A huge cache of tools from the late Stone Age, unearthed from a cave in Jordan, reveal how humans may have started organising into more complex social groups by planning tasks and specialising in different technical skills.
The rich array of artefacts from Mughr el-Hamamah, or Cave of the Doves, shows a mix of techniques for making points, blades, scrapers and cutting flakes.
"These toolmakers appear to have achieved a division of labour that may have been part of an emerging pattern of more organised social structures," said lead researcher Aaron Jonas Stutz, an Emory University anthropologist.
Late Stone Age or Upper Palaeolithic began in the region 45,000 years ago, according to researchers.
"The finds from Mughr el-Hamama give us a new window onto a transitional time, on the cusp of modern human cultural behaviours, bridging the Middle and Upper Palaeolithic," Stutz said.
This pivotal time also marked the ebbing of Neanderthals as a last wave of anatomically modern humans spread out from Africa and into the Near East.
This region, also known as the Levant, comprises the eastern Mediterranean at the crossroads of western Asia and northeast Africa.
As the final surge of modern humans passed through the Levant, they would likely have encountered human populations that arrived earlier, and they may also have inter-bred with Neanderthals.
"We don’t know if these toolmakers were mainly Neanderthals or anatomically modern humans, but recent evidence from other studies now raises the possibility that they were a mix of different populations," Stutz said in the paper published in The Journal of Human Evolution.
"What we see at the Mughr el-Hamamah site is that individuals were starting to live, work and form families in larger, more culturally structured social networks," Stutz added.
Mughr el-Hamama overlooks the Jordan Valley, opposite the Nablus Mountains on the West Bank.
"We can speculate that several families shared the space and worked alongside one another," he added.
"They were investing in the kinds of activities that require maintaining relationships and group planning. They were gearing up for a clearly defined division of labour, including firewood gathering, plant gathering, hunting and food foraging," co-researcher Liv Nilsson Stutz said.