Algerian fossils question East Africa as the sole origin of stone tools

The oldest known widespread stone tool technology, called Oldowan, would have appeared in East Africa about 2.6 million years ago and then spread to all over the continent.

But new evidence suggests that technology, rudimentary multipurpose cobblestones, may in fact have emerged independently in different parts of Africa. This is according to archaeologists who discovered stone tools and animal bones cut up on a high Algerian plateau.

The limestone and flint tools recently discovered date back about 2.4 million years, almost the same age as the oldest tools of this type, found in Gona, Ethiopia, and dating back to 2.6 million years.

This discovery means that hominins were present in the Mediterranean suburbs of North Africa about 600,000 years earlier than expected. The work is published on November 29 in Science¹.

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As with early stone tool discoveries in East Africa, researchers have not discovered any nearby hominin remains. It is therefore not clear if these objects were made by a species of Homo or a related kind.

This discovery suggests that hominines may have understood the idea of ​​using tools in several parts of Africa at once, rather than simply adopting a fashion that is more important than the idea of ​​using the same method. is prevalent from the East African Rift Valley, according to the research team led by archaeologist Mohamed Sahnouni. Spanish National Center for Research on Human Evolution in Burgos.

Sahnouni's team spent eight years probing the Ain Boucherit site in northern Algeria. They have unearthed a mine of chopping and cutting tools next to the notched and hammered bones of elephants, hyenas, pigs, crocodiles and other animals.

Dating dilemma

In the Rift Valley, objects yield relatively easily to their age through the argon – argon dating of the volcanic ash deposits in which they are found. There are no such rocks in the Algerian mountains.

Scientists have therefore used three distinct techniques to constrain the date: magnetostratigraphy, which exploits the recording of a rock from the direction of the Earth's magnetic field when it has solidified; the electron spin resonance of the quartz grains in the deposits, to deduce the date on which an object was buried; and checking the periods during which the animals whose bones were found with the tools existed.

None of these techniques is a direct technique, but since all three approaches are consistent, the team is convinced that their results are correct.

Multiple origins

The age difference between these tools and those found in the Rift Valley is too short for rock technology to have crossed deserts and mountains until North Africa, says Sahnouni. "I think that rightly argues for a multiple origin of stone technology."

Much of the earliest records of hominins-fossils and stone tools comes from East Africa – largely because of the research tradition initiated here by the spectacular discoveries on the fossils and tools of anthropologists Louis Leakey and Mary Leakey in the 1950s and 1960s, says Sahnouni. But also because of the ease of preservation and dating, which creates a possible bias in the data.

"We have to be careful not to build elaborate storylines based on where conservation is best," says Chris Stringer, a specialist in human evolution at the Natural History Museum in London. "It also remains to be determined whether there were direct links between hominines from North Africa and East Africa about 2.4 million years ago. , or if [they] could have evolved largely independently. "

Ignacio de la Torre, an archaeologist at University College London, acknowledges that he was probably exaggerating the importance of East Africa in this area. But he also quotes the 2015 report from a Kenyan site of stone tools dating back about 3.3 million years ago.². If the discovery of Kenya is confirmed, he adds, "this will show that stone technology first appeared in East Africa".