Why do we have wisdom teeth if they cause so many problems?

Wisdom teeth are third molars, the last to erupt, typically in the late teens or early twenties. They were functional in ancestral populations eating tough, abrasive, minimally processed food, which wore teeth down substantially over a lifetime and made a third set of grinding surfaces useful. Larger jaws accommodated them. What changed is the jaw rather than the teeth: comparative studies of skeletal remains show jaw size decreasing over the last several thousand years, with softer cooked and processed diets reducing the mechanical loading that stimulates jaw growth during development.

The mismatch produces the modern problem. When there is insufficient room, third molars become impacted, erupting at an angle, partially emerging, or remaining trapped in bone, which can cause pain, infection of the surrounding gum tissue, damage to adjacent teeth, cysts, and crowding. Not everyone is affected: a meaningful proportion of people have wisdom teeth that erupt normally and function fine, and some people never develop them at all, with rates of congenital absence varying substantially between populations and reaching high levels in some East Asian and Indigenous groups.

Whether to remove asymptomatic wisdom teeth is genuinely contested. Prophylactic extraction has been standard practice in the United States for decades, while health systems in several other countries, including the United Kingdom, recommend against removing them unless there is disease or a clear likelihood of it, citing evidence that routine extraction of healthy impacted teeth lacks demonstrated benefit and carries surgical risks including nerve injury and dry socket. The reasonable position is that impacted or diseased teeth should come out, and that removal of healthy, fully erupted, cleanable third molars deserves an explicit discussion of the evidence with your dentist or surgeon rather than being assumed.