These days wisdom teeth serve little purpose and are often ‘impacted’ (wedged in) as there is insufficient space in our jaw to accommodate these last molar teeth.  This is because as mankind has evolved, so have our eating habits.  Hundreds of years ago our diet consisted of food that was coarse and difficult to break down, so our jaws had to work harder and thus developed into large bone.  We also lost teeth at an earlier age due to decay and this often created enough room for our third molars.  However due to changes in our diet and modern dentistry, we now generally don’t have enough room for our wisdom teeth causing them to often become impacted.