The discovery of 2.4 million-year-old stone tools and bones slaughtered at a site in Algeria shows that our hominin relatives far spread to northern Africa far earlier than archaeologists had expected. This finding adds credence to the newly emerging suggestion that ancient hominins lived – and evolved – outside the Garden of Eden which was supposed to be in East Africa.
This extraordinary discovery can be traced back to 2006, when Mohamed Sahnouni, lead author of the new study and an archaeologist at the National Research Center for Spanish Human Evolution, discovered several interesting artifacts at a site called Ain Boucherit in northeast Algeria near the city of El-Eulma . These items are embedded in layers of sediment exposed by deep ravines.
Two years later, Sahnouni found another layer on the site, one of which was even older. From 2009 to 2016, his team carefully worked at Ain Boucherit, revealing a collection of stone tools and the remains of slaughtered animals.
Using dating techniques, Sahnouni and his colleagues set a date for two stratigraphic layers, dubbed AB-Up and AB-Lw, at 1.9 million and 2.4 million years, respectively. The items in these two layers are now the oldest known artifacts in North Africa, the oldest 1.8 million-year-old stone tool discovered in the late 1990s on a nearby site called Ain Hanech.
The tools found in the AB-Lw layer, at 2.4 million years, are 600,000 years older than those found in Ain Hanech, and 200,000 years younger than the oldest tools found in East Africa (and the world, for that matter ) – Oldowan Gona, Ethiopia, dated 2.6 million years ago. Scientists used to believe that early hominins evolved in this African region, spreading north about a million years later. But this finding now shows a much earlier distribution date to the continent.
To put these dates into perspective, our species, Homo sapiens, appeared 300,000 years ago. So the unknown hominins who built these tools are blabbering around eastern and northern Africa about 2.3 million years before modern humans hit the scene. The new discovery at Ain Boucherit, whose details were published today in Science, shows that North Africa is not only a place where human ancestors lived and developed tools – it was the place where they evolved.
Indeed, this new study feeds into the emerging narrative, in which humans evolved throughout the African continent as a whole, and not only in East Africa according to conventional thinking. What's more, it must spur an increase in archeological interest in northern Africa.
For now the layer, Sahnouni uses three different techniques: magnetostratigraphy, Electron Spin Resonance (ESR) dating, and biochronological analysis of animal bones found mixed with tools.
Eleanor Scerri, an archaeologist from Oxford University who is not affiliated with the new study, said the researchers did a great job with dating, saying it was "very difficult" to accurately date ancient hominin sites.
"The authors have combined several dating methods to produce an age estimate for the initial occupation [AB-Lw layer] it became around 2.4 million years ago, "Scerri told Gizmodo." They do this by reconstructing a sequence of geomagnetic reversals preserved in locality, which is globally quite good. The researchers then found a chronological location of … layers of work in this sequence through a combination of electronpin resonance (ESR) of minerals in sediments and fossil identification. [animals]. "
Scerri said this method well limits dates but involves some uncertainties and assumptions.
Jean-Jacques Hublin, researcher from the Max Planck Institute for Evolutionary Anthropology – also not involved with new research – was not happy with the dating techniques used by Sahnouni and his colleagues.
"Extraordinary claims require extraordinary evidence and people can have some objections regarding the age proposed for Ain Boucherit and Ain Hanech sites," Hublin told Gizmodo. "Palaeomagnetism is not a dating method. It helps to limit the dates obtained by other methods and is subject to various interpretations."
Fair enough. This is indeed an extraordinary claim, so independent efforts to determine these layers and artifacts will support the research conclusions.
"If confirmed, the findings show that hominins occupied North Africa almost one million years earlier than previously thought," Scerri said. "These dates will also make Oldowan in North Africa only slightly younger than in East Africa."
By Oldowan, Scerri refers to the oldest known stone tools industry in the world. This technology changed the irreversible history of the evolution of hominins, setting the stage for more sophisticated stone tools, such as the next Acheulean culture.
