The rise in sea level has destroyed the traces of shells in many prehistoric coastal sites

The archaeological remains of coastal occupation in the form of clusters of shells are usually found on the shores of today, and evidence indicating that shellfish are a source of food goes back to 164,000 years ago. During this period, the sea level has changed considerably and the coastline has shifted to the kilometer scale. This study, published in PLOS ONE, reveals that this movement of the coasts has had an impact on the majority of shelly clusters by causing the current elimination or submersion of shells, and thus has distorted our understanding of the coastal subsistence spent in the world.

Shells, as food waste, are a common find on the coastal archaeological sites of the last 164,000 years – but many can now be hidden from view.

In this study, an international team of researchers quantified the models that were first described by the famous Australian archaeologist and anthropologist Betty Meehan in the 1970s. Meehan described how modern coastal foragers on the Australian coast transformed most of their shellfish directly to the shore to reduce the weight of transport and only carried shells that still contained meat more inland until their main place of residence. The researchers hypothesized that if prehistoric peoples used the same strategy on a given site and if the sea level had increased dramatically ever since, archaeologists today would find no more evidence of it. existence of large shells related to this population. If only a few shells were found near the site, researchers might assume that the population did not rely much on shellfish for their livelihood – which would of course be inaccurate.

With the help of a large group of more than 3,000 prehistoric vortex sites located on the Farasan Islands in the Red Sea, researchers assessed their spatial and temporal trends in the context of a long-term change in sea level. A selection of sites has been radiocarbon dated from 7,500 to 4,700 years ago. During this period, the sea level south of the Red Sea was still rising as glaciers melted at the end of the last ice age. The climb stopped about 6,000 years ago and the sea level was slightly higher (2-3 m) than today. This has been followed by a gradual drop in our current level of the sea for about 2,000 years, with the exception of the rise of recent decades.

Coastal exploitation of shellfish has changed little during this period, and shell accumulation rates based on radiocarbon dating indicate that 10 times more shellfish deposited on the direct shore than on "post-shore" sites, similar to Meehan's ethnological research. However, despite their larger size, no littoral site has been preserved, but it closely monitors sea level change in this region and indicates a large number of sites that had to be lost in the sea from the beginning of coastal livelihood.

Usually well preserved on archaeological sites, shells are easily washed away by rising sea levels.

"We already knew that the coastal sites were in a precarious situation and we often rely on sites located along steep cliffs or a few hundred meters inland to study the collection of seashells dating from 39, before the sea level of today, "says the first author, Niklas Hausmann, of the Max Planck Institute for the Science of Human History. "We now know that there is not a small piece left at the beach, but the bulk of the shell tissue, which really compromises our idea of ​​the amount of shellfish consumed at the sites, even slightly at the Inland. "

"Thanks to our study, we have shown that shellfish consumption is much higher than previously thought at a time when sea levels were lower, and we need to move away from it. "Simplified attitude" shellfish moss, "explains Hausmann.

Shellfish are often overrepresented in past coastal livelihood assessments because of hard shell hardness, which is better preserved than plants or even bones. However, the meat they contain is archaeologically invisible and could have been consumed anywhere. This study shows that the potential use of beachside treatment sites connected to habitat areas can not be neglected, especially when these coastal treatment sites can now be submerged.