Human settlement of East Polynesia earlier, incremental, and coincident with prolonged South Pacific drought

Abstract

The timing of human colonization of East Polynesia, a vast area lying between Hawai‘i, Rapa Nui, and New Zealand, is much debated and the underlying causes of this great migration have been enigmatic. Our study generates evidence for human dispersal into eastern Polynesia from islands to the west from around AD 900 and contemporaneous paleoclimate data from the likely source region. Lake cores from Atiu, Southern Cook Islands (SCIs) register evidence of pig and/or human occupation on a virgin landscape at this time, followed by changes in lake carbon around AD 1000 and significant anthropogenic disturbance from c. AD 1100. The broader paleoclimate context of these early voyages of exploration are derived from the Atiu lake core and complemented by additional lake cores from Samoa (directly west) and Vanuatu (southwest) and published hydroclimate proxies from the Society Islands (northeast) and Kiribati (north). Algal lipid and leaf wax biomarkers allow for comparisons of changing hydroclimate conditions across the region before, during, and after human arrival in the SCIs. The evidence indicates a prolonged drought in the likely western source region for these colonists, lasting c. 200 to 400 y, contemporaneous with the phasing of human dispersal into the Pacific. We propose that drying climate, coupled with documented social pressures and societal developments, instigated initial eastward exploration, resulting in SCI landfall(s) and return voyaging, with colonization a century or two later. This incremental settlement process likely involved the accumulation of critical maritime knowledge over several generations.

From Land and Sea: Overcoming the Challenges of Directly Dating Dog Remains on Polynesian Islands

“…This range is earlier than the time frame of colonization for the Northern Cook Islands estimated by Schmid and colleagues (2018). Our starting boundary is however consistent with the general conclusion that many East Polynesian Islands were occupied at roughly AD 1150-1300 (Wilmshurst et al 2011;Schmid et al 2018;Sear et al 2020). The model results place the earliest dog known on Rakahanga at cal.…”

“…These voyagers, referred to as the Lapita peoples, sailed eastward across the Pacific, founding settlements as far east as Tonga and Samoa in West Polynesia. Current models suggest that following a nearly 2000-year voyaging hiatus, the first human colonization of East Polynesia began at roughly AD 900 in the Southern Cook Islands (Sear et al 2020) and AD 1000-1200 in the Society and Gambier Islands (Wilmshurst et al 2011;Stevenson et al 2017;Schmid et al 2018). Over the following centuries voyagers colonized much of the remainder of East Polynesia including Hawaii, New Zealand, and Easter Island (Wilmshurst et al 2011;Dye 2016;Schmid et al 2018).…”

One Thousand Three Hundred Years of Variability in the Position of the South Pacific Convergence Zone

“…If the reconstruction accurately captures movements of the SPCZ in preinstrumental times, the eastward shift identified during the MCA period could have important implications for our understanding of colonization processes in East Polynesia. While the drivers of Polynesian migration are not known (Goodwin et al, 2014), paleoclimate evidence suggests that changing hydroclimatic conditions and prolonged drought may have instigated eastward exploration (Sear et al, 2020). A recently published synthesis of high precision radiocarbon samples from the region has narrowed the phases of colonization down to two periods, the earliest representing colonization of the Society Islands from Samoa during ∼1,025-1,120 CE, followed by migration to the outer islands from ∼1,190-1,290 (Wilmshurst et al, 2011).…”

Tempo and Trajectory of the Built Landscape on Ta‘ū Island, Manu‘a Group, American Sāmoa: Integrating Extensive Radiocarbon Dating With Joint Posterior Modeling

“…These initial demographic changes in West Polynesia are roughly contemporaneous with the settlement of East Polynesia (Rieth and Cochrane 2018), presumably from the wider West Polynesia region. Sear et al (2020) have proposed a correlation between the settlement of some East Polynesian islands and a prolonged regional drought in the late 1st millennium AD. We propose that this drought could have had an influence on the settlement reconfigurations we document on Ta'ū.…”