Tanzania, 1964. A touching moment between primatologist and National Geographic grantee Jane Goodall and young chimpanzee Flint at Tanzania's Gombe Stream Reserve. (Photo by Hugo van Lawick via National Geographic)

Young Slovaks dressed in traditional costumes throw a bucket of water at a girl as part of Easter celebrations in the village of Trencianska Tepla, Slovakia, April 9, 2012. Slovakia's men splash women with water to symbolize youth, strength and beauty for the upcoming spring season. (Photo by Samuel Kubani/AFP)

In this photo illustration a young girl licks a lollipop in which a scorpion is suspended on May 7, 2014 in Berlin, Germany. An increasing numbers of advocates worldwide are promoting insects as a viable source of food for humans, citing the high protein value, abundance and low cost. (Photo Illustration by Sean Gallup/Getty Images)

Young monks laugh at their own photos taken by a German photojournalist in the main courtyard of the Dzong on October 13, 2011 in Punakha, Bhutan. King Jigme Khesar Namgyel Wangchuck, 31 and Queen of Bhutan Ashi Jetsun Pema Wangchuck, 21 wed in Bhutan's historic 17th century Punakha Dzong the same venue that hosted the King's historical coronation ceremony in 2008. (Photo by Triston Yeo/Getty Images)

A man pours mud water on the head of his girl friend during the Boryeong Mud Festival at Daecheon Beach in Boryeong, South Korea, Friday, July 18, 2014. The annual mud festival features mud wrestling and mud sliding. (Photo by Ahn Young-joon/AP Photo)

Young couples compete in Rock' n'Roll & Co, an all- Russian acrobatic rock' n'roll competition in Kazan, Russia on November 4, 2017. Acrobatic rock’n’roll is a discipline for couples combining energetic dancing with acrobatic moves. (Photo by Yegor Aleyev/TASS via Getty Images)

A young woman holds her smartphone at Red Square with the Kremlin's Spasskaya Tower, right, and St. Basil Cathedral, center, in the background in Moscow, Russia, Monday, July 25, 2016. (Photo by Pavel Golovkin/AP Photo)

A young migrant cries as she waits to cross the Greek-Macedonian border, near the village of Idomeni, Greece March 3, 2016. Thousands of refugees and migrants wait on the border between Greece and Macedonia and about 30,000 refugees and other migrants are stranded in Greece, with 10,000 at the Idomeni border crossing to Macedonia. (Photo by Marko Djurica/Reuters)