ADELE Whyte’s father is Maori. As a child, when she asked about his side of the family, she was told a story of the seven founding waka that voyaged in a great fleet from a homeland called Hawaiki to bring the first settlers to Aotearoa, Land of the Long White Cloud. Each waka or ocean-going canoe had a name, and Whyte was told she could trace her ancestry back to the one called Takitimu.
Years later, a degree in microbiology and genetics under her belt, and on the hunt for a master’s thesis subject, Whyte’s interest was drawn again to Maori oral history. She quickly realised that there are several conflicting stories. Some describe a single mass migration, others say that more than 100 canoes brought colonisers over a period spanning a few hundred years. “There’s even a suggestion that the story I was told as a kid could be a Europeanised idea that then became popular among Maori,” says Whyte. She decided to use her expertise in genetic analysis to help resolve the issue.
Whyte’s study is one of many in recent years that aims to unravel the mystery of New Zealand’s earliest settlers, as well as those of the other Pacific islands. This is a subject of huge interest, not least because it marks the final stage in humanity’s spread around the globe. In just over 2000 years, the vast, uninhabited Pacific was conquered, from Vanuatu in the west, to Hawaii in the north, and to the sub-Antarctic islands in the far south. There is intense debate about when and how this migration took place, and especially about who these people were and where they came from. Amid the conflicting evidence, however, one man now thinks he has come up with a coherent story. “This is a theory that reconciles all the evidence, and synthesises it into a whole,” says Geoff Chambers, Whyte’s supervisor at the University of Victoria in Wellington, New Zealand. At the heart of Chambers’s theory is the idea that the Maori have geographically separate male and female ancestors.
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The first visitors to New Zealand may have arrived as far back as 2000 years ago, according to a controversial study based on radiocarbon dating of bones from the Pacific rat, Rattus exulans. However, even if there were early arrivals, complete with rats, settlement happened much later. In a landmark paper published in 1991, Atholl Anderson, now at the Australian National University (ANU) in Canberra, reviewed carbon dating techniques and results, and pushed the generally accepted date of settlement forward from 1000 to 800 years ago. “At the time everyone said Anderson must be wrong, but all the work done since then has basically confirmed it,” says Ian Smith, an archaeologist at Otago University, New Zealand.
It is also becoming clear that this migration was deliberate. Sites of the first settlements, reliably carbon-dated at between 700 and 800 years old, are spread throughout the two main islands, supporting the idea of a planned, large-scale migration. And Whyte’s own study offers more evidence to back this up. Her analysis of maternally inherited mitochondrial DNA from 61 living Maori indicates that today’s population is descended from around 190 women. Unfortunately, settlement of New Zealand is too recent to allow mtDNA to be used as a molecular clock to pinpoint the arrival time of these founding mothers. “But at least we know that people did not just drift here, as had once been thought, because one boat was not enough to give the diversity of mtDNA that we have found,” says Whyte.
But the mystery of where they came from is proving trickier to solve. There are people in the Cook Islands who claim their ancestors were the original settlers. They call themselves Maori, and can even point to places on the beaches where their ancestors built canoes to sail to New Zealand. But, says Chambers, there is no way of evaluating these claims. Excavations at New Zealand’s earliest sites of habitation reveal a range of ornaments and tools very similar to those made in Tahiti and the Cook Islands at about the same time. It is impossible, though, to home in on one specific island. Language comparisons suffer from the same problems of resolution.
Whichever island the canoes set out from, Anderson believes they stopped off on the way. Dating work from the island of Rapa in French Polynesia shows that it was colonised at about the same time as New Zealand. “And when you get to Rapa, you’re getting into an area where the winds blow from east to west in the summer,” says Anderson. “If you accidentally got caught in that wind stream or deliberately chose to sail in it, you could probably reach New Zealand in three weeks, whereas it’s much more difficult to get to New Zealand directly from Tahiti or Fiji, or Tonga or Samoa.”
