Arquivo da tag: Geoglifos

Long Before Making Enigmatic Earthworks, People Reshaped Brazil’s Rain Forest (N.Y.Times)

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By  JOANNA KLEIN FEB. 10, 2017

New research suggests people were sustainably managing the Amazon rain forest much earlier than was previously thought. Jenny Watling 

Deep in the Amazon, the rain forest once covered ancient secrets. Spread across hundreds of thousands of acres are massive, geometric earthworks. The carvings stretch out in circles and squares that can be as big as a city block, with trenches up to 12 yards wide and 13 feet deep. They appear to have been built up to 2,000 years ago.

Were the broken ceramics found near the entrances used for ritual sacrifices? Why were they here? The answer remains a mystery.

There are 450 geoglyphs concentrated in Brazil’s Acre State. Jenny Watling 

For centuries, the enigmatic structures remained hidden to all but a few archaeologists. Then in the 1980s, ranchers cleared land to raise cattle, uncovering the true extent of the earthworks in the process. More than 450 of these geoglyphs are concentrated within Acre State in Brazil.

Since the discovery, archaeological study of the earthworks and other evidence has challenged the notion that the rain forests of the Amazon were untouched by human hands before the arrival of European explorers in the 15th century. And while the true purpose of the geoglyphs remains unknown, a study published on Monday in The Proceedings of the National Academy of Sciences offers new insight into the lives of the ancient people who lived in the Amazon. Thousands of years before the earthworks were built, humans were managing the forests, using what appear to be sustainable agricultural practices.

“Our study was looking at the environmental impact that the geoglyph builders had on the landscape,” said Jennifer Watling, an archaeologist at the University of São Paulo, Brazil, who conducted the research while a student at the University of Exeter in Britain. “A lot of people have the idea that the Amazon forests are pristine forests, never touched by humans, and that’s obviously not the case.”

Dr. Watling and her team reconstructed a 6,000-year-old environmental history of two geoglyph sites in the Amazon rain forest. To do this, they searched for clues in soil samples in and around the sites. Microscopic plant fossils called phytoliths told them about ancient vegetation. Bits of charcoal revealed evidence of burnings. And a kind of carbon dating gave them a sense of how open the vegetation had been in the past.

About 4,000 years ago, people started burning the forest, which was mostly bamboo, just enough to make small openings. They may have planted maize or squash, weeded out some underbrush, and transported seeds or saplings to create a partly curated forest of useful tree products that Dr. Watling calls a “prehistoric supermarket.” After that, they started building the geoglyphs. The presence of just a few artifacts, and the layout of the earthworks, suggest they weren’t used as ancient villages or for military defenses. They were likely built for rituals, some archaeologists suspect.

Dr. Watling and her colleagues found that in contrast with the large-scale deforestation we see today — which threatens about 20 percent of the largest rain forest in the world — ancient indigenous people of the Amazon practiced something more akin to what we now call agroforestry. They restricted burns to site locations and maintained the surrounding landscape, creating small, temporary clearings in the bamboo and promoting the growth of plants like palm, cedar and Brazil nut that were, and still are, useful commodities. Today, indigenous groups around the world continue these sustainable practices in forests.

“Indigenous communities have actually transformed the ecosystem over a very long time,” said Dr. Watling. “The modern forest owes its biodiversity to the agroforestry practices that were happening during the time of the geoglyph builders.”

Hundreds of ancient earthworks built in the Amazon (Science Daily)

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Date:
February 7, 2017
Source:
University of Exeter
Summary:
The Amazonian rainforest was transformed over 2,000 years ago by ancient people who built hundreds of large, mysterious earthworks.

Geoglyph photos. Credit: Jenny Watling

The Amazonian rainforest was transformed over two thousand years ago by ancient people who built hundreds of large, mysterious earthworks.

Findings by Brazilian and UK experts provide new evidence for how indigenous people lived in the Amazon before European people arrived in the region.

The ditched enclosures, in Acre state in the western Brazilian Amazon, were concealed for centuries by trees. Modern deforestation has allowed the discovery of more than 450 of these large geometrical geoglyphs.

The function of these mysterious sites is still little understood — they are unlikely to be villages, since archaeologists recover very few artefacts during excavation. The layout doesn’t suggest they were built for defensive reasons. It is thought they were used only sporadically, perhaps as ritual gathering places.

The structures are ditched enclosures that occupy roughly 13,000 km2. Their discovery challenges assumptions that the rainforest ecosystem has been untouched by humans.

The research was carried out by Jennifer Watling, post-doctoral researcher at the Museum of Archaeology and Ethnography, University of São Paulo, when she was studying for a PhD at the University of Exeter.

Dr Watling said: “The fact that these sites lay hidden for centuries beneath mature rainforest really challenges the idea that Amazonian forests are ‘pristine ecosystems`.

“We immediately wanted to know whether the region was already forested when the geoglyphs were built, and to what extent people impacted the landscape to build these earthworks.”

Using state-of-the-art methods, the team members were able to reconstruct 6000 years of vegetation and fire history around two geoglyph sites. They found that humans heavily altered bamboo forests for millennia and small, temporary clearings were made to build the geoglyphs.

Instead of burning large tracts of forest — either for geoglyph construction or agricultural practices — people transformed their environment by concentrating on economically valuable tree species such as palms, creating a kind of ‘prehistoric supermarket’ of useful forest products. The team found tantalizing evidence to suggest that the biodiversity of some of Acre’s remaining forests may have a strong legacy of these ancient ‘agroforestry’ practices.

Dr. Watling said: “Despite the huge number and density of geoglyph sites in the region, we can be certain that Acre’s forests were never cleared as extensively, or for as long, as they have been in recent years.

“Our evidence that Amazonian forests have been managed by indigenous peoples long before European Contact should not be cited as justification for the destructive, unsustainable land-use practiced today. It should instead serve to highlight the ingenuity of past subsistence regimes that did not lead to forest degradation, and the importance of indigenous knowledge for finding more sustainable land-use alternatives.”

The full article will be released in the Proceedings of the National Academy of Sciences of the USA and involved researchers from the universities of Exeter, Reading and Swansea (UK), São Paulo, Belém and Acre (Brazil). The research was funded by the Arts and Humanities Research Council, National Geographic, and the Natural Environment Research Council Radiocarbon Facility.

To conduct the study, the team extracted soil samples from a series of pits dug within and outside of the geoglyphs. From these soils, they analysed ‘phytoliths’, a type of microscopic plant fossil made of silica, to reconstruct ancient vegetation; charcoal quantities, to assess the amount of ancient forest burning; and carbon stable isotopes, to indicate how ‘open’ the vegetation was in the past.

Journal Reference:

  1. Jennifer Watling, José Iriarte, Francis E. Mayle, Denise Schaan, Luiz C. R. Pessenda, Neil J. Loader, F. Alayne Street-Perrott, Ruth E. Dickau, Antonia Damasceno, Alceu Ranzi. Impact of pre-Columbian “geoglyph” builders on Amazonian forests. Proceedings of the National Academy of Sciences, 2017; 201614359 DOI: 10.1073/pnas.1614359114