Early humans used grinding tools that were potentially part of a process for making simple breads, discoveries in what is now the north of Saudi Arabia show.
The findings, published in the journal Plos One, provide a deeper understanding of the subsistence strategies and cultural practices of Neolithic populations in a region where the preservation of organic matter is limited because of the aridity.
Northern Arabia was once considerably greener and wetter, making it much more conducive for early human populations to find water and game.
However, due to the present dry climate, little organic matter has been preserved, posing challenges to the reconstruction of Neolithic lifestyles.
Researchers adjusted dating methods to consider changes in the atmosphere's carbon levels over time.
Maria Guagnin, one of the lead authors from the Max Planck Institute of Geoanthropology, told The National one of the sites had a build-up of several layers "and the layers with the grinding tools were dated to about 7,000 to 8,000 years ago".
"The second site is also Neolithic with most of the fireplaces dated to between [about] 5300 and 4800 BC," she said.
Through the use of high-powered microscopes, researchers from the Max Planck Institute, the National Research Council of Italy, the Institute of Heritage Science and University College London conducted a use-wear analysis of grinding tools discovered at Jebel Oraf in the Nafud desert.
These grinding tools are believed to have been used to process bone, pigment and plant matter.
Moreover, these tools were repurposed over their lifespan until they were ultimately broken and placed on hearths.
By comparing the wear patterns on these ancient tools with modern experimental ones, scientists determined that different grinding activities leave distinct traces on the tool's surface.
"The findings allow us for the first time to get an understanding of the organic materials that were processed at the site, which have not survived because of the extreme aridity in the region today," Ms Guagnin told The National.
"The grinding stones are really striking. We now know that these highly mobile herders carried heavy grindstones – up to 3kg – with them because they used these tools for a range of different materials, which were all important for their daily life."
The Neolithic tools exhibited signs of being used to process meat and bones, suggesting that bones might have been crushed to gain access to the marrow.
While there is no evidence of domesticated grains in this period in northern Arabia, the study’s authors believe wild plants were ground and perhaps even baked into simple breads.
“The hearths where we found the grinding tools were extremely short-lived, indicating that Neolithic people might have been highly mobile,” Ms Guagnin said.
“Breads would have been a portable and ideal food for such populations.”
In addition, the tools provided evidence of pigment processing, which may have been associated with art.
The study suggests that pigments were processed on a larger scale than previously thought, suggesting the existence of more Neolithic rock art than the few surviving panels indicate.
“The Neolithic residents of Jebel Oraf clearly valued grinding tools,” said Giulio Lucarini, the study’s other lead author from the National Research Council of Italy.
“Many were extensively used, some to the extent that they had holes, indicating they might have been transported. This emphasises that these heavy grinding tools played a vital role in their daily routines.”
"The grinding tools we analysed were all made of sandstone, which is locally available," Ms Guagnin told The National.
"However, sandstone is not available directly at the site – they seem to have had grindstone workshops some kilometres away and then brought the tools to a camp site next to an ancient lake."
The methodology used in this research is a rarity for archaeological finds from the Arabian Peninsula.
However, it offers invaluable insights into the production, use and re-use of these ancient tools, shedding light on the daily lives, economy and art of the people who used them.
Researchers collaborated closely with the Saudi Ministry of Culture during the study, with further partnerships involving King Saud University and institutions from the UK, Ireland and Australia.
