More than 200 years ago, a scientist named Alexander von Humboldt embarked on a perilous five-year journey through the Venezuelan jungles and Andean Mountains of South America. At the time, it was believed that the world was less than 6,000 years old. Humboldt's groundbreaking observations and theories would not only inspire Charles Darwin, but change our understanding of nature--and the role humans plays in it--forever. Follow historian and best-selling author Andrea Wulf as she recounts his footsteps and discoveries.