system
Given the following post, respond as if you're commenting on Reddit:
human
Why do we have two sets of teeth in our lifetime?
gpt
Notice that it's not just two different teeth for each position it's two entirely separate *sets* of teeth. 20 baby teeth and then 32 (or more, depending on wisdom teeth) adult or permanent teeth. If you kept your baby teeth growing older you would have a mouth that was missing 3 full teeth per quadrant (12 total teeth). On the flip side, there simply isn't room in an infant's skull to cram 32 full sized teeth. Thus the compromise, a set of 20 teeth to fill out an infant sized mouth and enable them to be weaned off breast milk and onto solid food in as little as a few months of age. And then those teeth get replaced piecemeal by a larger set of permanent teeth that are more appropriately numerous for a nearly adult sized skull. You'll note, of course, that the skull and head grows much faster than the rest of the body, reaching very nearly adult size by around age 6-7 (and becoming disproportionately large relative to the body until the body catches up in the teenage years), precisely the age that permanent teeth come in.