Researchers at Nagoya University in Japan have shed light on how early humans in the Paleolithic selected specific rocks for making tools, rather than just based on how easy they were to break. This finding suggests that they had advanced technical skills to identify the best stone for each tool.
As Homo sapiens spread from Africa to Eurasia, they used stone tools made from stones such as obsidian and flint to cut, cut, and make weapons. Nagoya University archaeologists Eiki Suga and Seiji Kadowaki focused their study on prehistoric sites in Jebel Qalkha, Jordan, analyzing flint nodules used in the Middle and Upper Paleolithic periods (70,000 to 30,000 years ago). They believe that people in the Paleolithic knew which rocks were suitable for making tools and therefore specifically selected them. They preferred smooth, translucent flint because it was easy to break and formed sharp edges.
The researchers used a Schmidt hammer and a Rockwell hardening device to test the mechanical properties of the rocks. They found that fine-grained flint required less force to break than medium-grained flint, making it more attractive for making small stone tools. However, previous studies showed that medium-grained flint was more common than fine-grained flint in stone tools during the late Middle Paleolithic and early Upper Paleolithic. This was because much of the fine-grained flint in the area had numerous internal fractures caused by geological activity, making it unsuitable for large stone tools.
It therefore appears that people in the Paleolithic chose medium-grained flint for large tools, even though it was a difficult material to modify, as it tended to have a longer lifespan. This provides a fascinating insight into the behavior of our ancestors, as they selected flint based on several factors in addition to ease of breaking and were able to identify the most suitable rock for making stone tools.
Suga was excited by the results, which suggested the complexity of our ancestors’ behavior. “This study shows that Paleolithic people changed their choice of raw materials to adapt to the morphologies and production techniques of their stone tools,” he said. “We believe that these prehistoric people had a sensory understanding of rock properties and consciously selected the stone material to use based on the shape and manufacturing technique of the desired stone tools. This conscious selection of stone material may have been an important part of the production of stone tools. This may show an aspect of flexible technological behavior adapted to the situation.
These discoveries provide valuable information about how Homo sapiens thrived and adapted to their environment and are important evidence for elucidating the evolution of human engineering behavior, environmental adaptation, and the population growth process at this time.
Explaining the increase in “high-quality chert” in Early Paleolithic artifacts in southern Jordan: Quantitative study of chert mechanical properties and fracture predictability