Wisdom Tooth - Vestigiality and Variation

Vestigiality and Variation

Wisdom teeth are vestigial third molars that used to help human ancestors in grinding down plant tissue. The common postulation is that the skulls of human ancestors had larger jaws with more teeth, which were possibly used to help chew down foliage to compensate for a lack of ability to efficiently digest the cellulose that makes up a plant cell wall. As human diets changed, smaller jaws gradually evolved, yet the third molars, or "wisdom teeth", still commonly develop in human mouths.

Agenesis of wisdom teeth in human populations ranges from practically zero in Tasmanian Aborigines to nearly 100% in indigenous Mexicans. The difference is related to the PAX9 gene (and perhaps other genes).