Endocranial asymmetry in New World monkeys: a comparative phylogenetic analysis of morphometric data

GONZALEZ, PAULA N.; VALLEJO-AZAR, MARIANA; ARISTIDE, LEANDRO; LOPES, RICARDO; DOS REIS, SERGIO F.; PEREZ, S. IVAN

BRAIN STRUCTURE & FUNCTION

SPRINGER HEIDELBERG

Año: 2021

1863-2653

Brain lateralization is a widespread phenomenon although its expression across primates is still controversial due to the reduced number of species analyzed and the disparity of methods used. To gain insight into the diversifcation of neuroanatomical asymmetries in non-human primates we analyze the endocasts, as a proxy of external brain morphology, of a large sample of New World monkeys and test the efect of brain size, home range and group sizes in the pattern and magnitudeof shape asymmetry. Digital endocasts from 26 species were obtained from MicroCT scans and a set of 3D coordinates was digitized on endocast surfaces. Results indicate that Ateles, Brachyteles, Callicebus and Cacajao tend to have a rightward frontal and a leftward occipital lobe asymmetry, whereas Aotus, Callitrichinae and Cebinae have either the opposite pattern or no directional asymmetry. Such diferences in the pattern of asymmetry were associated with group and home range sizes. Conversely, its magnitude was signifcantly associated with brain size, with larger-brained species showing higher interhemispheric diferences. These fndings support the hypothesis that reduction in inter-hemispheric connectivity in larger brains favors the lateralization and increases the structural asymmetries, whereas the patterns of shape asymmetry might be driven by socio-ecological diferences among species.