GUNS, GERMS AND STEEL - Cloverport Independent Schools

3 0 4 " GUNS, GERMS, AND STEEL
regions as one of the world's centers of independent origins of plant
domestication. No remains of the crops actually being grown in the highlands
6,000 years ago have been preserved in archaeological sites. However,
that is not surprising, because modern highland staple crops are plant
species that do not leave archaeologically visible residues except under
exceptional conditions. Hence it seems likely that some of them were also
the founding crops of highland agriculture, especially as the ancient drainage
systems preserved are so similar to the modern drainage systems used
for growing taro.
The three unequivocally foreign elements in New Guinea highland food
production as seen by the first European explorers were chickens, pigs,
and sweet potatoes. Chickens and pigs were domesticated in Southeast
Asia and introduced around 3,600 years ago to New Guinea and most
other Pacific islands by Austronesians, a people of ultimately South Chinese
origin whom we shall discuss in Chapter 17. (Pigs may have arrived
earlier.) As for the sweet potato, native to South America, it apparently
reached New Guinea only within the last few centuries, following its introduction
to the Philippines by Spaniards. Once established in New Guinea,
the sweet potato overtook taro as the highland's leading crop, because of
its shorter time required to reach maturity, higher yields per acre, and
greater tolerance of poor soil conditions.
The development of New Guinea highland agriculture must have triggered
a big population explosion thousands of years ago, because the highlands
could have supported only very low population densities of huntergatherers
after New Guinea's original megafauna of giant marsupials had
been exterminated. The arrival of the sweet potato triggered a further
explosion in recent centuries. When Europeans first flew over the highlands
in the 1930s, they were astonished to see below them a landscape
similar to Holland's. Broad valleys were completely deforested and dotted
with villages, and drained and fenced fields for intensive food production
covered entire valley floors. That landscape testifies to the population densities
achieved in the highlands by farmers with stone tools.
Steep terrain, persistent cloud cover, malaria, and risk of drought at
lower elevations confine New Guinea highland agriculture to elevations
above about 4,000 feet. In effect, the New Guinea highlands are an island
of dense farming populations thrust up into the sky and surrounded below
by a sea of clouds. Lowland New Guineans on the seacoast and rivers are
villagers depending heavily on fish, while those on dry ground away from