Dr. Amy Lu is an assistant professor at Stony Brook University. She was awarded a Leakey Foundation Research Grant during our spring 2016 cycle for her project entitled “Understanding weaning trajectories in a wild primate – the gelada (Theropithecus gelada).”
Weaning is a critical life history transition for primates and other mammals. In humans, premature weaning can lead to higher infant mortality and poor development outcomes; yet both the causes and consequences of early weaning remain poorly understood in wild primates. More recently, the pace of weaning has also been linked to the development of the gut microbiome, an important system linked to adult health and disease. Thus, developing a comprehensive understanding of weaning should be an important priority in anthropological research.
Our project uses a suite of innovative techniques in isotope biochemistry, photogrammetry, and genomics to characterize weaning relative to growth, gut microbiome establishment, and fitness in a wild primate – the gelada.
In particular, we ask: (1) What is the normative trajectory of weaning in wild infant geladas? (2) How do social factors related to maternal condition or acute events such as a male takeover alter the trajectory of weaning? Here we focus not only on infant age at weaning, but also the timing of weaning relative to growth, which may more accurately represent curtailed maternal investment (i.e., premature weaning). (3) Finally, does premature weaning lead to downstream consequences in survival or the gut microbiome?
We will answer these questions by collecting cross-sectional and longitudinal data on ~50 infants from 8 social groups across three years. Results from this study will provide a unique dataset that will explain variable weaning strategies from both a proximate and ultimate perspective.