Archaeology

Those elusive Neanderthals

The 'how, where and when' of possible Neanderthal coexistence with Cro-Magnons, and their extinction, continue to exercise a varied community of researchers. The latest interpretations of the fossil and archaeological records were aired at two meetings.

Will we ever really know what happened to the Neanderthals — the distinctive humans who occupied Europe immediately before the modern-looking Cro-Magnons appeared1? At two meetingsFootnote 1 held in late summer in Gibraltar and Liège, Belgium, there was plenty of new evidence from the fossil and archaeological records to discuss. But we are still far from pinning down the processes that caused Neanderthals to vanish about 30,000 years ago, after existing for at least 200,000 years before that.

Previous views on the question have ranged from a denial that they disappeared at all (they simply evolved into modern humans) to arguments that they were killed off rapidly by invading, vastly superior Cro-Magnons. These days, both DNA and morphological studies support the majority view that Neanderthals were indeed a separate lineage, and probably species, to modern humans. But equally there is growing evidence from dating techniques that Neanderthals did not vanish overnight, and that in some ways they were as behaviourally sophisticated as the Cro-Magnons.

In Gibraltar there was the prospect of some dramatic news, in two presentations by E. Trinkaus (Washington Univ., St Louis). In one he argued that modern features such as femoral shape and muscle attachments to the humerus of a late Neanderthal skeleton from St Césaire, France, dated to about 36,000 years ago, are morphological signs of behavioural change. These changes might reflect new patterns of activity, or the use of technological innovations. In the other, Trinkaus described his interpretation of a child's skeleton from Lagar Velho, Portugal, as showing a mixture of Neanderthal and Cro-Magnon features, implying that there was gene flow between the populations. These interpretations provoked discussion — not least because, in the first instance, he used skeletal plasticity as the explanation of a mixed morphology, and in the second he invoked gene flow between the two types. Several participants argued that the Lagar Velho skeleton is actually that of a modern human. But further details of this controversial specimen will be published shortly and allow a more informed debate about it.

Increased knowledge of the vagaries of Europe's climate over the past 100,000 years is beginning to influence thinking about Neanderthal extinction. Cores from the Greenland icecap and the floor of the North Atlantic reveal remarkable oscillations in temperatures during that time. Figure 1 shows a vegetation curve based on pollen from the sediments of Lake Monticchio2, Italy — the dramatic fluctuations show how severe the effects of the changing climate could have been on both Neanderthals and Cro-Magnons in reducing the environment's capacity to support them. According to one view (C. Finlayson, Gibraltar Museum), Neanderthals became extinct simply because they could not cope with the increasing severity of climatic change around 30,000 years ago. The Cro-Magnons, who according to Finlayson were better adapted to the increasing open-country environments, simply colonized the vacant habitats. An alternative view (proposed by R. White, New York Univ., and ourselves, among others) is that extinction probably stemmed from various factors, including climatic instability coupled with competition for resources from Cro-Magnons.

Figure 1: Climatic ups and downs in Europe.
figure1

Here the number of tree taxonomic groups (expressed as a percentage) is used as the proxy indicator of variation in climate; the record was created from pollen in sediments of Lake Monticchio, Italy2. Around the time of the Neanderthals' demise, about 30,000 years ago, there seem to have been very swift climatic shifts, occurring over intervals as brief as 20 years. But what contribution these made to Neanderthal extinction remains a matter of debate.

Neanderthals and Cro-Magnons are known to have occupied sites across Europe and western Asia. At the Gibraltar meeting, however, the archaeological presentations centred on the Iberian peninsula. New 14C dates are available for one site, at Bajondillo in southern Iberia (A. Baldomero Navarro, Málaga Univ.). These seem to indicate a Cro-Magnon presence there about 34,000 years ago. This is slightly earlier then previously known for the region, but is still relatively late compared with elsewhere in Europe, and is consistent with other evidence that Neanderthals may have excluded the Cro-Magnons for a longer period in southern Iberia.

The diversity and complexity of human responses to their physical and social environments was a recurring theme. One source of evidence is the inferred arrangement of Neanderthal activities around hearths at the Catalan site of Abric Romaní (M. Vaquero, Univ. Rovira i Virgili, Tarragona), which could show that the social structure and organization of Neanderthals were — at least in part and in some places — similar to those of modern hunter–gatherers. At Abric Romaní there are indications that a variety of domestic activities took place around large hearths inside the rock shelter, with more specialized actions occurring at smaller hearths outside.

At the Liège congress there were three topics relevant to Neanderthal extinction. The first was an assessment of 'acculturation', meaning the influence Neanderthals and Cro-Magnons may have exerted on each other. Second, there was an assessment of what we mean by Aurignacian culture, and what it might tell us about modern human behaviour. The Aurignacian is the earliest Eurasian archaeological industry generally associated with Cro-Magnons, and is known from artefacts such as beads, bone carvings and certain stone tools, including small ones probably designed to be set compositely into a wooden shaft.

