Effects Of Exploration And Maternal Influence On Cognitive Development In Free-Ranging Rhesus Macaques

Christine Fleener

From the moment we are born, we are forced to make sense of our environment, and it is by exploring our environment that we are able to gather information about increasingly larger spaces, domains, and relationships. The onset of independent locomotion is known to facilitate a pervasive set of changes in perception, spatial cognition, and social and emotional development, but the details of this process or whether there are any lasting effects is still unclear. For my dissertation, I am interested in understanding how an infant’s early interactions with a maternal caregiver influence their stress physiology and exploratory behaviors, and how these early experiences shape an individual’s social and spatial cognition from infancy into juvenility. As testing multiple factors in a variety of human infants can be an invasive and impossible task, we turn to analogous non-human primates.

I have spent the last four years working at the Caribbean Primate Research Center on the small island of Cayo Santiago, Puerto Rico in order to address these inquiries. Cayo Santiago is inhabited entirely by around 1,500 free-ranging rhesus macaques and has only been accessible to researchers for the last 75 years in order to address many social and biological questions in a natural setting. From this population, we selected a subset of 50 infants to monitor from birth and have been collecting extensive behavioral and biological data throughout their first years of life, establishing one of the largest longitudinal data sets.

Over 8,000 hours of behavioral data were collected on how much each infant moved independently, away from and towards their mother, as well as how each mother reacted to their infant with abuse, rejection, or caudling. We recorded how the infants used their space for foraging or play, and how they interacted with other social group members. The Social Sciences Division (SSD) Summer Research Grant enabled me to focus my attention on compiling and analyzing this massive data set.

Additionally, we tracked fecal glucocorticoid levels throughout their life course in order to understand each individual’s stress physiology, and once a year each individual was trapped to collect cerebrospinal fluid and plasma to measure cortisol and oxytocin concentrations, white blood cell count, and for genotyping. During this time I administer a battery of cognitive tests I established to assess stress reactivity and social and spatial cognition. The SSD Summer Research Grant has given me the support necessary to code and analyze previously collected data and prepare for the upcoming season of trapping in which I will be able to collect further biological and cognitive data when my subjects are over two years old.

With the support of this Summer Research Grant, I have been able to synthesize my ideas and interests and complete my dissertation proposal, while also expanding my impact by sharing my results in various forums such as the Animal Behavior Society’s annual conference in Anchorage, Alaska this summer and inviting notable researchers from other institutions to present at our Comparative Behavioral Biology Workshop here at the University of Chicago. The opportunities provided by the Division of Social Sciences have reached far beyond my own project and have made a meaningful impression on the scientific community.


Christine Fleener is a student in the Department of Comparative Human Development