Anderson believes the colonisation of New Zealand was part of an expansion blitz through Polynesia. The archaeological record shows, for instance, that it took just a few hundred years for people to spread from Vanuatu to Fiji. And his own research indicates that when people did finally make it to New Zealand, some immediately set off again to look for new land. In 1998, for example, Anderson and his team found a Polynesian earth oven on Enderby, one of the Auckland Islands more than 500 kilometres south of New Zealand, containing 700-year-old charcoal.
Radiocarbon dating of samples collected by his team last year support this surprisingly early date. “This is what I would call a starburst colonisation,” says Anderson. “As soon as people found New Zealand, they not only explored it extremely rapidly, but all the areas around it.”
But who were these great explorers? One idea is that Polynesians are descended from people already living in the western Pacific – in eastern Indonesia or western Melanesia, an area that includes New Guinea and the surrounding islands. But the distinctive pottery of the region seems to support an alternative theory – that Polynesians can trace their ancestors back to Taiwan or China.
Peter Bellwood from the ANU was among the first to suggest this. He points out that between about 3200 and 3500 years ago, highly decorative pottery and shell ornaments began to appear in the Bismarck Archipelago off Papua New Guinea. This is characteristic of the Lapita culture, which includes other distinctive features such as domesticated animals, ocean-going canoes and a range of crops. While there is no clear sign of Lapita culture west of the Bismarck Archipelago, Bellwood argues that it developed from farming groups that appeared about 6000 years ago in southern China and Taiwan.
Bellwood’s idea forms the basis of a theory of human migration into the Pacific region dubbed the Express Train to Polynesia. “I’m not sure I would have come up with that term – after all, it did take 4000 years,” says Bellwood. According to the theory’s main proponent, Jared Diamond from the University of California, Los Angeles, Austronesian-speaking farmers left Taiwan about 5500 years ago. They reached the Philippines about 5300 years ago and Near Oceania (New Guinea and the Bismarck Archipelago) about 3600 years ago. Within about 400 years they had spread to the uninhabited remote Oceania (Vanuatu) and central Polynesia (Cook Islands), then north to Hawaii (1500 years ago) and south to New Zealand (Nature, vol 336, p 307) (see Map).
Linguistic support
The Express Train theory gets some support from linguistics. There are about 1200 Austronesian languages, and research by Robert Blust of the University of Hawaii has shown that they fall into 10 subgroups. The languages in nine of those subgroups are spoken only by indigenous people in Taiwan; the tenth is spoken from Madagascar to Easter Island, and from Taiwan to New Zealand. Since languages in that tenth group are very closely related, Blust argues that they all evolved from a language that arose in or around Taiwan. The relationship between them has recently been analysed by Russell Gray and Fiona Jordan from the University of Auckland, New Zealand. They borrowed techniques from evolutionary biology to create phylogenetic trees based on the relationships between species (Nature, vol 405, p 1052) and found evidence for Diamond’s proposed sequence of migration. Gray and his team are now trying to estimate when the languages diverged.
But if the archaeology and linguistics paint a reasonably consistent picture of Pacific migration through to New Zealand, the genetics does not. And this is where Chambers thinks his theory can reconcile the evidence where others fail. Any theory of Pacific settlement must account for seemingly conflicting results from studies of maternally inherited mtDNA and the paternally inherited Y chromosome.
Many researchers believe that comparisons of mtDNA samples back Taiwan as the origin of all Polynesians. Between 90 and 95 per cent of today’s populations have a characteristic deletion of nine base pairs in one region of their mtDNA. This marker can be traced back to Taiwan, and was taken to support the Express Train hypothesis.
Whyte’s Maori mtDNA research also points to Taiwan, according to Chambers, as does his research into genes related to the breakdown of alcohol. The work on alcohol dehydrogenase genes shows that specific variations found in New Zealand Maori are also found in Taiwan but not elsewhere in Asia. “This is strong evidence for Taiwan as the starting point,” says Chambers. “And that also jives well with the linguistic data.”
