An oddly circular hole in a Neanderthal's shoulder bone may be the oldest known evidence of an ancient human fatally wounded with a wooden spear.
That's according to research published today in Scientific Reports.
The UK and Spanish team also found evidence of burial and caregiving behaviour in the species.
First author Emma Pomeroy, an archaeologist at the University of Cambridge, says it shows Neanderthals were even more complex than previously understood.
"We see evidence of two contrasting facets of human nature — care and violence — juxtaposed in the same individual," Dr Pomeroy said.
"We have a tendency to romanticise hunter-gatherer or pre-agriculture lifestyles as peaceful and close to the natural world … but it's not that simple."
But other experts were not convinced by the evidence outlined in the study.
Neanderthal lived with 'painful' tooth injury
The Shanidar Cave In Iraqi Kurdistan has revealed a plethora of Neanderthal remains since it was first excavated 1953.
The new study looks at recently discovered 75,000-year-old remains of a Neanderthal man in his 40s known as Shanidar A.
"Their body was placed in a very specific spot in the cave, tucked in behind a huge rock that stood between them and the cave mouth," Dr Pomeroy said.
"Over the subsequent years or decades, the remains of at least four other Neanderthal individuals were placed directly above."
Shanidar A's remains, which include a mostly complete hand, teeth and a left shoulder blade, have multiple signs of damage.
The teeth, which the team says were quite damaged, healed partially while the man was still alive.
Seven teeth from Shanadar A were found in the cave in Iraqi Kurdistan. (Supplied: Dr Emma Pomeroy)
"They must have been hit very hard in the face, which made one of their bottom front teeth split in half," Dr Pomeroy said.
"The broken edge became covered in hardened plaque showing they continued living afterwards without that part of the tooth.
"The injury would have been incredibly painful."
This, the researchers said, might indicate the man's family group provided care and support, at least in the short term.
"They likely needed some care and support from their group with drinking, communicating, eating," she said.
Killed with a wooden spear
While Shanidar A survived the dental issues, the team suggested an unusual, smooth-edged and circular hole in his shoulder blade indicated the likely cause of his demise.
Lack of healing on the bone, and fragments found nearby suggested the injury happened about the time of death.
The researchers suggest a spear might have pierced muscle, bones and potentially organs. (Supplied: University of Cambridge)
"It had to be something that could make a hole through a shoulder blade and all the muscle, bones and organs over the top – something like a weapon," Dr Pomeroy said.
The team hypothesised the circular hole was made with a wooden spear.
Wooden spears dating between 200,000–400,000 years old have been found in Europe.
"The diameter of the shaft near the pointed end fits well with the size of the hole in the scapula," Dr Pomeroy said.
"[But] we can never be sure because, of course, the wood has not preserved.
Conclusion 'needs more support'
Sofia Samper Carro, an archaeologist at the Australian National University not involved with the discovery, said that, while some of the conclusions were "bold", the team needed more evidence to support its claims.
"I think it's a bit of a stretch with the justification they have so far,"
she said.
Dr Samper Carro agreed the circular damage to the shoulder blade was "weird" and not how bones usually break.
"Bones usually break in more kind of orthogonal … more linear fractures," she said.
Neanderthal remains were first found in Shanidar Cave in 1953. (Supplied: Professor Graeme Barker)
However, she said, it was "very difficult" to know the cause of death, unless the weapon was also found.
"It's unusual that you get those circular shapes, but correlating that with the cause of death? I think it's a bit too much," she said.
Despite this, Dr Samper Carro said the site still had plenty to offer.
Dr Pomeroy's team is still excavating the Shanidar Cave site, examining the transition period when modern humans began to use it.
"We are investigating what Neanderthals and humans ate based on the animal bones they left behind, how they prepared plant and animal food … and a whole host of other questions," Dr Pomeroy said.
"There is so much fascinating work still to do."