Some Neotropical hunter- gatherer tribes are
territorial and have been known, at least in the past,
for high levels of aggression (shrunken human heads
are part of the cultural artifacts of some Amazonian
aboriginal groups). Tribal warfare was probably a
response to the need to protect areas of forest for the
exclusive use of a single tribe. Tribal raids, as noted
above, were also done to procure women, ensuring
genetic outbreeding through aggression, a custom
inculcated within the culture.
There are few “pristine” hunter- gatherers in the
Amazon Basin and essentially none in Central
America. Most people now use agriculture of some
sort to supplement their diets and most have direct
contact with the modern world. Shotguns are rapidly
replacing blowguns.
When Europeans first arrived in South America
around 1500, the estimated total population of
aboriginal humans throughout Amazonia was as
much as 6.8 million, though some estimates suggest
a number half that size. By the early 1970s, the
indigenous population was only 500,000, and in Brazil
alone the number dropped precipitously from about
a million to about 200,000 during the 20th century.
By 1988, the estimate for all of Amazonia was only
about 250,000, a 24- fold decrease from an estimated
6 million. Amerindian populations were reduced by a
lethal combination of conquest and genocide, slavery,
and, probably most significant, by the introduction of
various European diseases, to which the Amerindians
had little natural resistance. In Amazonia, tribes
that inhabited várzea, who represented the largest
Amerindian populations, fared worse than all others,
being essentially decimated by Europeans. Only those
tribes such as the Yanomami, the Javari, the Xingu,
and others that inhabited remote and inaccessible
forest survived the conquest period, and even they
suffered reductions in population whenever there was
European contact.
Today, most Amerindian tribes live on
anthropological reserves or “indigenous areas,” called
resguardos, lands in which aboriginal groups are
permitted to follow their traditional lifestyles. In Brazil,
Indian lands are administered by the government
agency Fundação Nacional do Indio (FUNAI), or
National Indian Foundation. This agency governs a
huge area representing 100.2 million ha (248 million
ac) in 371 reservations in the Brazilian Amazon,
representing roughly 20% of Brazilian Amazonia.
In the northern state of Roraima, about 42% of the
land area is reserved for use by Indians, even though
they represent only about 15% of the population of
Roraima.
Numerous issues face indigenous tribes. Amerindian
populations continue to be forced into retreat in some
areas, as people with different cultural backgrounds,
often from overpopulated, extremely poor urban areas,
migrate to the new frontier of the rain forest, some to
begin subsistence farming, some in search of gold.
This trend has greatly accelerated in Amazonian Brazil
due to the continually expanding Trans- Amazonian
highway system and, most recently, by the construction
of major hydroelectric dams (chapter 18). In some
areas aboriginal tribes (for example, the Nambikwara
tribe of Mato Grosso, Brazil) have been exploiting their
own lands for short- term profit, granting permission
to outsiders for logging and gold mining.Impact of Hunter- Gatherers
Do hunter- gatherers eventually deplete local game
populations? A study of the Siona- Secoya Indian
community in terra firme rain forest of northeastern
Ecuador, documented 1,300 kills representing 48
species, including various mammals, large birds, and
reptiles. The average number of kills per 100 man-
hours of hunting was only about 21 (within a sample
size of 802 man- days and 6,144 man- hours) and the
mean number of kills per man- day of hunting was only
1.62. These figures do not suggest that hunting pressure
was sufficient to deplete the animal populations and
are consistent with other studies. In contrast, if one
looks at the entire rural population of Amazonian
Brazil, including colonists as well as aboriginals,
subsistence hunting takes on far greater impact. There
are numerous examples of hunting pressure being
responsible for the local depletion of animals.Agriculture in the Neotropics
Agriculture, which developed about 10,000 years ago,
differs from simple gathering (finding plants useful
as food or fiber and then collecting them) in that the
plants in question are selectively chosen and cultivated,
increasing their population densities at the expense
of cohabiting species. Humans use work energy to
nurture and protect the plants chosen for agriculture368 chapter 17 human ecology in the tropics