A new research led by Spanish scientists casts doubt on the widely accepted theory that the last Neanderthals persisted in southern Iberia, Spain, at the same time that modern humans advanced in the northern part of the Iberian Peninsula.
“It is improbable that the last Neanderthals of central and southern Iberia would have persisted until such a late date, approximately 30,000 years ago, as we thought before the new dates appeared,” said Dr Jesús Jordá of the Spanish National Distance Education University, co-author of the study published in the Proceedings of the National Academy of Sciences.
The scientists applied a new technique in order to repeat analyses at the sites of Jarama VI and Zafarraya, considered up to now two of the last refuges of the Iberian Neanderthals.
To the usual radiocarbon dating method, the ultrafiltration protocol was added, which aims to purify the collagen of the bone samples from contaminants. The AMS dating technique was applied that requires minimum sample quantities.
The team, by applying this new method, assures that the Neanderthal occupation of these sites did not last until as late as previously thought; instead it should be placed approximately 45,000 years ago.
“The problem with radiocarbon dating alone is that it does not provide reliable dates older than 50,000 years,” Dr Jordá said. “An additional problem is contamination; the older the samples are the more residues are accumulated. If contaminants are not removed the obtained dates are incorrect.”
New analyses were applied to bone remains found in the archaeological deposits in association with Middle Paleolithic stone artifacts. Bones bearing clear signs of human manipulation (cut marks, marks of percussion or intentional breakage) were selected in order to rule out possible intrusions by carnivores. Despite the fact that samples were collected from numerous sites in southern Iberia, it was only possible to date those of Jarama VI and Zafarraya, as the remaining samples did not contain enough collagen to be dated.
Cueva Antón is the only site that still provides recent dates in accordance with what has until now been postulated in relation to the persistence of the Neanderthals. However, neither the technological remains are clearly related to the Neanderthals nor are the dated charcoal samples perfectly associated with the lithics.
In view of the new data according to Dr Jordá “prehistory books would need revision”, especially as new results become available. “Although it is still controversial to change the theory in force, the new concept, which presents new data indicating that Neanderthals and Homo sapiens did not co-exist in Iberia, is becoming accepted.”
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Bibliographic information: Rachel E. Wood et al. Radiocarbon dating casts doubt on the late chronology of the Middle to Upper Palaeolithic transition in southern Iberia. PNAS, published online before print February 4, 2013; doi: 10.1073/pnas.1207656110
