In the Amazon's Carajas National Forest, Vale, the Brazilian mining giant, is pushing the expansion of one of the world's largest open-pit iron ore complexes, a project that will destroy dozens of caves and rock shelters where humans lived more than 8,000 years ago. Scholars say that the caves offer insight into what may be the earliest stages of human settlement in the world's largest tropical rain forest, helping to piece together the puzzle of how the Americas came to be inhabited.
     Despite archaeological concerns, the government - which previously owned the mining company, and still holds shares - granted the company a license allowing the expansion. Vale acknowledged that at least 24 of the caves to be destroyed are of 'high relevance'. It said it would preserve caves in another part of the state to compensate for their loss.
     Brazilian courts can require companies to preserve archaeological sites, or at least transfer archaeological material to universities or museums where it can be studied, before work continues. "This is a crucial moment to learn about the human history of the Amazon, and by extension the peopling of the Americas," said Genival Crescencio, a cave explorer and historian. "We should be preserving this unique place for science."
     The Amazon is a hotbed of archaeological investigation, as researchers find evidence that far more people might have lived in the region than once considered possible. At Pedra Pintada, archaeologist Anna Roosevelt has shown that hunter-gatherers moved to the region 10,900 to 11,200 years ago, far earlier than once thought.
     Outside the Amazon, remarkable discoveries have been announced at other Brazilian sites. At Lapa do Santo, a rock shelter near the city of Belo Horizonte, archaeologists found the New World's oldest known figurative petroglyph - a drawing of a man with an oversize phallus - thought to have been made 10,500 to 12,000 years ago.
     Frederico Drumond Martins, a government biologist who oversees the Carajas National Forest, said future mine expansions could destroy every last cave. Renato Kipnis, a respected archaeologist in Sao Paulo whom Vale hired to survey the caves, said that the company had prohibited him from discussing their archaeological significance.

Edited from The New York Times (15 December 2012)