Niche dynamics of Palaeolithic modern humans during the settlement of the Palaearctic

Abstract

Aim During the Late Pleistocene (c. 126–10 ka), modern humans (Homo sapiens) expanded their geographical range across Eurasia and eventually colonized the Americas. Although the routes by which they migrated have been intensively analysed, the dynamics of their realized climatic niche are still largely unknown. We assess temporal changes in the climatic niche of modern humans, the geographical distribution of their climatic niche and whether niche dynamics correlate with the magnitude of climate change and cultural advances, between 46 and 11 ka. Location Palaearctic. Methods Using the radiocarbon dated archaeological record and spatial palaeoclimatic simulations, we quantify different parameters of the realized climatic niche of modern humans (niche overlap, niche breadth and climatic marginality) between consecutive 1000–2000 year intervals. Moreover, using climate envelope models, we map the potential distributions of modern humans for each time interval and identify the regions that remained more climatically suitable and stable for modern humans through time. Results Between 46 and 22 ka the climatic niche of modern humans expanded, including periods of intense growth in niche breadth at 40 and 30 ka. Changes in seasonal water availability and technological innovations partly correlate with dynamics in niche parameters. We document a persistent climatically suitable mid‐latitude belt in south Siberia linking western Europe to the Far East that may have facilitated human migration, and a potential climatic refugium in Beringia. Main conclusions The climatic niche of modern humans changed across the Late Pleistocene, as the result of both climatic and cultural changes. These populations of hunter‐gatherers occupied novel climatic conditions but also remained in previously occupied areas under changing climates during the settlement of the Palaearctic. Our approach can provide clues as to where early modern humans may have overlapped in geographical and environmental space with Neanderthals or Denisovans, as evidenced by their contribution to the genetic heritage of some current populations.

Impacto del calentamiento global en la distribución y supervivencia del pinsapo (Serranía de Ronda)

“…Aunque la distribución espacial del nicho de una especie pueda estar sujeta a todo tipo de modificaciones, ocasionadas por cambios climáticos, la acción de agentes bióticos o por actividades humanas, se concibe que el nicho ecológico de un taxón, mientras éste existe como tal, es una cualidad constante en el tiempo. Por consiguiente, se entiende que las predicciones se realizan por debajo del umbral y la escala en que se producen las acomodaciones, adaptaciones o especiaciones de los seres vivos, si bien es posible adecuar la metodología para analizar nichos ecológicos dinámicos, como podría ser el caso de especies tan excepcionales como la nuestra, el Homo sapiens (Giampoudakis et al, 2016).…”

A new terrestrial palaeoenvironmental record from the Bering Land Bridge and context for human dispersal

“…The ultimate ‘push’ factor was the rising sea level that accompanied the release of water from melting ice sheets leading to the eventual and complete flooding of the BLB, which accelerated at the beginning of the Holocene, around 11 500 years ago [ 63 ]. However, a chief environmental ‘pull’ for early eastward human and megafaunal dispersal across Beringia may have been ameliorating climate after the LGM, most notably the seasonal changes in moisture [ 3 ] associated with deglaciation that created suitable habitats for Northeast Asian hunter–gatherers [ 63 ], along with other environmental changes on the BLB and in Eastern Beringia [ 7 , 31 , 68 ].…”

“…It has been postulated that even during the cold and dry LGM, the relatively low-lying BLB acted as a mesic barrier, inhibiting the dispersal of some open-habitat, faunal species between Eastern and Western Beringia [ 68 , 70 ]. Marked changes in moisture have been identified as an important attribute to megafaunal turnover in Beringia [ 22 , 71 ] and human niche dynamics in the Palaeoarctic [ 3 ]. The mesic barrier proposed for the BLB during the LGM would have greatly expanded into much wider-spread wetlands and peatlands with the progressively warmer and wetter conditions during the BA, evident at the site of St. Paul Island.…”

“…Palaeoenvironmental factors have been postulated to have had marked consequences for human dispersal into the Americas [ 3 ] and for faunal biogeography [ 22 , 66 , 71 ]. Our new multiproxy-based temperature and hydrologic reconstructions from a terrestrial site located on the south-central BLB revealed relatively warm and wet conditions during the BA, which validate this theory.…”

“…The modelled palaeoenvironmental context of human adaptation and dispersal across Beringia includes the important roles of temperature, moisture and vegetation [ 3 ], but remains speculative due to a distinct lack of empirical palaeoenvironmental data from the now-submerged BLB ( figure 1 ). Most of the multiproxy data from Eastern Beringia covers the Holocene [ 17 ] rather than the Late Glacial [ 18 ].…”