why do we have two sets of teeth
Why do we only get two sets of teeth, while sharks get as many as they want? Biologists often say Cform follows function,D meaning that, due to the evolutionary process, the morphological features of an organismBs body are fitted to the activities of an organism. Shark teeth are embedded in the gums rather than directly affixed to the jaw, and are constantly replaced throughout life. Whereas the roots of the human teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums.
Teeth are made of multiple tissues of varying density and hardness in human-beings unlike the sharks. Some years ago, while writing a history page for a local paper here, I came across old census reports made by the army at the time, as was the common practice. They contained several references to people on their third sets of teeth. Maybe, because of improved dental hygiene, we've evolved away the need for them.
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.
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