A three-week-old chihuahua puppy named Tom Thumb poses in a tea cup on April 7, 2009 in Renton, Scotland. The pup, which measures eight inches long, is thought to be one of the smallest dogs born in the UK and is just two inches short of a world record. (Photo by Jeff J Mitchell/Getty Images)

Girls cry as they get separated from their family at the border line dividing Macedonia and Greece August 21, 2015. At least 1,000 migrants and refugees pressed against Macedonian police lines on the Greek-Macedonian border on Friday and at least 10 people appeared to faint in the crush. People could be heard screaming and medical workers raced to treat those who passed out or were hurt. The crush ensued after police let several hundred through into Macedonia, having kept them out since Thursday under an emergency decree. (Photo by Ognen Teofilovski/Reuters)

A man holds a pigeon during the British Homing World show of the year at Blackpool's Winter Gardens in Blackpool, north west England on January 17, 2016. Homing pigeon fanciers from across Europe gathered to find the Supreme Show Champion with judges casting their eyes over hundreds of birds on show. The Royal Pigeon Racing Association organises the event and has Queen Elizabeth II, who keeps pigeons at Sandringham, as its patron. (Photo by Andrew Yates/Reuters)

A mahout (a person who rides an elephant) decorates his elephant using chalk while preparing for the Elephant Festival at Sauraha in Chitwan, south of Kathmandu, December 26, 2014. Elephants and mahouts from Chitwan will participate in the Elephant festival, which involves elephant races, elephants playing an exhibition soccer match and taking part in various other sporting activities. The event will start from 26 December and will end on 30 December, 2014. (Photo by Navesh Chitrakar/Reuters)

This photo taken on January 28, 2018 shows participants taking part in games on stage during the “&Proud” LGBT festival in Yangon. Races, games, music and fun were just some of the highlights of the “&Proud” LGBT festival, which took place in a Yangon public park for the first time at the weekend in a country where same-s*x relations are still officially illegal. (Photo by Ye Aung Thu/AFP Photo)

WOOTTON, UNITED KINGDOM - APRIL 07: Hot air balloons prepare to depart from Lydden Hill race circuit near Canterbury to take part in mass crossing of the Channel on April 7, 2011 in Wootton, England. 51 balloonists of various nationalities from across Europe took off from Kent making for Calais, France at about 7am. It is the first time a Guinness World Record bid has been made for "the largest group of hot air balloons to make the Channel crossing". (Photo by Oli Scarff/Getty Images)

Participants take part in the Color Run near the Eiffel Tower in Paris April 19, 2015. The Color Run is a five-kilometre race, held in cities across the U.S. and also worldwide, with the aim of promoting healthy living and to benefit a charity that organizers choose in each of the cities that the run visits. Participants are doused from head to toe in different colors at each kilometre. (Photo by Benoit Tessier/Reuters)

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)