Pleistocene Water Crossings and Adaptive Flexibility Within the Homo Genus

Dylan Gaffney

doi:10.1007/s10814-020-09149-7

Abstract

Pleistocene water crossings, long thought to be an innovation of Homo sapiens, may extend beyond our species to encompass Middle and Early Pleistocene Homo. However, it remains unclear how water crossings differed among hominin populations, the extent to which Homo sapiens are uniquely flexible in these adaptive behaviors, and how the tempo and scale of water crossings played out in different regions. I apply the adaptive flexibility hypothesis, derived from cognitive ecology, to model the global data and address these questions. Water-crossing behaviors appear to have emerged among different regional hominin populations in similar ecologies, initially representing nonstrategic range expansion. However, an increasing readiness to form connections with novel environments allowed some H. sapiens populations to eventually push water crossings to new extremes, moving out of sight of land, making return crossings to maintain social ties and build viable founder populations, and dramatically shifting subsistence and lithic provisioning strategies to meet the challenges of variable ecological settings.

Highlights

Crossing substantial bodies of water—lakes, straits, seas, and oceans—to arrive at new landmasses has previously been seen as a unique innovation within our species, Homo sapiens
At the same time, following the discovery of numerous Middle Pleistocene H. sapiens sites across eastern Eurasia, unilinear models for the dispersal of coastally adapted Late Pleistocene H. sapiens along the southern coast of Eurasia are untenable (Dennell and Petraglia 2012; Rabett 2018)
No hominin remains were found during excavations, but the results suggest that H. erectus or an unknown hominin species crossed to the Philippines during a sea-level low stand in Marine Isotope Stage (MIS)-20 or earlier

Summary

Introduction

Crossing substantial bodies of water—lakes, straits, seas, and oceans—to arrive at new landmasses has previously been seen as a unique innovation within our species, Homo sapiens. These mobility behaviors often correspond with, but are not necessarily causally linked to, the scale and success of colonization, for which we have distinct evidence in the form of paleoenvironmental change, faunal extinctions, tool modification, ancient genetics, settlement scale and longevity, and lithic landscape learning Using such datasets, we can start to address the nature, timing, and scale of water crossings made by different regional populations throughout the Pleistocene and how they articulate with colonization processes in new environs. Using the adaptive flexibility hypothesis, we can posit that hominins, whether they crossed water gaps intentionally or not, would have displayed wider behavioral variability during introduction phases of the colonization process, perhaps sampling from varied and novel food webs and experimenting with new raw materials to overcome technological challenges such as constructing watercraft to further expand resource patches Perhaps counterintuitively, these innovations would come at the time when a founder population was small and most sensitive to local extinction (Leppard 2015c, 2016). Because of the region’s steep geomorphology, records of Pleistocene island and coastal occupation survive, where in other parts of the world it is

Method

A Teppa di U Lupinu

Discussion

Conclusion

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