Abstract
During a behavioral study of free-ranging rhesus monkeys, non-pregnant females were observed to show sexual behavior both at mid-menstrual cycle and peri-menstrually. The basis of the dual estrous periods appears to be dual maxima in estrogen secretion. Peri-menstrual estrus may be an evolutionary vestige from a tupaiid-type sexual cycle. The occurrence of sexual behavior proximal to menstruation forces a redefinition of the term ‛es-trus.’

This publication has 0 references indexed in Scilit: