North Korean leader Kim Jong Un, his wife Ri Sol Ju and Song Tao, head of the International Department of Communist Party of China (CPC) Central Committee, applaud with ballet dancers in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang April 17, 2018. (Photo by Reuters/KCNA)

Children in a Hong Kong refugee resettlement area watch as former Vice President Richard Nixon shows them his badminton service. Nixon visited Hong Kong, April 4, 1964, during his tour of countries in the Far East. (Photo by AP Photo)

A truck transporting 20 tons of fish lost its load after crashing on a road near Liepen, eastern Germany on April 20, 2018. (Photo by Stefan Sauer/AFP Photo/DPA)

A mother takes a selfie while breastfeeding her baby at the “Hakab Na 2018”, an event held in celebration of National Breastfeeding Awareness Month at the SMX Convention Center in Pasay City, Philippines on Sunday, August 5, 2018. Now on its sixth year, the event is a gathering of families, lactation experts, peer counselors and breastfeeding advocacy supporters and was aimed at promoting the importance of providing support to breastfeeding mothers. (Photo by Avito C. Dalan/PNA Photo)

Teens got their glad rags on as they hit the town in Newcastle city centre, United Kingdom on August 16, 2018, as they celebrate their exam results. (Photo by North News and Pictures/NNP)

Police are highly visible at the Notting Hill carnival with several arrests, stop and search and a “knife detection gate” in operation, August 27, 2018 in west London, England. 133 arrests were made at the carnival yesterday with 20 knives seized. (Photo by South West News Service/Action Press/Picturedesk)

Two Czech Gripen fighter planes demonstrate a flight interception of a Belgian air force transport plane over the Czech Republic, as part of NATO drills on September 12, 2018. (Photo by Francois Lenoir/Reuters)

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)