The secretive indri (Indri indri) of Madagascar, the largest living lemur. It is also critically endangered and highly evolutionarily distinct with no close relatives, which makes its branch one of most precarious on the mammal evolutionary tree. In the likely event that the indri goes extinct, we will lose 19m years of unique evolutionary history from the mammal tree of life. (Photo by Pierre-Yves Babelon/Aarhus University)

A Polisario fighter sits on a rock at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. At a rocky outpost in Western Sahara, a new generation of soldiers who have never known war are mobilising as tensions resurface in one of Africa's oldest disputes after a quarter century of uneasy peace. (Photo by Zohra Bensemra/Reuters)

A pedestrian carries an umbrella as they stroll past an advertisment as a rainstorm moves through Sacramento, Calif., Wednesday, February 13, 2019. Rain is falling widely in Northern California and is expected to spread south. (Photo by Rich Pedroncelli/AP Photo)

Syrian refugee boys play with toy guns at Eminonu district in Istanbul, Turkey, 08 January 2019. (Photo by Sedat Suna/EPA/EFE)

Sun Rongchun, 57, exercises with an improvised cervical traction device attached to a high bar at a sports complex in Shenyang, Liaoning province, China on April 9, 2019. (Photo by Sheng Li/Reuters)

People celebrate media announcing that Democratic U.S. presidential nominee Joe Biden has won the 2020 U.S. presidential election in Alphabet City neighborhood of Manhattan, in New York City, U.S. November 7, 2020. (Photo by Andrew Kelly/Reuters)

Aerial view of a farmer feeding ducks at a farm on November 6, 2020 in Sihong County, Jiangsu Province of China. (Photo by Zhang Lianhua/VCG via Getty Images)

A supporter of the opposition parties shouts asking for peace as riot police are block access to the house of the former president Henri Konan Bedie, in Abidjan, Ivory Coast, Tuesday, November 3, 2020. (Photo by Leo Correa/AP Photo)