Dr. P.A. Smithe was sent by the American Red Cross as a doctor and surgeon to work at a hospital in Vienna. He sailed to Europe in December 1915 and returned home in August 1916, according to his daughter, who donated his images to the National World War I Museum. Photo: Turkish army, including cavalry, infantry and artillery. (Photo by Dr. P.A. Smithe/National World War I Museum, Kansas City, Mo.)

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)

Two wolfhounds take part in a dogfight in a stadium in the Kyrgyzstan capital Bishkek on November 5, 2017, during fights organized by a local breeders aiming to improve the Asian Shepherd breed, organizers said. (Photo by Vyacheslav Oseledko/AFP Photo)

A bloodied man who carried dead and wounded, speaks on the phone at the site of a suicide attack an explosion that struck a protest march, in Kabul, Afghanistan, Saturday, July 23, 2016. Witnesses in Kabul say that an explosion causing multiple casualties struck the march by members of Afghanistan’s largely Shiite Hazara ethnic minority group, who were demanding that a major regional electric power line be routed through their impoverished home province. (Photo by Omar Sobhani/Reuters)

A Colombian anti-narcotics policeman stands guard after burning a cocaine lab, which police said belongs to criminal gangs, in a rural area of Calamar in Guaviare state, Colombia, August 2, 2016. Colombian law enforcement has destroyed 104 cocaine laboratories capable of producing some 100 tonnes of the drug annually, the head of the anti-narcotics police said on Tuesday. (Photo by John Vizcaino/Reuters)

One of the most significant challenges related to cancer in Nepal is the lack of awareness around the prognosis of the disease, as many patients, their families and even healthcare professionals consider cancer to be an incurable disease at any stage. This results in significant delays in bringing patients to hospitals, and high rates of advanced stage cancers and mortality. (Photo by Omar Havana)

In this March 3, 2015 photo, a group of California sea lions rest on a large bouy in the San Ignacio lagoon, in the Pacific Ocean, near Guerrero Negro, in Mexico's Baja California peninsula. (Photo by Dario Lopez-Mills/AP Photo)

In this March 12, 2015 photo, a man tours a graffiti exhibition at the Museum of Modern Art, in Bogota, Colombia. The city-run museum recently held an exhibition highlighting the work of Bogota street artists who go by aliases such as Joems and the MonsTruacioN collective. (Photo by Fernando Vergara/AP Photo)