14.5 Differential Rates of Population Decline
239
Isolated from a global context, the parameters for population decline provided
in Table 14.2 may seem too extreme to be believable. The global context, however,
shows the derived rates to be far from anomalous. The death of one-third of the
population in the upland parishes of Scotland in the 1690s – a decline rate of 3.3%
p.a. – twice that of Option 6 and higher than any rate in Table 14.2, links poor
growing land with starvation and population decline. For England during the Little
Ice Age, Lamb offers a clear example of differential rates of population decline The
data he quotes for Oxfordshire, Northamptonshire and Norfolk from AD 1280 to
AD 1350 [25], for example, records differential rates for population decline in these
counties in the first 70 years of the Little Ice Age. (The Little Ice Age had an earlier
onset in the northern than in the southern hemisphere.) The decline rate in those 70
years for the population of Northamptonshire and Oxfordshire villages was 1.5%
per annum. But the rate of decline for Norfolk villages in the same period at 3% p.a.
was twice that of villages in Oxfordshire and Northamptonshire.
A context of climate-driven demography enables us to predict that populations in
poorer areas, with lower ceilings of population sustainability, and with high populations in relation to resources, will suffer greater decline. From the case for Norfolk
we can argue analogously for a differential rate of population decline between
richer and poorer areas in New Zealand and specifically between horticultural areas
defended by pa and less rich horticultural areas or non-horticultural areas where
pa density was low or pa were absent. In New Zealand the higher temperatures of
the north would have been largely responsible for a differential in the Little Ice
Age, for they determined the areas of New Zealand where tropical cultivars could
be successfully grown. Yet, although in the north horticulture clearly offered the
best chance for survival, this was only the case if horticultural land and its harvests could be defended. The extraordinary scale of pa-building, which we shall
argue mostly took place in the first two generations of the Little Ice Age, can
be seen as an inevitable consequence of the struggle for survival implicit in the
skeletal data, in the evidence for environmental deterioration from midden analysis, and in the drastic lowering of ceilings of sustainability implicit in the record
of species extinctions listed above and in Chapter 12. The comparison between the
fates of human populations in Iceland and Greenland, the first surviving, the second becoming extinct, suggests that populations in some of the non-horticultural
areas of the North Island in the Little Ice Age may have suffered a fate akin to the
Greenlanders.
The rate of population decline in any one area would have depended directly on
how high its resource ceiling was and how high its population was in relation to
that ceiling. While it is claimed that moderate chronic malnutrition results in only
a small decrease in female fertility, it is known than famine and starvation impact
directly on female fertility and on infant survival (see Bongaarts [26] and Spielmann
[27]). Conflict over land and resources in conditions of threatening or actual
starvation would, moreover, have impacted on male mortality through warfare.
Populations in areas with lower resource ceilings would have succumbed to starvation and population loss first and more drastically than those in better resourced
areas.
239
Isolated from a global context, the parameters for population decline provided
in Table 14.2 may seem too extreme to be believable. The global context, however,
shows the derived rates to be far from anomalous. The death of one-third of the
population in the upland parishes of Scotland in the 1690s – a decline rate of 3.3%
p.a. – twice that of Option 6 and higher than any rate in Table 14.2, links poor
growing land with starvation and population decline. For England during the Little
Ice Age, Lamb offers a clear example of differential rates of population decline The
data he quotes for Oxfordshire, Northamptonshire and Norfolk from AD 1280 to
AD 1350 [25], for example, records differential rates for population decline in these
counties in the first 70 years of the Little Ice Age. (The Little Ice Age had an earlier
onset in the northern than in the southern hemisphere.) The decline rate in those 70
years for the population of Northamptonshire and Oxfordshire villages was 1.5%
per annum. But the rate of decline for Norfolk villages in the same period at 3% p.a.
was twice that of villages in Oxfordshire and Northamptonshire.
A context of climate-driven demography enables us to predict that populations in
poorer areas, with lower ceilings of population sustainability, and with high populations in relation to resources, will suffer greater decline. From the case for Norfolk
we can argue analogously for a differential rate of population decline between
richer and poorer areas in New Zealand and specifically between horticultural areas
defended by pa and less rich horticultural areas or non-horticultural areas where
pa density was low or pa were absent. In New Zealand the higher temperatures of
the north would have been largely responsible for a differential in the Little Ice
Age, for they determined the areas of New Zealand where tropical cultivars could
be successfully grown. Yet, although in the north horticulture clearly offered the
best chance for survival, this was only the case if horticultural land and its harvests could be defended. The extraordinary scale of pa-building, which we shall
argue mostly took place in the first two generations of the Little Ice Age, can
be seen as an inevitable consequence of the struggle for survival implicit in the
skeletal data, in the evidence for environmental deterioration from midden analysis, and in the drastic lowering of ceilings of sustainability implicit in the record
of species extinctions listed above and in Chapter 12. The comparison between the
fates of human populations in Iceland and Greenland, the first surviving, the second becoming extinct, suggests that populations in some of the non-horticultural
areas of the North Island in the Little Ice Age may have suffered a fate akin to the
Greenlanders.
The rate of population decline in any one area would have depended directly on
how high its resource ceiling was and how high its population was in relation to
that ceiling. While it is claimed that moderate chronic malnutrition results in only
a small decrease in female fertility, it is known than famine and starvation impact
directly on female fertility and on infant survival (see Bongaarts [26] and Spielmann
[27]). Conflict over land and resources in conditions of threatening or actual
starvation would, moreover, have impacted on male mortality through warfare.
Populations in areas with lower resource ceilings would have succumbed to starvation and population loss first and more drastically than those in better resourced
areas.