People often ask, "Why do we have wisdom teeth if there is no room in the jaws for them?" The answer has a lot to do with diet. In an article titled "Management of Asymptomatic Impacted Wisdom Teeth" in the British Journal of Oral and Maxillofacial surgery, the author noted that the average, highly abrasive diet of Neolithic man wore down his teeth, which caused a reduction in molar size from front to back.
This size decrease from the abrasive food which man consumed allowed for the forward migration of the teeth and thus created adequate space for the eruption of a wisdom tooth or teeth. Less wear occurs in modern man because of the arrival of processed foods and the reduced amount of chewing necessary to consume food.
Combining this with a decrease in the loss of teeth and cavities as a result of modern dentistry requires people nowadays to address at least one impacted or partially impacted wisdom tooth through dental surgery.