The application of improved radiocarbon-dating techniques to samples from archaeological sites ranging from Russia to Spain has redefined the timing of the final disappearance of Neanderthals from Europe. See Letter p.306
The question of when and how the Neanderthals became extinct has long fascinated scientists. Three key advances have begun to transform our understanding of this process: better removal of contaminants from ancient samples, more targeting of human fossils and artefacts for dating, and extension of calibration curves to 50,000 years ago for radiocarbon dates. On page 306 of this issue, Higham et al.1 combine these developments to investigate how the biological and cultural transition from Neanderthals to modern humans might have occurred. The authors conclude that Neanderthals and their associated archaeological industries were gone from Europe between 41,000 and 39,000 years ago, leaving the continent to our species.
Improvements in methods for pretreating samples before radiocarbon dating, including the removal of humic-acid contaminants from charcoal2 and the ultrafiltering of non-degraded collagen molecules from bone samples3, have increased confidence in the accuracy and precision of radiocarbon dates older than 25,000 years ago. In cases in which ultrafiltration did not purify the sample satisfactorily, amino acids characteristic of collagen can be extracted for dating4. The resulting dates have given us a finer-grained picture of changes in human behaviours and species in the key period between 50,000 and 30,000 years ago, when modern humans (Homo sapiens) reached Europe and, eventually, replaced Neanderthals.
Higham and colleagues applied such pretreatments and dating methods to carefully selected samples from 40 sites. The samples included Neanderthal bones and artefacts from the Mousterian and Châtelperronian stone-tool industries, which are frequently associated with Neanderthals, and Uluzzian artefacts, possibly made by modern humans (Fig. 1). The authors then used Bayesian age models to convert their radiocarbon dates to calendar years, using stratigraphic positions of samples from each site to refine calibrated ages.
According to the authors, Europe at 45,000 years ago was essentially Neanderthal, with small pockets of modern humans, represented by the Uluzzian stone-tool industry, in regions such as Italy. Their models plot changing spatial distributions of Neanderthals and modern humans over the subsequent five millennia, with temporal overlaps between Neanderthals and modern humans of between 2,600 and 5,400 years, depending on region. In human terms, these transitions spanned some 130 to 270 generations, culminating in the restriction of the Neanderthal presence in Europe to France at 40,000 years ago and their eventual extinction. Contrary to previous models5,6, the authors find no convincing evidence of Neanderthal survival in Iberia after 40,000 years ago.
The copious data collected by Higham et al. test traditional, assumed associations between human species and archaeological industries. The assumption that we can attribute Mousterian industries (which are based on triangular or roughly oval flakes derived from carefully shaped nodules) to Neanderthals is simplistic, because we know that modern humans made similar tools in the Levant and Africa7,8. Conversely, claims of a late Neanderthal presence in regions such as Gibraltar6 have been based purely on the supposed exclusive association of European Mousterian industries with that species. There are no associated Neanderthal remains with such late (post-40,000 years ago) Mousterian industries, and thus the evidence for extended survival of Neanderthals in Iberia remains hypothetical.
Crude equivalences between human species and archaeological industries suited archaeologists when dating methods were similarly rudimentary. However, improvements in chronological accuracy and precision, and the incorporation of information derived from studies of ancient DNA and environments now allow more dynamic and mosaic models of change to be explored. 'Transitions' need not be seen as intermittent, sudden shifts from one set of stable conditions to another, but as dynamic processes operating at multiple spatial and temporal scales.
Higham et al. do not explore all the ramifications of their data. For example, morphological changes in human fossils can be directly dated and compared with time estimates for genetic evidence of interbreeding between Neanderthals and non-African modern humans. Currently, the greatest amount of gene flow is thought to have occurred around 77,000–114,000 years ago9, long before the claimed skeletal evidence for interbreeding at 45,000–35,000 years ago10. This seeming asynchronicity between genetic and skeletal patterning has yet to be explained.
In addition, the authors do not discuss why the Châtelperronian — a Neanderthal industry from France and northern Spain — apparently ended at much the same time as the modern-human Uluzzian industry of Italy and Greece, 39,000–40,000 years ago. Makers of the Uluzzian were perhaps partially affected by the nearby Campanian Ignimbrite volcanic eruption at around 39,400 years ago11, but we have no evidence of this eruption, and thus its associated cultural impact, farther west in France12. Thus, multiple reasons, including dispersal of new technologies (such as the Aurignacian) and modern-human groups, must be explored to explain the disappearance of these 'transitional' archaeological industries.
Spatial gaps also exist in Higham and colleagues' coverage: western Europe and the Mediterranean zones of eastern Europe are well represented, but inland central and eastern Europe are effectively excluded from their models. Archaeologically, the latter regions contain a diverse array of industries, often situated in patches of high plant productivity13 (Fig. 1), the chronology and human-fossil associations of which are poorly understood. To assess further the behavioural, ecological and biological mosaics at the time of the transition from Neanderthals to modern humans, we need to bring this region up to the precision and coverage of the rest of Europe.
More chronological work is now required: new sites need to be dated, and reanalyses are required for problematic samples. Higham and colleagues' study has thrown down the gauntlet, and future researchers will need to try hard to demonstrate Neanderthal survival in Europe after 40,000 years ago. Researchers should instead focus on the more interesting questions of how and why human species and behaviours varied spatio-temporally in Europe in the period between 50,000 and 30,000 years ago, because understanding such patterns may provide fascinating insight into human ecology, social networks and the exchange of ideas at that time.
Higham, T. et al. Nature 512, 306–309 (2014).
Bird, M. I. et al. Radiocarbon 41, 127–140 (1999).
Bronk Ramsey, C., Higham, T., Bowles, A. & Hedges, R. Radiocarbon 46, 155–163 (2004).
Marom, A., McCullagh, J. S., Higham, T., Sinitsyn, A. A. & Hedges, R. E. Proc. Natl Acad. Sci. USA 109, 6878–6881 (2012).
Zilhão, J. in El Origen del Hombre Moderno en el Suroeste de Europa (ed. Cabrera Valdés, V.) 127–145 (UNED, 1993).
Finlayson, C. et al. Nature 443, 850–853 (2006).
McBrearty, S. & Brooks, A. J. Hum. Evol. 39, 453–563 (2000).
Stringer, C. B., Grün, R., Schwarz, H. P. & Goldberg, P. Nature 338, 756–758 (1989).
Prüfer, K. et al. Nature 505, 43–49 (2014).
Trinkaus, E. Proc. Natl Acad. Sci. USA 104, 7367–7372 (2007).
De Vivo, B. et al. Miner. Petrol. 73, 47–65 (2001).
Lowe, J. et al. Proc. Natl Acad. Sci. USA 109, 13532–13537 (2012).
Allen, J. R. M. et al. Quat. Sci. Rev. 29, 2604–2618 (2010).
About this article
The Middle Palaeolithic Site of Buzdujeni in Moldova: Establishing the Archaeological and Environmental Record
Journal of Paleolithic Archaeology (2018)
Quaternary International (2017)