system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we have baby teeth?
gpt
Short version: It's advantageous to have matching upper and lower teeth. This is hard to do if you always regrow teeth, like sharks.

On the other hand, only growing one set of teeth is problematic, since your head grows so much during your early life - the baby teeth would be too small for an adult's head.