Parts of Mexico's remote southern jungles have barely changed since the time of the ancient Maya.
In the eyes of President Andres Manuel Lopez Obrador, a railway his government is building — known as the Tren Maya — will bring modern connectivity to areas for generations deprived of significant economic benefits.
But the railway and its hasty construction also critically endanger pristine wilderness and ancient cave systems beneath the jungle floor, droves of scientists and environmental activists say.