The research, published in the Journal of Human Evolution, also supports the hypothesis that there was neither interaction nor coexistence between humans and Neanderthals during the period.
Cova Gran is a large shelter covering a total surface area of 2,500 meters squared,
discovered in 2002, located in the area of Les Avellanes-Santa Linya -La Noguera. Investigators worked on an area of 60 meters squared, excavating a large area which has enabled them to reconstruct the way in which the people who inhabited the shelter lived.
Archaeologists were able to recover materials from the Middle Palaeolithic attributable to Homo neanderthalensis, and from the Upper Palaeolithic, which corresponds to Homo sapiens, separated by sterile strata of sediment which allows their differentiation.
The exceptional conditions of conservation of these archaeological remains, which have remained unaffected by biological and geological changes, have meant that the materials used by each of these species has been conserved without the need for significant earth movements, contrary to that which has been indicated in other archaeological sites. This detailed analysis of the tool remains recovered allows major differences to be observed in the way in which they were made, implying that they were made by different species.
This is something that has also been recognized in other sites in Western Europe, and it goes to strengthen the hypothesis that the two species neither lived together nor interacted with each other, although they may have lived in the same geographical area during the period from 40,000 to 30,000 years, which is generally referred to as the Middle/Upper Palaeolithic "transition".
Cova Gran was occupied successively by Neanderthals and "modern" humans in small groups of 15 to 20 people with a similar lifestyle: hunting, gathering, making tools for their daily activities and obtaining and processing food for which the use of fire was essential. In spite of this, each species used very different techniques and primary materials.
Among the remains found that are attributable to Homo sapiens are several perforated sea snail shells, generally considered to be an indicator of the distribution of the species throughout Africa, the Middle East and Western Europe. They also denote the existence of a symbolic language and cognitive capacities for which there is no evidence during the Middle Palaeolithic.
These objects indicate that Homo sapiens travelled widely across lands from the Mediterranean coast to the Pyrenean foothills, a distance of over 150 kilometers, although the researchers do not rule out the existence of social networks which would connect groups separated by large distances and through which these objects would circulate. If this were the case, the ornaments would be a key symbolic element in the social structure of this people and a clue to their identity.
The work also offers new data about the period in which the first representatives of the so-called "modern humans" appeared in the Iberian Peninsula and the extinction of the Neanderthals, a question that has generated some heated debate within the area of Paleoanthropology. The Carbon 14 dated samples in Cova Gran make references to a period of between 34,000 and 32,000 years in which this biological replacement in the Western Mediterranean occurred.
The study also discusses the validity of C14, the method habitually used to date archaeological remains from that period. Although C14 is a vital tool for dating archaeological sites, one conclusion to emerge from the study is that the period between 40 and 30 thousand years cannot be considered as "historic" years.
This observation has rekindled the controversy that has existed for some time in archaeology about whether C14 is a totally reliable timepiece. The radioactive isotope regularly disintegrates but from 30,000 years its presence in samples is residual and, in many cases, the samples have been exposed to processes of change that are difficult to identify.
Citation: Jorge Martínez-Morenoa, Rafael Moraa, Ignacio de la Torre, 'The Middle-to-Upper Palaeolithic transition in Cova Gran (Catalunya, Spain) and the extinction of Neanderthals in the Iberian Peninsula', Journal of Human Evolution, March 2010, 58(3), 211-226; doi:10.1016/j.jhevol.2009.09.002