Kaw-Claa, a Tlingit native woman in full potlatch dancing costume, 1906. (Photo by Case & Draper/Buyenlarge/Getty Images)

In Omdurman, the largest city in Sudan, the Qadiriyya Sufi order meets every Friday outside Sheikh Hamed Al Nil mosque, which houses the tomb of their 19th century Sufi leader. (Photo by Ala Kheir, John Burns and Ibrahim Algrefwi/Brownbook)

A picture made available on 20 October 2015 shows a foreign tourist posing for a souvenir photograph with a figure of a tiger head at a private zoo on Phuket Island, Thailand, 17 October 2015. Each day hundreds of tourists, including young children, visit the private tiger zoo where visitors are allowed to touch and pose for photographs with unchained tigers inside their enclosures. (Photo by Rungroj Yongrit/EPA)

“People of the River”. This is a Karo tribe family; father, mother, two sisters and two brothers. The tribe, who live along the Omo River in east Africa, incorporate rich symbolism into their rituals by using ornate body art, headdresses and body scarification to express beauty and significance. (Photo by Jatenipat Ketpradit/International Portrait Photographer of the Year)

32 year old Mahada Khatum repairs a fishing net outside her home in the Shamalapur Rohingya refugee settlement on April 11, 2014 in Chittagong district, Bangladesh. Some years ago she escaped violence and discrimination from the Zomgara Baharchara village in the Meherulla district of Myanmar. (Photo by Getty Images/Stringer)

A Leyland lorry during the railway strike, “we supply both milk and baby” is chalked on the bonnet. (Photo by A. R. Coster/Topical Press Agency/Getty Images). 3rd October 1919

Imagine living in the sea where it is permanently dark, cold, and food is hard to find. For many animals at depth, it may be weeks to months between meals. If you find something to eat, you have to hang on to it. This is why so many deep-sea fishes have lots of big teeth. This dragonfish, spotted off the coast of Australia, even has teeth on its tongue. They would be terrifying animals ... if they weren’t the size of a banana. (Photo by Julian Finn/Museum Victoria)

Two dummy tanks being pushed along a road by German soldiers. (Photo by Hulton Archive/Getty Images). Circa 1925