Gesher Benot Ya’aqov Reveals Hominin Stone Tool Planning 800,000 Years Ago

Nearly 800,000 years ago, hominins established camps on the shore of a lake in the area now known as the Jordan Valley. There, they produced large tools that demanded forethought and technical ability.

The evidence indicates that they did not simply pick up any available stone. Rather, hominins deliberately located particular basalt sources and selected specific rocks for specific tool types, following patterns that endured for thousands of years.

A new study has matched the geochemical signatures of stone tools from Gesher Benot Ya’aqov (GBY) with their geological origins, including sources now deeply buried beneath the ground.

Dr Tzahi Golan and Dr Yoav Ben Dor of the Geological Survey of Israel conducted the work. Professor Naama Goren-Inbar of the Hebrew University of Jerusalem, who has excavated GBY for decades, was a co-author of the research.

Gesher Benot Ya’aqov: a favoured hominin location

GBY ranks among the most substantial Acheulian sites known. Hominins visited it again and again, leaving stone implements, traces of fire, butchered animal bones and fish remains.

Dating to around 780,000 years ago, the site lies at the former location of paleo-Lake Hula. The lake has vanished, but its sediments preserved the archaeological evidence with exceptional detail.

Basalt was the main raw material used for their large cutting implements, such as handaxes and cleavers.

Producing these tools was not a straightforward or rapid task. It involved several steps: choosing a suitable slab, forming it into a core, detaching large flakes, then shaping those flakes into completed implements.

For hominins, converting unworked stone into effective tools meant planning in advance and recognising the characteristics of the material.

Rocks differ in their internal structure, how they fracture and the features that affect the shaping of an object designed for cutting.

Tracing basalt tools to their sources

The researchers examined the chemical composition of artefacts from several archaeological layers, comparing them with basalt specimens from exposed outcrops near the site.

Their testing included major, trace and rare-earth elements, providing sufficient chemical resolution to differentiate between basalt flows with reasonable certainty.

They also used samples from a borehole drilled directly at GBY. It reached basalt layers that are now buried far beneath the modern surface.

Across hundreds of thousands of years, fault movement, erosion and accumulating sediment hid these rocks below the landscape.

The Jordan Valley is geologically unstable. The Dead Sea Transform fault system crosses the region, and the terrain inhabited by these hominins has been repeatedly altered since then.

Basalt flows once quarried by them may have subsided underground or been entirely eroded. Borehole evidence enabled the team to reconstruct an ancient land surface that has since disappeared.

Different tools required different stone

The findings revealed more than a preference for nearby resources. Giant cores, which formed the initial blocks for the full tool-production sequence, largely came from local sources, including some of the basalt flows now underground.

In certain instances, the source corresponded with outcrops situated within roughly 1 kilometre of the site.

Cleavers, however, told a different story. Their geochemical signatures indicated sources absent from the sampled outcrops.

This difference is significant because Acheulian toolmakers devoted more work to producing cleavers than to any other implement in their toolkits.

The sourcing results provide further evidence. Cleavers required a suitable type of stone as well, and these hominins seem to have known where it could be obtained.

At a practical level, they recognised that particular tasks needed particular materials, and they were prepared to travel to acquire them.

Knowledge transmitted between generations

The repeated pattern is particularly notable. Identical sourcing choices occur in several archaeological horizons separated by thousands of years.

This was not a single inventive individual discovering an effective approach. It represented a tradition.

The pattern indicates extensive familiarity with the landscape, including an awareness of which rocks justified the journey to collect them. It also implies that people understood which materials performed best for different purposes.

For millennia, this knowledge endured as it was transmitted from generation to generation.

Evidence for deliberate planning

Early hominins are often imagined as opportunists who used whatever their surroundings provided.

Instead, this research presents a different picture. It indicates beings with a detailed practical understanding of their environment, who planned toolmaking through several stages.

They also knew the local geology sufficiently well to seek particular outcrops for particular uses.

This understanding was not confined to one generation. Hominin parents, elders and expert toolmakers handed it down over generations through a form of transmission that remains incompletely understood.

The lake beside which they camped has disappeared, while some basalt flows they quarried now lie buried below the valley floor.

Yet the pattern behind the hominins’ decisions-which rock, for which tool, from which location-lasted long enough for scientists to reconstruct it almost a million years later.