Human ancestors visited the same quarries for hundreds of thousands of years

Scientists have finally solved the mystery of why ancient human ancestors made stone tools from the same quarries for hundreds of thousands of years.

The answer turns out to have been something of an elephant in the room.

“The question is, why do we find rock outcrops that were used for the production of flint tools, surrounded by thousands of stone tools, and next to them rock outcrops containing flint that was not used for the production of tools?” asks Professor Ran Barkai from Tel Aviv University, Israel.

“Ancient humans required three things: water, food and stone. While water and food are necessities for all creatures, humans relied on stone tools to hunt and butcher animals, as they lack the sharp claws or fangs of other predators,” Barkai explains.

Barkai is the senior author of a paper published in the Springer journal Achaeologies.

“A study of indigenous groups that lived until recently, with some still alive today, shows that hunter-gatherers attribute great importance to the source of the stone – the quarry itself – imbuing it with potency and sanctity, and hence also spiritual worship,” Barkai says.

“People have been making pilgrimages to such sites for generations upon generations, leaving offerings at the rock outcrop, while adjacent outcrops, equally suitable for stone tool production, remain untouched. We sought to understand why; what is special about these sites?”

Ancient humans have been making stone tools for millions of years. Barkai and his colleagues conducted a study of tool-making sites dating to the Palaeolithic (Old Stone Age, 3.3 million–12,000 years ago).

The sites are in the Upper Galilee region in northern Israel and southern Lebanon. They have large flint reserves for crafting and are within walking distance of major Palaeolithic sites of the Hula Valley – Gesher Benot Ya’akov (790,000 years old) and Ma’ayan Baruch (500,000 years old).

There are thousands of quarries in the area where, until about 500,000 years ago, Homo erectus made tools and left offerings. But flint was present in other locations untouched by these ancient people.

Barkai’s decided to cross-reference the migration routes of elephants – a staple in the diet of prehistoric humans – with the location of flint quarries and found a correlation.

“An elephant consumes 400 liters of water a day on average, and that’s why it has fixed movement paths,” says lead author Dr Meir Finkel, also at Tel Aviv University. “We find quarrying and knapping sites in the Upper Galilee located a short distance from elephant butchering sites, which are positioned along the elephants’ paths.”

The researchers applied this model and found similar tendencies in the Palaeolithic in Asia, Europe and Africa involving elephants and mammoths as well as other large prey like hippos and camels.

“It appears that the Palaeolithic holy trinity holds true universally: Wherever there was water, there were elephants, and wherever there were elephants, humans had to find suitable rock outcrops to quarry stone and make tools in order to hunt and butcher their favourite mega herbivores,” says Barkai. “It was a tradition: For hundreds of thousands of years the elephants wandered along the same route, while humans produced stone tools nearby. Ultimately, those elephants became extinct, and the world changed forever.”