Teenagers on roller skates hold on to each other as they are pulled by a vintage car to move along a street in Havana, Cuba March 19, 2016. (Photo by Ivan Alvarado/Reuters)

A man poses for a photograph in front of a mural of Democrat US presidential nominee Hillary Clinton clad in a swimsuit bearing the colours of the US flag in West Footscray in Melbourne on July 30, 2016. An Australian mural of US presidential nominee Hillary Clinton in a revealing, stars and stripes swimsuit may be taken down, after it has reportedly been deemed offensive. (Photo by Paul Crock/AFP Photo)

Honda MotoGP rider Dani Pedrosa (R) of Spain sprays champagne on an attendant next to Yamaha MotoGP rider Valentino Rossi (C) of Italy after winning the Japanese Grand Prix at the Twin Ring Motegi circuit in Motegi, north of Tokyo, Japan, October 11, 2015. Rossi placed second. (Photo by Issei Kato/Reuters)

“The Challenge!” Young boy relishes in a game of tug of war before school. Photo location: Lake Titicaca, Peru. (Photo and caption by Paul Heyman/National Geographic Photo Contest)

Britain's skip Eve Muirhead, right, embraces Anna Sloan after defeating Switzerland to win the women's curling bronze medal at the 2014 Winter Olympics, Thursday, February 20, 2014, in Sochi, Russia. (Photo by Robert F. Bukaty/AP Photo)

“Himalayan Dog”. This dog just appeared out of nowhere and followed us for an entire week during our trekking trip in the Himalayan outback. He always used to sleep in front of our tent and guarded us in the nights. When I decided to get up at 4 a.m. to climb the next 5000 m peak for sunrise he accompanied me as well. On the top he was sitting for the entire 30 minutes on this place looking straight into the countryside. Photo location: Ladakh, India. (Photo and caption by Sebastian Wahlhuetter/National Geographic Photo Contest)

Five year old George holds an orange to feed the Owl butterflies at the Natural History Museum in London, Thursday, March 30, 2017. Hundreds of tropical butterflies were released to launch the Natural History Museum's Sensational Butterflies exhibition, starting for the public on March 31, 2017. (Photo by Frank Augstein/AP Photo)

Bikers push their motorbikes during a traffic block as they take part in the “Enduropale” motorcycle endurance race on the beach of Le Touquet, northern France, February 1, 2015. About 1100 motorbike and 600 quad bike riders descend on Le Touquet every year for the racing endurance event. (Photo by Pascal Rossignol/Reuters)