Animal rights activists from the group “Animal Equality” are covered with plastic sheets to represent meat packaging as they stage a protest during “Day Without Meat” event in Barcelona, Spain, on March 20, 2013. (Photo by Lluis Gene/AFP Photo)

A genetically engineered featherless rooster struts around the campus of the Hebrew University of Jerusalem's Department of Agriculture May 22, 2002 in Rehovot, Israeli. After two years of research, departmental scientists announced the naked chicken, as it has been dubbed, as a low calorie bird because the lack of feathers means the chicken has less fat. It also matures earlier than its feathered counterparts. (Photo by Moshe Milner/GPO/Getty Images)

Participants run at the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. This annual running event which requires participants to run half-naked, was organized to promote environmentally friendly lifestyles. (Photo by Kim Kyung-Hoon/Reuters)

Angel Paz, dressed as a calavera, waits with family for the start of the Gran Procession of the Catrinas, to mark the upcoming Day of the Dead holiday, in Mexico City, Sunday, October 23 2016. (Photo by Anita Baca/AP Photo)

A Waura Indian woman watches the activities of this year's “quarup”, a ritual held over several days to honour in death a person of great importance to them, in Xingu National Park, Mato Grosso State, August 24, 2013. This year the Waura tribe is honouring their late cacique (chief) Atamai, who died in 2012 and helped created the Xingu Park, and his important contribution in facilitating communication between white Brazilians and Indians. (Photo by Ueslei Marcelino/Reuters)

This brave swimmer certainly has a brrracing workout each weekend she skinny dips in one of the coldest rivers in Europe which regularly plummets to temperaturess of –9C. Inna Vladimirskaya, 32, strips off on the banks of the Dnieper river, in Kiev, Ukraine, every Sunday morning, and takes a swim after jogging along the snowy banks of the river in the nip. (Photo by David Tesinsky/Caters News Agency)

A grave cleaner holds up a skull during exhumation works at the Cemetery General in Guatemala City May 24, 2013. If a lease on a grave has expired or not been paid, grave cleaners will break open the crypts to remove and rebury the bodies. (Photo by Jorge Dan Lopez/Reuters)

Dried and shrivelled corpses, some fully clothed and some in coffins, line the wall of a vault of the Pantheon Cemetery on the summit of Cerro del Trozado in Mexico. They were removed from the crypts because of non-payment of cemetery fees. The hot dry air stopped the bodies from rotting. Most of them were placed here between the turn of the century and WW I. (Photo by Three Lions/Getty Images). Circa 1955