Cranial surgery is tricky business, even under 21st-century conditions (think aseptic environment, specialized surgical instruments and copious amounts of pain medication both during and afterward).However, evidence shows that healers in Peru practiced trepanation - a surgical procedure that involves removing a section of the cranial vault using a hand drill or a scraping tool - more than 1,000 years ago to treat a variety of ailments, from head injuries to heartsickness. And they did so without the benefit of the aforementioned medical advances.

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