120,000 years ago, in modern northern Saudi Arabia, a group of Homo sapiens, humans identical to ourselves, stopped near a lake also frequented by camels, buffalos and elephants larger than current species. The visitors did not stay long, the lake being only a stopover on a long journey.
The scene was reconstructed by researchers in a study published Thursday, September 17 in the journal Science Advances, after the discovery of ancient traces of human and animal footsteps in the Nefoud desert, new clues on the paths taken by our distant ancestors after leaving Africa.
The Arabian Peninsula today is made up of large unwelcoming deserts, but scientists have for a decade established that it was once greener and wetter. “There were times in the past when the deserts that dominate the interior of the peninsula turned into great meadows, with the presence of permanent lakes and rivers”, told Agence France-Presse (AFP) a co-author of the study, Richard Clark-Wilson, of the British Royal Holloway University.
Dated impressions thanks to stimulated optical luminescence
The first author of the study, Mathew Stewart, of the Max Planck Institute in Germany, says he discovered the footprints during his doctorate in 2017, after the erosion of sediment at the site of an ancient lake called “Alathar” (” the trace “, in Arabic).
“Footprints are a unique form of fossil evidence that represents an instant in time, on the order of hours or days. We do not have this resolution with the other statements ”, he said.
The prints were dated using a technique called Stimulated Optical Luminescence, which involves emitting light towards the quartz grains and measuring the energy emitted by them.
Of the hundreds of footprints found, seven were confirmed to belong to hominids, four of which belonged to two or three individuals traveling together, given their common orientation, distance between them and differences in size.
A very attractive territory for humans
For the researchers, the stature and mass of the humans indicate that they were modern humans and not Neanderthals, the latter not having been present in this region at the time anyway.
The fact that no stone tool was discovered led the researchers to rule out that the site was permanently inhabited. “It seems that these people passed by the lake to get water and find food, at the same time as the animals”, says Mathew Stewart.
The presence of elephants suggests that the area was abundant in vegetation and water. Scientists also unearthed 233 fossils on site, supporting the hypothesis that carnivorous species came to hunt herbivores around the lake, as they do today in African savannas.
It has been established that humans colonized Eurasia from Greece and the Levant, exploiting coastal resources. These new works indicate that “The inland routes, following lakes and rivers, may have been particularly important”, according to Mathew Stewart. “The presence of large animals such as elephants and hippos, combined with the vast grasslands and abundant aquatic resources, may have made northern Arabia very attractive to humans between Africa and Eurasia.”, summarizes another co-author, Michael Petraglia, of Max Planck.
