An archaeological dig on the island of Chios has unearthed evidence of a successful head operation carried out over 2,000 years ago in accordance with the writings of Hippocrates, the most famous of ancient doctors. According to a Culture Ministry announcement yesterday, the operation - a process known as trepanning that involved the removal of a disc of bone from the skull - had been carried out on a man who died aged 50, between 150 and 100 BC. He was buried in a large cemetery on the fringes of the island's ancient capital, in the area now known as Atsiki. The grave, a simple rectangular affair bereft of any offerings and providing no clue as to the identity of its occupant, was found earlier this year during a rescue excavation ahead of a building project on the site. 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. Trepanning is known to have been practiced at least 10,000 years ago, and in primitive societies the operation was probably seen as a way of releasing evil spirits from the head. In ancient Greece, it was performed to save patients with severe head wounds from death by internal bleeding or infection. Hippocrates recommended trepanation for wounds that involved indentation of the skull accompanied by fracture or contusion. He wrote a detailed manual on the delicate operation, instructing surgeons to frequently cool their saws to prevent overheating the bone. Several other trepanned skulls have been found in ancient Greek graves.