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

Maudy – Kalulushi, Zambia. Maudy was born in a hut in a small village close to Kalulushi, in Zambia. She grew up playing in the street with the other children in the village, who all attend the same school, where students ages 3 to 10 years old are in the same class. The village has no shops, restaurants or hotels, and just a few children are lucky enough to have toys. Maudy and her friends found a box full of sunglasses on the street, which quickly became their favorite toys. “Toy Stories” project. (Photo and caption by Gabriele Galimberti)

Jordan Matter showcases their athletic prowess in everyday situations such as a martial artist shaving with a samurai sword, an ice hockey goalie shopping and a gymnast balancing from a street sign. Photo: “River View” – Jacob Jonas & Jill Wilson – Acro Yoga Specialists. (Photo by Jordan Matter)

In this two photo combination picture, the Eiffel Tower with its usual lighting at left, and after the lighting was switched off at right, at the occasion of the Earth Hour, in Paris, France, Saturday March 28, 2015. This Saturday, 28 March 8:30 p.m. local time, individuals, businesses, cities and landmarks around the world are switching off their lights for one hour to focus attention on climate change. (Photo by Remy de la Mauviniere/AP Photo)

In this Monday, June 15, 2015 photo, Ahmad Abu Jereda, 16, carries Max, the male lion cub, as he passes by Palestinians at the main garden in Gaza City, in the northern Gaza Strip. A pair of lion cubs are stuck at a Gaza-Israel border crossing en route to a Jordan animal sanctuary, after being kept for a year by a family in crowded Gaza. Saduldin al-Jamal had bought the cubs from the Gaza zoo, hit during last summer's Israel-Hamas war. His family would take them to parks or the beach and children – those brave enough – would come up to pet them. (Photo by Adel Hana/AP Photo)

Actress Liv Tyler, 40, stripped in shots for the Triumph Essence's Autumn/Winter 2017 campaign in November, 2017. The Essence line is Triumph’s premium offering, with this season taking on the theme of “opulent Art Nouveau”, featuring designs in velvet embellished mesh, Leavers lace and silk satin. (Photo by Rankin/The Mega Agency)

Father Angel (L), parish priest of San Anton Church blesses a dog during the celebrations of San Anton in Madrid, Spain on January 17, 2018. (Photo by Fernando Alvarado/EFE via ZUMA Press)

Seiichiro Nishimoto, CEO of Shelter Co., poses wearing a gas mask at a model room for the company's nuclear shelters in the basement of his house in Osaka, Japan on April 26, 2017. With nearby North Korea increasing its show of power day by day with missile launches and nuclear tests, people in Japan are preparing for the worst by building private nuclear shelters, Reuters reports. (Photo by Kim Kyung-Hoon/Reuters)