Why do humans only get 2 sets of teeth in your life?

Answer 1

Here's my hypothesis. Humans or pre-humans probably only grew 1 set of teeth once upon a time. A few of them probably grew 2 sets as some sort of mutation. These beings were probably much more likely to make it to adulthood and therefore much more likely to pass their teeth genes onto their progeny. This was a huge evolutionary advantage.

There are supposedly people out there that grow a 3rd set of teeth but apparently it is a PITA. Especially if you're taking care of the second set. Even if the 3rd set was advantageous to survive longer it isn't a major advantage over 2 sets since the beings with 2 sets still live long enough to make and raise kids.

So even if 3 sets is an advantage it doesn't make you any more likely to be successful at creating kids. So it isn't an evolutionary advantage and therefore the frequency of people with this mutation doesn't increase.

Just my thoughts on the subject. Not tested, researched, or necessarily right.

Answer 2

You only have a set number of teeth because this is what is biologically advantageous. These teeth are supposed to last a lifetime.

Answer 3

There are four different tooth types, and all four type has their function.