Hormonal Modification of Social Behavior

Abstract

[male] and [female] sex-hormone therapy was employed on castrate [female] chimpanzees to provide information on the direction and persistence of hormonally-induced modifications in social dominance-subordination relationships. Estrogen ([alpha] estradiol, Progynon DH), 2 mg./day, and methyl testosterone (Oreton-M), 50 mg./day, were administered orally or by implanted pellets on 4 exptl. days separated by a 3-week control period. Dominance-subordination was studied by a competitive reaching for a single nut placed in a cup while the given experimentally paired animal was looking on. Ten test trials were interspersed with 10 free-feeding trials introduced to control the motivational differences between the animals. Both estrogen and androgen improved the dominance status of a previously subordinate castrate [female] , reversing the social relationship reliably in both drug conditions. Androgen was shown to have a more persistent effect and was unrelated to the tumescence-detumeseence cycle.