20 August 2014
Neanderthals and modern humans were both living in Europe for between 2,600 and 5,400 years, according to a new paper published in the journal, Nature. For the first time, scientists have constructed a robust timeline showing when the last Neanderthals died out. Significantly, they have strong evidence to suggest that Neanderthals disappeared at different times across Europe rather than being rapidly replaced by modern humans.
A research team, led by Professor Thomas Higham of the University of Oxford, obtained new radiocarbon dates for around 200 samples of bone, charcoal and shell from 40 key European archaeological sites. The sites, ranging from Russia in the east to Spain in the west, were either linked with the Neanderthal tool-making industry, known as Mousterian, or were ‘transitional’ sites containing stone tools associated with either early modern humans or Neanderthals.
The chronology was pieced together during a six-year research project by building mathematical models that combine the new radiocarbon dates with established archaeological stratigraphic evidence. The results showed that both groups overlapped for a significant period, giving ‘ample time’ for interaction and interbreeding. The paper adds, however, it is not clear where interbreeding may have happened in Eurasia or whether it occurred once or several times.
Professor Thomas Higham said: ‘Other recent studies of Neanderthal and modern human genetic make-up suggest that both groups interbred outside Africa, with 1.5%-2.1% or more of the DNA of modern non-African human populations originating from Neanderthals. We believe we now have the first robust timeline that sheds new light on some of the key questions around the possible interactions between Neanderthals and modern humans. The chronology also pinpoints the timing of the Neanderthals’ disappearance, and suggests they may have survived in dwindling populations in pockets of Europe before they became extinct.’
In 2011, another Nature paper featuring Dr Katerina Douka of the Oxford team obtained some very early dates (around 45,000 years old) for the so-called ‘transitional’ Uluzzian stone-tool industry of Italy and identified teeth remains in the site of the Grotta del Cavallo, Apulia, as those of anatomically modern humans. Under the new timeline published today, the Mousterian industry (attributed to Neanderthals and found across vast areas of Europe and Eurasia) is shown to have ended between 41,030 to 39,260 years ago. This suggests strongly that there was an extensive overlapping period between Neanderthals and modern humans of several thousand years. The scientific team has for the first time specified exactly how long this overlap lasted, with 95% probability.
The Uluzzian also contains objects, such as shell beads, that scholars widely believe signify symbolic or advanced behaviour in early human groups. One or two of the Châtelperronian sites of France and northern Spain (currently, although controversially, associated with Neanderthals) contain some similar items. This supports the theory first advanced several years ago that the arrival of early modern humans in Europe may have stimulated the Neanderthals into copying aspects of their symbolic behaviour in the millennia before they disappeared. The paper also presents an alternative theory: that that the similar start dates of the two industries could mean that Châtelperronian sites are associated with modern humans and not Neanderthals after all.
There is currently no evidence to show that Neanderthals and early modern humans lived closely together, regardless of whether the Neanderthals were responsible for the Châtelperronian culture, the paper says. Rather than modern humans rapidly replacing Neanderthals, there seems to have been a more complex picture ‘characterised by a biological and cultural mosaic that lasted for several thousand years’.
The Châtelperronian industry follows the Mousterian in archaeological layers at all sites where both occur. Importantly, however, the Châtelperronian industry appears to have started significantly before the end of Mousterian at some sites in Europe. This suggests that if Neanderthals were responsible for both cultures, there may have been some regional variation in their tool-making, says the paper.
Professor Higham said: ‘Previous radiocarbon dates have often underestimated the age of samples from sites associated with Neanderthals because the organic matter was contaminated with modern particles. We used ultrafiltration methods, which purify the extracted collagen from bone, to avoid the risk of modern contamination. This means we can say with more confidence that we have finally resolved the timing of the disappearance of our close cousins, the Neanderthals. Of course the Neanderthals are not completely extinct because some of their genes are in most of us today.’
