Third molars have been referred to as “teeth of wisdom” since the Seventeenth Century and simply “wisdom teeth” since the Nineteenth Century. The third molars generally appear much later than other teeth, usually between the ages of 17 and 25 when a person reaches adulthood. It is generally thought among linguists that they are called wisdom teeth because they appear so late, at an age when a person matures into adulthood and is “wiser” than when other teeth have erupted.
Lately, science has added some credence to the idea that the third molar does indeed erupt when a person is “wiser”. Recent research has shown the brain continues to grow and develop right on through adolescence: in fact, most researchers believe the brain does not reach full maturity until the age of 25. Perhaps, then, our ancestors weren't so far off the mark — that the eruption of “wisdom teeth” is a sign that the carefree days of childhood have given way to the responsibilities of adulthood.