“I’ve
always been interested in
indigenous technology,” Dr. Clark Erickson was saying. As an anthropologist
(associate professor of anthropology) and archaeologist (associate curator
of the American section of the University Museum of Archaeology and Anthropology),
he describes his approach as one that studies “people in the past and
how they were responsible for creating the landscape that we have today.”


Erickson
recently discovered an impressive people-made landscape in the Amazon
Basin of northeastern Bolivia: a massive, 500-square-kilometer series
of zigzagging earthworks and ponds that appears to have been a pre-Hispanic
fishing weir. It also appears to have been an effective means of “enhancing
the environment to raise the bio-mass of fish.”
“The
native peoples used this technology to harvest sufficient animal protein
to sustain large and dense populations in a savanna environment,” he wrote
in an article in the November 9 issue of Nature. “Rather than domesticate
the species that they exploited, the people of Baures domesticated the
landscape.” Although he acknowledges that it is difficult to date the
earthworks precisely, tests have suggested that the weirs date from at
least as far back as the 16th and 17th centuries. The Spanish did not
control that area until the early 18th century.
Erickson
had spent the early 1990s in that region examining other “massive earthwork
transformations” that involved the draining and piling up of earth to
make raised fields suitable for crops. But when he took a plane ride over
the area in 1996, he didn’t know what to make of the zigzag patterns.
It was only after walking and studying the area, he says, that he realized
that the distinct v-shaped openings were, in fact, part of a fishing weir
that was “much more massive than any system I’d read or heard about.”
During
the rainy season, from November to May, the grassy savanna would have
been covered by more than a foot of water. The fish would have migrated
to and spawned in that water, and would have been trapped there as the
floodwaters receded. The zigzag structures, he wrote, would have “provided
a means to manage and harvest these fish”—funneling them into a sort of
chute where they would be caught in nets or baskets—while the artificial
ponds “provided a way to store live fish and [edible] snails until needed.”
Palm trees planted near the ponds also provided fruit, fronds and wood.
Unlike
the “ephemeral” contemporary fish weirs in the region, which are rebuilt
each season, Erickson says that the zigzag weirs and large causeways “may
have been used for water management,” extending the flooding period by
“capturing the first rains and holding floodwaters into the dry season.”
The
discovery could have important implications for that region today, since
fish is still a vital part of the diet.
“This
particular technology certainly needs to be studied before we can talk
about implementing it again,” he acknowledges. “But it would be much more
rational to look at how these people managed these models than to import
models” from other parts of the world.