The Fate of Homo neanderthalensis

All the available paleoanthropological, archeological, and molecular evidence strongly supports the displacement of more "primitive" endemic human populations by modern humans who recently arrived from Africa. In the case of the Neanderthals at least, it appears to have been displacement by rapid extinction.

The correlation in western and central Europe between the disappearance of Neanderthals from both the paleontological and archeological records, around 27,000 years ago, and the appearance of modern humans, Cro-Magnons, around 30,000 years ago (with some evidence of earlier colonization around 40,000 years ago), strongly supports the rapid-extinction model (see Stringer & Gamble, 1993; Stringer & McKie, 1996; Klein, 1999; Tattersall & Schwartz, 2000). While it may be argued that the association between the Saint-Cesaire Neanderthal (Figure 8.8) and an apparent Chatelperronian tradition (see earlier) supports continuity between Middle

Figure 8.8 ► The classic Saint-Cesaire Neanderthal specimen from France.

and Upper Paleolithic populations, it is also possible that this was a local Mousterian cultural adaptation. Indeed, the Chatelperronian industry associated with the Saint-Cesaire Neanderthal is recognized as closely resembling the Mousterian tradition Type B, thus likely representing a local variant of a Mousterian technology (Klein, 1999).

Other evidence does suggest, however, that the two groups interacted a little. Is it really a coincidence that Neanderthals began developing bladelike variants of the Mousterian at precisely the time when H. sapiens was spreading among them? At Arcy-sur-Cure, a late (<33,000 years ago) Neanderthal site in southern France, there is even, for the very first time, decorative art — animal teeth pierced as if for a necklace and ivory rings — as well as bone and ivory tools (Hublin et al., 1996). Did they obtain these objects from Cro-Magnons by trade, or did they make them themselves by copying their new neighbors? Overall, however, there appears to have been limited contact between these groups. As suggested by the paleodemographer Jean-Pierre Bocquet-Appel (in Arsuaga, 2002), the Neanderthals never attained a high population density, and far-flung populations were obliged to exchange individuals in order to keep up a viable population. This resulted in a spreading of biological (and cultural) resources very thinly. But with the emergence of H. sapiens, we witness the appearance of ever-increasing groups. As these large and dense population clusters became reproductively viable and economically self-sufficient, they also became more biologically and culturally closed. Or to put it another way, we may be witnessing the emergence of a form of biological and cultural elitism.

Finally, we return to the theme of interbreeding. From time to time, quite a number of fossils have been claimed to be hybrids, or "Neanderthals showing evidence of gene flow," or even "modern humans showing evidence of gene flow." But only one of these claims carries conviction: the skeleton of a 4-year-old child, about 25,000 years old, from Lagar Velho in Portugal (Duarte et al., 1999). Even given its extreme youth, the skeleton shows characteristics that are unmistakeably those of a mixture: Like modern humans it has small teeth (with especially small front teeth) and a modern pelvis, but like Neanderthals the limb bones are robust and short, and there is a telltale large juxtamastoid eminence on the temporal bone. The lower jaw by itself shows mixed characters — it combines a Neanderthallike retreating mandibular symphysis with a modern pointed chin (note, the chin in modern humans results from the recession of the superior incisor alveolar border of the mandible due to the retraction of the dental complex, which "leaves behind — inferiorly" a chin; thus a chin is not an outgrowth, but exactly the opposite condition [see Enlow & Hans, 1996]). This does not mean that we bear Neanderthal genes — they have long since disappeared — but it does mean that possibly some of the last Neanderthals, the last of their kind, had joined Cro-Magnon hordes and interbred with them.

The populations of H. neanderthalensis from western Asia appear after the emergence of modern H. sapiens in this region and eastern Africa. For example, the relatively modern-looking populations from Herto in Ethiopia date to around 160,000 years ago, and the Skhul and Qafzeh hominins date to perhaps 120,000 years ago, while the Neanderthals from Kebara, Amud, and Shanidar at least date to less than 70,000 years ago (see Trinkaus, 1983; Stringer, 1998; Tchernov, 1998; T.D. White et al., 2003). Of significance is that the modern-looking humans from Skhul and Qafzeh are associated with typically African fauna and represent a likely northern migration from Africa into the coastal zones of the Levant. The Neanderthals, however, are associated with typical Eurasian fauna and, unlike the modern humans from Skhul and Qafzeh, were not restricted to the coastal plains but even occupied parts of present-day Syria and Iraq. It is likely that the modern humans located around the coastal regions migrated or expanded their range into this region from the south during the more mild and temperate periods of 130,000-70,000 years ago. With the change in climatic conditions from 70,000 years ago, however, it is likely that Neanderthal populations migrated or expanded their range into western Asia from the north, displacing the modern human populations (see Stringer & Gamble, 1993; Stringer, 1998; Klein, 1999).

