Since males don't use their nipples for nursing little ones, why do they still have them? In males the nipples are vestigial, there but with no real function -- just like the remnants of hip bones in whales and vestigial tail bones in humans. Even though they don't use them, evolution hasn't made them completely disappear. While having breast tissue does make them able to get some of the same diseases that affect females, like breast cancer, this is extremely rare and not enough of a reason for the nipples to completely disappear. Evolution hasn't proven them to beneficial, but they continue to exist because there haven't been any real negatives to having vestigial nipples. Since both males and females possess the genes for nipples, they both have them.