Stone Tools Shed Light on Division of Labor

Thousands of stone tools from the early Upper Paleolithic were recently unearthed from a cave in Jordan, and now they are shedding light on the dawn of the division of labor among early humans.

"We have achieved remarkably accurate estimates of 40,000 to 45,000 years ago for the earliest Upper Paleolithic stone tools in the Near East," anthropologist Aaron Stutz, from Emory University, said in a statement. "Our findings confirm that the Upper Paleolithic began in the region no later than 42,000 years ago, and likely at least 44,600 years ago."

It was during this time that researchers now believe humans may have started organizing into more complex social groups by planning tasks and specializing in different technical skills.

"Our work really seems to support that idea," Stutz said. "The finds from Mughr el-Hamamah give us a new window onto a transitional time, on the cusp of modern human cultural behaviors, bridging the Middle and Upper Paleolithic."

Mughr el-Hamamah, or Cave of the Doves, located in Jordan in the Near East, was where Stutz and his colleagues found a rich array of artifacts, which showed a mix of techniques for making points, blades, scrapers and cutting flakes.

Many discoveries of Near Eastern tools dating prior to the early Upper Paleolithic show that humans focused on just one technology. The tools tend to look similar and likely served many uses - the Stone Age version of a Swiss Army Knife.

"It takes a good bit of cleverness to be able to devise a tool that helps you cover lots of different situations," Stutz explained. "And it makes sense in a context where you don't necessarily know what you're going to need your piece of flint for that day."

The group of toolmakers at Mughr el-Hamamah, however, used different technologies to get different tools.

"They were investing in the kinds of activities that require maintaining relationships and group planning," Stutz said. "They were gearing up for a clearly defined division of labor, including firewood gathering, plant gathering, hunting and food foraging."

They produced large quantities of blades for knives, and for hafting onto spears, using a prismatic blade technique that yields long, narrow points that are nearly identical. Using this method, the toolmakers could have efficiently produced the armature for multiple hunters going out on a lengthy foray, increasing the chances for finding and striking a target, researchers explained.

"It would have been socially advantageous for individuals to give blades that they made to others, to entice them to stay together as a group," Stutz added. "That kind of reciprocity builds relationships. And the stronger the connectivity of your social networks, the greater chance of increasing the number of calories and the quality of nutrients for the group."

Artifacts from the cave also included scraping tools, made on thick blades for hafting onto a handle and likely used for working wood and animal hides.

Other tools continued to be crafted with what is known as the Levallois technique, which was more often used to make the multi-use flakes and triangular points common in earlier periods.

These diverse tool technologies, which were reportedly in use the entire time these early humans occupied the cave, support the idea that hunter-gatherer populations started to band together in larger, more interconnected social networks.

As humans began to dominate the landscape, the researchers theorize, they reached a population density threshold for living in larger groups and gained access to a range of technologies. That process may have helped tip the balance for the rise of modern human culture and the disappearance of the Neanderthals.

The findings are described in more detail in The Journal of Human Evolution.

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