Pupils of the Dao ethnic tribe return home from school along a hillside path at Suoi Thau village in Hoang Su Phi district of Vietnam's northern province of Ha Giang, located at the border with China, September 18, 2015. (Photo by Reuters/Kham)

Giant panda Meng Meng plays on a tree at a Siberian tiger-breeding base in Changchun, China on December 10, 2015. (Photo by Xu Chang/Xinhua Press/Corbis)

A couple hugs while standing near a Christmas tree made out of plastic bins and plastic hampers outside the Museum of History in Monterrey, Mexico, December 4, 2015. The humble Christmas tree has a rich history, from evergreen trees used to symbolise eternal life in Ancient Egypt to tree worship among pagan Europeans. The modern version has its origins in Germany, where the song “O Tannenbaum” is still a festive favourite. Today the traditional tree with lights and decorations appears in cities including Washington, Moscow and Beirut. Alternative constructions range from recycled rubbish in Mexico City to old window frames in Rakvere, Estonia. Whatever the shape or size, the message is the same: Merry Christmas. (Photo by Neil Hall/Reuters)

A picturesque supercell formation in the northwest of Booker, Texas from June 2013. (Photo by Mike Olbinski/Barcroft Media)

People sit at an oversize picnic table in Soho Square in London May 19, 2014. (Photo by Luke MacGregor/Reuters)

A pangolin carries its baby at a Bali zoo, Indonesia, Thursday, June 19, 2014. The pangolin baby was born on May 31. (Photo by Firdia Lisnawati/AP Photo)

Noriaki Iwashima gestures as he lies in a coffin to try it out during an end-of-life seminar held by Japan's largest retailer Aeon Co in Tokyo October 24, 2014. Funeral arrangements are normally left to those who have been left behind but the latest trend in Japan, which literally translates to “End of life” preparations, is for the ageing to prepare their own funerals and graves before they set off on their journey to the great beyond. With a population that is expected to shrink by nearly 30 million people over the next 50 years, the market for funerals, graves and anything related to the afterlife is still very much alive. (Photo by Toru Hanai/Reuters)

Jiejin Qiu, who is six months pregnant with her first baby, poses underwater during a photo shoot at a local wedding photo studio in Shanghai, in this September 5, 2014 file photo. (Photo by Carlos Barria/Reuters)