A mahout (a person who rides an elephant) decorates his elephant using chalk while preparing for the Elephant Festival at Sauraha in Chitwan, south of Kathmandu, December 26, 2014. Elephants and mahouts from Chitwan will participate in the Elephant festival, which involves elephant races, elephants playing an exhibition soccer match and taking part in various other sporting activities. The event will start from 26 December and will end on 30 December, 2014. (Photo by Navesh Chitrakar/Reuters)

A member of “Laughter Doctors of Ciudad Juarez” performs at a children's hospital in Ciudad Juarez March 11, 2015. Through clown performances, music and interactive activities, the group of doctors visit different hospitals throughout the border city, using laughter to help aid the recovery of young and elderly patients suffering from serious illness or injury, as well as provide hope for the hospitalized patients and their families, local media reported. (Photo by Jose Luis Gonzalez/Reuters)

Throughout the course of the long war in Afghanistan, Coalition troops have relied on thousands of military working dogs to help keep them safe, and make their jobs easier. The dogs are trained to detect explosives, to find illegal drugs, to search for missing comrades, or target enemy combatants. Not only are they active on the front lines, but behind the lines they serve as therapy dogs, service dogs, and loyal companions. They also share the same risks as the ground troops, suffering injuries and sometimes death on the battlefields. Gathered here are images of these dogs and their handlers in Afghanistan and back home, from over the past several years, part of the ongoing series here on Afghanistan.

History Created on 15th June 92 Young poor & Physically challenged Couples tied in a lifelong knot of Marriage “Free of Cost” Combined Marriage Function at Ramlila Ground on behalf of “Narayan Sewa Sansthan”. “Although we are unable to move without the support of a crutch or might take the help of others in performing every activity, still, we can afford to become a support for each other”. With this spirit, 92 young disabled and poor brides &bridegrooms promised to support each other throughout their life. The historical Ramliila Ground of Delhi became the witness of this mega event. Photo: Mass wedding in Delhi.

The Spanish photographer Xavi Bou digitally combines sequential pictures of birds to create a single image, or chronophotograph, that reveals the shapes of their flight paths against Catalonian skies. His work shows the variety and beauty to be found in the daily activities of the local birds, including spiralling storks, swooping starlings and giddy swifts. Here: European herring gulls at Llobregat Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)

Born 29 December 1990 in Cambridge, UK. Lives and works between London and Essex. Spending the first 6 months of 2013 living in America, currently residing in New York. (Photo by Jack Davison)

The stunning Milkyway in Midwestern U.S.A. captured by photographer Randy Halverson in 2013. The stunning skies in Midwestern U.S.A. captured by photographer Randy Halverson. The videographer captured rare footage of the Milky Way, the elusive Northern Lights and raging night storms in some of the most isolated regions of the U.S.A. The footage, which spans the skies of South Dakota, Wyoming and Utah, was taken between spring and autumn 2013. The 47-year-old spent 40 nights scattered across the eight-month period sat near his camera to capture the clear footage. Randy from Kennebec, South Dakota has been shooting timelapse for over 4 years. (Photo by Randy Halverson/Barcroft Media)

A stunning photographic collection featuring portraits of people from 30 countries and the food they eat in one day. In this fascinating study of people and their diets, 80 profiles are organized by the total number of calories each person puts away in a day. Featuring a Japanese sumo wrestler, a Massai herdswoman, world-renowned Spanish chef Ferran Adria, an American competitive eater, and more, these compulsively readable personal stories also include demographic particulars, including age, activity level, height, and weight. Essays from Harvard primatologist Richard Wrangham, journalist Michael Pollan, and others discuss the implications of our modern diets for our health and for the planet. This compelling blend of photography and investigative reportage expands our understanding of the complex relationships among individuals, culture, and food.