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 sandstorm hits the city of Zhangye in Gansu province, China on November 27, 2018. (Photo by Reuters/China Stringer Network)

Mackenzie Brown from the USA warms up on stage prior the final ofthe 47th Prix de Lausanne in Lausanne, Switzerland, 09 February 2019. Launched in 1973, the Prix de Lausanne is an international dance competition for young dancers. The best dancers will be awarded with scholarships granting free tuition in a world-renowned dance school or dance company. (Photo by Valentin Flauraud/EPA/EFE)

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)

Shaymaa Ismaa’eel, a 24-year-old Muslim woman passes by a group of angry protesters at an Islamic conference in Washington, DC on April 21, 2019. In response, she crouched in front of them and flashed a peace sign. The photo, posted on Instagram, prompted an outpouring of support. (Photo by Shaymaa Ismaa'eel/Instagram)

A first white-handed gibbon infant born at the Skopje Zoo is seen with his mother in Skopje, North Macedonia on May 9, 2019. (Photo by Ognen Teofilovski/Reuters)

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)

A man passes by a wall with graffiti in Beirut, Lebanon, on May 29, 2019. (Photo by Bilal Jawich/Xinhua News Agency/Alamy Live News)