Here’s what Professor Hallux has to say:
To find the answer we need to go back to before you’re even born!
We’re inside the womb with a very tiny growing baby. Now this might surprise you but for the first few weeks of growth, ALL babies in the womb grow as females – yes even the boys! It is during this time that nipples are created and everyone gets a pair.
After about 60 days, if the baby is going to be a boy, the DNA blueprint inside its cells gives the orders to release a hormone called testosterone –and that’s when the main differences between boys and girls begin.
Unlike women’s nipples, men’s can’t feed babies. The theory is that because they’re not harmful, evolution has just left them where they are.