Students attend a stewardess skill training for the upcoming 2017 entrance examination for art majors in colleges in Luoyang, central China's Henan Province, January 4, 2017. Along with how to stand, how to sit is also covered in these classes. (Photo by Li Bo/Xinhua/Barcroft Images)

A woman takes a selfie in front of a sculpture of a rooster that local media say bears resemblance to U.S. President-elect Donald Trump, outside a shopping mall in Taiyuan, Shanxi province, China December 30, 2016. (Photo by Jon Woo/Reuters)

Muay Thai boxer Nong Rose Baan Charoensuk, who is transgender, trains at a gym in Buriram province, Thailand, July 3, 2017. Born Somros Polchareon, Rose said she identified as a woman at an early age and began wearing makeup and a sports bra in the ring.(Photo by Athit Perawongmetha/Reuters)

For more than 2,000 years, women from the Baiga tribe in the highland district of Dindori, in central India’s Madhya Pradesh state, have been tattooed. Sumintra, 25, from Bona village, has the markings across her forehead, legs and arms. The women who work as tattoo artists are knowledgable about the different types of designs and pigments preferred by various tribes, and their meanings are passed to them by their mothers. The tattooing ‘season’ begins with the approach of winter. (Photo by Ronny Sen/WaterAid/The Guardian)

A Chinese tourist wears protective gloves as she holds a baby Siberian tiger as they pose for pictures at the Heilongjiang Siberian Tiger Park on August 16, 2017 in Harbin, northern China. The center is one of two Siberian tiger parks in the Chinese province of Heilongjiang, about 500 kilometers (300 miles) from the border with Russia. It is considered the world's largest for breeding the Siberian, or Amur, tiger which is listed as endangered by the World Wildlife Federation. (Photo by Kevin Frayer/Getty Images)

Gorillas sit next to a ruler during a photocall for the annual weigh-in at London Zoo in London, Britain August 24, 2017. During the weigh-in, animals across the zoo have their vital statistics recorded including their height and weight and the information is then shared with zoos across the world to help zookeepers compare important information on thousands of endangered species. (Photo by Neil Hall/Reuters)

Residents wade through flood waters from Tropical Storm Harvey in Beaumont Place, Houston, Texas on August 28, 2017. Houston was still largely paralyzed Monday, and there was no relief in sight from the storm that spun into Texas as a Category 4 hurricane, then parked itself over the Gulf Coast. (Photo by Jonathan Bachman/Reuters)

Arctic treasure by Sergey Gorshkov (Russia). An arctic fox carries its egg trophy from a raid on a snow goose nest and heads for a suitable burial spot. Finalist 2017, Animal Portraits. (Photo by Sergey Gorshkov/2017 Wildlife Photographer of the Year)