Not a bathtub: A consideration of sea-level physics for archaeological models of human migration

• Published in: Journal of Archaeological Science
• Main Authors: Borreggine, Marisa, Powell, Evelyn, Pico, Tamara, Mitrovica, Jerry X., Meadow, Richard, Tryon, Christian
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2022
• Subjects: Migration; Numerical modeling; Sea-level change; Glacial isostatic adjustment; Paleogeography; Deglacial; Archaeology; Ice Sheet
• Online Access: https://doi.org/10.1016/j.jas.2021.105507

Accurately reconstructing past sea level is key to simulating potential migration pathways of ancient hominins, including early Homo sapiens. Models of ancient human migration events commonly construct estimates of paleoenvironments using the "bathtub" model, in which sea level is assumed to rise and fall according to a "eustatic" (global average) value over time. However, large uncertainties exist on past ice sheet sizes and shapes, particularly prior to the Last Glacial Maximum (LGM), ∼26,000 years ago. Moreover, regional sea level varies significantly due to the effects of glacial isostatic adjustment (GIA). That process includes Earth's gravitational, deformational, and rotational response to changing surface (ice plus ocean) loads across the ice age. Here, we offer an updated account of the physics of GIA-induced sea-level change and consider the impacts of these effects, together with a newly published ice sheet history, on sea-level changes across the last glacial cycle. As illustrations, we highlight the significance of these issues for studies of ancient human migration from Sunda to Sahul and for the timing of the final, post-LGM flooding of the Strait of Dover. These examples demonstrate the importance of incorporating updated ice sheet histories and accurate sea-level physics into archaeological research. © 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Received 9 April 2021, Revised 19 October 2021, Accepted 19 October 2021, Available online 11 November 2021. We acknowledge support from the Dean's Competitive Fund for Promising Scholarship, Faculty of Arts and Science, Harvard University (M.J.B., J.X.M.). T.P. acknowledges funding from NSF EAR Postdoctoral Fellowship and UC President's Postdoc Fellowship Program. We thank the editor and the four anonymous reviewers for their constructive advice in regards to earlier versions of this manuscript. Researchers desiring regional ...