April 19 (UPI) -- More than 5,000 years ago, a group of people living in what's now France drilled a hole in a cow's head. Researchers believe the ancient bovine skull is the earliest evidence of animal surgery yet recovered.
Scientists used advanced imaging to study the hole and determined it could not have been made by a violent encounter with another animal. Aside from the hole, the skull and related bones show no evidence of trauma. As such, scientists believe the hole was made purposefully by humans.
Paleontologists and archaeologists have found similar holes in human skulls as old as 10,000 years.
"I have analyzed many, many human skulls ... all from the neolithic period and they all show the same techniques -- and the technique you can observe in the cow's skull [is] the same," Fernando Ramirez Rozzi, Rozzi, a paleontologist at the French National Center for Scientific Research, told the Guardian.
The purpose of these holes, whether they're evidence of crude medical treatment or ritual, is a topic of ongoing debate.
Researchers agree that the holes in question reveal an impressive mastery of surgical skills. The majority of holes are precise, and evidence of healed bones suggests the incisions were made while the people were alive.
The newly discovered cow skull explains the mastery. According to Rozzi and research partner Alain Froment, an anthropologist at the Museum of Mankind in Paris, the skull offers proof that early humans were practicing their surgical skills on animals.
The duo published their analysis of the cow skull this week in the journal Scientific Reports.
Though medical tools and techniques have become more sophisticated since the Neolithic, neurosurgeons still remove portions of the human skill to relieve the pressure caused by severe brain swelling.
It's possible early humans were trying to save the cow's life, but fossil evidence suggests an abundance of cows in the area -- raising the question of why perform cow surgery if there are plenty of other healthy cows? And, if the cow was suffering of an epidemic, then why are there not holes in the skulls of all the other cows?
The answer, Rozzi and Froment claim, is that the cow wasn't being saved. It was sacrificed in the name of science. If true, it's likely the cow helped save lives, as a surprising number of ancient trepanation procedures, roughly 50 percent, were successful.
"The success of ancient surgical interventions is typically testified by bone regrowth around the cranial hole, the degree of bone recovery being indicative of the post-operative survival time," Pier Paolo Petrone, an anthropologist at the University of Naples who wasn't involved in the research, told Gizmodo. "If complications such as hemorrhaging, brain damage, wound infection, or meningitis did not occur after [cranial surgery], and if primary bone healing took place, long-term survival was often observable."