Residents ride on top of an overcrowded “Jeepney”, a locally manufactured public transport, along a highway in Mogpog town on Marinduque island in central Philippines April 8, 2015. (Photo by Erik De Castro/Reuters)

People ride on a truck as they return to their families ahead of the Eid al-Adha festival in Khartoum September 11, 2016. (Photo by Mohamed Nureldin Abdallah/Reuters)

A truck carrying gold miners across the Sahara desert to far northern Niger drives outside Agadez, Niger, May 9, 2016. (Photo by Joe Penney/Reuters)

A group of fashionable nonagenarians pose for a photo in Pengzhou, Sichuan, China on October 12, 2016. (Photo by Rex Features/Shutterstock)

Commuters hang off a local passenger train in the morning in Colombo, Sri Lanka September 8, 2016. (Photo by Dinuka Liyanawatte/Reuters)

Robot inventor Wu Yulu sits on a rickshaw driven by a robot which he invented in his village in rural Beijing's Tongzhou district, China, 17 November 2016. The 54-year-old Chinese farmer living in rural Beijing's Tongzhou district invented 63 robots in the past 30 years. Wu, who only received primary school education, plans to give up the agricultural work for his robot products. He regularly participates in exhibitions, transfers patent rights and teaches at the university to earn money. (Photo by Wu Hong/EPA)

A military guard carries flowers through the Cementerio Santa Ifigenia where the remains of former Cuban President Fidel Castro were entombed December 4, 2016 in Santiago de Cuba, Cuba. The tomb stands to the side of a memorial to the rebel soldiers killed in an attack that Castro led on Santiago's Moncada barracks on July 26, 1953, and in front of the mausoleum of Cuban national hero Jose Marti. (Photo by Chip Somodevilla/Getty Images)

A student from “the cliff village” in Atule'er climbs newly-constructed steel ladders after school to go home for holidays, in Liangshan Sichuan province, China, November 19, 2016. The steel ladders which replaced the unsafe vine ladders shortened the time taken for the children to go home, from three hours to two. (Photo by Reuters/Stringer)