Two Inuit children at Point Barrow, Alaska, holding the tusks of a large walrus, probably killed for food, circa 1930. (Photo by General Photographic Agency/Getty Images)

This picture taken on March 16, 2017 shows a crew member introducing the dining car of the Train Suite Shiki- Shima, operated by East Japan Railway, in Tokyo during a press preview. The luxury sleeper Shiki- Shima, which can accommodate up to 34 passengers, has 10 cars, including a lounge car, a dining car and two observatory cars. The train has only 17 cabins, all suites, and the most expensive room, known as Shiki- Shima Suite, is priced at 950,000 yen (8480 USD) per person when shared by two people. (Photo by AFP Photo/JIJI Press)

Children of the Roma community play as they cool off in a fountain in the main square of Pristina, Kosovo on June 14, 2017. (Photo by Armend Nimani/AFP Photo)

A tomtit bird flies past a squirrel running on a fence after a snowfall in a park in Almaty, Kazakhstan, January 12, 2016. (Photo by Shamil Zhumatov/Reuters)

People look at huge waves crashing on the San Esteban de Pravia seafront, northern Spanish region of Asturias February 8, 2016. (Photo by Eloy Alonso/Reuters)

The Bolenberg chapel sits on a rise overlooking vineyards where leaves change colors to mark a change in the season in Orschwihr in the Alsace region of France, October 12, 2015. (Photo by Jacky Naegelen/Reuters)

People dressed in costumes have a break while marching during the Vijanera Festival, in the small village of Silio, northern Spain, Sunday, January 3, 2016. The Vijanera masquerade, of pre-Roman origin, is the first carnival of the year in Europe symbolizing the triumph of good over evil and involving the participation of crowds of residents wearing different masks, animal skins and brightly coloured clothing with its own complex function and symbolism and becoming the living example of the survival of archaic cults to nature. (Photo by Francisco Seco/AP Photo)

Local residents crowd a swimming pool during a hot weather in Suining, Sichuan province, 27 July 2008. (Photo by Reuters/Stringer)