AI and chemical analysis reveal early humans traveled miles for flint to make handaxes

According to researchers, "These early humans had high social and cognitive abilities: they were familiar with their surroundings, knew the available resources, and made great efforts to procure the high-quality raw materials they needed. For this purpose, they planned and carried out long journeys, and transferred this essential knowledge to subsequent generations."

The study that included these findings was published in Geoarchaeology.

The source of raw materials analyzed

The current study sought the source of the raw material utilized to make thousands of handaxes discovered at two prehistoric sites in the Hula Valley: Gesher Benot Ya'aqov (750,000 YBP) and Ma'ayan Barukh (500,000 YBP), both of the Acheulian civilization. 

The team reports that around 3,500 handaxes were found scattered on the ground at Ma'ayan Barukh, with thousands more discovered at Gesher Benot Ya'aqov. 

"The average hand axe, around 10cm long and 200g in weight, was made by reducing five times bigger stones - at least 1kg of raw material. In other words, the 3,500 handaxes discovered at Ma'ayan Barukh alone required 3.5 tonnes of flint. But, where did they go?" said Prof. Gonen Sharon of the MA Program in Galilee Studies at Tel-Hai College. 

The new study by the team could finally find answers to this important question. The process involved researchers obtaining samples from 20 handaxes, 10 from Gesher Benot Ya'aqov and 10 from Ma'ayan Barukh, crushing them into powder, then dissolving the powder in acid in a clean lab. They analyzed the concentration of roughly 40 chemical elements in each sample using an ICP-MS (inductively coupled plasma mass spectrometer), a cutting-edge technology that correctly monitors the concentration of dozens of elements down to a precision of one particle per billion.

"The complex process, from collecting and preparing the samples to the chemical analysis, produced a very large amount of data for each sample. To enable optimal matching between data from the archaeological artifacts and data from the flint exposures, we developed a dedicated algorithm based on several computational steps, alongside machine learning models. Thus, we were able to classify the archaeological artifacts according to the database derived from the geological samples," said Dr. Yoav Ben Dor from the Geological Survey of Israel.

The study concluded that these individuals living in the Hula Valley hundreds of thousands of years ago, most likely homo erectus hominids, showed advanced cognitive and social capacities. "To procure suitable raw materials for producing their vital handaxes, they planned and carried out 20km hikes that included an ascent from 70 to 800 meters above sea level. Moreover, they passed on this important knowledge from one generation to the next, over many millennia. All these suggest a high level of sophistication and ability, which modern researchers do not usually attribute to prehistoric humans from such an early period," said Prof. Erez Ben-Yosef of Tel Aviv University.

Abstract:

The Hula Valley has two key Acheulian sites: Gesher Benot Ya'aqov (GBY), a large flake Acheulian site with hundreds of basalt bifaces and a significant number of flint handaxes, and Ma'ayan Barukh (MB), where more than 3500 flint handaxes were collected. Over the last one million years, the valley was filled by alluvium and basalt flows, devoid of flint sources suitable for handaxe production. We conducted archaeological and geological surveys combined with an inductively coupled plasma mass spectrometry geochemical study to determine the source(s) of flint, comparing elemental compositions of handaxes from GBY and MB with those of different flint sources using a novel statistical method. The results demonstrate that Hula Valley Acheulian flint handaxes were derived from Eocene flint. For GBY, the nearest matching source for its small number of excavated handaxes is a secondary deposit of the Dishon streambed found ~8 km northwest of the site. A more likely source for both GBY and the thousands of MB handaxes is the Dishon flint extraction and reduction complex located 20 km to the west, a possibility also supported by the near absence of production waste flakes at the sites themselves. These findings support direct procurement strategy as early as the Lower Paleolithic.