Convicted murderer Hector Alvarado Mazariegos, right, drops to the ground as he is hit by bullets of a Guatemala firing squad in the public cemetery at Mazatenango, June 28, 1975. His companion, Rocael Ortiz, met the same fate a few seconds later. Both were convicted of murder. (Photo by AP Photo/Anzueto)

«After Presents», 1996. Siri Kaur: “I was 14 when Simran was born in 1990. We have different mothers, so we grew up separately and I made pictures with her whenever I saw her. The work of Sally Mann and Nan Goldin gave me permission to see my family as a valid art subject. This image shows the aftermath of Christmas morning. Simran is unselfconsciously lounging on the floor, melding into her beloved dog”. (Photo by Siri Kaur)

A tiger cub has a short chat with a chimp. (Photo by Ian Tyas/Keystone Features/Getty Images). 27th November 1979

Three secondary schoolboys smoking an illicit cigarette in Hyde Park, London. (Photo by Evening Standard/Getty Images). May 1972

Women in Chicago being arrested for wearing one piece bathing suits, without the required leg coverings. (Photo by Topical Press Agency/Getty Images). 1922

Fisherwomen laying barrels with salt in preparation for herring curing, 1937. (Photo by Topical Press Agency)

A child, from Municipal school Parana, poses during the project “Fencing School” in Rio de Janeiro, Brazil, March 30, 2016. Children in Rio de Janeiro lift their sights and their swords to new idols, as a round of fencing workshops takes to public schools. The International Fencing Federation, together with the Brazilian and state federations, will reach 40 public schools in March and April. The aim is to whip up a following for the Olympic sport, little known in the soccer-mad nation, as Rio sets the stage for the Summer Games in August. (Photo by Sergio Moraes/Reuters)

Surfers surf at Surf Snowdonia in Conwy, North Wales, September 3, 2015. The surf park, which cost $22.8 million, opened on August 1 and is the world's first commercial artificial surfing lake, according to the company.The pool is 300 metres (980 ft) long and 110 metres (360 ft) wide, containing a total of six million gallons of water. A bi-directional snowplough-shaped wave-generation mechanism, towed on a cable between the two central towers, moves up and down the pool on a three-rail track, generating the waves. (Photo by Andrew Yates/Reuters)