At the beginning of the 20th century, Edward S. Curtis set out to document what he saw as a disappearing race: the Native American. From 1907 to 1930, Curtis took more than 2,000 photos of 80 tribes stretching from the Great Plains to the Pacific Northwest and Alaska. He then published and sold these photos, along with narrative text, in 20 volumes of work known as “The North American Indian”. It is one of the most significant collections of its kind, “probably the most important photographic document of its age and its topic,” said Jeffrey Garrett, associate university librarian for Special Libraries at Northwestern University. (Photo by Edward S. Curtis)

A worker lays rails across the bed of a drained area of a lake used for the production of salt at the Sasyk-Sivash lake near the city of Yevpatoria in Crimea, October 5, 2014. The area has a long tradition of salt production, prepared from salt flats flooded with water from the Black Sea. (Photo by Pavel Rebrov/Reuters)

An installation of Canadian artists Caitlind Brown and Wayne Garrett is displayed during the Lumina Light Festival in Cascais September 14, 2014. Lumina Light Festival shows artworks of artists from several countries, which are displayed during a tour around Cascais. (Photo by Rafael Marchante/Reuters)

Australian Aboriginal hunter Marcus Gaykamangu of the Yolngu people, carries an Australian native lizard called a goanna over his shoulder as he walks away from a billabong near the “out station” of Yathalamarra, located on the outksirts of the community of Ramingining in East Arnhem Land November 22, 2014. (Photo by David Gray/Reuters)

Female porters carry a holy woman belonging to the Jain community through a street to collect food from local residents living in nearby areas, during early morning in the western Indian city of Ahmedabad December 19, 2014. (Photo by Amit Dave/Reuters)

A fledgling solar system containing deep within it enough water vapor to fill all the oceans on Earth five times, located in our Milky Way galaxy about 1,000 light years from Earth in the constellation Perseus. (Photo by Reuters/NASA/JPL-Caltech)

Miss Earth 2016 candidates wearing environmental statement sashes lineup during a press presentation in Manila, Philippines, 11 October 2016. Eighty three young women from around the globe converged in Manila for the international beauty event. Miss Earth is a pioneering beauty pageant that serves as a vehicle for environmental advocacy. (Photo by Mark R. Cristino/EPA)

A group of frogs hitched a lift on a passing crocodile. Clearly comfortable in the croc’s company the amphibians wait patiently for their chauffeur to move. But the bemused crocodile doesn’t appear to be going anywhere in a hurry. The hilarious images were captured by Tanto Yensen, 36, from Jakarta, Indonesia. (Photo by Tanto Yensen/Media Drum World Photo Agency)