Six thousand years ago, people across Europe shared a cultural tradition of using freshwater mussel shells to craft ornaments, according to a new study. A team of international researchers, as well as academics from the University of York, extracted ancient proteins from prehistoric shell ornaments, which look remarkably similar despite being from at distant locations in Denmark, Romania, and Germany, and discovered they were all made using the mother-of-pearl of freshwater mussels.

The people made these ornaments between 4200 and 3800 BC, and they were even found in areas on the coast where plenty of other shells would have been available.

According to the evidence of archaeology, the ornaments, known as "double-buttons," might have been pressed into the leather to decorate armbands and belts.

Dr. Beatrice Demarchi, senior author of the study from the Department of Archaeology at the University of York and the University of Turin, Italy, said that they were shocked to discover that the ornaments were all made from freshwater mussels because it implies that this material was highly regarded by prehistoric craftsmen, wherever they were in Europe and whatever cultural group, they belonged. The finding of the study suggests that the existence of a European-wide cross-cultural tradition for the manufacture of these double-buttons.

 Most times, investigators overlooked the freshwater mollusks as a source of raw material in prehistory, despite the strength and resilience of mother-of-pearl, because many archaeologists believed that their local origin made them less "prestigious" than exotic marine shells.

Dr. Andre Colonese from the Department of Archaeology at the University of York and co-author of the study said that the ornaments are connected with the Late Mesolithic, Late Neolithic, and Copper Age cultures. Some of these groups were still living as hunter-gatherers, but in the south, they were farmers with switching to a more settled lifestyle.

Right now, the researchers are working on extracting proteins from fossilized mollusks, a method which they have dubbed "paleo shellomics." These new methods could offer fresh insights into some of the earliest forms of life on earth, enhancing our knowledge of evolution.

In his word, Dr. Demarchi explained further that this is first-time researchers have been able to retrieve ancient protein sequences from prehistoric shell ornaments to identify the type of mollusk from which they were made.

He concluded that this research is an essential step towards understanding how mollusks and other invertebrates evolved. The researchers hoped that these methods would enable them to track an evolutionary process which began at least 550 million years ago.