Human Evolution in Polynesia: a Molecular Biological Study

Abstract

Human evolution is an extremely interesting and contentious topic that incorporates data from a wide variety of disciplines. Molecular studies are becoming increasingly important for reconstructing human history, as new techniques allow faster recovery of results, and genetic tests provide an independent test for colonisation theories that are usually based on archaeological and linguistic evidence. Mitochondrial DNA (mtDNA) is an extremely useful genetic marker that is widely used in molecular biology for establishing phylogenetic links between individuals and populations. In the current study the 3' Hypervariable Region (3' HVI) of mtDNA from human populations living in New Zealand (Aotearoa) was analysed. The HVI mtDNA diversity in the New Zealand Maori population was significantly reduced compared with Polynesian and Melanesian populations, with an extremely high frequency (~87%) of the 'Polynesian CGT motif’ haplotype. Additionally, the 9-bp deletion, common in Polynesian populations, has reached fixation (100%) in the Maori samples. These results support a settlement scenario with repeated population bottlenecks. The mtDNA HVI haplotype frequencies in this study, combined with those from previous studies, were used in computer simulations to estimate the number of females required to found the current Maori population. Approximately 56 women, and an equal or greater number of men, were estimated to have been present in the founding waka. This estimate is too large to support any settlement models with a small number of founders and effectively rules out the possibility of 'accidental discovery', instead supporting a planned settlement of Aotearoa in agreement with traditional knowledge. Analysis of interdisciplinary data has allowed current theories for the origins of the Polynesians and proto-Austronesians to be consolidated by introducing a 'Synthetic Total Evidence Theory'. It is likely that once published this theory will stimulate intense discussion and debate and will continue to grow as further evidence is obtained and incorporated into this model.