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)

This 1950s photo provided by the Estate of Vivian Maier and John Maloof Collection shows Maier in a self-portrait as she looks into a storefront wearing a hat in New York. New research about Maier shows the enigmatic Chicago nanny was obsessive about honing her skills as a photographer starting in 1950. (Photo by Vivian Maier/Estate of Vivian Maier and John Maloof Collection via AP Photo)

A photographer tested the concentration of several pairs of dogs as he captured their reactions to treat time in a series of shots. Christian Vieler, 47, of Waltrop, Germany, has been a professional dog photographer since 2016. He came up with the idea of snapping two dogs catching treats simultaneously. Here: Basset Hounds. (Photo by Vieler Photography/Caters News Agency)

Soldiers stand guard in Maua square where a cotton candy vendor passes by in Rio de Janeiro, Brazil, Saturday, July 9, 2016, as security is deployed to get to know the areas they'll be patrolling during the Olympics. Roughly twice the security contingent at the London Olympics will be deployed during the August games in Rio, which are expected to draw thousands of foreigners to a city where armed muggings, stray bullets and turf wars between heavily armed drug gangs are routine. (Photo by Leo Correa/AP Photo)

Take me away, deer, Russia. The Nenet people of Arctic Russia use reindeer and sledges as a prime mode of transport. The animals’ navigational ability means that in severe conditions they are sometimes the only hope of survival. (Photo by Kamil Nureev/Smithsonian Photo Contest)

Hooded demonstrators vandalise a shop window in Mexico City, during the commemoration of the 50th anniversary of the 1968 Tlatelolco student massacre, on October 2, 2018. Fifty years ago, Mexican troops opened fire on student demonstrators, killing hundreds just days before Mexico City hosted the 1968 Olympics – one of the darkest episodes in a year of global turbulence. (Photo by Ronaldo Schemidt/AFP Photo)

It's a 30-day-old Echidna baby, known as a “puggle” – one of only 24 ever bred in captivity. The proud parents are Tippy and Pickle of Australia Zoo. The tiny baby, whose s*x has not yet been identified, hatched from a soft egg and will continue to develop and nurse inside Tippy's warm pouch. (Photo by Australia Zoo/Rex/Sipa Press)

National Geographic invites photographers from around the world to enter the 2013 National Geographic Photography Contest. The grand-prize winner will receive $10,000 (USD) and a trip to National Geographic headquarters in Washington, D.C., to participate in the annual National Geographic Photography Seminar in January 2014. Photo: “We just want to move to search to the Leopard at that morning but we found a group of giraffes come toward a small lake and start drinking it was a nice moment when the Giraffe finish from drinking and leave a letters “S” with motion in the air”. (Photo and caption by Majed Ali/National Geographic Photography Contest)