The extinction of Neanderthals (Homo neanderthalensis): a question with many questions and few answers. But, above all, a question to which anyone interested in human evolution has given more than one thought. And then the big question arises: were (or are we) anatomically modern humans (AMH: anatomically modern human) responsible for the extinction of that other human species? The short answer would be "no". The long and likely correct answer is that the extinction of Neanderthals was a multifaceted process that varied in different regions they inhabited. In this process, the ecosystem and all its components were vital to the survival of human groups.
Chronologically speaking, one would have to place oneself between 30,000 and 50,000 years ago, during what is known as the transition from the Middle Paleolithic to the Upper Paleolithic (MUPT: Middle to Upper Palaeolithic transition). It was a period of change in technology (both lithic and osseous), symbolism, subsistence strategies, and territorial exploitation. During this period, coexistence between Neanderthal and sapiens groups was recurrent. Thanks to advances in genetics, today we have evidence of hybridization between both species. For many researchers, the transition from the Middle Paleolithic to the Upper Paleolithic is considered a turning point in the cultural evolution of human groups. In this article, we will focus on what was happening in the Iberian Peninsula, although the territory occupied by Neanderthals was much larger.
As mentioned in the first paragraph, it is essential to understand the relationship of human groups with their environment, including animal and plant species and environmental conditions. Throughout Earth's history, there have been climate changes that have shaped different landscapes. Within the Quaternary period (from 2.6 million years ago until today), there are records indicating cyclic climatic changes. Thus, it distinguishes between stadials (relatively cold periods) and interstadials (relatively warm periods). In the Iberian Peninsula, two major climate zones can be observed: the Eurosiberian region to the north and west, and the Mediterranean region to the south and east. Analyses of stable isotopes, pollen, and micromammals suggest that towards the end of MIS 3 (MIS: Marine Isotope Stage), between 59,000 and 27,000 years ago, the climate became colder, leading to a more open landscape. The disappearance of the Mousterian (technological complex associated with Homo neanderthalensis) occurred earlier in the Eurosiberian region than in the Mediterranean region. That is, the persistence of Neanderthals in southern latitudes relates to more stable climatic conditions. However, despite these last representatives of Homo neanderthalensis resisting in climatic refuges with relatively mild conditions, the species eventually disappeared. At the same time, the arrival of Homo sapiens to the Iberian Peninsula coincided with a rapid recovery of biomass and productivity in ecosystems.
In summary, it has been demonstrated that the disappearance of Neanderthals coincided with a climate change that resulted in an ecosystem with lower productivity and thus fewer resources. On the other hand, populations of Homo sapiens arriving at the Iberian Peninsula found more favorable climatic conditions that would facilitate their survival. Therefore, there is talk of a replacement of Neanderthal populations by anatomically modern human populations. In conclusion, the debate about the disappearance of Neanderthals continues, but it is clear that changes in ecosystems play an important role.
Bibliography
Álvarez, D. S. (2012). The transition from the Middle Paleolithic to the Upper Paleolithic in Asturias: The La Viña shelter (La Manzaneda, Oviedo) and El Sidrón cave (Borines, Piloña) (Doctoral dissertation, University of Oviedo).
Vidal-Cordasco, M., Ocio, D., Hickler, T., & Marín-Arroyo, A. B. (2022). Ecosystem productivity affected the spatiotemporal disappearance of Neanderthals in Iberia. Nature ecology & evolution 6, 1-14.
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