Who Killed the Neanderthals?

Human Evolution (2006) 21:337–340 DOI 10.1007/s11598-006-9029-2 Who Killed the Neanderthals? Emiliano Carnieri Published online: 11 January 2007 # Springer Science + Business Media B.V. 2007 Abstract Homo neanderthalensis, evolved from the European populations of H. heidelbergensis, and shows some special morphological traits, probably due to an adaptation to particular climatic conditions. It also appears that H. neanderthals had a specialized diet which was mostly carnivorous. Anatomically modern humans of the European Upper Palaeolithic seem to differ from the alimentary behaviour that characterized the Neanderthals; their diet was more varied, with a greater contribution from freshwater alimentary resources (molluscs and fishes). Comparison between the various strategies of subsistence adopted by the two species allows us to propose a hypothesis about the extinction of H. neanderthalensis. Keywords H. neanderthals . diet . climatic adaptation . extinction Introduction Until a few decades ago, the evolution of human lineage was interpreted as an anagenetic, linear process: it was “simple” – a passage from biologically and culturally more archaic forms to more progressive forms until the onset of our species. With new and improved research techniques (absolute dating and the study of DNA from living and fossil species) coupled with the discovery of new fossils, there has been a profound change in the way we interpret the evolutionary history of hominids. In particular, it was shown that two or more species of hominids coexisted in the same period and in the same territory. Apparently, multiple species of hominids have been the rule, not the exception, for the past 2.5 million years. Co-Existence of H. neanderthal and H. sapiens The more famous and best-documented case of coexisting hominids regards the two species of the genus Homo, H. neanderthalensis and H. sapiens. There remains considerable E. Carnieri (*) Museo di Storia Naturale del Mediterraneo, Via Roma 234, 57127 Livorno, Italy e-mail: e.carnieri@provincia.livorno.it 338 Human Evolution (2006) 21:337–340 discussion about the meaning and consequences of this “meeting”. The only certain data is that modern humans replaced the Neanderthals, in the Levant and in the European continent, in several thousands of years, and that the genetic contribution of the latter to modern human populations is null or insignificant [1]. More articulated and complex is the debate about the lithic artefacts – i.e., the relationships between the Mousterian industries, the so-called industries of transition, and those of Upper Palaeolithic, and about the interactions between the two species and the factors that determined the extinction of H. neanderthalensis. The Neanderthals evolved from European populations of H. heidelbergensis, between 250,000 and 130,000 years B.P. This species is characterized by several special morphological traits, probably due to an adaptation to particular climatic conditions. Subsistence Strategies of H. neanderthal Recently, d’Errico [4] emphasized that before and during the period of contact between the two species, there were no substantial behavioural and cultural differences (ecology and subsistence strategies, lithic technology, ability to work bone and ivory materials, burials, use of colours and personal ornaments, etc). Only later, when H. neanderthalensis had already disappeared, H. sapiens developed a greater cultural diversification. In particular, the subsistence strategies of Neanderthals were based on hunting, including ungulates of medium and great dimensions. A recent study seems to demonstrate that the hunting practiced by Neanderthals and by the first European anatomically modern humans showed the same level of specialization. However, the diet of H. neanderthalensis was variable from a chronological and geographic point of view. Before 50,000 years B.P., the most important food seemed to have been meat. In the following period, the diet was more diversified: Neanderthals also used other resources (molluscs, fishes, birds) as indicated by archaeological evidence from Vanguard Cave, Devil Tower at Gibraltar and Moscerini Cave in Italy. The phenomenon seems interesting, especially when we consider sites in southern Europe, where Neanderthals survived longer. An analysis of the dental microwear of the mandible teeth of the so-called “Gibraltar child” has shown a mostly carnivorous diet, as seen in Inuit and Fuegini populations [5]. Analysis of stable isotopes on Neanderthal specimens from Marillac and Saint Césaire (France), Scladina (Belgium) and Vindija (Croatia) confirmed these conclusions [6]. H. neanderthalensis seems to have been a species at the top of the ecological pyramid, hunting animals of large and medium dimensions, even if – probably – vegetables were also included in the diet [3]. Draw Near Hunting, Paleopathology and Lithic Points In addition, the study of Neanderthal palaeopathology suggests a strategy of hunting of “draw near” type: the Neanderthals probably confronted their victims from a short distance. A confirmation of the results of palaeopathological investigations comes from the comparison of artefacts, such as projectile points attributed to H. neanderthal and those made by H. sapiens. Palaeolithic lithic points are different in terms of aerodynamics and average kinetic energy from those made of bone or stone dated to the Upper Palaeolithic. The former are more effective due to their low speed, but high penetration, for shortdistance encounters, whereas the latter are more effective for killing an animal if launched from a greater distance and with a greater speed [4, 7, 8]. Human Evolution (2006) 21:337–340 339 More Varied Diet in H. sapiens