Kinaston, Rebecca, 2010. Prehistoric diet and health in the western Pacific Islands

The mode of subsistence of the earliest populations that colonised Remote Oceania, the people associated with the Lapita Cultural Complex, remains a contentious issue and, for many Pacific islands, the extent to which chronologically later prehistoric populations relied upon horticultural products is unknown. The overarching aim of this thesis is to assess the diet and subsistence of six prehistoric Pacific Island skeletal samples to understand the possible health implications of these dietary patterns. This research is the first study focused on analysing variations in diet between the sexes and between age cohorts within prehistoric Pacific Island skeletal samples to assess the possible health implications of potentially culturally moderated food-related practices.

The materials used in this study span 3000 years of Pacific Island prehistory and include four Lapita-associated skeletal samples from Vanuatu (Teouma [n=49], Uripiv [n=5] and Vao [n=4]) and Papua New Guinea (Watom [n=4]) and two skeletal samples that date much later in prehistory (600-400 BP) from Papua New Guinea (Nebira [n=31]) and the Solomon Islands (Taumako [n=158]).

The objectives of this study were to characterise the diet of these six skeletal samples by analysing carbon, nitrogen and sulphur stable isotopes of bone and tooth collagen (the distal root portion of the first molar root, formed from ages 5-9) in conjunction with tooth wear and oral health indicators (caries, calculus, periapical cavities, periodontal disease and antemortem tooth loss) to assess if these methods were comparative or complementary for reconstructing past diet. The second objective used the prevalence of linear enamel hypoplasia (LEH) as a non-specific indicator of stress to assess the health of the skeletal samples. The third objective was to compare the dietary and health profiles of the adults and subadults to assess whether there were differences between survivors and non-survivors. Lastly evidence LEH was compared between the cemetery samples to investigate whether the possible diachronic dietary transitions were associated with a decline in health.

The dietary results indicated that there were temporal variations in diet and subsistence; the chronologically earliest sample, Teouma, practised a broad-spectrum hunting/gathering and marine foraging subsistence and, at the other sites, there was an increase on the reliance of horticultural products over time. The exception to this trend was the skeletal sample from Taumako, which had dietary evidence of a heavy reliance on marine products. Sexual differences in the protein portion of the diet only occurred at Teouma, the chronologically earliest site. The LEH results indicated there was a decline in health over time. At Taumako there were dietary and health differences between the survivors and non-survivors; the non-survivors were consuming less protein and had more evidence of stress than the survivors. At a number of sites, the stable isotope values of tooth collagen indicated that, as children, the adult individuals had consumed more protein from higher trophic levels than as adults.

From these data it is suggested that the stable isotope analysis may have over-represented the high protein marine portion of the diet, although it did show evidence of dietary change over time. The dental evidence assisted in the stable isotope analysis of diet, but the consumption of betel nut may have affected the oral health in a number of skeletal samples and therefore could influence the effectiveness of using oral health as a dietary indicator in the Pacific islands. The dietary differences between the sexes observed in the earliest populations may have been a result of 'ranked' social structure of Lapita-associated populations. The later populations may have had culturally-induced dietary differences between males and females but these may have centred around foods that could not be identified by the current analyses because they were of a similar food type, but prepared in a 'special' manner, such as a pudding, making any differences invisible isotopically. The analysis of childhood diets (of the adults who survived) did not follow the dietary patterns observed in modern-day Pacific islands, which document a lower protein diet of children compared to adults. However, the diet of the non-survivors did agree with modern accounts, and this type of diet may have contributed to their early death. The health assessments indicated that there was an increase in stress as populations became more reliant on horticulture, although it is inconclusive as to whether or not this was a result of a decrease in nutritional quality and/or a response to the higher prevalence of infectious disease associated with larger population sizes and increased sedentism.