Scientific interest in ancient trepanations began in 1865 when the archaeologist Ephraim G. Squier (1821–1888) discovered a pre-Columbian skull in Peru showing signs of the operation. The artifact was later sent to Paris and entrusted to the studies of Dr. Paul Broca (1824–1880). Today we know that this procedure was performed as far back as the Stone Age in every part of the world, and it is therefore possible to declare trepanation the oldest surgical intervention in history.
From an etymological point of view, the term “trepanation” simply means to perforate the bone, usually the skull, and does not take into account the size, technique, or purpose of the operation. For this reason, any type of cranial perforation or surgical opening can be considered trepanation.
In the preface to Trepanation, Trephining and Craniotomy, History and Stories (Springer, 2019), Josè M. Gonzàlez-Darder highlights the uncertainty that permeates contemporary research regarding the origins of trepanation:
“[…] In primitive or prehistoric cultures, where no written records exist, it is impossible to know with certainty the reasons for this practice. Almost everything in this field of investigation is speculative.”

The interests and motivations justifying the use of this procedure have changed over time: from magical rituals to remedies for migraines, from the treatment of madness to craniotomy in modern surgery, and from recreational use to the achievement of altered states of consciousness.