Unwise Evolution

Oh the joys of break: endless TV, pints of ice cream, and the thought of school lost behind the fog of drugs….Wait, what?

Well when you get your wisdom teeth out over spring break that is about all you can do. With an icepack to the face, eating blended bananas, the single scientific question I could muster was, why do humans grow teeth that do not fit in their mouth? After looking into the matter, it appears there are several contributing factors.

This is what my cheeks looked like.

The pain and suffering I felt from my wisdom teeth protruding through my too small jaw was, indirectly, a trade off for my big brain. Our early ancestors had big jaws and small brains, with weak jaw muscles allowing for the growth of the third set of molars. With bigger brains, we taught ourselves how to process our food, making mushier meals that had less wear and tear on our molars. With less weathering on the teeth, there is even less room for the wisdom teeth to grow in. Additionally, the processed diet reduces jaw growth, leaving no space for those molars. In the Proceedings of the National Academcy of Sciences, it is suggested that the shift to agriculture and the resulting change to our diets caused our jaws to become shorter, meaning less space for our teeth.

So why have we not evolved a mouth sans wisdom teeth? The problems associated with wisdom teeth, and dental crowding in general, are too prevalent and recent to be attributable to evolution. Additionally, dentistry is too effective for evolution to have weeded them out. Wisdom teeth do not grow through the gum until quite late in life, usually after people have reached the reproductive age, so there are weaker selection forces against them. Another explanation is that the genes responsible for molar growth are also important for other things, therefore they must not mutate and evolve.

Some Japanese scientists suggest that tooth pulp could be a good source of stem cells and an alternative to embryonic cells, showing there can be benefits to wisdom tooth extraction. 

This bit of wisdom does not help ease the pain of a throbbing mouth.