Stone tool discovery challenges entire theory of early human intelligence and evolution

Imagine our early human ancestors standing in the ancient landscapes of southern Jordan, thoughtfully examining rocks before deciding which ones to use for their tools.

It turns out they weren’t just grabbing any stone that was easy to break; they had specific preferences and technical skills in choosing the right material.

Archaeologists Eiki Suga and Seiji Kadowaki have been exploring this fascinating aspect of early human behavior.

They’re from Nagoya University in Japan, and their recent research offers new insights into how Paleolithic humans selected rocks for tool-making.

Their study, published in the Journal of Paleolithic Archaeology, focuses on prehistoric sites dating from 70,000 to 30,000 years ago.

These sites are in the Jebel Qalkha area of southern Jordan, a crucial region as Homo sapiens expanded from Africa into Eurasia.

Early humans, rocks, and tools

As early humans moved into new territories, they relied on stone tools made from materials like obsidian and flint.

Understanding how they crafted these tools helps archaeologists piece together aspects of their culture and daily life.

Suga and Kadowaki analyzed flint nodules from outcrops that ancient people used during the Middle and Upper Paleolithic periods.

They wanted to see if early humans were intentionally selecting certain types of flint based on its properties.

They hypothesized that these humans looked for flint that was translucent and smooth because it could be easily shaped into sharp edges. This suggests a level of sophistication in recognizing the best materials for specific tools.

Testing the rocks’ qualities

To investigate, the team used two devices: a Schmidt Hammer and a Rockwell Hardness Device.

The Schmidt Hammer measures the strength of concrete or rock. The hammer hits the surface with a defined amount of energy, and the rebound is measured. That value is then used to determine the strength of the material.

The Rockwell device presses a diamond point into the rock to test its strength. It then calculates the material’s hardness based on the depth of the indentation left behind.

Initially, as expected, they found that fine-grained flint required less force to fracture than medium-grained flint.

This made it more attractive for producing smaller tools. In fact, many stone tools from the Early Upper Paleolithic period, around 40,000 to 30,000 years ago, were made from fine-grained flint.

But here’s where it gets interesting.

An earlier study by the same team revealed that during the Late Middle Paleolithic and the Initial Upper Paleolithic periods, from 70,000 to 40,000 years ago, medium-grained flint was more commonly used for tools.

So, if fine-grained flint was easier to work with, why did our ancestors sometimes opt for the tougher medium-grained variety?

Tools were carefully chosen by early humans

Digging deeper, the researchers discovered that much of the fine-grained flint in the area had internal fractures caused by geological activities.

These fractures made the flint unsuitable for larger tools, like Levallois products and robust blades.

Therefore, even though medium-grained flint was harder to modify, it was more durable for making larger tools.

This indicates that Paleolithic humans made deliberate choices based on the intended use of the tool, balancing ease of crafting with durability.

“This study illustrates that the Paleolithic humans changed their choice of raw material to suit their stone tool morphologies and production techniques,” Suga explained.

“We believe that these prehistoric humans had a sensory understanding of the characteristics of the rocks and intentionally selected the stone material to be used according to the form and production technique of the desired stone tools.”

Much smarter than we thought back then

This research offers a window into the thoughtful decision-making of our ancestors.

They weren’t just using what was readily available; they were assessing the qualities of different materials and selecting the best one for the job.

“This intentional selection of the lithic raw material may have been an important component of the production of stone tools,” Suga said.

“This may show some aspect of flexible technological behavior adapted to the situation.”

Their ability to adapt and make these choices reflects a level of technological and cognitive sophistication that adds depth to our understanding of human evolution.

Why does any of this matter?

There are still many questions about how and why Homo sapiens expanded their reach between 50,000 and 40,000 years ago.

While ancient DNA has shown that modern humans interacted and interbred with Neanderthals and Denisovans, it doesn’t tell us the whole story.

“If we want to know what happened that allowed Homo sapiens to thrive, we need to study cultural remains, such as stone tools, excavated from archaeological sites,” Suga pointed out.

“This kind of resource use is an important record for elucidating the evolution of human technological behavior, environmental adaptation, and the process of population growth at that time.”

By examining these tools and the materials chosen to make them, researchers can piece together how early humans adapted to their environments and what strategies they used to survive and flourish.

Humans, tools, and early evolution

To sum it all up, this study emphasizes the importance of archaeology in understanding human history.

The choices made by Paleolithic humans in selecting their materials reveal a level of ingenuity and adaptability that has been a hallmark of our species.

As we continue to explore and discover more about our ancestors, each finding adds a new piece to the puzzle of human evolution.

It’s a reminder of the complex journey that has led us to where we are today and the innate curiosity and problem-solving skills that have always been part of human nature.

The full study was published in the Journal of Paleolithic Archaeology.

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