Ca. 6500BCE

In 1872 skulls discovered in Neolithic gravesite in central France with 40 of 120 showing roundish holes 2-3 inches wide. The skull holes, studied by Paul Broca in Paris, were of both genders and all ages, and virtually none were accidental, pathological, traumatic, thus providing evidence of Neolithic practice of trephining skull down to layer of tissue encasing brain and spinal cord (dura mater). Among this and other samples, the usual estimates for survival of different samples of trephined skulls range from 50 percent to 90 percent with most estimates on the higher side (Gross, ch 1). In early modern Europe, surgeons used the operation primarily in cases of skull fracture (Evans & Read, 37).