20.11 Low Maori Genetic Diversity
365
settlement history of New Zealand and of the Pacific. Prehistory, as we suggested
in the Introduction, depends on a consilience of evidence from many disciplines.
We have suggested how the insights archaeology provides can be complemented by
using ancient records and oral traditions to illuminate prehistory and by exploiting
the enabling power of mathematics and science and the chronological precision of
climate proxy data. In keeping with our pleas for a wider, more inclusive approach
to oceanic prehistory, we turn now from a reading of ancient genealogies to the
modern discipline of genetics to conclude our case for a Lapita-age first settlement
of New Zealand.
20.11 Low Maori Genetic Diversity
Maori has the lowest genetic diversity of any Polynesians and very low genetic
diversity by any standard. Geneticists tailoring their interpretations of New Zealand
genetic history to accord with current archaeological thinking (New Zealand considered as having at most a history of 800 years) cite as the cause for the low
genetic diversity of Maori the accretion of genetic bottlenecks through a cumulative sequence of migrations (from Near to Remote Oceania to Western Polynesia
to Eastern Polynesia to New Zealand). Thought to represent the last migrations to
have taken place in the Pacific, the populations of New Zealand, Hawaii and Easter
Island at the three apices of the “Polynesian triangle” are seen as being “at the end
of chains of migration” [15].
The paradigm implicit in this theory is one of logical stepwise, west–east conquest of the Pacific. Because it is thought to have been settled last, New Zealand
especially is seen as a terminus on a branch-line that followed innumerable mainline
migrations from Western Polynesia to Eastern Polynesia.
This theory of course presumes a late solely Eastern Polynesian origin for
Maori – a presumption contradicted by tradition and by the evidence that we have
presented in this book. The “chains of migration” explanation for low Maori genetic
diversity is confounded by the possibility that New Zealand was settled at least 1,000
and possibly as much as 1,900 years before Eastern Polynesia.
There are alternative explanations for the low genetic diversity of Maori.
In this chapter we have considered the possibility of a near-extinction event
in early New Zealand prehistory. A near-extinction event, of course, has major
implications for loss of genetic diversity. In 1027 BC New Zealand would have
had a population of about 797 (a figure arrived at by using the power law
estimate for population growth and a founder population of 289). If this population were halved through some catastrophe, it would be reduced to less than
the minimum of 500 Flannery cites as necessary to guarantee long-term survival. Just as serious would be the associated loss of genetic diversity, though
given the colonists were kin-based to begin with, it would be hard to estimate
the extent of the loss. Certainly, coalescence would be speeded up, perhaps
many or most of the rarest haplotypes would have been lost at the time of
365
settlement history of New Zealand and of the Pacific. Prehistory, as we suggested
in the Introduction, depends on a consilience of evidence from many disciplines.
We have suggested how the insights archaeology provides can be complemented by
using ancient records and oral traditions to illuminate prehistory and by exploiting
the enabling power of mathematics and science and the chronological precision of
climate proxy data. In keeping with our pleas for a wider, more inclusive approach
to oceanic prehistory, we turn now from a reading of ancient genealogies to the
modern discipline of genetics to conclude our case for a Lapita-age first settlement
of New Zealand.
20.11 Low Maori Genetic Diversity
Maori has the lowest genetic diversity of any Polynesians and very low genetic
diversity by any standard. Geneticists tailoring their interpretations of New Zealand
genetic history to accord with current archaeological thinking (New Zealand considered as having at most a history of 800 years) cite as the cause for the low
genetic diversity of Maori the accretion of genetic bottlenecks through a cumulative sequence of migrations (from Near to Remote Oceania to Western Polynesia
to Eastern Polynesia to New Zealand). Thought to represent the last migrations to
have taken place in the Pacific, the populations of New Zealand, Hawaii and Easter
Island at the three apices of the “Polynesian triangle” are seen as being “at the end
of chains of migration” [15].
The paradigm implicit in this theory is one of logical stepwise, west–east conquest of the Pacific. Because it is thought to have been settled last, New Zealand
especially is seen as a terminus on a branch-line that followed innumerable mainline
migrations from Western Polynesia to Eastern Polynesia.
This theory of course presumes a late solely Eastern Polynesian origin for
Maori – a presumption contradicted by tradition and by the evidence that we have
presented in this book. The “chains of migration” explanation for low Maori genetic
diversity is confounded by the possibility that New Zealand was settled at least 1,000
and possibly as much as 1,900 years before Eastern Polynesia.
There are alternative explanations for the low genetic diversity of Maori.
In this chapter we have considered the possibility of a near-extinction event
in early New Zealand prehistory. A near-extinction event, of course, has major
implications for loss of genetic diversity. In 1027 BC New Zealand would have
had a population of about 797 (a figure arrived at by using the power law
estimate for population growth and a founder population of 289). If this population were halved through some catastrophe, it would be reduced to less than
the minimum of 500 Flannery cites as necessary to guarantee long-term survival. Just as serious would be the associated loss of genetic diversity, though
given the colonists were kin-based to begin with, it would be hard to estimate
the extent of the loss. Certainly, coalescence would be speeded up, perhaps
many or most of the rarest haplotypes would have been lost at the time of