Climate change and the evolution of human ecology

The thesis focuses on the modifications that our species caused to environment from prehistory to current days investigated through a huge amount of anthropological, faunal, and bioclimatic data. The text is divided in different sections to better describe the relationship between people and the different components of terrestrial ecosystems. Since the Homo sapiens history is strictly linked to the evolution of the other human species, I first reviewed how the long-term history of human–environment interaction has affected the evolutionary biology of different human species. Specifically, I investigated the role of the climatic-driven changes in human species distribution assessing the different responses of Homo species to climate conditions. In this context, I also tested the role of culture as factor for the widening of human climatic niche. In the second part of the thesis, I investigated more the relationship between Homo sapiens and our phylogenetically and temporally closer human species, that is Homo neanderthalensis. I assessed their responses to climatic changes by comparing the temporal evolution of their climatic niche in according to intense climatic oscillations occurred during the Late Pleistocene. I found Homo sapiens had greater ecological plasticity over Neanderthals, which probably allowed this species to better react to climatic worsening at 44 and then at 40 ka, a date that almost coincides with estimated Neanderthal’s extinction. Moreover, I tested the hypothesis of climatic-driven habitat fragmentation as main cause of Neandethal’s demise. As results, data suggest Neanderthals potential habitat appears to be very reduced and fragmented during the last phase of their occupation, whereas for H. sapiens did not detect a similar pattern. Lastly, I provided evidences in favor of a social interactions between H. sapiens and Neanderthals also supported by genomic evidences rather than the onset of competitive exclusion phenomenon between the two human species. The last part of the thesis is focused on the role of human influence on Megafauna extinction occurred during the Late Pleistocene. I started analyzing the different trophic role of mammal species within community assembly and ecosystem functioning at large temporal and spatial scales. After that, I focused on the contribution of climatic changes and human appearance on Megafauna’s demise in Eurasia. I analyzed how the habitat spatial structure of mammal species changed during the last 200 kylo years. I found a primary role of climate in Megafauna extinction, whereas I demonstrated human presence was a non-decisive extinction factor for extinct herbivorous megafauna species.