Dating the initial arrival of humans on pristine island ecosystems

Establishing the timing and sequence of events in the human settlement of new landmasses is key to understanding drivers of ecological impact

The last major prehistoric dispersal of modern humans occurred with the discovery and settlement of the remote and scattered islands of East Polynesia.  This remarkable episode included the colonisation of more than 500 tropical, subtropical, temperate, and subantarctic islands comprising 289,000 km2 of land scattered over 20 million km2 of ocean.

Previous work dating woody seed cases of native trees with distinctive chew marks made by the introduced commensal Pacific rat showed that New Zealand could not have been settled any earlier than the middle of the 13th century. The Pacific rat spread with voyaging humans in the Pacific region, therefore its earliest presence indicates initial human contact. Analysis of a huge database of published radiocarbon dates from archaeological sites throughout the eastern Pacific has shown that New Zealand was settled not late or early relative to other islands in this region, but at virtually the same time as the rest of East Polynesia.

Over 1400 radiocarbon dates from 14 East Polynesian archipelagos were analysed to show that initial prehistoric colonsation from Tonga-Samoa was earliest in the Society Islands c. AD1025-1120; centuries later than previously assumed. It then dispersed to all the remaining island groups, which were settled in less than a century of each other, between c. AD1200-1290.  Only radiocarbon dates based on the most reliable dating material (charcoal and twigs from short-lived plants, seeds and leaves) were used to make this robust conclusion.

A precise time for initial settlement on an island is important to determine as it provides the starting point for establishing the rate of ecological and cultural change following the arrival of humans and their introduced commensals.

Key contact

Contact Janet Wilmshurst Janet Wilmshurst

Key collaborators

Atholl Anderson and Matiu Prebble (Australian National University); Nick Porch (Deakin University)

Funders

Royal Society of New Zealand Marsden Fund; Landcare Research Core Funding