Revellers with their bodies and faces painted attend the "Zombie Walk" parade in Sao Paulo, Brazil, November 2, 2015. (Photo by Paulo Whitaker/Reuters)

A Hindu Sadhu smokes marijuana from a chillum inside the Pashupatinath Temple premise in Kathmandu, Nepal on March 6, 2016. Holy men from India and Nepal come to celebrate the festival of Maha Shivaratri by smoking, smearing their bodies with ash, offering prayers devoted to the Hindu Deity, Lord Shiva. (Photo by Skanda Gautam via ZUMA Wire)

Photochromes are vibrant and nuanced prints hand-coloured from black-and-white negatives. Created using a process pioneered in the 1880s, these images offer a fascinating insight into the world when colour photography was still in its infancy. A Tour of the World in Photochromes is at the Swiss Camera Museum, Vevey, until 21 August. Here: Street food in the Strada del Porto in Naples, Italy, 1899. (Photo by Swiss Camera Museum/The Guardian)

Two hippopotamus are fed with pumpkins at the Hanoi Zoo, in Hanoi, Vietnam, 25 October 2018. The zoo has been the home for more than 800 animals of over 90 different species, including three hippopotamus, since it was built in 1976. (Photo by Luong Thai Linh/EPA/EFE)

(L-R) Maria Silva, Milena Cortes, Maria Arteaga, Jackeline Bastidas and Gissy Abello pose for a picture at the Famproa dogs shelter where they work, in Los Teques, Venezuela, August 25, 2016. Venezuelans struggling to feed their families let alone their pets are dumping animals on the streets, in parks and at makeshift homes overrun with scrawny animals amid an economic crisis. An hour from Caracas in Los Teques, hundreds of dogs bark and run around the streets scavenging for food outside a makeshift shelter. (Photo by Carlos Garcia Rawlins/Reuters)

A wild elephant that strayed into the town moves through the streets as people follow at Siliguri in West Bengal state, India, Wednesday, February 10, 2016. The elephant had wandered from the Baikunthapur forest on Wednesday, crossing roads and a small river before entering the town. The panicked elephant ran amok, trampling parked cars and motorbikes before it was tranquilized. (Photo by AP Photo)

A police officer stands at a police cordon near the scene of a terror attack in London, U.K., on Sunday, June 4, 2017. A van swerved into Saturday-night crowds on London Bridge, before three men got out and went on a stabbing rampage through nearby bars. (Photo by Luke MacGregor/Bloomberg)

This image of a young bareback rider was taken in the village of Palenque de San Basilio, in Colombia’s Bolívar department. Founded by freed slaves in the 17th century, it became the first free town in the Americas, following a decree by the Spanish crown. Most of today’s inhabitants are direct descendants of those slaves and have preserved many of their customs, including their own language, Palenquero. (Photo by Sebastián Suki Beláustegui/The Guardian)