Trepanning is a surgical procedure by which the disc bone of the skull is removed. Now archeologists in Greece have found evidence of this procedure done between 150 – 100 BC.

bq. Excavators were intrigued to find a round hole 1.62 centimeters in diameter to the rear of the skull, in the left parietal bone. Anthropologist Asterios Aidonis, who works with antiquities officials, identified the small opening as the result of a trepanning. As the edges of the bone showed signs of growth and healing, it is believed that the patient survived for five or six years after the operation.

And according to the article this was a procedure practiced for atleast 10,000 years.

[Source: “KathiMerini”:http://www.ekathimerini.com/4dcgi/_w_articles_politics_100014_04/09/2003_33683]