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Ice and ocean constraints on early human migrations into North America along the Pacific coast

Founding populations of the first Americans likely occupied parts of Beringia during the Last Glacial Maximum (LGM). The timing, pathways, and modes of their southward transit remain unknown, but blockage of the interior route by North American ice sheets between ~26 and 14 cal kyr BP (ka) favors a...

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Autores principales: Praetorius, Summer K., Alder, Jay R., Condron, Alan, Mix, Alan C., Walczak, Maureen H., Caissie, Beth E., Erlandson, Jon M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9963817/
https://www.ncbi.nlm.nih.gov/pubmed/36745804
http://dx.doi.org/10.1073/pnas.2208738120
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author Praetorius, Summer K.
Alder, Jay R.
Condron, Alan
Mix, Alan C.
Walczak, Maureen H.
Caissie, Beth E.
Erlandson, Jon M.
author_facet Praetorius, Summer K.
Alder, Jay R.
Condron, Alan
Mix, Alan C.
Walczak, Maureen H.
Caissie, Beth E.
Erlandson, Jon M.
author_sort Praetorius, Summer K.
collection PubMed
description Founding populations of the first Americans likely occupied parts of Beringia during the Last Glacial Maximum (LGM). The timing, pathways, and modes of their southward transit remain unknown, but blockage of the interior route by North American ice sheets between ~26 and 14 cal kyr BP (ka) favors a coastal route during this period. Using models and paleoceanographic data from the North Pacific, we identify climatically favorable intervals when humans could have plausibly traversed the Cordilleran coastal corridor during the terminal Pleistocene. Model simulations suggest that northward coastal currents strengthened during the LGM and at times of enhanced freshwater input, making southward transit by boat more difficult. Repeated Cordilleran glacial-calving events would have further challenged coastal transit on land and at sea. Following these events, ice-free coastal areas opened and seasonal sea ice was present along the Alaskan margin until at least 15 ka. Given evidence for humans south of the ice sheets by 16 ka and possibly earlier, we posit that early people may have taken advantage of winter sea ice that connected islands and coastal refugia. Marine ice-edge habitats offer a rich food supply and traversing coastal sea ice could have mitigated the difficulty of traveling southward in watercraft or on land over glaciers. We identify 24.5 to 22 ka and 16.4 to 14.8 ka as environmentally favorable time periods for coastal migration, when climate conditions provided both winter sea ice and ice-free summer conditions that facilitated year-round marine resource diversity and multiple modes of mobility along the North Pacific coast.
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spelling pubmed-99638172023-02-26 Ice and ocean constraints on early human migrations into North America along the Pacific coast Praetorius, Summer K. Alder, Jay R. Condron, Alan Mix, Alan C. Walczak, Maureen H. Caissie, Beth E. Erlandson, Jon M. Proc Natl Acad Sci U S A Physical Sciences Founding populations of the first Americans likely occupied parts of Beringia during the Last Glacial Maximum (LGM). The timing, pathways, and modes of their southward transit remain unknown, but blockage of the interior route by North American ice sheets between ~26 and 14 cal kyr BP (ka) favors a coastal route during this period. Using models and paleoceanographic data from the North Pacific, we identify climatically favorable intervals when humans could have plausibly traversed the Cordilleran coastal corridor during the terminal Pleistocene. Model simulations suggest that northward coastal currents strengthened during the LGM and at times of enhanced freshwater input, making southward transit by boat more difficult. Repeated Cordilleran glacial-calving events would have further challenged coastal transit on land and at sea. Following these events, ice-free coastal areas opened and seasonal sea ice was present along the Alaskan margin until at least 15 ka. Given evidence for humans south of the ice sheets by 16 ka and possibly earlier, we posit that early people may have taken advantage of winter sea ice that connected islands and coastal refugia. Marine ice-edge habitats offer a rich food supply and traversing coastal sea ice could have mitigated the difficulty of traveling southward in watercraft or on land over glaciers. We identify 24.5 to 22 ka and 16.4 to 14.8 ka as environmentally favorable time periods for coastal migration, when climate conditions provided both winter sea ice and ice-free summer conditions that facilitated year-round marine resource diversity and multiple modes of mobility along the North Pacific coast. National Academy of Sciences 2023-02-06 2023-02-14 /pmc/articles/PMC9963817/ /pubmed/36745804 http://dx.doi.org/10.1073/pnas.2208738120 Text en Copyright © 2023 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by-nc-nd/4.0/This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) .
spellingShingle Physical Sciences
Praetorius, Summer K.
Alder, Jay R.
Condron, Alan
Mix, Alan C.
Walczak, Maureen H.
Caissie, Beth E.
Erlandson, Jon M.
Ice and ocean constraints on early human migrations into North America along the Pacific coast
title Ice and ocean constraints on early human migrations into North America along the Pacific coast
title_full Ice and ocean constraints on early human migrations into North America along the Pacific coast
title_fullStr Ice and ocean constraints on early human migrations into North America along the Pacific coast
title_full_unstemmed Ice and ocean constraints on early human migrations into North America along the Pacific coast
title_short Ice and ocean constraints on early human migrations into North America along the Pacific coast
title_sort ice and ocean constraints on early human migrations into north america along the pacific coast
topic Physical Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9963817/
https://www.ncbi.nlm.nih.gov/pubmed/36745804
http://dx.doi.org/10.1073/pnas.2208738120
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