Rt€@lll

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The changes described above can occur in communities lndergoing modernizalion or ag
a result of urbanization. These processes can take place within a particular geoqraphic
location and society or when people migrate to a new society. These issues and their
important consequences will be discussed further in the next section.
Miqration. urbanization and health chanqes
The importance and extent of migration in the Pacific has already been referred to in
the Pacific as people move !o find work and improved living conditions. The majority are
hoping to provide better opportunities for edueation for their children and s life that can
include the "good lhings" they associate with a cash economy. Younger people migrate for
schooling or for trade training or simply to have the chance to see and take part in greater
opportunities they have heard about.
The migration may take place from outer island to main island centre' from rural
villages to lhe urban centre or from Pacific Islands to the western industrial societies zuch
as New Zealand and Australia.
The contrast between different groups for conditions zuch as blood pressure has been
referred !o and is shown in Figure I and Figure 2 for Rarotonga and Pukapuka. S[udies of
urban and nural groups in Samoa and Tonga have shown that Lhe urban groups have
significantly higher blood pressures and are heavier compared with those in the rural villages
(Zimmett et al., 1980; Finau et al.' 1983).
The factors influencing the changes of blood pressure wi[h age may provide important
infonmation concerning hypertension and the way in which it develops and so give more
effective leads lo its prevention. Tln opportunity Lo study subjects moving from a society
where blood onessure is not comrnon to one where blood pressure increases with age and
contributes to a range of cardiovascular problems has been presented by the Tokelau Island
Migrant Study and some of these nesulls will be detailed. The basic hypolheses beinq tested
concerning social change and disease were first put fonward by the late John Cassel and
their tesing has been an important part of the Tokelau Island Miqnant Study. The first
relates the changes in blood pressune to physical factors including changes in diet' higher
calorie intake, an increase in sodium and a decrease in potassium intake, gain in weight and
other life style changes; the second involves psychosocial factors such as a stressful life
changes, status incongruity, weakening or loss of support systems and coping strategies. It
has also to be necognized that both hypotheses rn€ly play a part.
The Tokelau Island Mignant study was commenced in 1967 with the support of the
Medical Research Council of New Zealand and the World Health OrganizaLion, and has been
developed as a multidisciplinary longitudinal study (Prior' 1974I
Tokelau is nrade up of three small alolls, (Fakaofo, Nukunonu and Atafu)' lying some
480 km north east of Samoa. Tokelau became a New Zealand dependency in 1925 and the
inhabitants were granted N.Z. citizenship in 1948. Tokelauans are of Polynesian origin and
consLitute a distinct atoll society with many features that are unique compared to other
groups in the Pacific.
In 1956 the population was 1980 in Tokelau, around 500 in N.Z.' 600 in Western Samoa
and I50 in Hawaii. A hurricane in January 1965 caused some devastation with loss of coconut
trees and darnage to buildinqs. The N.Z. Government set up a resettlement programme aimlng
to bring aromd 1000 of Lhe population to New Zealand over a five year period. The Tokelau
Island Migrant Study was established in 1967 and has been maintained since then. There have
been rnajor rounds of medical examinations in Tokelau in 1968, L97L' 1976 and 1982 and in
N.Z. in ie7Z-t4, L975-77 and 1980-8I. In 1980-8I there were 2570 tokelauans in N.Z. and in
1982, 1610 in Tokelau The involvement of social anthropologists from the outset and the
inclusion of Tokelauans in the study Leam l'ras helped expand and develop the study and also
to maintain a very high participation rate of around 94-95% in New Zealand and 97-99% in
Tokelau (Prior, 1974).
The genealogies collected by the anthropologists have been built up into a major
pedigree tite that is now altowing rnore critical examination of the part played by genetic
and Lnvironnental faetors in a number of important nredicel condiiions includinq hypertensiont
diabetes, coronary heart disease risk factors, athma and joint disorders (Ward et aL, f980).