The rainforest is partly the product of human design

A new study published by the Proceedings of the National Academy of Sciences suggests that the Amazonian forests in the Acre state of Brazil were managed by human inhabitants for thousands of years, further supporting the theory that much of the Amazon rainforest was already to some extent a product of human design by the time Europeans arrived in the region more than 450 years ago.

Scientists and explorers have discovered hundreds of geometric earthworks — over 450 pre-Columbian (pre-AD 1492) geometric ditched enclosures (“geoglyphs”) occupying about 13,000 km2 of the Acre state in Brazil. These huge earthworks were concealed for centuries within the upland interfluvial rainforest, directly challenging the “pristine” status of this ecosystem and its perceived vulnerability to human impacts — suggesting that this region was also deforested to a large extent in the past, challenging the apparent vulnerability of Amazonian forests to human land use. 

In a study co-authored by Jennifer Watling of the University of Sao Paulo and University of Exeter and colleagues, researchers show that bamboo forest dominated the region for at least 6,000 years and that small, temporary clearings were made to build the geoglyphs; however, construction occurred within an anthropogenic forest, meaning that the forest had already been actively managed by its human inhabitants for millennia

http://popular-archaeology.com/issue/winter-2017/article/study-shows-pre-columbian-builders-managed-amazonian-forests