The ecological context of human ovarian function.

New methods for monitoring ovarian function have allowed an extension of research venue beyond typical clinical settings to studies of human populations in their natural settings. Such studies have confirmed that patterns of variation in ovarian function with age and energetic factors are general features of human reproductive biology. Age patterns of ovarian function are extremely robust across populations of distinct genetic, ecological and cultural backgrounds. Comparable ovarian responses to energetic stresses are likewise observable in different populations where they arise as correlates of local ecologies rather than as correlates of voluntary patterns of diet or exercise. Maternal age and energetic factors also appear to interact with lactation in the modulation of postpartum, ovarian function. Average levels of ovarian function, however, differ considerably between populations, perhaps correlated with chronic environmental conditions that affect growth, development, and the establishment of adult set-points. Western populations appear to represent an extreme of the spectrum of variation in ovarian function, a fact which may relate to the epidemiology of breast and ovarian cancer.