Abstract # 1064 Event # 208:

Scheduled for Saturday, August 20, 2005 09:15 AM-09:30 AM: Session 15 (Parliament Room) Oral Presentation


AGE AND MONOAMINE OXIDASE A (MAOA) GENOTYPE EFFECTS ON IMPULSIVE BEHAVIOR IN MALE RHESUS MONKEYS (Macaca mulatta)

T. K. Newman1, C. S. Barr1, S. J. Suomi2, D. Goldman1 and J. D. Higley1
1National Institute on Alcohol Abuse and Alcoholism/NIH, 5625 Fishers Lane, Room 3S-32, Rockville, MD 20852, USA, 2National Institute on Child Health and Human Development/NIH
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     In multi-male, female-bonded Old World monkey species, males typically must emigrate from their natal troop upon reaching sexual maturity. Younger migrants face greater risks, including premature death, but may profit through increased reproductive opportunities. In previous work, we have demonstrated that 1) MAOA genotype influences impulsive behavior in captive subjects, and 2) that younger, free-ranging migrants tend to be more impulsive. Here, we test the hypothesis that MAOA genotype effects on impulsivity are modulated by age. Fifty-seven unrelated males living in social groups were assessed for their latency to approach (LAT) a stranger using an Intruder Challenge Test. Genotypes were clustered based on inferred high or low MAOA enzymatic activity (MAOA-HA/MAOA-LA). An ANOVA model of age and MAOA genotype on LAT was significant (F = 5.75, P = 0.0018), with main effects of genotype (F = 5.74, P = 0.020), age (F = 4.44, P = 0.039), and a marginally significant interaction between variables (F = 3.84, P = 0.055). That is, younger males with the MAOA-LA genotype were much faster to approach an intruder and were equivalent in approach time to older subjects with either genotype. Cross species sequence comparisons of the MAOA gene suggest that the locus is under selection. We suggest that impulsive behavior leading to early dispersal may be an adaptive mechanism through which selection may operate.