Abstract # 136:

Scheduled for Saturday, June 19, 2010 01:45 PM-01:55 PM: Session 25 (Medallion Ballroom B) Oral Presentation


J. Higley1,2,3, B. Roberg1, M. Schwandt2, S. Lindell2, C. Barr2 and S. Suomi3
1Brigham Young University, Department of Psychology, Provo, UT 84602, USA, 2LCTS, NIAAA, NIH Animal Center, Poolesville, MD 20837, 3LCE, NICHD, NIH Animal Center, Poolesville, MD 20837

We investigated the effect of the serotonin transporter genotype on aggression using the Fairbank’s Intruder Challenge Test. Triads of rhesus macaques [Macaca mulatta, N=201] of various ages were tested with familiar cagemates in their home cage. An unfamiliar same-age and same-sex intruder was placed at the periphery of the homecage and the frequency of contact aggression with the intruder, as well as the contact aggression between the residents, was recorded for 30 minutes. Results: male resident monkeys engaged the intruder in more contact aggression, but females showed more aggression toward their familiar cagemates [F=3.974, P=0.020]. Male residents with the short allele engaged the intruder in more contact aggression than did male residents homozygous for the long allele. Similarly, female residents with the short allele engaged their familiar cagemates in significantly more aggression than did female residents homozygous for the long allele [F=4.655, P=0.032]. There was evidence for a resident-genotype X intruder’s-genotype interaction with contact aggression highest when short allele male subjects were paired with a short allele male intruder [F=9.698, P=0.002]. This study provides the first evidence that the genotypes of two interacting individuals mediate the escalation of aggression. It also suggests an evolutionary divergence between the sexes that is based on genotype, indicating a sex-genotype interaction for contact aggression.