The third topic was assessment of the timing of the transition, 45,000–30,000 years ago, between the Middle Palaeolithic (Neanderthals) and Upper Palaeolithic (generally Cro-Magnons) in Eurasia. The Châtelperronian — which is characterized by a form of stone knife with a blunted diagonal edge, found for example at St Césaire — seems to be the only early Upper Palaeolithic industry that can definitely be associated with Neanderthals. But there are several other industries without associated fossil material.

Speculation about the effects that incoming Cro-Magnons might have had on Neanderthals in Europe depends on accurate dating of the archaeological cultures. Two schools of thought compete here. One holds that Neanderthals began the transition to 'modern' behaviour before Cro-Magnons arrived as, for instance, at Abric Romaní. The other is that the arrival of Cro-Magnons with behaviourally modern Aurignacian technology stimulated a similar development in Neanderthals. To tackle these issues, archaeologists will have to assess how much significance can be attached to constructs such as the Middle Palaeolithic, Aurignacian and Châtelperronian.

A better chronology of behavioural change and Neanderthal extinction is also required. At the moment, archaeological 14C determinations often come up with a younger age for bones than for charcoal — this is because bones contain proportionately less carbon, and are more susceptible to contamination with younger 14C. Where both bone and charcoal from the same level have been dated, some bone dates statistically match those on charcoal, but others are much younger and often make little stratigraphic sense. Most Châtelperronian dates are on bone samples, and so could either be about the right age or be underestimates — without comparable charcoal samples we cannot be certain. Resolving this issue will have a great influence on thinking about when and how Neanderthals achieved 'modern', Upper Palaeolithic behaviour.

The 14C determinations also need to be corrected to account for variability in 14C production. Intervals between 14C dates will be expanded or contracted when we convert them to calendar years, and such changes can alter long-established views on the chronological pace and even the succession of human behavioural change. Cross-calibration curves are one answer, and it has become possible to calibrate dates against a curve ('CalPal'3) derived from a marine core4 and lake sequence5 (B. Weninger, Köln Univ.; O. Jöris, Monrepos, Neuwied).

These curves are working models only, but several speakers in Liège described how they calibrated their 14C determinations with CalPal. For instance, not only have Middle and Upper Palaeolithic 14C dates from France and Iberia been corrected to calendar years, but they have also been subdivided into dates for bone and charcoal (O. Jöris). The charcoal dates are consistently older than those for bone, and the pattern was even clearer after calibration. Such techniques will no doubt develop apace over the next few years, but these curves are complex and progress will not be straightforward. We can be sure, given the discrepancy between 14C and calendar years of up to four millennia or so during the period 40,000–30,000 years ago, that many radiocarbon ages in the phase when the last Neanderthals and the first Cro-Magnons are assumed to have coexisted will be underestimates. But we cannot yet tell whether the upshot will be a longer or shorter inferred period of coexistence.

What of the future for these kinds of studies? More reliable chronologies are one item on the wish list. Another is identifying the makers — Neanderthal or Cro-Magnon — of some enigmatic European industries in the range 30,000–45,000 years ago, such as the Szeletian and the Bohunician. These industries are characterized by stone 'leafpoints', which are probably a form of projectile tip. They have previously been considered to be a central and eastern European analogue to the Châtelperronian — that is, a Neanderthal behavioural foray into the 'modern' world of the Upper Palaeolithic6. But in rethinking the transitional period we might in some cases consider the possibility that they are Cro-Magnon. A final wish is to be able to extract DNA from the earliest Cro-Magnons and compare it with the growing number of Neanderthal sequences. This has proved difficult so far, both because of preservation problems and because it will be far trickier to tell whether Cro-Magnon, as opposed to Neanderthal, DNA is contaminated with our own DNA.

Above all, both conferences showed that European prehistory cannot be studied in isolation — we will be better able to answer many questions about Neanderthals and Cro-Magnons when we have a comparably rich fossil and archaeological record from western Asia.

Notes

  1. 1.

    *Neanderthals and Modern Humans in Late Pleistocene Eurasia, Gibraltar, 16–19 August 2001; XIVth Congress Union Internationale des Sciences Préhistoriques et Protohistoriques (UISPP), Liège, 2–8 September 2001.

References

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    Stringer, C. & Gamble, C. In Search of the Neanderthals (Thames & Hudson, London, 1993).

  2. 2

    Allen, J. R. M. et al. Nature 400, 740–743 (1999).

  3. 3

    CalPal; http://www.calpal.de

  4. 4

    Voelker, A. H. L. et al. Radiocarbon 42, 437–452 (2000).

  5. 5

    Kitagawa, H. & van der Plicht, J. Radiocarbon 40, 505–515 (1998).

  6. 6

    Allsworth-Jones, P. The Szeletian (Clarendon, Oxford, 1986).

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