Supporters of the presidential candidate Muhammadu Buhari and his All Progressive Congress hits another supporter with a motorbike during celebrations in Kano, Nigeria March 31, 2015. (Photo by Goran Tomasevic/Reuters)

Christmas party goers seen on December 14, 2018 in Liverpool, United Kingdom. Revellers hit the bars as they partied hard on the second-to-last Friday before Christmas. (Photo by Mercury Press)

A pedestrian leaps across a flooded portion of the La Paz and Seventh Street intersection as a winter storm arrived, Thursday, December 6, 2018 in Victorville, Calif. The second round of a fall storm dumped snow and rain that jammed traffic on Southern California highways and loosened hillsides in wildfire burn areas on Thursday. (Photo by James Quigg/The Daily Press via AP Photo)

Hugo Gonzalez of Lake Worth works to put final strokes on his rendition of a Raksha demon. (Photo by Thomas Cordy/The Palm Beach Post)

Photographer David Emitt Adams creates tintypes on discarded cans he collects from the Sonoran Desert. In his artist statement, Adams says that some are more than four decades old, which have earned a deep reddish-brown, rusty coloration. (Photo by David Emitt Adams)

In a north London hospital, scientists are growing noses, ears and blood vessels in the laboratory in a bold attempt to make body parts using stem cells. It is among several labs around the world, including in the U.S., that are working on the futuristic idea of growing custom-made organs in the lab. (Photo by Matt Dunham/AP Photo)