It is only with the emergence of Homo sapiens that humans have been in a position to significantly change their environment, rather than being changed by it. Before this, the human was just another large mammal, with its own role to play within the large-mammal community system. As such, hominins were open to the same selective pressures that impacted other mammals, and they were certainly part of any dispersal pattern that affected these mammalian communities. Turner (1984), Vrba (1985), and Tchernov (1998) have each demonstrated that the presence of hominins within the Plio-/Pleistocene fossil record have been shown to correlate strongly with the presence of principle mammalian fauna, showing that they were an integral component of their mammalian communities. The increasing southward and eastward expansion of glacial conditions resulted in a retreat from these northern regions of the existing floral and faunal groups. This southeast migration also included herds of red deer, wild horse, and roe deer. It is also likely that at least some Neanderthal populations dependent on these

Figure 8.9 ► The Tabun Neanderthal from Mount Carmel, Israel.

resources also shifted southeastward, eventually settling in western Asia, as convincingly argued by Tchernov (1988:80, 87):

It is probably true that any hominid dispersal was a natural part of any emigration until the late upper Palaeolithic period. Given that hominids play an integral part in the ecological events, hominid dispersals and faunal changes are actually part of the same phenomenon____[T]he new environmental configuration across Europe challenged the foraging technologies, the social structure, and the spatial organization of Mousterian populations, forcing them to move into the Mediterranean lands.

It is likely that such dispersal patterns were intermittent, as shown by the early penetration into this region by the Tabun Neanderthals (Figure 8.9), who may be the only Neanderthal population to have preceded H. sapiens in western Asia (Stringer, 1998), with later Neanderthal populations moving into the region around 70,000 years ago. The disappearance of H. neanderthalensis from this region is similar to that outlined for Europe, that is, rapid extinction. From around 40,000 years ago we see in this region a more sophisticated toolkit, similar to those documented in Europe from around 30,000 years ago. We also see for the first time remains of modern H. sapiens, dating to around 40,000 years ago (see Stringer & Gamble, 1993; Klein, 1999; Tattersall, 1999).

Until recently, the easternmost Neanderthal appeared to be the child burial at Teshik-Tash, in Uzbekistan. Did the high Tianshan Range limit

Figure 8.10 ► The Chinese Neanderthal-like specimen form Maba.

them to the east? Perhaps not, because Mousterian surface scatters are known from Mongolia, too. Now comes a startling finding: One of us [Groves (in press)] shows that the Maba calotte, from Guangxi in southeastern China, is a Neanderthal (Figure 8.10)! The conclusion seems inescapable: the en bombe vault, the rounded orbits and supraorbital torus, the huge frontal sinus, and the protruding nasal skeleton. By what route did they get there, these Chinese Neanderthals, and when? Are they more like members of the "Steinheim group," descended from the Narmada people? The Neanderthals are the best known of all our fossil kin, but we still have a great deal to learn about them.

In conclusion, all available evidence suggests that H. neanderthalensis originated from an indigenous European ancestor, which we associate with the "Steinheim group." Paleontological evidence from Atapuerca and the recent molecular evidence both suggest that the Neanderthal lineage is significantly older than previously thought, dating back to around 500,000 or perhaps to 700,000 years ago. The geographic and genetic isolation of a European Ice Age population resulted in its morphological differentiation, which over time resulted in speciation. We also suggest that initially the "cold-adapted" morphology of H. neanderthalensis was an exaptation, which developed further as a result of selection pressures, which eventually enabled them to occupy their distinct ecological niche, though it in no way restricted them to this type of habitat (still, this same Neanderthal niche may have inhibited occupation by other, less-adapted nonNeanderthal populations).

As we will see in the next chapter, modern H. sapiens originated in Africa around 200,000 years ago. It is also from around this time that we see an initial short-term territorial expansion into western Asia by early modern humans, associated with a similar migration by other African faunal groups during the more temperate periods from around 120,000-70,000 years ago. Conversely, around 70,000 years ago we see the return of colder climates and the colonization, or recolonization if Tabun is as much as 120,000 years old, of large areas in western Asia by H. neanderthalensis, with perhaps a remigration from Europe around 50,000 years ago. It is from around 40,000 years ago that we see within the paleontological and archeological record of both western Asia and Europe the arrival of truly modern humans into these regions. By 30,000 years ago, modern H. sapiens had firmly established themselves in these regions, and the last known Neanderthal refuge, Zafarraya Cave in the far south of Spain, in the extreme southwest of Europe, dating to 27,000 years ago, witnesses their extinction.

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