25. What DNA evidence exists in New Zealand suggesting human habitation over two thousand years ago?

Previous blogs have explored two categories of evidence suggesting the possibility of human habitation in New Zealand over two thousand years ago.

1. Māori Oral History Evidence

2. Archaeological Evidence: Artefacts and Features

Two additional categories will be introduced in upcoming blog posts.

3. Evidence from DNA Analysis

4. Origins of the Māori Language

3.      Evidence from DNA Analysis

The Māori population exhibits significant physical diversity, with variations in skin tone, hair colour, and facial features. This means there is no singular "typical" Māori appearance, and individuals can vary greatly within the population due to intermarriage and geographical differences across iwi (tribes) throughout New Zealand. Some Māori may have darker skin tones, while others may have lighter complexions. The population also displays a range of hair colours, from dark brown to blonde and even red, reflecting the diverse genetic heritage.

Genetic studies of Māori people aim to trace their heritage, utilizing markers such as mitochondrial DNA (mtDNA) and the Y chromosome. Both are inherited in a haploid manner, meaning they are passed down relatively unchanged from one generation to the next, though through different lineages—mtDNA from the mother and the Y chromosome from the father.

Genetic studies on Māori ancestry show the following trends:  Reference: Underhill P.A. et al. Maori Origins, Y-Chromosome Haplotypes and Implications for Human History in the Pacific, Human Mutation 17:271-280 (2001)

1. Diversity of Ancestry:

   • Y-Chromosome Data: This indicates a diverse paternal heritage, with significant contributions from European, Melanesian, and East Asian lineages. Approximately 40% of the Y-chromosome haplotypes are of European origin, another 40% are linked to a Melanesian haplotype, and the remaining show East Asian or mixed origins.

   • mtDNA Data: This shows a more homogeneous maternal ancestry, with 85% of Māori samples exhibiting a 9-bp deletion in Region V, characteristic of Southeast Asian populations. This is a genetic marker indicating a more homogeneous maternal ancestry amongst Maori females. The remaining 15% of the samples are of European origin.

     
     

2. Geographic Origins:

   • Y-Chromosome Data: The data reveals a complex pattern of gene flow involving both Melanesian and Southeast Asian influences, suggesting multiple migration events and interactions.

   • mtDNA Data: This suggests a predominant Southeast Asian influence, supporting the theory of a rapid and relatively uniform Austronesian expansion into Polynesia.

In summary, while the Y-chromosome data points to a more complex and diverse paternal ancestry, with significant contributions from Melanesian and European populations, the mtDNA data suggests a predominant Southeast Asian maternal ancestry.

These findings support the idea that people migrated from the Southeast Asia and New Guinea regions to Polynesia, and eventually to New Zealand. However, they also raise the possibility that some migration might have occurred directly from Southeast Asia and New Guinea to New Zealand. Who do you think were New Zealand's first settlers?

Your next read in the series: 26. How has the Māori language evolved from its origins as an oral tradition to a written and modern language?