Various European explorers, traders, missionaries, and others – from Captain James Cook onwards – speculated about where the ancestors of the Hawaiians and other Polynesians came from, and about when they had made their migrations into and across the Pacific.
But the first to systematically compile a large body of empirical data relevant to these questions, and to lay out a formal argument and theory, was Abraham Fornander, primarily in his classic An Account of the Polynesian Race (1878–1885), but also in a posthumously published summary.
Fornander was not an archaeologist; he did not draw upon the material record of ancient sites or artifacts. Fornander, who became fluent in Hawaiian, regarded the Hawaiian traditions as historical accounts of real individuals.
He also realized that these accounts could be placed into a relative chronology using the genealogies of the chiefly lines which he also collected and analyzed. Fornander estimated Hawaiian settlement at around AD 450. Later, Emory, analyzing linguistics, proposed a date of around AD 1150.
Professional anthropology incorporating archaeology took hold in Polynesia in the early 20th century. Early on, archaeology lacked any direct methods for dating Polynesian sites or artifacts, and was largely relegated to the mapping of surface architecture. Oral traditions, along with detailed ethnographic comparisons, were the main sources for historical reconstruction.
Evidence for human settlement of an island or archipelago can come from two different sources: (1) direct artifactual evidence from human settlements such as sand dune occupations or rockshelters; and …
(2) indirect evidence in the form of proxy signals of anthropogenic disturbance, such as increases in charcoal fluxes in lake or swamp sediments, rapid changes in pollen frequencies in these sediments, or the appearance plants and animals that live near or benefit from association with humans (such as weeds, insects or rats.)
The invention of radiocarbon dating helped to spark a boom in Polynesian and Pacific archaeology. In the 1940s, Professor Willard F Libby and his associates developed radiocarbon dating – a method to measure the age of organic materials.
The Nobel Prize in Chemistry 1960 was awarded to Libby “for his method to use carbon-14 for age determination in archaeology, geology, geophysics, and other branches of science”.
For radiocarbon dating to be possible, the material must once have been part of a living organism. This means that things like stone, metal and pottery cannot usually be directly dated by this means unless there is some organic material embedded or left as a residue.
Radiocarbon dating depended upon the discovery cosmic rays, which constantly bombard Earth and turn some carbon atoms in living tissue into radioactive isotope carbon-14. (University of Chicago)
The radiocarbon date tells us when the organism was alive (not when the material was used.) The dating process is always designed to try to extract the carbon from a sample which is most representative of the original organism.
The radiocarbon formed in the upper atmosphere is mostly in the form of carbon dioxide. This is taken up by plants through photosynthesis. Plant eating animals (herbivores and omnivores) get their carbon by eating plants. All animals in the food chain, including carnivores, get their carbon indirectly from plant material, even if it is by eating animals which themselves eat plants.
Once an organism dies the carbon is no longer replaced. Because the radiocarbon is radioactive, it will slowly decay away. There will usually be a loss of stable carbon too but the proportion of radiocarbon to stable carbon will reduce. (University of Chicago and University of Oxford)
Over the following decades, radiocarbon dating technology and techniques improved. While significant improvements were made, but the greatest advance came in 1977 with Richard A Muller’s use of accelerator mass spectrometry (atoms are converted into a beam of fast moving ions. The mass of these ions is then measured by the application of magnetic and electric fields.)
Equally important to the refinements in laboratory methods was the realization by archaeologists that they needed to pay close attention to the kinds of samples they submitted for dating.
This was especially the case for wood charcoal, perhaps the most commonly dated material from Polynesian sites. In the early years of radiocarbon dating, when the crude laboratory methods required large sample sizes, there was a tendency to select the largest pieces of charcoal.
The entire contents of hearths or earth ovens (often including tens or even hundreds of individual charcoal fragments) were often submitted in bulk to the dating laboratory.
The problem was that such samples in many cases included old growth timber, which had an ‘in built’ age that was potentially much older than the time at which the wood was actually burnt in the hearth or oven.
The date returned by the radiocarbon lab may have been an accurate indication of the age of the timber, but not of the ‘target date’ of human use of the site.
The most important step in developing new protocols for radiocarbon sample selection was the taxonomic identification of wood charcoal based on anatomical characteristics by comparison to a reference collection of known woody plant species for the particular region or island.
So, what does the updated technology and techniques show as the time of Hawaiian settlement in the Islands?
Dating of a number of key Eastern Polynesian sites, using AMS radiocarbon methods on better controlled (identified) samples has lent considerable support that the central archipelagoes of Eastern Polynesia did not begin to be settled until after AD 800 or later.
The ‘proxy’ paleo-environmental evidence for human presence in Hawai‘i, which for now comes almost exclusively from O‘ahu and Kauai Islands, leaves no doubt that human activities were creating significant disturbances on both of these islands by AD 1200. This then sets an upper bound on Polynesian settlement. The earliest dates on human introduced rat bones on O‘ahu are consistent with Polynesian arrival around AD 1000.
Re-dating of the site at Bellows, Waimānalo, O‘ahu puts the occupation of that small area at between AD 1040–1219. Obviously, this range falls closely between the lower and upper bounds indicated by the Eastern Polynesian chronologies and the paleo-environmental evidence.
Based on what we know now, it is suggested here that initial Polynesian discovery and settlement of the Hawaiian Islands occurred between approximately AD 1000 and 1200. (The bulk of the information here is from Kirch.)
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