We typically have two nipples because mammals have twice as many nipples as they need to feed their little ones.
Dogs are likely to have 10 nipples because they usually have 5 puppies.
Cats are likely to have 8 nipples because they usually have 4 kittens.
And humans tend to have 1 baby at a time, so we usually have 2 nipples.
Think of these extra sets of nipples as a backup nipple. And some people have an extra, or extra, extra, extra, extra nipple.
Let’s talk about the third nip. When we’re forming into a baby you start off with a female blueprint. So we were all female at one point…kind of. That’s because nipples develop before our sex is determined.
Milk lines appear when we’re developing and it runs from our armpit to our thigh. These milk lines turn into thick ridges and the ones on your chest turn into 2 nipples. Then the rest of the milk ridges fall away, but for some people, the rest of those ridges didn’t fall away. This leads to an extra nipple.