences & Neurology
  • Precuneus
  • Geometric morphometrics
  • Brain morphology
  • Macaques
  • Apes
  • INTRINSIC FUNCTIONAL ARCHITECTURE
  • DEFAULT-MODE
  • AFRICAN APES
  • GENUS HOMO
  • GEOMETRIC MORPHOMETRICS
  • PARIETAL CORTEX
  • SHAPE VARIATION
  • ADULT HUMANS
  • GREAT APES
  • MONKEYS

Midsagittal Brain Variation among Non-Human Primates: Insights into Evolutionary Expansion of the Human Precuneus

Tools:

Journal Title:

Brain, Behavior and Evolution

Volume:

Volume 90, Number 3

Publisher:

, Pages 255-263

Type of Work:

Article | Post-print: After Peer Review

Abstract:

The precuneus is a major element of the superior parietal lobule, positioned on the medial side of the hemisphere and reaching the dorsal surface of the brain. It is a crucial functional region for visuospatial integration, visual imagery, and body coordination. Previously, we argued that the precuneus expanded in recent human evolution, based on a combination of paleontological, comparative, and intraspecific evidence from fossil and modern human endocasts as well as from human and chimpanzee brains. The longitudinal proportions of this region are a major source of anatomical variation among adult humans and, being much larger in Homo sapiens, is the main characteristic differentiating human midsagittal brain morphology from that of our closest living primate relative, the chimpanzee. In the current shape analysis, we examine precuneus variation in non-human primates through landmark-based models, to evaluate the general pattern of variability in non-human primates, and to test whether precuneus proportions are influenced by allometric effects of brain size. Results show that precuneus proportions do not covary with brain size, and that the main difference between monkeys and apes involves a vertical expansion of the frontal and occipital regions in apes. Such differences might reflect differences in brain proportions or differences in cranial architecture. In this sample, precuneus variation is apparently not influenced by phylogenetic or allometric factors, but does vary consistently within species, at least in chimpanzees and macaques. This result further supports the hypothesis that precuneus expansion in modern humans is not merely a consequence of increasing brain size or of allometric scaling, but rather represents a species-specific morphological change in our lineage.

Copyright information:

© 2017 S. Karger AG, Basel.

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