Subsequently, since the Gravettian, the anatomically modern man seems to adopt a more varied alimentary behaviour. The studies on dental microwear, stable isotopes and trace elements in archaeological bones, as well as archeological (enormous variability and wealth of the material culture) and zooarcheological evidence bear witness to a change towards a different subsistence (more varied diet and with a greater intake of alimentary resources from inner waters such as molluscs and fish) [3, 6]. Results from analyses of stable isotopes on the Upper Palaeolithic record from Russia, Czech Republic and England emphasize this phenomenon. The study of trace elements on palaeolithic Italian remains (Paglicci and Parabita, dated to the Gravettian; Continenza, Romanelli, Romito and Vado all’Arancio, dated to the Epipalaeolithic) [3] have indicated a considerable variability in the diet of these human groups that covered a great part of the Upper Palaeolithic. Hypothesis on H. neanderthal Extinction Bearing these data in mind, it is possible to formulate a hypothesis that explains the extinction of H. neanderthalensis. Obviously, further studies and a greater amount of data are necessary to confirm these suggestions. Extinction is part and parcel of biological evolution; it is a natural and unavoidable phenomenon. The passing away of a species is more probable if some conditions take place: a limited area of distribution, populations of small dimensions and therefore characterized by an important phenomenon of genetic drifts, a long biological cycle, marked specialization, a high position within the trophic chain, and finally the arrival of a new species that occupies the same ecological niche. In this case, the extinction of a species is followed by the arrival of a new and morphologically similar species: this is the case of H. neanderthalensis and H. sapiens. Anatomically modern man reached Europe approximately 40,000 years ago and cohabited with the Neanderthals probably for few thousands years. It seems that the two Homo species had similar strategies in hunting and gathering, similar diet and similar exploitation of the territory. It is difficult to establish if there was a direct competition between the Neanderthals and anatomically modern humans and, in case there was, to what extent. However, the arrival in Europe of H. sapiens and the extinction of Neanderthals seem to be strongly connected. It is probable that various factors could have interacted together. The data which allowed the reconstruction of strategies of subsistence among Neanderthals have indicated their role as super-predators in the ecosystem. The more or less rapid climatic changes documented for that period could have determined the rarefaction or extinction of some preferential preys of Neanderthals and/or the shortage of territories available, with a consequent reduction of the population and “withdrawal” into climatically adequate shelter areas. In this situation, the Neanderthals could have adopted various alimentary strategies (especially in the southern regions), a form of adaptation that has enabled them to endure the various climatic crises of that period. It is possible that the arrival and the presence of our species had impeded access to the usual or alternative alimentary sources that were previously only exploited by H. neanderthalensis. Moreover, a small difference in the mortality rate between the two species could have been a sufficient factor that led to the extinction of Neanderthals. In the case of H. neanderthalensis and H. sapiens, the phenomenon could have been determined from various factors. One of the causes can be found in minimal differences in alimentary behaviour [2, 3] that favoured our species. The 340 Human Evolution (2006) 21:337–340 other cause could be attributed to the difference in hunting strategies. The strategy practiced by Neanderthals (short distance and/or drawn near) could have carried a higher risk, with a greater number of more or less serious injuries, compared to that practiced by anatomically modern men (at a greater distance). In conclusion, we can suppose that a compound of climatic, biological, behavioural and cultural factors had determined the decline, genetic isolation in small groups and, ultimately, extinction of Neanderthals. References 1. Caramelli D, Lalueza-Fox C, Cristiano Vernesi C, Lari M, Casoli A, Mallegni F, Chiarelli B, Dupanloup I, Bertranpetit J, Barbujani G, Bertorelle G (2003) Evidence for a genetic discontinuity between Neanderthals and 24,000-year-old anatomically modern Europeans. PNAS 100:6593–6597 2. Carnieri E (2002) Microusura dentaria in popolazioni paleolitiche della Penisola Italiana, Tesi di Dottorato di Ricerca in Archeoantropologia, XIV Ciclo (inedita), Università degli Studi di Torino, pp 1–149 3. Carnieri E, Tartarelli G, Bartoli F, Mallegni F (2002) Strategies of subsistence of European human populations during the Middle and Upper Paleolithic. 13th Congress of the European Anthropological Association (Abstract), p 37 4. d’Errico F (2003) The invisible frontier. A multiple species model for the origin of behavioral modernity. Evol Anthropol 12:188–202 5. Lalueza-Fox C, Pérez-Pérez A (1993) The diet of the Neanderthal child Gibraltar 2 (Devil’s Tower) through the study of vestibular striation pattern. J Hum Evol 24:29–41 6. Richards M, Pettitt P, Stiner M, Trinkaus E (2001) Stable isotope evidence for increasing dietary breadth in the European mid-Upper Palaeolithic. PNAS 97:7663–7666 7. Shea J (1997) Middle Palaeolithic spear point technology. In: Knecht H (ed) Projectile technology. Plenum Press, New York, pp 79–106 8. Villa P, d’Errico F (2001) Bone and ivory points in the Lower and Middle Palaeolithic of Europe. J Hum Evol 41:69–112