Rio de Janeiro's state military policemen aim their guns during a violent protest in a favela next to Copacabana, Rio de Janeiro on April 22, 2014. Violent protests broke out in Rio's landmark beachfront district, Copacabana, following the death of a resident last weekend during clashes with the Army in a nearby favela. (Photo by Christophe Simon/AFP Photo)

Revelers dressed as Santa Claus or in festive costumes arrive for the start of SantaCon 2018 in New York City December 8, 2018. SantaCon is an annual event where people dress as Santa Claus or other Christmas characters parade in several cities around the world. (Photo by Timothy A. Clary/AFP Photo)

Wise Guys & Die Klasse der Auszubildenden zum Forstwirt der Lehranstalt für Forstwirtschaft in Bad Segeberg – Sägewerk Bad Segeberg

1974: American boxer Muhammad Ali, formerly Cassius Clay, strikes an aggressive pose at a press conference on November 29, 1974. (Photo by Harry Dempster/Express/Getty Images); American actor Will Smith at the Royal Premiere of the film Ali in London on December 11, 2001. Smith starred as Muhammad Ali in the film. (Photo by Dave Hogan/Getty Images)

Emily Hasler, an English Heritage employee at Charles Darwin's home, Down House, cleans a rabbit bone in his old study on April 2, 2011 in Downe, England. Staff at the house are cleaning and preparing the property ahead of their peak visitor season. The house contains the study where Darwin wrote “On the Origin of Species”, as well as family rooms and an extensive garden that inspired the renowned scientist. (Photo by Oli Scarff/Getty Images)