Summary of “Why Our Ancestors Drilled Holes in Each Other’s Skulls”

To date, thousands of skulls bearing signs of trepanation have been unearthed at archaeological sites across the world.
Many trepanned skulls show signs of cranial injuries or neurological diseases, often in the same region of the skull where the trepanation hole was made.
None of the skulls showed any signs of having suffered any injury or illness, before or after the trepanation had been performed.
The skulls of two young women with obelion trepanations had been discovered years earlier: one in 1980 and another in 1992.
The holes had been made in a variety of different locations around the front and side of the skull, and all of the skulls showed signs of having suffered a physical trauma, suggesting that the trepanations had been performed to treat the effects of the injuries.
Thanks to the trepanation holes themselves, we can infer a surprising amount about the fate of the people after they received their trepanation.
Their skulls showed bone healing around the edges of the trepanation holes – although the bone never completely re-grew over the holes.
Three of the 12 skulls showed only slight signs of healing around the trepanation hole, suggesting that their owners only survived between two and eight weeks after the operation.

The orginal article.