peru

The Inca Trail to Machu Picchu is one of the most popular hikes in the world. It’s so popular that in recent years, the Peruvian government has had to limit trail traffic by plastering the trek with a lot of red tape. You have to apply months ahead for a permit, hire a certified guide and show your passport at four different checkpoints along the way. Despite the hassle, each day hundreds of people sign up. And for good reason: The Inca knew how to lay out a scenic route.

The Inca knew there was something sinister about the cinnabar they hauled out of the ground at Huancavelica in Peru hundreds of years ago. They called the mine the Mine of Death. Now, a new study has exposed a 3,500-year history of mercury pollution from the cinnabar mines, a much longer legacy than researchers had previously realized.