Previous research had suggested that the Iberian Peninsula (modern-day Spain and Portugal) and the site of Gorham’s Cave, Gibraltar, might have been the final places in Europe where Neanderthals survived. Despite extensive dating work, the research team could not confirm the previous dates. The paper suggests that poor preservation techniques for the dating material could have led to contamination and false ‘younger’ dates previously.
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Notes to Editors:
- Images and video of Thomas Higham doing field work is available via the Nature Press Office (email: firstname.lastname@example.org). Video of Thomas Higham in the lab and interview clips are also available via email@example.com
- The paper, ‘The timing and spatio-temporal patterning of Neanderthal disappearance’, by Thomas Higham et al will be published by Nature.
- Once live, the link to the paper can be found here: http://dx.doi.org/10.1038/nature13621
- The Natural Environment Research Council (NERC) funded this work (NE/D014077/1). Additional funding was received from the Leverhulme Trust, through the Ancient Human Occupation of Britain (AHOB) project, the NRCF (NERC Radiocarbon Facility) programme, Keble College (Oxford) and the European Research Council. The Oxford Radiocarbon Accelerator Unit) is part-funded by the NERC (http://www.nerc.ac.uk/).
- Professor Thomas Higham is the Deputy Director of the Oxford Radiocarbon Accelerator Unit, Research Laboratory for Archaeology and the History of Art and interim Director of the Advanced Studies Centre at Keble College, Oxford. For his profile, go to http://www.arch.ox.ac.uk/TH1.html
- Senior co-author Dr Katerina Douka is a post-doctoral scientist at the Oxford Radiocarbon Accelerator Unit, Research Laboratory for Archaeology and the History of Art. She was a doctoral research student at Keble College, Oxford. For her profile, go to http://www.arch.ox.ac.uk/KD1.html
- Senior co-author Dr Rachel Wood is a Research Officer at the Australian National University. Prior to obtaining her position there she was a doctoral research student in Oxford at the Research Laboratory for Archaeology and the History of Art and Keble College. For her profile, go to http://people.rses.anu.edu.au/wood_r/
- Further research is being undertaken in this area under new funding provided by the ERC. For more information on Oxford’s PalaeoChron project go to http://www.palaeochron.org
The research, led by the University of Oxford, was conducted in collaboration with The British Museum, London; The Natural History Museum, Australian National University, Queen’s University of Belfast, University of Maryland, University of the Basque Country, Universidad Autónoma de Madrid, Fundación Instituto de Investigación de Prehistoria y Evolución Humana – Cordoba (Spain), URS Corporation (USA), Università degli Studi di Siena, Muséum National d’Histoire Naturelle (France), Universität Tübingen, Service public de Wallonie, Musée de l'Homme, Paris, Università degli Studi di Trento, Institut Royal des Sciences Naturelles de Belgique, University of Massachusetts, University of Arizona, Universitat de Girona, Universitéde Toulouse le Mirail, Archäologisches Forschungszentrum und Museum für menschliche Verhaltensevolution, Neuwied, the CNRS (France), Trent University (Canada), Università di Genova, Ephoreia of Paleoanthropology of Southern Greece, Università di Ferrara, Universidad de Oviedo, University of Colorado, Universidad de La Laguna and University College Dublin.
- Radiocarbon dating is used for the reliable dating of archaeological material back to around 55 000 years ago. The radioactive isotope of carbon (14C) is formed in the upper atmosphere and later enters the biosphere and is found in all living organisms. When death of an organism occurs, however, no further replenishment of 14C takes place and only decay continues as the remaining 14C decays back to its parent isotope. Scientists know the half-life of radiocarbon (5568 ± 30 yr), which is the time it takes for half of the 14C to decay away. This allows an age to be determined after the abundance of remaining radiocarbon has been measured. Oxford uses accelerator mass spectrometry (or AMS), which makes it possible to directly measure individual 14C atoms. This effectively reduces the weight of material required and makes the measurements much quicker to achieve. AMS can routinely date samples of 1mg carbon or less. For this, around 200-500 mg of bone is needed.