Russian soldiers write home while serving on the Eastern Front during World War I, circa 1915. (Photo by Hulton Archive/Getty Images)

A baby rhesus macaque (Macaca mulatta) looks up as it plays with a tiger cub at a zoo in Hefei, Anhui province, August 2, 2012. (Photo by Jianan Yu/Reuters)

U.S. President Donald Trump boards Air Force One to depart for Vietnam from Beijing Airport in Beijing, China on November 10, 2017. (Photo by Jonathan Ernst/Reuters)

A new species of monkey found in the Democratic Republic of the Congo and identified as Lesula (Cercopithecus lomamiensis) is seen in this undated photograph from an article published September 12, 2012 in the science journal PLOS One. The monkey was first seen in 2007 by researchers John and Terese Hart of the Peabody Museum of Natural History at Yale Research Project. The finding of C. lomamiensis represents only the second new species of African monkey to be discovered in the past 28 years, according to the research article. (Photo by Hart J. A., Detwiler K. M., Gilbert C. C./Reuters)

A camel rests at a fuel station in the Judean desert near the West Bank city of Jericho January 11, 2015. Reuters photographers from Mali to Mexico have shot a series of pictures of fuel stations. Whether it is plastic bottles by the roadside in Malaysia or a futuristic forecourt in Los Angeles, fuel stations help define our world. Oil prices steadied above $48 a barrel on Tuesday, recovering from earlier losses as the dollar weakened against the euro. Oil prices have dropped nearly 60 percent since peaking in June 2014 on ample global supplies from the U.S. shale oil boom and a decision by OPEC to keep its production quotas unchanged. (Photo by Baz Ratner/Reuters)

A Sotheby's employee holds a rare 52.82-carat white diamond ring at Sotheby's auction house on April 12, 2010 in London, England. Price: 7 million USD. (Photo by Dan Kitwood/Getty Images)

Santa Claus wears a mask as he pushes a sleigh full of curbside grocery orders to an Aldi customer at a parking lot in Palatine, Ill., Saturday, December 19, 2020. For this weekend only, Santa Claus is delivering groceries to Aldi customers in Palatine and several other towns in the Chicago area. (Photo by Nam Y. Huh/AP Photo)

A cast member from The Lion King goes to take up her position for the performance during The Olivier Awards 2019 with Mastercard at the Royal Albert Hall on April 07, 2019 in London, England. (Photo by David Levene/The Guardian)