In his 1967 study, "Prehistoric and Early History of Trepanation," Professor F.P. Lisowski of the University of Tasmania, Australia, cites the work of two anthropologists who suggested that trepanation might have been practiced in Japan.

One of them, Michael Rykel, reported in 1962 on five skulls unearthed in Hokkaido that may indicate trepanation was long ago practiced by the Ainu.

However, Japanese experts are hesitant to agree. There is no evidence it was practiced in prehistoric times, they say, and the evidence that it may have been used medically as far back as the Kamakura Period (1185-1333) is "problematic."