That’s what researchers concluded after flying a plane equipped with remote sensing instruments over an approximately 4,497-square-kilometer (1,736-square-mile) region in Brazil. They detected 396 new earthworks, suggesting that the Southwest Amazon could contain more of these structures than researchers ever expected—somewhere between 24,000 and 30,000 in total. Martti PärssinenArchaeologists had identified geoglyphs in this Amazon region before but never on this scale. That discovery helps to correct the perception “that the Amazon region is a region of ‘untouched nature.’” But 2,000 years ago, archaeological evidence suggests ancient humans lived in balance with the environment, even while shaping the land with possibly tens of thousands of geoglyphs, Pärssinen says.