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7 The Horticultural Context
The horticultural sophistication that the Polynesian peoples acquired from
their Spice Island ancestors almost certainly had its origin in the history of
the Spice Islands and Wallacea as a major centre for early plant and animal
domestication.
It is important to realize that the spices that the Spice Islanders traded were not
harvested from wild trees. Over a very long period of time, the qualities of the
spices had been genetically enhanced by human-assisted natural selection and by
hybridization. The clove trees that produced cloves for trade were very different
from the wild clove trees that still grow on the island of Halmahera. The cultivated clove grew on the tiny Halmaherian offshore islands of Tenate, Tidore, Mutir,
Machian and Bachian. Through a long process of genetic manipulation, the taste,
perfume and the lasting qualities of the harvested clove flowers were intensified, the
medicinal qualities of the spice as an antiseptic, an aphrodisiac and local anaesthetic
increased. Nurtured for a long period of time on these five islands, these cultivated
clove trees lost much of the genetic diversity of the wild forms and became so
adapted to the unique microclimates of the five islands that, until the 16th century,
they could not be persuaded to grow elsewhere in the region or indeed in the world.
The limited genetic diversity of the cultivated clove, of course, greatly enhanced its
commercial value. It gave the Spice Islanders a monopoly in both its production and
trade.
Two distinct processes are involved in plant domestication. The more usual is
human-assisted natural selection, often used to extend the natural planting range
of a domesticated plant. We see this technique, for example, used in the humanassisted development of rice cultivars that could be rain-fed on terraced hillsides
rather than grown in swamps. We see it too in the development of rice cultivars
with a longer ripening time which could exploit the longer hours of sunlight in the
temperate zones as opposed to the shorter ripening times in the tropics.
The second process involves hybridization. This involves preventing natural pollination in selected plants, harvesting pollen from other carefully chosen plants and
then artificially fertilizing the depollenated plants. Where the plants involved belong
to the same variety, the process is simple. But often the most significant improvements occur by crossing varieties that may be so significantly different genetically
(for example, having different chromosome counts) that the resultant plants are
infertile. They can only, thereafter, be reproduced vegetally, usually through the
planting of suckers. The survival and future history of that cultivar becomes entirely
dependent thereafter on human intervention. The domestication of the breadfruit
and banana in Wallacea provides good examples. Their vegetal mode of reproduction – the cultivated banana, for example, is seedless – is proof that deliberate
hybridization was involved in their domestication.
The downside of domestication through hybridization is the loss of genetic
diversity and loss of the possibility of future genetic adaptation. There is current
concern in Australia, for example, that if an overseas virus affecting bananas reaches
Australia, it may cause the end of banana cultivation in the country. Means of further natural selection or human-assisted natural selection to acquire resistance to a
virus end when plants can no longer be reproduced by seed. Genetic engineering in
7 The Horticultural Context
The horticultural sophistication that the Polynesian peoples acquired from
their Spice Island ancestors almost certainly had its origin in the history of
the Spice Islands and Wallacea as a major centre for early plant and animal
domestication.
It is important to realize that the spices that the Spice Islanders traded were not
harvested from wild trees. Over a very long period of time, the qualities of the
spices had been genetically enhanced by human-assisted natural selection and by
hybridization. The clove trees that produced cloves for trade were very different
from the wild clove trees that still grow on the island of Halmahera. The cultivated clove grew on the tiny Halmaherian offshore islands of Tenate, Tidore, Mutir,
Machian and Bachian. Through a long process of genetic manipulation, the taste,
perfume and the lasting qualities of the harvested clove flowers were intensified, the
medicinal qualities of the spice as an antiseptic, an aphrodisiac and local anaesthetic
increased. Nurtured for a long period of time on these five islands, these cultivated
clove trees lost much of the genetic diversity of the wild forms and became so
adapted to the unique microclimates of the five islands that, until the 16th century,
they could not be persuaded to grow elsewhere in the region or indeed in the world.
The limited genetic diversity of the cultivated clove, of course, greatly enhanced its
commercial value. It gave the Spice Islanders a monopoly in both its production and
trade.
Two distinct processes are involved in plant domestication. The more usual is
human-assisted natural selection, often used to extend the natural planting range
of a domesticated plant. We see this technique, for example, used in the humanassisted development of rice cultivars that could be rain-fed on terraced hillsides
rather than grown in swamps. We see it too in the development of rice cultivars
with a longer ripening time which could exploit the longer hours of sunlight in the
temperate zones as opposed to the shorter ripening times in the tropics.
The second process involves hybridization. This involves preventing natural pollination in selected plants, harvesting pollen from other carefully chosen plants and
then artificially fertilizing the depollenated plants. Where the plants involved belong
to the same variety, the process is simple. But often the most significant improvements occur by crossing varieties that may be so significantly different genetically
(for example, having different chromosome counts) that the resultant plants are
infertile. They can only, thereafter, be reproduced vegetally, usually through the
planting of suckers. The survival and future history of that cultivar becomes entirely
dependent thereafter on human intervention. The domestication of the breadfruit
and banana in Wallacea provides good examples. Their vegetal mode of reproduction – the cultivated banana, for example, is seedless – is proof that deliberate
hybridization was involved in their domestication.
The downside of domestication through hybridization is the loss of genetic
diversity and loss of the possibility of future genetic adaptation. There is current
concern in Australia, for example, that if an overseas virus affecting bananas reaches
Australia, it may cause the end of banana cultivation in the country. Means of further natural selection or human-assisted natural selection to acquire resistance to a
virus end when plants can no longer be reproduced by seed. Genetic engineering in