Early humans traveled long distances to find colorful stones for tools

Ancient foragers in southern Africa did not settle for whatever stones lay at their feet. New evidence shows they walked, traded, or rafted many miles to secure vividly colored rocks.

The rocks included red jasper, green chalcedony, and black and white chert, used for knives, scrapers, and spearpoints. These choices reveal both technological savvy and an eye for aesthetic or symbolic appeal.

The research was led by Gregor D. Bader in the Department of Early Prehistory and Quaternary Ecology at the University of Tübingen.

Chasing colorful stones for tools

Together with colleagues at the Senckenberg Center for Human Evolution and Paleoenvironment, the team traced the origin of hundreds of stone tools from four Eswatini sites dating back as far as 40,000 years.

The study focused on Hlalakahle, Siphiso, Sibebe, and Nkambeni – camps once dotted across grasslands now bordering South Africa and Mozambique. Each yielded blades and flakes of colorful stone for tools unlike the drab local bedrock.

“Artifacts from numerous archaeological sites are kept there,” Bader said, noting that Eswatini’s dense museum collections allowed a landscape-wide view rather than the usual single-site snapshots.

Tiny samples reveal big journeys

To match stone tools to the source the team drilled pinhead-sized samples and bombarded them with neutrons. “Although the method is destructive, only tiny sample quantities are required and the results are excellent,” Bader explained.

The resulting gamma rays sketched a geochemical fingerprint as unique as a barcode. When researchers compared those codes with river gravels and outcrops in the Mgwayjza Valley, matches clicked into place.

Human-made blades of green chalcedony and red jasper carried the same elemental signature as rocks lying 12 to 60 miles west, an astonishing gap for groups who roamed on foot. Black and white chert drew from pockets even farther afield.

Routes across a rolling savanna

How did the stone travel? “We have calculated whether the stones used may have been transported via the local Komati and Mbuluzi rivers,” Bader said.

“However, this could only have happened as far as Hlalakahle, and the other three sites of Siphiso, Sibebe, and Nkambeni are a long way from there.”

The geometry points to people moving, not just rivers. According to Bader, even if the hunter-gatherers took the shortest routes, there are still considerable distances between the rock deposits and the places where the stones were used.

“In addition, an exchange of materials with other early human groups is conceivable,” noted Bader.

Stone color preferences changed

Chemical matches also revealed a swing in color preference. In the Middle Stone Age, from about 40,000 to 28,000 years ago, toolmakers favored the sleek blacks and whites of chert and the cool greens of chalcedony.

By the Later Stone Age, roughly 30,000 to 2,000 years ago, red jasper had become the star.

“Both colors occurred close together in the same valley and in the same river deposits, so we can assume a deliberate selection of different materials at different times,” Bader said. Climate change, group identity, or spiritual meaning may have driven the switch.

Colorful stone tools hint at identity

“Colorful and shiny materials seemed attractive to early humans; they often used them for their tools. We can only speculate as to whether the colors had a symbolic meaning,” Bader noted.

Red, linked to blood or fire, might have signaled vitality; green could have echoed fresh vegetation; black might have denoted endurance.

Whatever the message, carrying a scarlet-flecked knife or jade-toned scraper would have declared its maker’s reach and taste.

Tracing ancient journeys through color

The findings enlarge a picture of Stone Age mobility already hinted at by shell beads ferried inland and ochre mined from distant cliffs.

Now, thanks to nuclear probes and meticulous museum work, those journeys come into sharper focus. Small bands paced river valleys, traded nodules, and swapped ideas long before roads or herding.

As analytical techniques refine, the team hopes to test adjacent regions and older strata, mapping the spread of color preference across the subcontinent and through time.

Each geochemical fingerprint adds a waypoint to humanity’s first supply chains and shows that creativity, even then, traveled far on foot.

The study is published in the Journal of Archaeological Studies

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