Visitors of the world's longest tree top walk between the trees of the Bavarian forest on November 6, 2009 in Neuschoenau, Germany. The path, 1300 meters long and in 8 to 25m height, winds up to an impressive tower with a height of 44 meters. The wooden construction is integrated into the forest and delivers a natural experience. (Photo by Miguel Villagran/Getty Images)

Bristol Zoo's baby gorilla Kukena holds onto his mother's arm as he ventures out of his enclosure at Bristol Zoo's Gorilla Island on May 4, 2012 in Bristol, England. The seven-month-old western lowland gorilla is starting to find his feet as he learns to walk having been born at the zoo in September. Kukena joins a family of gorillas at the zoo that are part of an international conservation breeding programme for the western lowland gorilla, which is a critically endangered species. (Photo by Matt Cardy)

A beggar who lay at the side of a road pretending he had no legs was moved on by police who made him stand up and walk away. The man lay slumped on his front in Chengdu, in Sichuan Province, China, with his legs tucked under him, and his jeans stretched out to make it appear he had no legs. He is approached by a police officer, who bends down and talks to him for some moments. The officer then reaches out and helps the man to his feet before guiding him across the road. Chengdu is one of a number of cities where officials have tried to clamp down on begging. (Photo by Rex Features)

In this handout image provided by the Police of Swiss canton Valais the wreckage of a bus is seen after it crashed inside a motorway tunnel on March 13, 2012 in Sierre, Switzerland. 28 people, including 22 children, returning from a skiing holiday died in this bus accident. (Photo by Police Cantonale Valaisanne via Getty Images)

Dr. Adolfo Roitman presents a part of the Isaiah Scroll, one of the Dead Sea Scrolls, inside the vault of the Shrine of the Book building at the Israel Museum on September, 26, 2011. in Jerusalem, Israel. For the first time some of the Dead Sea Scrolls are available online thanks to a partnership between Google and Israel's national museum. (Photo by Lior Mizrahi/Getty Images)

People watch participants, whose faces are painted as popular Mexican figure “Catrina”, during the annual Catrina Fest, part of Day of the Dead celebrations, in Mexico City, Mexico, November 2, 2016. (Photo by Edgard Garrido/Reuters)

American free climber Dean Potter walks on a 41-meter-long and two-centimeter-wide slackline over Enshi Grand Canyon at an altitude of 1,800m on April 22, 2012 in Enshi, Hubei Province of China. Potter successfully finished the lone slackline walk in about three minutes without taking any protective measures. (Photo by ChinaFotoPress/ChinaFotoPress)