15.3 An Explanation for the Fortification Sequence of Maori Pa
255
for population growth rates. Though skeletal evidence has offered a means for
estimating population growth rates, statistical problems in the past have hampered
analysis. In this chapter and in the last we have been able to demonstrate the usefulness and consilience of several independent approaches for estimating population
growth rates covering the time span in New Zealand from first settlement to the first
decades of the Little Ice Age. Skeletal evidence, evidence from field archaeology
and a power law analysis reveal similar demographic patterns and their demographic
estimates are consistent with one another. Derived population growth rates using a
power law approach show the implausibility of even a very early second-wave first
settlement for New Zealand at the end of the global cold period in 400 BC. And
a power law approach, which involves the minimum of demographic assumptions,
supports a date for first settlement close to the beginning of the Lapita migration
period (3,600–3,000 years ago). The consilience of demographic evidence obtained
by independent methods provides robust support for the prediction inherent in our
central paradigm of a first-wave Lapita-age first settlement of New Zealand.
15.3 An Explanation for the Fortification Sequence of Maori Pa
In the last section, as in Chapter 14, our focus has been on demographic analysis. We
turn now to a consideration of the human consequences of the population losses that
have been demonstrated through analysis. Skeletons record Harris lines in bones
which indicate periods of starvation in childhood. They record “fern-root planes”
in teeth which show a high dietary dependence on fern root which over time led to
enamel loss, tooth infection, blood-poisoning and early death. High infant mortality,
low life expectancy for children and adults and evidence of premature ageing all
reflect the harsh conditions of the Little Ice Age and their impact on human life.
The scale of pa-building and the population capacity of pa in the north of the North
Island reflect the psychological and physical stress accompanying an ever-present
risk of attack. The history of pa fortification, our focus in this section, shows such
stress spanning centuries. The impact of continuing population losses is reflected in
the history of pa defence itself.
In Chapter 14 we suggested a relationship between fast falling populations and
the fortification sequence of pa. From average population decline rates for pa areas
in the Little Ice Age, it is clear that the total pa population would have halved
roughly every 107–108 years. We have termed this the “half-life” of a pa and suggest
that successive fortifications were tied to this half-life, the point at which only half
the warriors present at the beginning of each half-life were left to defend the pa. To
abandon a large pa sited in an optimally defensible position because it had only half
the number of warriors needed to defend it would rarely have been a good option.
A better alternative would have been to add additional fortifications to make the pa
defensible by half the number of warriors that would originally have protected it.
A modern analogy suggests itself: that of Gustav Erikson and his grain ships.
These, the last great sailing ships, plied their way from South Australia to the Oland
Islands of Finland in the 1930s, carrying South Australian wheat to Europe. With
255
for population growth rates. Though skeletal evidence has offered a means for
estimating population growth rates, statistical problems in the past have hampered
analysis. In this chapter and in the last we have been able to demonstrate the usefulness and consilience of several independent approaches for estimating population
growth rates covering the time span in New Zealand from first settlement to the first
decades of the Little Ice Age. Skeletal evidence, evidence from field archaeology
and a power law analysis reveal similar demographic patterns and their demographic
estimates are consistent with one another. Derived population growth rates using a
power law approach show the implausibility of even a very early second-wave first
settlement for New Zealand at the end of the global cold period in 400 BC. And
a power law approach, which involves the minimum of demographic assumptions,
supports a date for first settlement close to the beginning of the Lapita migration
period (3,600–3,000 years ago). The consilience of demographic evidence obtained
by independent methods provides robust support for the prediction inherent in our
central paradigm of a first-wave Lapita-age first settlement of New Zealand.
15.3 An Explanation for the Fortification Sequence of Maori Pa
In the last section, as in Chapter 14, our focus has been on demographic analysis. We
turn now to a consideration of the human consequences of the population losses that
have been demonstrated through analysis. Skeletons record Harris lines in bones
which indicate periods of starvation in childhood. They record “fern-root planes”
in teeth which show a high dietary dependence on fern root which over time led to
enamel loss, tooth infection, blood-poisoning and early death. High infant mortality,
low life expectancy for children and adults and evidence of premature ageing all
reflect the harsh conditions of the Little Ice Age and their impact on human life.
The scale of pa-building and the population capacity of pa in the north of the North
Island reflect the psychological and physical stress accompanying an ever-present
risk of attack. The history of pa fortification, our focus in this section, shows such
stress spanning centuries. The impact of continuing population losses is reflected in
the history of pa defence itself.
In Chapter 14 we suggested a relationship between fast falling populations and
the fortification sequence of pa. From average population decline rates for pa areas
in the Little Ice Age, it is clear that the total pa population would have halved
roughly every 107–108 years. We have termed this the “half-life” of a pa and suggest
that successive fortifications were tied to this half-life, the point at which only half
the warriors present at the beginning of each half-life were left to defend the pa. To
abandon a large pa sited in an optimally defensible position because it had only half
the number of warriors needed to defend it would rarely have been a good option.
A better alternative would have been to add additional fortifications to make the pa
defensible by half the number of warriors that would originally have protected it.
A modern analogy suggests itself: that of Gustav Erikson and his grain ships.
These, the last great sailing ships, plied their way from South Australia to the Oland
Islands of Finland in the 1930s, carrying South Australian wheat to Europe. With