In this photo taken on July 19, 2014, a man looks at an excavation as an A.R.M.H., Association for the Recovery of Historical Memory, volunteer digs on the search for the body of Perfecto de Dios, in a hidden grave in Chaherrero, Spain. Across Spain, volunteer teams of archeologists, anthropologists and forensic scientists head out every year on expeditions to dig for suspected mass graves – a legacy of Spain's fascist past during the time of General Francisco Franco. (Photo by Daniel Ochoa de Olza/AP Photo)

Antek Marciniec holds onto a slackline after falling off as he highlines between two cliffs at Diamond Bay on December 21, 2014 in Sydney, Australia. Slacklining is a balance sport in which participants walk on a flat nylon webbing anchored between two points with the tension adjusted to allow for slack, providing an experience similiar to that of walking on a trapmoline. Highlining is a style of slacklining where the two anchor points are set up with significant elevation from the ground or water. (Photo by Cameron Spencer/Getty Images)

A reveller dressed up as Austrian drag queen and 2014 Eurovision song contest winner Conchita Wurst takes part in New Year's celebrations in Coin, near Malaga, southern Spain, early January 1, 2015. Villagers and revellers dressed up in funny costumes to take part in the New Year's celebration. (Photo by Jon Nazca/Reuters)

Russian cosmonaut Alexander Skvortsov, Expedition 40 flight engineer, attired in a Russian Orlan spacesuit, participates in a session of extravehicular activity (EVA) in support of science and maintenance on the International Space Station on August 18, 2014. During the five-hour, 11-minute spacewalk, Skvortsov and cosmonaut Oleg Artemyev (out of frame) deployed a small science satellite, retrieved and installed experiment packages and inspected components on the exterior of the orbital laboratory. (Photo by NASA)

The Viking longboat burns during the annual Up Helly Aa festival in Lerwick, Shetland Islands, on January 28, 2014. Up Helly Aa celebrates the influence of the Scandinavian Vikings in the Shetland Islands and culminates with up to 1,000 “guizers” (men in costume) throwing flaming torches into their Viking longboat and setting it alight later in the evening. (Photo by Andy Buchanan/AFP Photo via Getty Images)

A Haka is performed before the ceremonial departure of the 'vaka' or traditional canoes ahead of their cross-Pacific voyage from Viaduct Harbour on April 13, 2011 in Auckland, New Zealand. Powered by sun and wind only, the 15,000 nautical mile journey to Hawaii via French Polynesia will set off on April 15, aiming to raise awareness of environmental issues such as ocean noise pollution, acidification and anoxic waters, whilst recapturing traditional Pacific voyaging. The votyage is named “Te Mana o Te Moana” meaning “The Spirit of the Sea”. (Photo by Phil Walter/Getty Images)

Volunteer rescuers prepare to drag a beached humpback calf to sea at Surfers Paradise Beach on August 8, 2011 on the Gold Coast, Australia. The humpback calf was stranded on the beach yesterday for hours before volunteer rescuers were able to drag it back to the sea. SeaWorld Australia says a mother and calf humpback were sighted near where the calf was released and are hoping to get photos to verify it is the same calf and that it has been reunited with it's mother. (Photo by 2011 SeaWorld Australia via Getty Images)

A Chinese future bride has her friends playing with her dress during a pre-wedding photoshoot in front of the Eiffel tower in Paris, France, August 28, 2015. As young Chinese become wealthier, they take abroad the tradition of taking their wedding photos days before they are married, rather than on their wedding day. (Photo by Philippe Wojazer/Reuters)