This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Neanderthals are largely associated with colder climates across Eurasia. But researchers know that both Homo sapiens and Neanderthals moved through nearby Southwest Asia between about 100,000 and 50,000 years ago, and Arabia was a crossroads between Africa, Europe and Asia during the Ice Age.
Although no Neanderthal bones have ever been found in Arabia, a new study on stone tools in Arabia suggests Neanderthals roamed this warmer region 60,000 to 50,000 years ago. The study, published in Quaternary Science Reviews, links Neanderthal tool-flaking methods to tools from a site called Jebel Katefeh-1 (JKF-1), near an ancient lake in Saudi Arabia's Nefud Desert. Stone tools found across different sites in Arabia show striking differences, which researchers have had trouble explaining.
Fossils are scarce in Arabia, so stone tools are crucial for determining what populations may have lived there. To determine which populations occupied the sites, researchers needed to separate the effects of climate, geography, toolstone, site use and population history, all factors that might have contributed to the tool differences. JKF-1 had previously been dated too broadly to identify its place in regional human history, with a range spanning 90,000 to 50,000 years ago.
Past studies had shown Neanderthals expanded south into the Levant and Zagros region roughly 75,000 to 50,000 years ago, while evidence of Homo sapiens populations was also present throughout the region and time period. The authors of the new study write, "Technological analysis has pointed to unexpected technological heterogeneity in Arabia, particularly at JKF-1, leading to a suggestion of a complex demographic picture in the region during MIS 5. However, as the existing chronological constraint for this occupation spans the timeframes of both H. sapiens and Neanderthal presences in Southwest Asia, examining the source of this heterogeneity has been prohibited." To determine whether the tools from JKF-1 were more likely from Homo sapiens or Neanderthals, the team designed statistical tests that could evaluate whether tool variation was due to assemblage age, landscape setting, environmental conditions, assemblage size, composition and raw material use, site type or population history.
The method used a stone-tool artifact dataset of 704 complete prepared stone flakes, spanning parts of Africa, Arabia and the Levant between 100,000 and 50,000 years ago. It provided a basic description of key attributes to capture important characteristics of variability in the tools. The tool samples associated with Homo sapiens and Neanderthals were differentiated with more than 93% agreement in the reference dataset.
The team says population history best explains the differences in the shape of prepared stone flakes, according to its model. The results showed that stone tools from JKF-1 had features more similar to tool assemblages linked with Neanderthals than to those linked with Homo sapiens, with the model showing a median Neanderthal likelihood of 78% for the key stone-tool shape pattern. Only four artifacts showed a greater probability of being attributed to Homo sapiens populations than Neanderthals.
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