Our teeth are amazing structures. They have to break food without breaking themselves--and they chew up to millions of times over the course of our lifetimes. They are also built from the raw materials that come from those very foods. We can think of chewing as a perpetual death match in the mouth, with plants and animals developing tough or hard tissues for protection, while teeth evolve ways to sharpen or strengthen themselves to overcome those defenses.

That said, who among us has perfect teeth? Many of us have dental issues, like cavities, periodontal disease, impacted wisdom teeth, and other orthodontic problems. Other mammals tend not to have these same issues. What makes us so different? Part of the answer seems to lay in the fact that our ancestors did not evolve to eat the kinds of foods we feed our kids today. The educator of this lesson, Peter Ungar, wrote an article for the online magazine Aeon that discusses this idea further. 

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