People ride a prototype of a driverless vehicle as it is moves through a pedestrian area in Greenwich, east London, February 11, 2015. Britain has begun testing driverless cars in four cities, launching the first official trials ahead of a series of planned rule reviews to accommodate the new technology. (Photo by Suzanne Plunkett/Reuters)

Young female Ibex on the fork of Disteis (2,200 m), near the top of the Jof di Montasio (Friuli, Italy). (Photo by Stefano Zocca)

“Asaro from the Eastern Highlands”. The mudmen could not cover their faces with mud because the people of Papua New Guinea thought that the mud from the Asaro river was poisonous. So instead of covering their faces with this alleged poison, they made masks from pebbles that they heated and water from the waterfall, with unusual designs such as long or very short ears either going down to the chin or sticking up at the top, long joined eyebrows attached to the top of the ears, horns and sideways mouths. (Photo and caption by Jimmy Nelson)

People wearing bear furs perform during a festival of New Year ritual dances attended by hundreds in Comanesti, northern Romania, Wednesday, December 30 2015. In pre-Christian rural traditions, dancers wearing colored costumes or animal furs, toured from house to house in villages singing and dancing to ward off evil, in the present the tradition has moved to Romania's cities too, where dancers travel to perform the ritual for money. (Photo by Vadim Ghirda/AP Photo)

People carrying torches march during the traditional Bonfire Celebrations in Lewes, Britain on November 4, 2017. Lewes holds Britain's largest Bonfire night celebrations. The event marks Guy Fawkes Night and the uncovering of the Gunpowder Plot in 1605 and commemorates the memory seventeen Protestant martyrs from the town who were burned at the stake. Thousands gather with flaming torches to march through the street and burn effigies. (Photo by Neil Hall/EPA/EFE)

An Indonesian woman watches an eruption from the Mount Sinabung volcano from Tiga Pancur village, in Karo in North Sumatra on November 3, 2017. Sinabung roared back to life in 2010 for the first time in 400 years. After another period of inactivity it erupted once more in 2013, and has remained highly active since. (Photo by Ivan Damanik/AFP Photo)

Members of p*ssy Riot perform in concert during Day For Night festival on December 16, 2017 in Houston, Texas. (Photo by Gary Miller/Getty Images)

A US Marine leads two Viet Cong suspects in restraints during the Tet Offensive on February 20, 1967. (Photo by Bettmann Archive/Getty Images)