14.5 Differential Rates of Population Decline
241
Climatic Optimum. It seems reasonable to suggest that the populations in the
pa areas may have peaked after the establishment of horticulture, and that they
may have been sustained, without significant loss, until the cold of the Little
Ice Age descended. The wide range of dating for the skeletal material studied
by Brewis et al. suggests, however, that some populations outside the warmer
richly resourced areas may have faced starvation during the Medieval Climatic
Optimum.
To summarize: that population decline occurred in New Zealand over 600 years,
in some areas at least, is not in doubt. The global context establishes the likelihood,
the skeletal evidence, and the demographic parameters derived from it establish
there was severe population decline over centuries. In all likelihood the poorest areas
with the highest populations in relation to resources exhibited the fullest decline. Pa
defending horticultural land and its harvests imply starvation and conflict over land
and resources. That there was population decline in pa areas is not in question, but
the severity and extent of that decline is unclear and the differential rates of decline
between richer and poorer areas need to be defined. Clearly there were modifying factors in the major pa areas. Applying the parameters derived from our skeletal
analysis to the whole of New Zealand for 600 years would lead to population extinction and would imply impossibly high population levels at the beginning of the Little
Ice Age.
One factor making for survival in the pa areas was so dominant that we suggest that it underpinned a completely different demographic regime in those areas.
This was the cultivation of kumara. It provided two survival advantages. As we have
repeatedly noted, defended stored kumara harvests provided some insurance against
starvation. But after the medieval introduction of horticulture, harvested kumara
would also have provided a weaning food for infants. Previously because of the
dearth of soft foods, infants would perhaps not have been fully weaned until they
were three or four. Access to kumara may have enabled breast-feeding in the pa
areas to be reduced to two years. This would have given a major boost to female
fertility by reducing the period of postpartum amenorrhoea and so reducing the
spacing of children [6]. Potentially this could have doubled female fertility. Though
the skeletal data suggests a maximum of five children for a woman, Maori tradition gives examples of rather larger numbers of children for some high-ranking and
therefore better nourished women from pa areas in Little Ice Age New Zealand.
Nuakaiwhakahua of Ng¯ ati Ruanui from the major pa area of Taranaki, for example,
is recorded as having nine children [28].
It can sensibly be argued that the demographic patterns revealed in Table 14.2
cannot have fully applied to the major pa areas and that a completely different demographic regime must have operated there. But in speaking of richer and
poorer areas in New Zealand, it should be stressed, we are thinking of a spectrum of survival possibilities for both richer and poorer areas. A range of survival
outcomes applies to each side of the pa/horticultural non-pa/non-horticultural division. Any population estimates applying to either side of the division represents
an average of variable survival outcomes. These outcomes depend on at least three
things:
241
Climatic Optimum. It seems reasonable to suggest that the populations in the
pa areas may have peaked after the establishment of horticulture, and that they
may have been sustained, without significant loss, until the cold of the Little
Ice Age descended. The wide range of dating for the skeletal material studied
by Brewis et al. suggests, however, that some populations outside the warmer
richly resourced areas may have faced starvation during the Medieval Climatic
Optimum.
To summarize: that population decline occurred in New Zealand over 600 years,
in some areas at least, is not in doubt. The global context establishes the likelihood,
the skeletal evidence, and the demographic parameters derived from it establish
there was severe population decline over centuries. In all likelihood the poorest areas
with the highest populations in relation to resources exhibited the fullest decline. Pa
defending horticultural land and its harvests imply starvation and conflict over land
and resources. That there was population decline in pa areas is not in question, but
the severity and extent of that decline is unclear and the differential rates of decline
between richer and poorer areas need to be defined. Clearly there were modifying factors in the major pa areas. Applying the parameters derived from our skeletal
analysis to the whole of New Zealand for 600 years would lead to population extinction and would imply impossibly high population levels at the beginning of the Little
Ice Age.
One factor making for survival in the pa areas was so dominant that we suggest that it underpinned a completely different demographic regime in those areas.
This was the cultivation of kumara. It provided two survival advantages. As we have
repeatedly noted, defended stored kumara harvests provided some insurance against
starvation. But after the medieval introduction of horticulture, harvested kumara
would also have provided a weaning food for infants. Previously because of the
dearth of soft foods, infants would perhaps not have been fully weaned until they
were three or four. Access to kumara may have enabled breast-feeding in the pa
areas to be reduced to two years. This would have given a major boost to female
fertility by reducing the period of postpartum amenorrhoea and so reducing the
spacing of children [6]. Potentially this could have doubled female fertility. Though
the skeletal data suggests a maximum of five children for a woman, Maori tradition gives examples of rather larger numbers of children for some high-ranking and
therefore better nourished women from pa areas in Little Ice Age New Zealand.
Nuakaiwhakahua of Ng¯ ati Ruanui from the major pa area of Taranaki, for example,
is recorded as having nine children [28].
It can sensibly be argued that the demographic patterns revealed in Table 14.2
cannot have fully applied to the major pa areas and that a completely different demographic regime must have operated there. But in speaking of richer and
poorer areas in New Zealand, it should be stressed, we are thinking of a spectrum of survival possibilities for both richer and poorer areas. A range of survival
outcomes applies to each side of the pa/horticultural non-pa/non-horticultural division. Any population estimates applying to either side of the division represents
an average of variable survival outcomes. These outcomes depend on at least three
things: