Stone Age Britons extracted salt from seawater using industrial-style processes more than 5500 years ago. The discovery means people in Great Britain were producing salt thousands of years earlier than thought, before the Bronze Age.
The technology may have been brought by migrants arriving from mainland Europe.
“It changes how we think about Neolithic society,” says Stephen Sherlock, an independent archaeologist based in Redcar, UK.
In mainland Europe, there is evidence of salt production from the heating of salty water as early as 6050 BC during the Neolithic: the last period of the Stone Age, before the invention of bronze. However, in Britain the earliest known evidence was from Brean Down in Somerset, where Bronze Age people were making salt around 1400 BC.
Sherlock has been excavating for many years at Street House, near the town of Loftus in north-east England. The site was occupied from the Neolithic, about 5700 years ago, into the later Bronze Age and the Iron Age that followed, and as recently as the 7th century AD in the Anglo-Saxon period of English history.
Geophysics revealed a buried structure about 200 metres from a Neolithic house, so Sherlock began digging.
“It was sealed by about a metre of clay,” says Sherlock. Beneath that was a distinctive pit measuring 2.8 metres by 2 metres, with a narrow trench leading into it. Three areas of the pit had been intensely burned, leaving charcoal deposits: Sherlock argues these were hearths. A hazelnut shell in the charcoal layer was radiocarbon dated to between 3766 and 3647 BC.
Similar structures are known from Iron Age deposits in Britain and are generally interpreted as “salterns” used for extracting salt from seawater. The water was placed in large ceramic pots, supported by stones over hot flames. The heat evaporated the water, leaving salt crystals. Sherlock found shards of pottery of a low quality characteristic of salt production.
“I showed these finds to salt-making experts,” says Sherlock. “They said you’d expect to find that in the Iron Age.”
Salt would have been the most valuable commodity in society, says Sherlock. It was hard to obtain and could be used to flavour or preserve food, for instance. “The people who controlled salt are going to be some of the richest.”
Journal reference: Antiquity, DOI: 10.15184/aqy.2021.25
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Source: Humans - newscientist.com