Brain surgery, even today a dramatic test of a surgeon's skill, was performed thousands of years ago under the most unsanitary conditions and sometimes with amazing success. Of all ancient people who experimented with cranial surgery, the most successful people were the indians of South America. Skulls unearthed from ancienct Inca graves reveal that people lived through surgery performed with only the most primitive of stone tools and scrapers. The primitive " surgeons " performed brain surgery wuthout any use of anesthetics, though it is assumed that some form of native drug was use to reduce pain.