By Erika, age 15

Why do men have nipples? A short, but simple question. The simple answer is that the default setting in baby formation is female. The sex of a fetus isn’t determined until later in development, after nipples have formed.

“Why is the default setting female?” you ask. Good question. It’s because girls are better, at least in child producing. You argue, “But you can’t get pregnant without a guy!” In humans this is true, if we are talking about getting pregnant without medical intervention. They require sperm to make a fetus. In other species, however, females can reproduce asexually, some of which don’t even have males in their species. There are actually hundreds of species that don’t need males like insects, lizards, snakes, and fish. One example is the whiptail species Cnemidophorus neomexicanus, which is entirely female, and they all reproduce asexually.

Many female Komodo dragons have had eggs develop without fertilization. One female zebra shark last saw her mate in 2012, but then had three pups in 2016. Each only had DNA from their mom. This shark is not the only female in the animal kingdom to switch to asexual reproduction. This has also been seen in a captive boa constrictor and an eagle ray.

This is why human fetuses start to develop female features before the sex is determined. No offense is meant to the males of course, it’s the way humans have evolved.