Researchers examined a bunch of sites known as Melka Kunture in Ethiopia's upper Awash River valley. They concentrated on 575 artifacts made from obsidian found at the Simbiro III site in Melka Kunture. The more than 500 artifacts – more than 30 of them consisting of teardrop-shaped hand axes that average about 4.5 inches long and weigh 0.7 pounds – were found at a layer of sand called Level C.
Fossil dating and geological data hint that relics buried at Level C are more than 1.2 million years old. The findings indicate that relatives of ancient humans may have frequently produced stone artifacts in an organized way, more than 500,000 years earlier than past finds in France and England.
The appearance of so-called workshops is considered a main achievement in stone tool creation. Since making stone tools requires skill and knowledge, the use of these tools among previous hominins – groups that include humans and the extinct species more directly linked to humans than any other animal – can provide a window into the evolution of the human mind.
Such workshops evolved as tool-making developed into a skill. People who cultivated such skills worked together in workshops to turn out enough of whatever tools were required by those in the particular area. (Related: Researchers find world's oldest stone tools in Kenya.)
One of those tools was the hand ax which could be employed for chopping or as a weapon. Other ancient humans may have also utilized these tools for scraping, butchering and digging.
Sapienza University of Rome archaeologist Margherita Mussi told LiveScience that the findings were "very new in human evolution."
Mussi also serves at the director of the Melka Kunture mission, which involves archaeologists from Italy and Spain. She said in an email that ancient hominins "are very often depicted as barely surviving, struggling with a hostile and changing environment. Here we prove instead that they were clever individuals, who did not miss the opportunity of testing any resource they discovered."
In their study published Jan. 19 in Nature Ecology and Evolution, the nearly exclusive use of obsidian at Simbiro III is uncommon during the Early Stone Age – from about 3.3 million to 300,000 years ago. Before and after Level C, obsidian tools were much more uncommon. Level C also encountered seasonal flooding, with a wandering river probably depositing obsidian rocks at the site.
Obsidian tools can have exceptionally sharp cutting edges. However, the volcanic glass is fragile and hard to craft without smashing. Obsidian axes from this level were much more regular in shape and size, indicating mastery of the crafting technique. By itself, obsidian usually only found extensive use in stone tool production starting from the Middle Stone Age, which ranged from about 300,000 to 50,000 years ago, researchers stated.
Still, it remains a mystery which hominin may have made these artifacts. According to Mussi, scientists have found remains about 1.66 million years old that may have been Homo erectus. Other fossils purportedly belonging to H. heidelbergensis have also been found, with their ages estimated to be about one million years old.
As stated by the Smithsonian Institution, H. erectus is the oldest known early human to possess body proportions identical to modern humans, whereas H. heidelbergensis may have been a normal ancestor of both modern humans and Neanderthals.
Mussi added that because the age of Level C at Simbiro III is more than 1.2 million years old, the hominins that created the obsidian hand axes there may have been closer in nature to H. erectus.
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