Females of most mammalian species have estrus cycles instead of menstrual cycles. Such females usually come into estrus (also called ‘in heat') only once a year, generally in the spring. This single estrus period is the only time mature, fertilizable eggs are present in the ovaries. Humans and a few other primate females, however, exhibit many menstrual cycles per year where fertilizable eggs are present in ovaries during each cycle. Discuss possible adaptive advantages to each of these two strategies of reproduction. Don't forget an hypothesis.