Behavioral effects of a synthetic mixture of aliphatic acids in rhesus monkeys ( Macaca mulatta)

Abstract

The stimulation of sexual behavior by a synthetic mixture of volatile aliphatic acids (acetic, propanoic, methylpropanoic, butanoic, methylbutanoic, methylpentanoic) was studied in male rhesus monkeys. Twelve intact adult males and 12 long-ovariectomized adult females were used in 24 paired combinations (541 tests each of 1 hr). A mixture of authentic acids similar to that found in the vaginal secretions of estrogenized females was applied to the sexual skin area of ovariectomized females immediately before tests with males. There was marked between-pair variability during the application of both control and test substances. However, using rigorous behavioral criteria, there was a well-marked stimulation either of male mounting attempts or of ejaculations in 12 of 24 pairs involving 9 of 12 males. Three males responded with both female partners, three responded with neither female partner, and six responded with one partner only. In the responding pairs, there were highly significant increases in mounting attempts and ejaculations, an effect that could be attributed only to treatment. We conclude, therefore, that these aliphatic acids (copulins), which act via olfactory pathways, have communicatory significance in rhesus monkeys.