The structures found in the bed of ancient lakes in Saudi Arabia show the successive spread of different cultures.
If you know what to look for in satellite imagery – such as small depressions or subtle color changes – in the sandy deserts of the Arabian Peninsula, you can see dried images of prehistoric lakes.
Eight years ago, an ancient lake in Saudi Arabia’s desert caught the attention of researchers. According to a new study, when researchers began exploring the area, they found thousands of stone tools, as well as evidence that numerous waves of Homo sapiens and their relatives migrated throughout Saudi Arabia for at least the last 400,000 years.
The results of this study reinforce the theory that the periodic and intermittent greening of this desert has played a major role in the spread of human populations outside Africa. This study also provides the best evidence that various groups of humans left the continent through the Sinai Peninsula. “Where there is a lake, there will be people and they will find their way,” said Jessica Thompson, a paleontologist at Yale University who was not involved in the study.
Today, the desert is infiltrated, sparsely populated, and full of sand dunes and drought-resistant shrubs. But past excavations and long-standing climate models have shown that over the past half-million years, short periods of wetter, warmer conditions have caused seasonal rainfall in the area, turning low-lying ponds into lakes and streams into rivers. In short, the very dry desert has turned into a lush meadow – a “green Arabia” – but eventually turns to sand again after the dry air returns.
In 2013, telephoto specialists turned their attention to several ancient riverbeds west of Nafud in northern Saudi Arabia that looked unusually colorful in satellite imagery. Michael Petraglia, an archaeologist at the Max Planck Institute for the Science of Human History (SHH), suspected that the marble-colored strips of sediment indicated several periods of emptying and filling with water.
He and his colleagues went to an area called Khall Amayshan 4. “When we got there, there were stone tools everywhere, and we immediately realized that this was a unique area,” said Hu Grokat, a Petraglia colleague at the Max Planck Institute.
Using an excavator, the researchers dug trenches in the lake bed. They dated the layers using optically stimulated luminescence, a technique that determines when grains of sand were last exposed to sunlight, and then identified the stone tools associated with each layer. Excavations at the site revealed that the lakes formed and dried up in six different time periods. Researchers in an article in the journal Nature It has been reported that stone tools are associated with five of these lakes that are now extinct, dating back to four hundred thousand, three hundred thousand, two hundred thousand, one hundred thousand and fifty-five thousand years ago. In another of these extinct lakes, 150 miles[150 km]to the east, stone tools were found in layers dating to two hundred and seventy-five thousand years ago.
In addition to the tools, the researchers found animal bones in many dried-up lakes, suggesting that large African animals, such as hippos, elephants and ostriches, followed this lush path outside Africa, at least in wet seasons. they did. No fossils belonging to the anthropoids were found in the new excavations.
It is not clear to which human species the tools in the two layers, which are older than the others, belonged, but these stone tools are usually attributed to the ancestral relatives of our species, such as Homo erectus. The tools found in layers from two hundred thousand, one hundred thousand and seventy-five thousand years ago were made smaller and more precise, thought to have been made by our own species. Grockat says what happened to these early migrants remains unclear.
However, Abdullah al-Sharkh, an archaeologist at King Massoud University and one of the authors of the study, says that even with the unknown, the study is revealing “much of what was buried under the sand for millennia.”
The latest tools – those dating back to fifty-five thousand years ago – are very similar to Neanderthal tools. Researchers have found the remains of Neanderthals in caves in the Middle East. If the new findings are substantiated, it would indicate that Neanderthals also entered the lush peninsula and may even have encountered our species there.
Of course, researchers have known for years that Saudi Arabia played an important role in early human migration. Grim Barker, an archaeologist at the University of Cambridge who did not play a role in the study, says the new study provides the most systematic design of these displacements in this critical area and points for the first time to successive waves of specific species at specific times.
Grokat says the location of many of these non-existent lakes – in the northern parts of the Arabian Peninsula – points to the Sinai Peninsula as the most likely route for human migration out of Africa (instead of the southern tip of the Arabian Peninsula as suggested by some researchers). Thomson agrees with this interpretation and says: ” [مهاجرتهای انسانی] through [شبهجزیره] “Sina seems to be the best model given the evidence.”