You’ve noticed that weird indent above your upper lip before, and you’ve probably sat in your room late at night wondering what it does. Don’t worry; it keeps me up at night too. But before I tell you what it does in humans, I’ll tell you what it does for other mammals. In most mammals, it enables the animal to carry moisture from the mouth to the nose pad, in order to keep the nose pad wet.
The reason they need to keep their nose moist, is because a wet pad traps odor particles better than a dry one. They can basically just smell better. Does that mean our Philtrum does the same thing? No, unfortunately, the Philtrum serves no purpose to humans and most primates. I’m sorry you had to find out this way. Check the source for more information on the Philtrum