Spencer Waters and James Dee Higley, Department of Psychology
Introduction
It is widely accepted that the neuropeptide oxytocin helps mediate pro-social behavior and bonding between humans as well as other primates. Current genetic research has shown a link between variants in the oxytocin receptor gene (OXTR) and measures of social skills in humans. Demonstrating a link between oxytocin genotype and sociality, implies biological underpinnings for social bonding and affiliation in both human and nonhuman primates, suggesting that neurophysiological mechanisms may function to modulate a wide variety of social behaviors.
This project aimed to investigate the role of oxytocin on the development of social affiliation and gregariousness within rhesus macaques (Macaca mulatta). Specifically, this project assessed developmental outcomes in social affiliation in both infant and adult subjects to evaluate whether allelic differences in the oxytocin receptor gene and social affiliation are associated. Ultimately, time constraints prohibited the complete analysis of collected data. As such, no conclusive findings are reported now; however, data analysis is projected to be completed in 2017, resulting in publication of the results at that time.
Methods
No animal subjects were harmed during this experiment. All rhesus macaque subjects were housed and treated safely as approved by the Institutional Animal Care and Use Committee (IACUC) at the California National Primate Research Center (CNPRC) at the University of California, Davis. Animals in this studied were handled within the ethical guidelines set forth by the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC).
Infant (60 – 90-day-old) rhesus macaques were videotaped during a series of standardized tests to measure temperaments and behaviors related to social affiliation. Specific behaviors that were measured included: lip smacking, social approach, environmental exploration, etc. The videos were recorded at the CNPRC in the years prior to the start of this project. A total of 41 infant subjects were used in this study. I used these existing video recordings to code behaviors related to social affiliation. These measures of social affiliation in infancy were then analyzed in conjunction with behavioral observations of these same subjects in present day—as adults.
Behavioral observations of the same 41 rhesus macaque subjects were conducted in adulthood. Each subject was observed four (4) times. Each observation session lasted five (5) minutes and was broken down into 15-second intervals. To avoid bias, interns other than myself observed and scored primate behaviors per the selected ethogram. Behaviors that were scored as frequencies—that is the total number of incidents for each behavior in each time interval was recorded. The behaviors that were scored are as follows: Social Proximity, Infant Proximity, Alone, Give Groom, and Receive Groom.
Each rhesus macaque subject was genotyped for allelic differences within the OXTR gene with the help from researchers at the CNPRC and the National Institutes of Health (NIH). DNA extractions were conducted at the CNPRC using blood samples; DNA samples were then sent to the NIH for genotyping.
Results
The data analysis for this project is not yet completed. Analysis of Variance (ANOVA) statistical techniques will be used to assess whether the OXTR gene can be used as a predictor for observed variance in social affiliation—as measured via the behavioral observations.
It is anticipated that less common variants of the OXTR gene will be negatively associated with measures of social affiliation. Specifically, it is hypothesized that rhesus macaque subjects who possess non-dominant alleles for the OXTR gene will exhibit lower frequencies of social proximity and social behavior (i.e. Grooming behavior). Ultimately, this relationship between the OXTR gene and social behavior is expected to be modulated by environmental differences (e.g. early rearing experiences, social dominance rankings, etc.). The potential finding that sociability in primates is influenced by both the OXTR gene and the environment would imply that gene-by-environment interactions have big implications in complex social behavior.
Discussion
As previously mentioned, the data analysis for this project is not yet complete. Regardless, the results of this project may have real-world implications. Current genetic research suggests Oxytocin functioning may play a role in the development of severe social deficits associated with autism spectrum disorder (ASD)—a disorder sometimes characterized by poor social skills such as: understanding social cues, common social behaviors, etc. Should this project successfully demonstrate that OXTR allelic differences are associated with social behavior, the future clinical implications could possibly provide future diagnostic tools (e.g. genotyping) and treatments (e.g. gene therapy) to individuals with ASD and/or social disorders.
Ultimately, this experience was an immensely rewarding one. The opportunity to collaborate with mentors from BYU, the CNPRC, and the NIH was very inspiring. I believe my prospects for gaining admission to graduate school are improved as a direct result of my involvement with this ORCA project. This hands-on experience with designing a research project and carrying out the methodology and data analysis solidified my desire to pursue higher education and work within the field of Bio-psychological research. Although my findings are not yet complete, I am passionate about my work and hope to present my results to a broader scientific community.
