Late glacial and Early Holocene migrations, and Middle Holocene settlement on the lower isthmian land-bridge

Abstract

Archaeological evidence from Late Pleistocene sites in South America indicates that human populations moved into and through the lower isthmian land-bridge by at least 16,000 cal BP. Extrapolations from DNA analyses of ancient and current populations are broadly supportive. The only archaeological trace of the earliest movements into the land-bridge consists of two point fragments similar to El Jobo points dated at Taima Taima to ca 15,800 cal BP. The earliest robust evidence of occupation on the land-bridge is the widespread presence of stone tools of the Clovis and Fluted Fishtail Point traditions. The striking similarities between the lithic reduction sequences leading to finished Clovis points in North America to the sequences in evidence at three quarry/workshop sites on the land-bridge (La Mula West and Nieto in Panama and Finca Guardiria [Turrialba] in Costa Rica) suggest a rapid demographic expansion of Clovis populations onto the land-bridge by 13,000 cal BP. The Fluted Fishtail Point Tradition may have overlapped, but most likely postdated the Clovis Tradition among land-bridge populations during the terminal Pleistocene ca 12,500–11,700 cal BP. A series of stemmed and/or tanged points characterized the Early Holocene (11,700–8200 cal BP) lithic assemblages. Point styles, and settlement densities and distributions showed little change during the Late Pleistocene and beginning of the Early Holocene. The appearance of domesticated crops and plant processing tools midway through the Early Holocene initiated a series of changes that led to larger and less mobile populations increasingly dependent on domesticated plants and thus bound to their houses, gardens and fields. Coincidently, bifacial flaking was abandoned as a lithic reduction strategy over much of the lower isthmian land-bridge terrain. Sites with archaeozoological evidence for inshore and estuarine fishing and coastal invertebrate collection are visible in Pacific estuarine zones by 7650 cal BP and on one of the Pearl Islands in Panama Bay islands by 6235 cal BP, in the Middle Holocene (8200-4200 cal BP), but any earlier sites of this nature would lie underwater because post-glacial sea-level rise had not yet levelled off (Redwood, 2020).