Our ancient ancestors may have ventured outside of Africa much earlier than previously believed, according to archaeologists working in Jordan. They say they have found stone tools there that were made and used 2.5 million years ago.
鈥淣ow we know that hominins left Africa at least 700,000 years before we thought,鈥� says at the University of S茫o Paulo in Brazil.
Our lineage appears to have remained in Africa for millions of years after it emerged there about 7 million years ago. The oldest widely accepted evidence of hominins outside Africa is from Dmanisi in Georgia, where there are 1.8-million-year-old fossilised remains identified as Homo erectus.
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Since 2013, Neves and his team have been excavating a rocky outcrop in the Upper Zarqa valley in Jordan. They focused on three rock layers. At the bottom is a layer of volcanic basalt, which their dating techniques show is 2.5 million years old. Above this is a layer of sediments laid down by a river, which contains the purported stone tools. Finally, on top is a layer of 1.95-million-year-old limestone., based on three different methods, in a 2019 study, to little notice.
To firm up their case, they have re-examined the purported stone tools and described them in detail. The tools, they say, are a type called Oldowan that have been found at multiple locations in Africa, dating back as far as .
The difficulty is that the researchers found these artefacts in what was once a fast-flowing river, says at the George Washington University in Washington DC. Some of the stones could have been reshaped to look like hominin-made tools simply by being bashed around in the water, he says. 鈥淭hat said, there are definitely objects in this collection that appear to be made through hard hammer percussion,鈥� he adds.
As such, he is persuaded that Neves and his colleagues really have made an important discovery. 鈥淢y take on this is that there is very likely a hominin in Jordan making artefacts prior to 2 million years ago,鈥� says Braun. 鈥淚 am uncertain exactly how much earlier than 2 million years ago.鈥�
Because some of the tools were found just above the basalt layer, Neves argues they are probably 2.5 million years old. This makes them older than any known fossils of H. erectus, implying that another hominin species was the first to leave Africa.
Neves points to Homo habilis, which may have been present or even earlier. 鈥淥ur hypothesis is that the first hominin to have left Africa was Homo habilis and not Homo erectus,鈥� he says.
Other researchers have claimed to have evidence of hominins outside Africa older than the Dmanisi remains. At Shangchen in China, researchers have described , while at Longgupo, also in聽China, there are stone artefacts and hominin remains that have been claimed to be 2.5聽million years old. There are also claims of stone tools in northern India 2.6 million years ago. However, none of these claims have been widely accepted. Either the artefacts themselves, or their ages, or both, have been questioned.
鈥淭he truth is that we know very little about the earliest excursions of hominins [outside Africa],鈥� says Braun.
Journal of Paleolithic Archaeology
