Snails are part of the human diet (albeit modestly at present) in various regions and countries of the world, especially in the Mediterranean area, Africa and Southeast Asia. On the other hand, in many other cultures, these gastropod mollusks (terrestrial ones) cause absolute culinary rejection.
The scientific community has cataloged some 35,000 species of snails to date, from the tiny Angustopila dominikae, 0.9 millimeters high and 0.8 mm wide, to the giant African snail of the species Lissachatina fulica, which can reach in phase adult up to 30 centimeters long and belongs to the Achatinidae family, as well as being included in the list of the 100 most harmful species in the world (in terms of invasive species).
The Lissachatina fulica is one of the more than 200 species of members of the Achatinidae family, many of which have dimensions that we can consider colossal, when compared to the average snail. The body and shell of the giant African snail Metachatinsia kraussi also exceed 15 centimeters, the species that is now pointed out as the most possible candidate to be a food of great importance in human populations in the east of present-day South Africa, at least 170,000 years ago. years. The presence of remains of giant snails in the Border Cave archaeological excavation, in this sense, shows that these gastropods were part of the life and social behavior (perhaps they were one of the first foods cooked and consumed in community of the time) of our kind.
A study published in the Quaternary Science Reviews (April 15) by researchers from South Africa, Belgium, Argentina, France and Norway shows for the first time detailed results on the shells of the giant snails found in this South African cave and evidence that these snails were cooked (and presumably consumed by humans), almost completely ruling out that these shells were collected for exclusively ornamental or decorative purposes, as previously suggested. The species that is believed to have been found in Border Cave could be Metachatinsia kraussi but they are not entirely sure, precisely because the remains found seem to have been heated (cooked) at high temperatures.
Among other details, the team of archaeologists led by Marine Wojcieszak from the University of the Witwatersrand in South Africa, now signing off on this new study, shows that snails were a source of food for humans for much longer than previously believed.
Humans and human ancestors have inhabited Border Cave for a long time, with a record stretching back over 227,000 years, to as little as 600 years ago. This very long stay left records buried deep in the sediment of the cave floor.
The most recent excavations were carried out between 2015 and 2019 and turned up something curious: a large number of snail shell fragments, from many layers buried at different times. These fragments were traced back to the family Achatinidae but how and why they were in the cave was unknown.
Wojcieszak and colleagues noted that these fragments varied significantly in color, “from a bright beige to dull brown and gray.” This color variation can occur when the shells are heated, but it was necessary to test whether that was the case with the Border Cave fragments and the method of heating.
The researchers took shell fragments from the Metachatina kraussi snail because it is representative of the family of snails that produced the shells found in Border Cave and subjected them to different heating conditions in an oven with temperatures ranging from 200 to 550 degrees Celsius for different periods. of time.
The shells, both from the archaeological assemblage and from the experimental shell fragments, were then carefully studied using infrared, Raman and scanning electron microscopy. Thus, heat-induced changes in the minerals in the shells could be observed and confirmed that the alterations in the Border Cave fragments were caused by heat, not by the environment or decomposition. These changes include changes in color and gloss, the introduction of minute cracks, and loss of water and weight.
Most of the fragments recovered from the cave showed signs of heating, probably from having been cooked on coals. Since the shells would not have been heated evenly, this could explain why some fragments appeared raw.
This suggests that the people who lived in Border Cave collected snails and brought them home to share. Snails move slowly and picking them up is not dangerous. Although they can harbor dangerous parasites, careful handling would help prevent disease, plus the creatures are rich in many vitamins and minerals. And, as the researchers point out, giant snails remain a popular food source in West African countries.
It seems counterintuitive to believe that such an easily obtained, easy to eat, and nutritious food would have gone unnoticed by early humans. The work of Wojcieszak and his team supports this idea.
The researchers note that, in fact, along with evidence of cooking and eating starchy vegetables at the site, the snails may have been a way to help feed a large group of people.
“Border Cave is currently the oldest known site where this subsistence strategy is recorded. Previous research has shown that whole charred rhizomes and edible fragments of Hypoxis angustifolia were also brought to Border Cave to be roasted and shared on site.” , write the authors of the new study.
“Thus, the evidence for both rhizomes and snails in Border Cave supports an interpretation of group members provisioning others at a home base, giving us insight into the complex social life of early Homo sapiens,” the researchers conclude.
