Postnatal endocranial volume growth in Galago moholi

Abstract

Our current knowledge of brain growth in non‐human primates is based on comparisons of brain weights in cadaveric newborns compared to adults. Previous work has revealed most strepsirrhine primates (e.g., lemurs and lorises) defer much of their brain growth to the postnatal timeframe. No studies have examined brain growth across postnatal ages, to determine when adult brain size is achieved relative to life history milestones such as weaning or eruption of adult dentition. Micro‐computed tomography via a Scano vivaCT 75 was utilized to scan six specimens, ranging from newborn (day 0) to adult. Amira software was then used to manually segment endocranial contours and generate endocranial volumes from each of the specimens. Preliminary data indicates that the neonatal Galago possesses roughly 44% of the endocranial volume of its adult counterpart. By the late infant stage (30 days), the Galago possesses roughly 70%, and by 60 days postnatal, 99% of the adult endocranial volume. This timeline precedes the weaning period seen at roughly 90 days. Other milestones are also reached at the same age. Galago is reported to be perfecting its signature leaps at 60 days, and in our sample, more than half of replacement teeth have erupted. Results do suggest that Galago, like other strepsirrhines, defers most brain growth to postnatal ages. But here, for the first time, we demonstrate a rapid increase in endocranial volume, well before complete feeding independence.