continue to reproduce in middle and old age. Aché data show that men evidence major declines in fertility after age 50 (Hill and Hurtado, 1996). However, we do not know the generality of this pattern across foraging groups, whether Aché men do not actively seek new reproductive opportunities in favor of grandparental investment, or whether they are simply not chosen as partners by women. It is possible that there is a great deal of variation in men's strategies both within and among societies. Greater focus on the mating and kin investment behavior of middle-aged and older men and on their impacts for survival and reproductive success of offspring and other kin in traditional societies is clearly necessary. An understanding of men's behavior may help solve the riddle of long life and menopause.
The general life-history model presented above predicts that increased returns to investments in embodied capital affecting either income or survival will