Remarkably, the stone tools found at Ain Boucherit are very similar to Oldowan tools in East Africa. Lithium Oldowan has a rock core with flakes that are removed from the surface, so that the edges are sharp. In addition to these tools, the researchers found very fragile ball-shaped stones, whose purpose was not entirely clear.
"Ain Boucherit's archeology, which is technologically similar to Gona Oldowan's, shows that our ancestors traveled throughout Africa, not just East Africa," Sahnouni said in a statement. "Evidence from Algeria has changed [our] previous views on East Africa [as] become a human birthplace. Actually, all of Africa is a human birthplace. "
To explain the existence of Oldowan technology in North Africa, the researchers posit two scenarios: Either this technology was developed by hominins in East Africa about 2.6 million years ago, who quickly spread themselves and their new technology to the north, or hominins living in North Africa creates Oldowan technology independently from other groups.
In terms of animal bones found, archaeologists found traces of mastodons, elephants, horses, rhinos, hippos, wild antelopes, pigs, hyenas, and crocodiles – oh my! Obviously, these ancient hominins were not voter eaters. Importantly, many of these animals are associated with open savanna environments and permanent freshwater bodies that are easily accessible. This might describe the landscape inhabited by Oldowan hominins at that time.
Analysis of fossil bones reveals distinctive signs of meat cutting, such as V-shaped shocks involved in evisceration and deflection, and the impact of notches suggestive of marrow extraction. Ain Boucherit is now the oldest site in North Africa with tangible archaeological evidence of meat use along with the use of stone tools.
"The effective use of sharp stone cutting tools such as knives at Ain Boucherit shows that our ancestors were not just scavengers," Isabel Caceres, an archaeologist at Rovira i Virgili University in Spain and co-author of the study, said in a statement. "It's not clear at this time [is] are they hunted, but the evidence clearly shows that they managed to compete with carnivores for meat and enjoy first access to animal carcasses. "
Unfortunately, no hominin bone was found in that location, so researchers could only make educated guesses about the exact species responsible for the device. That is already possible Homo habilis, early human species around at that time, or even late Australopithecines, The genus hominin associated with the famous Lucy fossil.
Scerri said this paper highlights the importance of North Africa, and also the Sahara, for archaeologists who want to learn more about human origins. The newspaper, he said, also raises new questions about the evolution of previous hominins, such as the origin and spread of Oldowan technology.
"This paper cannot answer these questions, but it changes the narrative by raising them, which basically shows that there might be an alternative to the dominant model from East Africa," he told Gizmodo.
"As the authors point out, fossils are 3.3 million years old Australopithecus bahghghali has been found in the area of Chad Sahara. The findings reported by Sahnouni and his colleagues add to the growing evidence that North Africa and the Sahara can also produce findings that change the game. "
Humans Are Not Developing from Single Ancestral Populations
In the 1980s, scientists learned that all humans living today came from a woman, nicknamed "Mitochondrial Eve", who lived in Africa between 150,000 and 200,000 years ago.
This finding is very consistent with Scerri's own research. In an Ecology and Evolution Trend paper published last July, Scerri and his colleagues claim that Homo sapiens has pan-African origin, and that our species does not evolve from a single ancestral population.
"In our model, human ancestors have spread throughout Africa," he explained. "Different populations come in contact with each other at different times and in different places, with these dynamic patterns of mixing and separation eventually leading to the emergence of behavioral and biological characteristics of contemporary human populations. Findings from Sahnouni and colleagues match this see, although it is quite loose because they precede the earliest luster of our species difference of around 1.8 million years. "
Going forward, Scerri hopes that scientists will make a more integrated effort to explore areas that are thought to be "less important" in Africa to get more accurate – and real – An overview of the evolution of hominins from time to time.
"Exploring the Sahara and other areas that are in the corners of a less glitzier map of humanity is likely to produce important results, which in no way diminishes the very important and valuable findings of east and south Africa."[Science]