Ussher, Ella Manaia
Description
This thesis presents the results of an archaeobotanical study of
agricultural development in the Kingdom of Tonga. Prior to this
study, there has been no direct archaeological evidence for
agriculture in Tongan prehistory. Through the implementation of
systematic archaeobotanical techniques, this study aimed to fill
this gap and address two key research questions: 1) whether early
colonisers were dependent on introduced crops, or if human
dispersal was fuelled...[Show more] predominantly by the exploitation of
natural resources; and 2) whether archaeobotanical data can
provide new evidence to examine the role of agriculture within
the development of the maritime chiefdom in Tonga through
agroecological modelling.
This research was divided into two main phases. The first
involved the construction of a comprehensive comparative
collection for macrobotanical (vegetative storage and fruit
parenchyma and endocarp), and microbotanical (starch) components
of economic and supplementary plant taxa from Tonga. As part of
this, a study of the morphological attributes of starch and
parenchyma was conducted that incorporated multivariate
statistical analyses of diagnostic attributes. Two methods for
taxonomic classification were suggested: automated classification
using Discriminant Function Analysis (DFA) of starch, and the use
of an Identification Flowchart Key for parenchyma.
In the second phase of research, archaeobotanical data from three
sites on Tongatapu, representing three different time periods in
Tongan prehistory, is presented. Macrobotanical and
microbotanical remains were extracted from these sites using
flotation, wet-sieving and bulk stratigraphic sampling and
compared to a comprehensive reference collection using a
combination of SEM and light microscopy. Sampled cultural
deposits at Talasiu (2750-2650 cal BP), Leka (1300-1000 cal BP)
and Heketa (800-600 cal BP) present new insights into the role of
plant taxa within late-Lapita, the Formative Period, and early
stages of the Classic Tu’i Tonga chiefdom. Modelling using
techniques from Human Ecology, specifically agroecology,
replicated past production systems using measures of system
efficiency such as nutritional value of taxa, labour investment
and productivity in terms of yields. These were compared to
expectations based on current literature, and a revised
chronology for agricultural development and links to social
complexity is presented.
This study demonstrates that multivariate statistical analysis
and identification flowcharts enable the discrimination of starch
and vegetative storage parenchyma from most Tongan plant taxa
based on metric and nominal morphological attributes. When
applied to archaeobotanical data these techniques indicate that
most staple cultigens and some supplementary or famine foods were
brought to Tonga within a few hundred years of initial Lapita
colonisation. Late prehistoric introductions likely included the
sweet potato (Ipomoea batatas) by 600 BP, transported via East
Polynesia through the extensive trade networks of the developing
Tongan state. Modelling past production systems linked decreased
system nutritional efficiency over time to horticultural
specialisation in primary crops and increasingly centralised
government on Tongatapu. Critically, this analysis modelled the
high nutritional efficiency of Lapita subsistence, and linked
this to the division of labour investment between both economic
and supplementary species within a decentralised social
hierarchy.
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