Anxiety, Heritability, Maternal environmental effects, Temperament


Primate behavior is influenced by both heritable factors and environmental experience during development. Previous studies of rhesus macaques (Macaca mulatta) examined the effects of genetic variation on expressed behavior and related neurobiological traits (heritability and/or genetic association) using a variety of study designs. Most of these prior studies examined genetic effects on the behavior of adults or adolescent rhesus macaques, not in young macaques early in development. To assess environmental and additive genetic variation in behavioral reactivity and response to novelty among infants, we investigated a range of behavioral traits in a large number (N = 428) of pedigreed infants born and housed in large outdoor corrals at the Oregon National Primate Research Center (ONPRC). We recorded the behavior of each subject during a series of brief tests, involving exposure of each infant to a novel environment, to a social threat without the mother present, and to a novel environment with its mother present but sedated. We found significant heritability (h 2 ) for willingness to move away from the mother and explore a novel environment (h 2 = 0.25 ± 0.13; P = 0.003). The infants also exhibited a range of heritable behavioral reactions to separation stress or to threat when the mother was not present (h 2 = 0.23 ± 0.13–0.24 ± 0.15, P < 0.01). We observed no evidence of maternal environmental effects on these traits. Our results extend knowledge of genetic influences on temperament and reactivity in nonhuman primates by demonstrating that several measures of behavioral reactivity among infant rhesus macaques are heritable.

Original Publication Citation

Fawcett GL, Dettmer AM, Kay D, Raveendran M, Higley JD, Ryan ND, Cameron JL, Rogers J. Quantitative Genetics of Response to Novelty and Other Stimuli by Infant Rhesus Macaques (Macaca mulatta) Across Three Behavioral Assessments. Int J Primatol. 2014;35(1):325-339. PMCID: PMC3970820.

Document Type

Peer-Reviewed Article

Publication Date


Permanent URL


Int J Primatol




Family, Home, and Social Sciences



University Standing at Time of Publication

Full Professor

Included in

Psychology Commons