Mismatches in resident and stranger serotonin transporter genotypes lead to escalated aggression, and the target for aggression is mediated by sex differences in male and female rhesus monkeys (Macaca mulatta)

• Published in: Hormones and behavior Vol. 140; p. 105104
• Main Authors: Hunter, Jacob N., Wood, Elizabeth K., Roberg, Brandon L., Neville, Leslie, Schwandt, Melanie L., Fairbanks, Lynn A., Barr, Christina, Lindell, Stephen G., Goldman, David, Suomi, Stephen J., Higley, J. Dee
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2022
• Subjects: 5-HTT; Aggression; Animals; Female; Genotype; Macaca mulatta - genetics; Male; Physical aggression; Rhesus macaque; Serotonin Plasma Membrane Transport Proteins - genetics; Sex Characteristics; Sex differences; 5-HTT; Sex differences; Rhesus macaque; Physical aggression
• ISSN: 0018-506X; 1095-6867; 1095-6867
• DOI: 10.1016/j.yhbeh.2021.105104

A variety of studies show that the s-allele of the serotonin transporter genotype (5-HTT) is related to aggression. However, influences of sex and 5-HTT genotype of both subject and opponent have not received as much attention in aggression research. Using a nonhuman primate model, the present study explores differences in rates of aggression exhibited by 201 group-housed male and female rhesus monkeys (Macaca mulatta; 122 females; 79 males) exposed to an unfamiliar age- and sex-matched stranger while in the presence of other same-sex members of their social group. The study also assesses whether the rates of aggression increase when the home-cage resident, the unfamiliar stimulus animal, or both possess the short (s) allele of the 5-HTT. Results showed that, when compared to females, males exhibited higher rates of physical aggression toward the stranger, and when both the male resident and the male stranger possessed the s-allele, rates of physical aggression toward the stranger increased five-fold. Resident females also engaged in higher rates of physical aggression when they possessed the s-allele, although unlike the males, their physical aggression was directed toward familiar same-sex members of their social group. The findings of this study indicate that rates of physical aggression are modulated by 5-HTT resident and stranger suggest a role of sexual competition in the phenotype of the 5-HTT genotype. Importantly, when two males with impulse deficits, as a function of the s-allele, are placed together, rates of violence exhibited by the dyad escalate substantially. [Display omitted] •Few studies have examined interactions between sex and 5-HTT genotype in violence.•Interactions between genotypes of two individuals in violence are also poorly-known.•We examined the contributions of these factors to violence in a primate model.•Male pairings showed high rates of violence when both males possessed the s-allele.•The s-allele amplified female violence toward other familiar females in the group.