Brain size growth in wild and captive chimpanzees (Pan troglodytes). Issue 7 (24th May 2018)

• Record Type: Journal Article
• Authors: Cofran, Zachary
• Is Part Of: American journal of primatology. Volume 80:Issue 7(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-05-24
• Subjects: captivity -- cross‐sectional -- ontogeny; Primates -- Periodicals; Primates -- Périodiques; 599.8
• DOI: 10.1002/ajp.22876
• Languages: English
• ISSNs: 0275-2565

Abstract

Abstract : Despite many studies of chimpanzee brain size growth, intraspecific variation is under‐explored. Brain size data from chimpanzees of the Taï Forest and the Yerkes Primate Research Center enable a unique glimpse into brain growth variation as age at death is known for individuals, allowing cross‐sectional growth curves to be estimated. Because Taï chimpanzees are from the wild but Yerkes apes are captive, potential environmental effects on neural development can also be explored. Previous research has revealed differences in growth and health between wild and captive primates, but such habitat effects have yet to be investigated for brain growth. Here, I use an iterative curve fitting procedure to estimate brain growth and regression parameters for each population, statistically comparing growth models using bootstrapped confidence intervals. Yerkes and Taï brain sizes overlap at all ages, although the sole Taï newborn is at the low end of captive neonatal variation. Growth rate and duration are statistically indistinguishable between the two populations. Resampling the Yerkes sample to match the Taï sample size and age group composition shows that ontogenetic variation in the two groups are remarkably similar despite the latter's limited size. Best fit growth curves for each sample indicate cessation of brain size growth at around 2 years, earlier than has previously been reported. The overall similarity between wild and captive chimpanzees points to the canalization of brain growth in this species. Abstract : Adult brain size is reached by around 2 years in chimpanzees, younger than generally appreciated. Brain size growth cannot be distinguished between wild and captive samples. Brain growth curves for wild (blue) and captive (red) chimpanzees. Although the average estimated size and age of growth completion differ slightly between samples, the differences are not significant.