The concealment of ovulation in humans is also sexually selected. While nearly all mammals advertise fertility by physiological means, humans do not—or at least, we do so far less than other species. We have also become sexually receptive throughout the year, rather than just seasonally. Concealment of ovulation serves some reproductive ends, but it also encourages something that humans do a lot of: we engage in nonreproductive sex—sex for pleasure, sex for bonding.
