Did you know that having two sets of teeth is actually an evolution from the Homo Erectus era? There were only a single set of teeth in the Homo Erectus and when they would bite down on rocks out of confusion, they'd end up chipping or losing the teeth. The smartest ones / the ones that survived found ways of taking those teeth and jamming them back into their gums in order to eat more protein, and the jaws naturally saw that having a second pair wasn't a bad idea. The first Homo erectus to have a second set of teeth, according to studies, was revered as a god, someone who could eat the tough meat. Naturally this person because the strongest alpha, had the most you know what (can't say in a christian smogoff) with other female members of the Homo Erectus species, and eventually had more and more children with two sets of teeth. This initially recessive gene soon became the dominant gene as more or more single-set Homo Erectus population died out and they because the Homo Sapiens we know, love and are today!