These two young siblings appear to cling on to a tree for dear life and even hold hands as they learn the ropes of climbing, on June 25, 2013. (Photo by Tim Fitzharris/Minden/Solent)

Russian President Vladimir Putin, center, uses a binocular, as Defense Minister Sergei Shoigu, left, and chief of Russia's military's General Staff Valery Gerasimov, right, observe military exercises near the Baikal Lake on Wednesday, July 17, 2013. (Photo by Alexei Nikolsky/AP Photo/RIA Novosti/Presidential Press Service)

In this handout image provided by Ogilvy, a burger made from cultured beef, which has been developed by Professor Mark Post of Maastricht University in the Netherlands (pictured) is shown to the media during a press conference on August 5, 2013 in London, England. The in-vitro burger, cultured from cattle stem cells, the first example of what its creator says could provide an answer to global food shortages and help combat climate change, was fried in a pan and tasted by two volunteers. The burger is the result of years of research by Dutch scientist Mark Post, a vascular biologist at the University of Maastricht, who is working to show how meat grown in petri dishes might one day be a true alternative to meat from livestock.The meat in the burger has been made by knitting together around 20,000 strands of protein that has been cultured from cattle stem cells in Post's lab. (Photo by David Parry)

A picture of Moon Ji-sung, a high school student who died in the Sewol ferry disaster, hangs in her room in Ansan April 7, 2015. Her dream was to be a flight attendant. Nearly a year after the Sewol ferry sank on April 16, 2014, with the death of 250 students, some families keep their children’s bedrooms intact to remember and honour their loved ones. More than 300 people, most of them students and teachers from Danwon High School, are dead, or missing and presumed dead, after the Sewol ferry sank on a routine trip from the port of Incheon, near Seoul, to the holiday island of Jeju. (Photo by Kim Hong-Ji/Reuters)

Dajana Djuric, 25, who has worked as a chimney sweep since the age of six, cleans a chimney in Brcko, Bosnia and Herzegovina. Dajana Djuric, believed to be the only female chimney sweep in Bosnia and Herzegovina, has to contend with perilous roofs in the depth of winter. (Photo by Dado Ruvic/Reuters)

An actress dressed as Wonder Woman walks between visitors during the season inauguration of the Madrid Warner amusement park in San Martin de Valdeiglesias, near Madrid, Spain, March 18, 2016. (Photo by Andrea Comas/Reuters)

In this May 3, 2016 photo provided by the New York State Department of Environmental Conservation, a deer with its head caught in the globe from a lighting fixture over its head stands in the woods in Centereach, N.Y. The deer was able to extricate itself with the help of Environmental Conservation Officer, Jeff Hull. Hull wrestled with the deer for a while and the globe shook free in the process. (Photo by New York State Department of Environmental Conservation via AP Photo)

A woman plays around as she walks across a glass-bottomed suspension bridge in a scenic zone in Pingjiang county in southern China's Hunan province Thursday, September 24, 2015. The bridge, 300 meters (984 feet) long and 180 meters (590 feet), opened to visitors on Thursday for the first time since its conversion from a regular suspension bridge was completed. (Photo by Chinatopix Via AP Photo)