Feature

Maori Migration

Where did the Maori come from? Part of the answer is falling into place thanks to new techniques for analysing human DNA.

Bernard Carpinter

The ancestors of the Polynesian people originally came from mainland Asia before island-hopping across the Pacific, and the ancestors of the Maori came to New Zealand from island groups north-east of New Zealand, according to DNA studies at Victoria University.

Dr Geoffrey Chambers, a Reader in the university's School of Biological Sciences, has been involved in a variety of projects which can track human migration patterns by comparing Maori DNA with that from other peoples in the Asia-Pacific region.

The international research programme that Chambers and his students have contributed to charts migration of the people who would eventually become the Maori. Starting from Taiwan, they voyaged through the Philippines and Indonesia to West Polynesia, and ultimately on to the islands of East Polynesia and then south-west to New Zealand.

Colonization of the Pacific by Polynesian peoples began around 5,000 years ago, with Aotearoa settled by Maori more than 600 years ago.

"There is an exact living record of these voyages of colonisation preserved in the DNA of their modern-day descendants who are still living in these places along the route," Chambers says.

For this work Chambers was able to make use of DNA data first obtained for other purposes by researchers in Victoria's Institute of Molecular Systematics (IMS) molecular biology laboratory. This includes research on the genetic protection against alcoholism. [Alcoholic Genes, June 1994]

This work made use of blood samples supplied by volunteers, and obtained through a special informed consent procedure. The Victoria data from several IMS human genetic studies in New Zealand were then compared with similar information from other populations around the world.

One key set of characters in these comparisons is three alcohol metabolism genes: ADH 2-2, ADH 3-1 and ALDH 2-2. The relatively high frequency of ADH 2-2 found in New Zealand Maori (0.42) links them with Cook Islanders (0.50) and, ultimately, with Oriental populations (0.72).

Data for the ALDH 2 gene implicates Taiwan as an initial staging post. The frequency of the ALDH 2-2 variant form of this gene is 0.30 in Japan and China, but only 0.05 in Taiwan -- and zero in Polynesia (Samoa/Rarotonga) and in New Zealand Maori. This result is consistent with Taiwan as a point of origin, Chambers says.

The IMS data fit well with information obtained elsewhere on two important mitochondrial DNA markers: the "Polynesian D-loop motif" (three highly characteristic nucleotides, CGT, found at particular sequence positions) and the "9-bp deletion", a highly characteristic set of missing nucleotides.

Following the deduced migration trail, the CGT Polynesian D-loop motif gradually becomes more prevalent until it is predominant in New Zealand Maori. Similarly, the 9-bp deletion marker increases from 16% in Japan and China to 100% in Samoa and New Zealand Maori.

"In some instances the level of genetic resolution is very high indeed," Chambers says.

For example, three rare mitochondrial DNA lineages found among Polynesians are known to come from Melanesia (3.5% of all mitochondrial DNA types), elsewhere in Oceania (0.6%) and South America (less than 0.1%). This South American component is very interesting, Chambers says, and may even indicate that at some point ancestors of the Maori travelled from their homes on Pacific Islands to South America and returned after intermarrying.

Forensic DNA profiling studies carried out at Victoria University have also added detail to this general picture by finding that Polynesians, in particular, show less genetic diversity than many other ethnic groups.

For example, the overall probability of finding two individuals possessing the same multi-locus DNA profile with a particular DNA probe was found to be one in 112 million for Asians, one in 47 million for Caucasians, one in 6.7 million for Polynesians, and one in 2.8 million for Maori.

"This is entirely consistent with a history of recent migration," Chambers says. "Each stage of a migration is a highly selective resampling of the original gene pool because each voyage was probably made by a relatively small group of people. If, as is likely, these people are closely related, then their descendants who grow up in their new island home will show increased genetic similarity."

Stages in the migration can be identified genetically and remain preserved in the genes of modern human populations along the route. The findings are supported by other studies being carried out by researchers in the Maori Studies and Linguistics Departments.

Distribution of the ADH 2-2 variant in the Pacific rim

Genes and Genealogy

Allan Coukell

Were the first human inhabitants of New Zealand accidental castaways, as some theories would have it -- or were they intentional colonizers?

Scientists and historians have debated the issue, but new DNA evidence suggests that the ancestors of present-day Maori New Zealanders were almost certainly part of a planned migration.

Rosalind Murray-McIntosh and her colleagues at Massey University examined the mitochondrial DNA (mtDNA) from a sample of Maori women and compared it with the mtDNA of people living in eastern Polynesia, where the ancestors of the Maori originated. Then, using computer modelling techniques, the researchers estimated how many women were present in the founding group 800 years ago. (Mitochondrial DNA is passed down the maternal line, so it can't give any direct evidence about the number of men.)

As they expected, the researchers found that the mtDNA sequences present in the Maori sample were a subset of the sequences found among residents of eastern Polynesia. They were surprised, however, at how few variants they found among the Maori they studied: among the 54 women in the sample, there were only four different sequences detected in the particular segment of mtDNA examined by the researchers (compared with 11 sequences known to occur in eastern Polynesia). Moreover, 47 of the Maori women shared a single sequence. This makes the mtDNA variability of Maori the lowest of any sizable population yet studied.

To determine what size of founding group was most likely to give rise to the present-day distribution of mtDNA among Maori, the researchers used a computer to model the growth of different sizes of eastern Polynesian subpopulations over 30 generations (corresponding to the 800 years that archaeological evidence suggests for human habitation of New Zealand). After running 20,000 simulations for each of 46 starting groups (ranging from 4 to 250 women), the researchers concluded that there were probably about 70 women in the founding group, and almost certainly no fewer than 50.

The calculations place an upper limit of 100 female colonizers, but the researchers acknowledge that this estimate does not take into account several factors, such as the possible presence of older, nonreproductive women in the founding population or the possibility that some Polynesians may have arrived after the initial population was already established.

Elizabeth Matisoo-Smith, an anthropologist at the University of Auckland, says these results "are very exciting, as long as they are not taken out of context." But she also notes that, rather than being evidence of a "Great Fleet", the mtDNA variation identified in Maori may represent evidence of post-colonisation contact between New Zealand and eastern Polynesia, as current theories of Polynesian prehistory suggest.

"These results provide further support for the deliberate exploration and settlement of the Pacific by ancestral Polynesians, and are in line with theories that have been developed and are being further developed as archaeological, genetic, and linguistic evidence accumulates."

Thus, it now seems certain that the ancestors of the Maori were not castaways, or indeed any small group. The large canoes of the Polynesians could probably accommodate 10 to 30 persons on a long voyage. Thus, a founding population of 70 women (and presumably at least 150 persons in total) must have arrived in a relatively large number of canoes. Such a founding population is lends support to the Maori oral tradition their ancestors were deliberate voyagers who sailed to New Zealand in a fleet of 8 to 10 canoes.

Bernard Carpinter is a journalist at Victoria University.
Allan Coukell is a freelance medical and science writer based in Auckland.