The simple body test that proves the theory of evolution

[TubbyTubby]

Humans used to have a Jacobson's organ, or a vomeronasal organ, which is found in snakes. In snakes, it's used to tell the snake about its environment since they can't hear and they don't see very well. Other senses in humans were developed, thus the vomeronasal organ was no longer needed.

What snakes do is flick their tongues out in the air and grab particles from it.
Cats also have it, as do many other animals. It is part of the olfactory system as it relates to smells.

I read in "My Inner Fish" that 3% of our entire genome is dedicated to olfactory receptors. That's insane.