Research over the past few years has shown that the now dry northern Arabian region was once very lush and verdant, providing ample water and wildlife resources for early Neolithic human societies. However, the region's current drought has left little organic material preserved, posing challenges for piecing together the lifestyles of Neolithic inhabitants.
Now, in a new study published in the journal PLOSONE, researchers from the Max Planck Institute for Palaeoanthropology, the Italian National Research Council Institute for Heritage Sciences (CNRISPC), and University College London performed wear analysis on ground tools unearthed from Jebel Oraf in Saudi Arabia's Nafud Desert, revealing this little-known chapter in the human story. Use-wear analysis shows that ground tools were used to work bones, pigments and plants, were sometimes reused for different purposes during their lifetime, and were finally broken and placed on a hearth.
In the new study, researchers used high-powered microscopes to compare use-wear patterns on archaeological and experimental tools. In experiments, grinding grains, other plants, bones, or pigments produced unique macro- and microscopic marks on the surfaces on which the tools were used, including fractures, rounded edges of individual grains, flat areas, striations, and different types of polish. Scientists have also found these unique marks on Neolithic grinding tools, identifying the materials worked on.
While animal remains had shown that meat was cooked and eaten at Jebel Olaf, wear patterns suggest that the meat and bones were first processed on grinding stones, revealing the possibility that the bones were cracked to obtain the marrow.
Grinding tools are also used for processing plants. Although there is no evidence that cereals were domesticated in northern Arabia during this period, the authors suggest that wild plants were ground and perhaps baked into simple bread.
Maria Guagnin, a researcher at the Max Planck Institute for Palaeoanthropology and one of the lead authors of the study, said: "We found that the tool-grinding hearths were extremely short-lived and that people were probably very mobile - bread was a good, easy-to-transport food for them."
The researchers also found evidence of pigment processing, which they believe may be related to Neolithic paintings. The results show that pigments were ground and processed on a much larger scale than previously assumed, suggesting that there may be more Neolithic rock art than the few surviving panels suggest.
"It is clear that grinding tools were very important to the Neolithic inhabitants of Jebel Olaf. Many of the tools were used extensively and some even had holes in them, suggesting that they were transported. This means that people carried heavy grinding tools with them and their function must have been an important element of daily life," said Giulio Lucarini of Italy's National Research Council, another lead author of the study.
This type of analysis has rarely been applied to archaeological material from the Arabian Peninsula, but it can provide important information about the manufacture, use, and reuse of ground tools, providing insight into the lives, economies, and arts of the people who made them.