Broken bits of shells found in a cave in South Africa have given researchers the earliest evidence for prehistoric people roasting and eating snails.
Other studies have pointed to snail consumption at sites in Europe around 30,000 years ago and in Africa around 40,000 years ago. 鈥淭here is a huge gap from that to our findings,鈥� says , who did the new work while at the University of Witwatersrand in Johannesburg, South Africa.
Excavations at Border Cave, in South Africa near its boundary with Eswatini, turned up the shell fragments in layers of dirt dating from 70,000 to 170,000 years ago. The shell scraps came in a spectrum of colours, so Wojcieszak and her colleagues wondered if heating had changed their hue.
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鈥淗eat treatment is a huge question in archaeological sites,鈥� she says. It is thought that our ancestors have used fire for at least 400,000 years, and there is some evidence of cooking as far back as 1.5 million years ago.
The prehistoric shells appear to be from the Achatinidae family of land snails, which can grow up to 16 centimetres long.
The researchers heated pieces of modern Achatinidae snail shell for periods from 5 minutes to 36 hours in a furnace and compared them with the ancient remains. Heating longer and at higher temperatures saw the fragments go from beige or brown to white and then grey. With heating, the shell also lost its shine and its molecular structure changed.
This indicates that the prehistoric shells had been heated to varying degrees, says Wojcieszak, suggesting that snails in their shells may have been placed on coals where they roasted unevenly. Heating also produced microscopic cracks, which were also observed on some of the ancient shells.
But the experiments don鈥檛 rule out the possibility that live snails burrowed into the ground and their shells were later heated by a fireplace, says Wojcieszak. There were, however, other remains of potential food items found nearby, including charred seeds and bones from large animals.
The study provides strong evidence that early humans who used the cave were systematically eating snails, says at Johannes Gutenberg University Mainz in Germany, who wasn鈥檛 part of the work. There may be other clues in the shells, he says, such as changes to pigments caused by heating, that may allow the researchers to narrow the temperature range of the potential cooking.
Quaternary Science Reviews
