Neanderthals and Modern Humans: An Ecological and Evolutionary Perspective (review)

The extinction of Neanderthals has long been the focus of both scientific discussion and considerable public interest. This group of extinct humans was the end product of a long evolutionary lineage that colonized Europe as early as 500,000 years ago. They lived in Western Eurasia until approximately 30,000 years ago, when they disappeared from the fossil record, about 10,000 years after modern humans arrived in Europe for the first time. Competition with these modern upper Paleolithic people is often invoked in scenarios of the Neanderthal demise, which usually assume modern human superiority ranging from superior hunting technology to better language skills. Recently, however, it has become increasingly apparent that climate may have played a more important role in this event instead.

In Neanderthals and Modern Humans, intended for the specialist rather than the interested general reader, Clive Finlayson attempts an ambitious synthesis of climatic and biogeographic data with archeological and fossil evidence, with the aim of providing an ecological model for the Neanderthal extinction. Finlayson, the Director of Museums and Heritage in the government of Gibraltar and an eminent ornithologist, brings a welcome ecological perspective to this discussion. His argument that the Neanderthal extinction resulted from climatic instability over protracted periods of time and was not related to competition from modern humans echoes other recent findings pointing to climate as a major determining factor in late Pleistocene human evolution in Europe (van Andel and Davies 2003). Finlayson's approach highlights the complex, mosaic nature of the distribution and survival strategies of human populations and is a refreshing change from simplistic, unidimensional models. His use of computer modeling of demographic responses to climatic and ecological change is innovative and raises many interesting ideas and testable hypotheses.

What Finlayson really strives for, however, is a unifying theory of late Pleistocene human evolution in Europe. In this he is less successful. Although many aspects of his work are interesting and noteworthy, his thesis is flawed on several counts. Pertinent evidence is often ignored or brushed aside, and general arguments are often based on the spatiotemporally limited demographic and climatic modeling of Iberia in the last 50,000 years.

The main components of Finlayson's model can be summarized as follows: Neanderthals and modern humans in Europe appear to be ecologically separated. Neanderthals were omnivorous and showed an adaptation to heterogeneous environments of relatively southerly latitudes. Repeated climatic deteriorations resulted in the shrinking of preferred Neanderthal habitats. This forced Neanderthals into Mediterranean refugia, fragmenting and depressing their populations in the process. Although Neanderthals attempted to respond behaviorally to deteriorating conditions by developing transitional industries, such as the Châtelperronian, their robust morphology was an impediment to colonization of the encroaching open plains habitats. The repeated effects of population fragmentation and depression resulting from long-term climatic instability led to their eventual extinction, even as climatic conditions were improving. In this regard, climatic and demographic models for the Iberian peninsula show Neanderthals behaving as though adapted to a warm climate.

Modern humans, on the other hand, were adapted to the Eurasian plains environments and were specialized herbivore–meat eaters. Their gracile, long-limbed skeletons were adapted to high mobility, and, combined with their behavioral innovations, this enabled them to develop the large group sizes and large home ranges necessary for successful exploitation of the Eurasian plains. Climatic deterioration would have resulted in the expansion of plains habitats at the expense of the more heterogeneous environments favored by Neanderthals. Simply by tracking their preferred habitat, modern humans arrived in areas previously occupied by Neanderthals, in most cases after the local Neanderthal populations were already extinct. Temporal and spatial overlap between the two groups was therefore minimal, and so were the opportunities for competition. With time, Neanderthals became extinct, even in their last refugia, and modern human populations expanded. Climatic and demographic modeling in the case study of Iberia shows modern humans behaving as though adapted to...