Alfonso Benito Calvo, a geologist at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), is a participant in a paper published in the journal Quaternary that has revealed that the Neanderthals of the cave Prado Vargas (Cornejo, Burgos) collected fossils of marine origin 46,000 years ago, and has shown for the first time that a species other than Homo sapiens was capable of creating the earliest fossil collection.

In this paper, coordinated by Marta Navazo Ruiz, a researcher at the Universidad de Burgos, the fifteen marine fossils discovered since 2016 during the systematic excavation of level 4 of this site were analyzed. Prado Vargas is part of the Ojo Guareña Natural Monument, one of Europe's largest karstic systems, with over 100 km of chambers, caves and galleries.

Taxonomic study of the fossils has revealed that all belong to the phylum of the mollusks (Mollusca), except for one, belonging to the phylum containing the echinoderms (Echinodermata). Among the mollusks, half belong to the class of bivalves (Bivalvia) and the other half to the gastropods (Gastropoda). 

Within the gastropods, the family best represented, with six specimens, is Tylostomatidae. This fossil group belongs to the same class as modern snails and they could reach 10 cm; they have a holostomatous shell with several spirals, the last of which is larger. The Tylostomatidae fossils found in the Prado Vargas cave were snails that lived on shallow seabeds millions of years ago.

Why did the Neanderthals collect fossils?

In their continuous wandering around the territory in search of food, wood to make their spears, and flint for knapping their tools, the Neanderthals of Prado Vargas located several deposits containing these fossils. Members of these groups picked them up and carried them to the cave, which is between two and four kilometers from the different likely fossil sources. 

For prehistoric collectors, these fossils must have had some special character beyond being merely physical objects, because only one of them shows marks of having been used, in this case as a hammerstone for manufacturing their stone tools. It seems clear that the selection and transport of these fossils by these Neanderthals into the cave held some meaning and symbolized something, which has led the research team to propose various hypotheses to explain this behavior. 

They might have been collected simply for aesthetic reasons because the Neanderthals found their shapes attractive; for exchange within the group or with other Neanderthal groups; as toys; or to reinforce their cultural identity as an element of the group's own social cohesion, in the sense that the fossils bound them directly with the territory they inhabited.

A childish pastime?

It is possible that the collecting was performed by the children of the group. Studies with our own species have shown that the collection of objects is a characteristic of childhood. According to specialists, collecting behavior appears in human children between the ages of 3 and 6, at the moment they begin to be aware of themselves, and it continues until they are 12 years old. Collecting continues during puberty, though less intensively, while from the age of 18 this behavior peters out and does not emerge again until they are about 40.

“It is possible that the Prado Vargas Neanderthals found the fossils either intentionally or by chance, but what is clear is that carrying them to the cave was deliberate, systematic and reiterated, and we can recognize their efforts and interest in collecting these fossils in this. Thus, the Neanderthals of this cave in Burgos have become the earliest fossil collectors we know of today in our evolutionary process”, conclude the authors.