Using high-resolution scans of real human embryos, the BBC has created this somewhat terrifying animation of a fish-like, one-month-old embryo rapidly developing a face up to the 10-week mark. Yes, we all started out resembling Admiral Ackbar.
Notes the BBC:
The early human embryo looks very similar to the embryo of any other mammal, bird or amphibian - all of which have evolved from fish. Your eyes start out on the sides of your head, but then move to the middle.
The top lip along with the jaw and palate started life as gill-like structures on your neck. Your nostrils and the middle part of your lip come down from the top of your head.
There is no trace of a scar; the plates of tissue and muscle fuse seamlessly. But there is, however, a little remnant of all this activity in the middle of your top lip - your philtrum.
Huh, so that's what that groove does. And I always thought it kept mustaches from falling off men's faces.