Drilling a hole in a live person’s head without anaesthetic might not at first sound like a good idea.
We now know of the benefits of performing a craniotomy (4) when there is raised intracranial pressure after trauma from a depressed skull fracture, or intracranial bleeding or swelling from other causes.
It seems very likely that our ancient ancestors were aware of this too, certainly in relation to trauma.
A popular theory postulated initially by Broca in the 19th century was that the earliest craniotomies by Neolithic man were done to exorcise evil spirits, thought to be the underlying cause of insanity or other illness. The picture is not a craniotomy but demonstrates similar 16th century belief in “Extracting the fool’s stone”
Broca thought that the resultant benefits in trephined patients with headache, paresis or epilepsy led to the procedure being more widely adopted, especially in cases of trauma.
There is limited evidence however of skulls having been trepanned before death without signs that this was done for trauma or disease. The point remains moot.