Not everyone draws the same conclusion from mtDNA, however. Martin Richards of the University of Leeds, UK, and Stephen Oppenheimer of the University of Oxford, looked at the “Polynesian motif” – a suite of four single-nucleotide polymorphisms. This motif is found throughout Polynesia as well as parts of eastern Indonesia and Melanesia, but it is not found in southern China, Taiwan or the Philippines – although an immediate ancestor, with three of the four polymorphisms, is found in these key “stations” on the Express Train route. The motif shows greatest diversity in eastern Indonesia, and work by Richards and Oppenheimer suggests that it originated in that region roughly 17,000 years ago, well before any Express Train might have passed through. So, they conclude that eastern Indonesia was home to an ancient, indigenous people who eventually migrated across the Pacific and ultimately to New Zealand. “While this fits the genetics, of course it means explaining the linguistics,” Richards concedes.
Chambers argues that any comprehensive theory must take account of the linguistics, as well as other evidence that is pro-Taiwan. “If you look only at the data that Oppenheimer and Richards have used, those maternal lineages could have arisen in Indonesia and spread in one direction to Taiwan and in the other to the Pacific. But when you take into account the alcohol genes and in particular the languages, you really begin to favour the explanation of Taiwan as the starting point,” he says.
All well and good except that studies of the Y chromosome seem to support Melanesian origins. In 2001, for instance, a team including Chambers reported findings from a study of Y chromosome markers in New Zealand Maori and men from other islands in the Pacific (Human Mutation, vol 17, p 271). About 40 per cent of their sample of 71 men showed clear evidence of Indonesian or New Guinean ancestry. Other researchers, including Mark Stoneking and Manfred Kayser of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, also believe that Y chromosome analysis indicates a strong Melanesian genetic contribution to the first Polynesians. They suggest this arises from fairly extensive interbreeding between Austronesian speakers who left south-east Asia (but not necessarily Taiwan) and indigenous Melanesians they met on their long route east.
But how to reconcile the evidence of a strong linguistic and mtDNA signal from Taiwan and a strong Y chromosome signal from Melanesia? For Chambers there is only one possible explanation – separate male and female lines. His idea is that both men and women left Taiwan and travelled to Melanesia but, once there, they needed to recruit local navigators – who would have been male – to help them migrate further east. Central to this theory is the idea that the ancestral Polynesian culture was matrilineal. “It would mean that women stayed with the land, and men were adopted into communities,” he says. “It makes good sense to us that if you’re moving places you need people with local knowledge, and you are always going to recruit navigators.”
Could this really be true? There is certainly support for the theory’s linchpin, matrilineal culture. In a paper published in Current Anthropology in December 2003 (vol 44, p S121), Per Hage of the University of Utah in Salt Lake City and Jeff Marck, formerly of the ANU, review knowledge about early Pacific societies. They argue, based on several lines of evidence, including the linguistics, such as the way various languages express kinship, that many societies were indeed matrilineal.
But others in the field are not convinced by Chambers’ ideas. Some experts believe that the pro-Melanesia Y chromosome signal could simply reflect more recent migrations. Populations are not isolated once they settle. Men in particular are likely to be involved in trade so the Y chromosome evidence may simply reflect later mixing. Others argue that the genetics is creating a confusing picture because sampling is incomplete. “I do not believe that we can say the Y and mtDNA data are indicative of different origins of lineages in the Pacific as yet,” says geneticist Matt Hurles of the Sanger Institute in Cambridge, UK. “More work and less talk is required.”
Bellwood agrees. He believes that, given time, the genetic results will come to support a single fairly recent origin for the Maori and their ancestors in China or Taiwan – with more interbreeding with Melanesians on the long route east than is allowed by the Express Train model. But, he says, the nature of the field means there probably will always be room for debate. “A lot of these things are essentially insoluble because they are so fuzzy. Where do Austronesians come from? Well, if you imagine 4000 years of reality over such a vast extent, there can never be a simple answer.”
Chambers, of course, would be happy if his idea were widely accepted. “I really believe that it brings various accounts presented as being in conflict together,” he says. But in the meantime, he and Whyte hope ongoing work on Maori history will throw new light on New Zealand’s first inhabitants as well as on the wider issue of settlement of the Pacific islands.
The case is yet to be resolved. But one thing is certain: given the fascinating attraction of the seafaring feats of these last great global colonisers, it is unlikely that Hurles’s call for less talk will be heeded any time soon.