A woman (C) shops for an offering at the witch doctor's street in La Paz, July 31, 2015. According to Andean culture, the all the month of August is a time to give offerings to “Pachamama” to give thanks for their farms and health. The Aymaras use coca leaves, candies, animal fat, llama fetuses, some dried fruits, powdered minerals and alcohol during these rituals. (Photo by David Mercado/Reuters)

Alkar Vito runs during the Children's Alka competition in Vuckovici village, Croatia, August 23, 2015. Children's Alka is a tournament which has been held every August in the Croatian village of Vuckovici since 1955, commemorating the victory over the Ottoman Turkish administration. The tournament is named after the ring, Alka, which children have to hit with their spears. (Photo by Antonio Bronic/Reuters)

Children fall as they slide down on a float along a chute to cross a pool of water and foam during the “Letniy Gornoluzhnik” (Summer mountain puddle rider) festival at the Bobroviy Log Fun Park near the Siberian city of Krasnoyarsk, Russia, August 23, 2015. The annual competition marks the end of the summer season at the Siberian ski, rest and entertainment resort. (Photo by Ilya Naymushin/Reuters)

An animatronic polar bear visits the London Underground on January 23, 2015, to mark the launch of Fortitude, Sky Atlantic&Otilde's new drama starring Stanley Tucci, Michael Gambon and Christopher Ecclestone, which premieres on Thursday 29th January at 9pm. A team of 19 Hollywood prop specialists spent six weeks designing and building the realistic replica animal with six to eight people working on the costume at any one time, using over 60 different materials. (Photo by David Parry/PA Wire)

Chief priest Gbenga Saala raises a cutlass to kill a dog during an annual prayer and sacrifice celebration of the iron god Ogun in Abuja, Nigeria, June 23, 2015. Every year worshippers offer a dog as sacrifice to Ogun, a traditional Nigerian deity, in hope of an auspicious year ahead. Taxi drivers, blacksmiths, panel beaters and mechanics – trades that depend on metal for their livelihood – pay homage to Ogun, led by high priest Gbenga Saala. As part of the ceremony, the priest pours the dog’s blood on symbols of these workers’ trade: keys, spanners and other tools piled up in a metal barrel. (Photo by Afolabi Sotunde/Reuters)

In this picture taken on January 11, 2021, young gymnasts train at the Li Xiaoshuang Gymnastics School in Xiantao, Hubei province. This summer's delayed Tokyo Olympics, which are now due to start on July 23, 2021, will be the defining moment for Chinese gymnasts who have trained relentlessly since as young as age four in the pursuit of gold. (Photo by Nicolas Asfouri/AFP Photo)

An arctic tern feeds its chick on the Farne Islands off the Northumberland coast, northern England July 8, 2013. The Farne Islands, which lie off the coast of northeast England, are home to a huge array of wildlife. The islands are owned and protected by the British conservation charity, the National Trust, which says they host some 23 species of seabird, as well as a substantial colony of grey seals, who come to have their pups there in the autumn. Every five years the National Trust carries out a census of the islands' population of puffins, and this year's survey showed there were almost 40,000 nesting pairs on the islands – an 8 percent rise from 2008. (Photo by Nigel Roddis/Reuters)

The Aletsch Glacier is pictured at dusk in Fiesch, Switzerland, August 11, 2015. One of Europe's biggest glaciers, the Great Aletsch coils 23 km (14 miles) through the Swiss Alps – and yet this mighty river of ice could almost vanish in the lifetimes of people born today because of climate change. The glacier, 900 metres (2,950 feet) thick at one point, has retreated about 3 km (1.9 miles) since 1870 and that pace is quickening. (Photo by Denis Balibouse/Reuters)