Correlation of serum testosterone levels with age in male chimpanzees

Serum testosterone was measured in a group of male chimpanzees of varying ages by radioimmunoassay using a specific antiserum to testosterone-3-carboxym ethyloxime-bovine serum albumin. The juvenile age group, ranging from one through six years (n=26), had a mean serum testosterone value of 13ng/100ml (range 3.5-59ng/100ml). The adolescent age group, spanning years seven through ten (n=19), had a mean value of 178ng/100ml (range 14.6-238ng/100ml). The adult group, comprised of animals over eleven years of age (n=29), had a mean peripheral serum testosterone value of 397ng/100ml (range 92-680ng/100ml). These data suggest that serum testosterone levels may be useful in determing the age and sexual maturity of chimpanzees of unknown age.