Serra da Capivara
The account
The first humans in the Americas would have arrived much earlier than the textbooks say, and Piauí would hold the proof.
What investigators found
The park has the largest concentration of rock paintings in the Americas. Dates of more than 30,000 years for human presence are defended by some and disputed by others.
The story
In southeastern Piauí, Serra da Capivara holds more than a thousand archaeological sites with paintings in red: hunting scenes, dances, sex, animals and human figures in motion, some thousands of years old. The national park was created in 1979 and became a UNESCO World Heritage Site in 1991.
Archaeologist Niède Guidon devoted her life to the place and argued that humans lived there more than 30,000 years ago, long before the accepted date for the arrival of humans in the Americas. The idea stirred controversy in the scientific world, which still debates whether the chipped stones found there were shaped by human hands. There are no aliens in this story, but there is an enormous mystery: who the first Brazilians were.