Pleistocene Water Crossings and Adaptive Flexibility Within theHomoGenus

Pleistocene water crossings, long thought to be an innovation ofHomo sapiens, may extend beyond our species to encompass Middle and Early PleistoceneHomo. However, it remains unclear how water crossings differed among hominin populations, the extent to whichHomo sapiensare 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 someH. sapienspopulations 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.

Automated summary

By modeling global data, it is found that water-crossing behaviors emerged in different regional hominin populations, initially representing nonstrategic range expansion, until some H. sapiens populations eventually pushed water crossings to new extremes, making significant adaptational adjustments.