Document Type


Date of Degree Completion

Spring 2022

Degree Name

Master of Science (MS)


Primate Behavior

Committee Chair

Lori Sheeran

Second Committee Member

Kara Gabriel

Third Committee Member

Jessica Vandeleest


Attachment theory is well established in humans, and current research findings of the attachment relationship in humans include how an individual’s attachment style impacts their stress levels – including cortisol levels and function of the Hypothalamic-Pituitary-Adrenal (HPA) axis. However, in non-human primates such as rhesus macaques (Macaca mulatta), though attachment behavior has been found, it has not been researched in as much detail as that of humans. In this study, adjective data from 52 infant rhesus macaques ages 2 and 3 months describing infant and maternal attitudes and the mother-infant relationship were analyzed. Secure, anxious, avoidant, and disorganized attachment styles were found at both months of infant age. All infants were securely attached at 2 months old, but all but 1 infant was avoidantly attached at 3 months old. Avoidant attachment at 3 months of infant age was found to have an impact on the infant’s HPA-axis function, in that infants with higher rates of avoidant attachment tended to have a lower percent suppression of endogenous cortisol by dexamethasone challenge. These findings help to extend the evolutionary history of attachment behavior further back along the phylogenetic tree while also suggesting a possible developmental pathway occurring within infant rhesus macaques that corresponds with the onset of weaning.

Available for download on Monday, July 19, 2027