containing pottery and other artifacts that date from
about 8,000 to 7,000 years before the present. The
pottery dates to about 1,000 years earlier than that found
in northern South America and 3,000 years earlier than
Andean and Mesoamerican pottery. Archaeologists
investigating this site suggest that by 2,000 years ago, a
large and agriculturally sophisticated population could
have been supported on the rich alluvial soils deposited
by the annual flood cycle along Amazonian floodplain
forests (várzea). The discoveries of archaeological
sites in various parts of Amazonia suggest that dense
aggregations of people settled permanently, practiced
efficient and sustained agriculture, and relied on rivers
to supply needed animal protein.
Mayan Impact in Central America
There is much archaeological evidence in Central
America suggesting that the Maya supported their
dense population by employing techniques of intensive
agriculture and silviculture. Such practices resulted in
large- scale landscape alterations, including extensive
forest clearance (see chapter 7). Intensive agriculture
in Central America was accomplished largely by two
methods, hill terracing and raised fields in swamps
and marshland. Hill terracing, still used today in
many tropical areas, involves the construction of walls
along hillsides, the walls acting to retard erosion and
trap soil washed by rains (plate 17- 2). (This method
was also widely practiced by the Inca in the Andes.)
Hill terracing permitted the Maya to cultivate a given
plot for much longer than ordinary slash- and- burn
techniques, because the soil fertility was preserved.
Raised fields involve the excavation of drainage canals
to reduce water levels and thus raise dry fields from
what was previously swampland. Ancient Maya not
only used the raised fields for agriculture, but also used
the canals for keeping fish and turtles, both important
protein sources. Imagine being in a small plane at low
altitude, flying over the Mayan Yucatán during the
height of the Classic Period. It would resemble the view
from a flight over midwestern North America, where
vast acreages of agriculture characterize the landscape.
The Maya of Tikal (plate 17- 3) cultivated the
ramon, or Breadnut Tree (Brosimum alicastrum). The
Breadnut is today abundant throughout Guatemala’s
Petén region. A single tree has the potential to yieldTerra Preta del Indio
In parts of Amazonia there are scattered patches of a unique latosol (or oxisol) soil (chapter 6) called terra preta del
Indio. The name is from the Portuguese for “black soil” or “black earth,” for unlike most latosols, terra preta is dark,
often black. The reason for its color is that it is rich in charcoal. It also contains pottery shards and organic material,
including plant remains, animal waste, and bones from fish and other animals. In fact, terra preta soils have as much
as 14% organic matter. Unlike most soils in Amazonia (particularly on terra firme), terra preta is nutrient rich, with high
concentrations of nitrogen, potassium, calcium, and other essential elements.Terra preta is a type of soil that was made by humans, an anthropogenic soil dated to between A.D. 450 and about- Apparently, indigenous people developed the technology and knowledge to cut the forest and burn it at low
temperature, allowing the accumulation of charcoal. Terra preta soils are sometimes 2 m (6.5 ft) deep indicating that
people had been present in the same location over many years, steadily building up the nutrient- rich soil. The utility
of terra preta was obviously to enhance local agriculture. These human- constructed soils were far greater in nutrient
content than the normal oxisols that make up most of the substrate in Amazonia. Terra preta remains are found along
river courses scattered throughout the Amazon Basin; these likely indicate locations of permanent human settlements
in pre- Columbian times. The high organic content and overall nutrient richness of terra preta shows a sophisticated
understanding of how to enhance agricultural production such that it could support relatively large human
populations. It has been suggested that terra preta could be used to enhance agriculture in the present century.
Plate 17- 2. Hill terracing is a pragmatic form of crop production
employed throughout the global tropics. This photo is from
Sabah, Malaysia, on Borneo. Photo by John Kricher.366 chapter 17 human ecology in the tropics