In this chapter we outline the last major human migrations with the discovery and settlement of the Pacific Islands. The last phase of this expansion resulted in colonization of the eastern Pacific with more than 500 remote islands ranging from tropical, subtropical, temperate, and sub-Antarctic, varying in size and landforms, and comprising just 289,000 km2 of land over more than 20 million km2 of ocean. Reanalysis of radiocarbon dates for the region shows that migrations into the most remote Pacific occurred just over 1000–800 years ago, proceeded more rapidly than previously held, and included dispersal of plants and animals that invaded and disrupted unique and fragile island biotas. Human impacts profoundly transformed pristine ecosystems with habitat loss, the impacts of invasive rats, dogs, and pigs, as well as human predation. Successful human colonization led to natural environments transformed into agriculturally productive systems.
Keywords: Migrations, colonization, radiocarbon, human impacts, eastern Polynesia
The handle of my steering paddle thrills to action,
My paddle named Kautu-ki-te-rangi.
It guides to the horizon but dimly discerned.
To the horizon that lifts before us,
To the horizon that ever recedes,
To the horizon that ever draws near,
To the horizon that causes doubt,
To the horizon that instills dread,
The horizon with unknown power,
The horizon not hitherto pierced.
The lowering skies above,
The raging seas below,
Oppose the untraced path,
Our ships must go.
The last major human migrations over the planet occurred with the discovery and settlement of the remote islands of southern and eastern Polynesia. This remarkable episode included colonization of more than 500 remote tropical, subtropical, temperate, and sub-Antarctic islands comprising just 289,000 km 2 of land scattered over more than 20 million km 2 of ocean. Settlement of these islands with concomitant dispersal of plants and animals disrupted unique island biotas that evolved in relative isolation. Human colonists profoundly transformed pristine ecosystems with vegetation change and introduced cultigens, weeds, and animals, as well as a wave of extinctions associated with habitat loss, predation, and the impacts of invasive rats, dogs, and pigs. Natural environments were transformed into agriculturally productive systems, raising island carrying capacities for humans.
Building a reliable chronology forms a critical foundation to explaining prehistory, historical ecology, and human biology on Rapa Nui. A survey of the literature for Rapa Nui over the past few decades reveals a slowly changing picture of the island's chronology. Indeed, estimates of colonization and prehistoric events that followed have varied for hundreds of years, complicating greatly the research built on such shifting foundations. In 2006, we published an analysis of radiocarbon dates associated with the earliest known archaeological record of Rapa Nui (Hunt and Lipo, 2006). Based on a suite of new radiocarbon dates from our excavations of the Anakena Dune as well as a compilation of available published dates, we established a ranking of radiocarbon date reliability as indications of human behavior. From these results, we concluded that the island was colonized at some point soon after AD 1200. This significantly shorter chronology was not what we had originally expected. Indeed, this seemingly late date indicated that the island had a prehistoric chronology at least 400 – perhaps even 800 – years shorter than previously assumed. Given the island's famous stone statues and monumental architecture, a shortened chronology challenged many of the claims made about population growth rates, direct and indirect human impacts on the environment, and processes for the emergence of cultural elaboration such as statuary and monument construction. Additional research from multiple archipelagoes across East Polynesia now confirms late colonization, consistent with new dates as well as multiple lines of evidence from the Eastern Pacific (Hunt and Lipo, 2006; Rieth et al., 2011; Wilmshurst et al., 2011). Ultimately, there exists no reliable evidence in support of human occupation of Rapa Nui prior to AD 1200 – a pattern found for late and rapid settlement over a vast region of East Polynesia (Rieth et al., 2011; Wilmshurst et al., 2011).
A later chronology for Rapa Nui conforms to the growing body of evidence that humans colonized Eastern Polynesia relatively late in prehistory, as well as researchers demanding higher standards for reliable radiocarbon dating (Anderson, 2009; Arnold, 2007; Hunt and Lipo, 2008; Kennett et al., 2006a; Lie et al., 2007; Prebble and Dowe, 2008; Prebble and Wilmshurst, 2009; Rieth et al., 2011; Wells and Stock, 2007; Wilmshurst et al., 2008; Wilmshurst et al., 2011).
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