An arrow-head discovered in 2006 by Archaeologists of the University of Cambridge Archaeological Unit, is displayed by one of the team uncovering Bronze Age wooden houses, preserved in silt, from a quarry near Peterborough, Britain, January 12, 2016. Archaeologists said on Tuesday they had discovered what were believed to be the best-preserved Bronze Age dwellings ever found in Britain, providing an extraordinary insight into prehistoric life from 3,000 years ago. (Photo by Peter Nicholls/Reuters)

Revellers take part in an annual block party before Carnival in downtown Rio de Janeiro, Brazil, January 16, 2016. The Rio de Janeiro Carnival will be held from February 5 to February 9. (Photo by Pilar Olivares/Reuters)

Serena Williams of the U.S. serves during her first round match against Italy's Camila Giorgi at the Australian Open tennis tournament at Melbourne Park, Australia, January 18, 2016. (Photo by Jason O'Brien/Reuters)

Hot air balloons take part in the 38th International Balloon Festival of Chateau-d'oex, Switzerland, 23 January 2016. For nine days balloonists from 15 countries take part in the ballooning event in the Swiss mountain resort famous for ideal flight conditions due to an exceptional microclimate. The festival takes place from 23 to 31 January. (Photo by Cyril Zingaro/EPA)

In this Monday, January 18, 2016 photo, Iranian rock climber, Farnaz Esmaeilzadeh, scales a climbing gym in the city of Zanjan, some 330 kilometers (207 miles) west of the capital Tehran, Iran. Esmaeilzadeh, 27, who has been climbing since she was 13, has distinguished herself in international competitions despite the barriers she faces as a female athlete in conservative Iran. (Photo by Ebrahim Noroozi/AP Photo)

A Green Crowned Brilliant is pictured at a Hummingbird feeding station on January 15, 2016 in Alajuela Costa Rica. Of the 338 known species of Hummingbird worldwide there are around 50 in Costa Rica. Hummingbirds are named for the distinctive sound made by their tiny beating wings, and are admired for their vibrantly coloured iridescent plumage. Their ability to hover, with wings beating between 12 and 90 times a second, and to fly backwards makes them different from all other birds. (Photo by Dan Kitwood/Getty Images)

People in hard hats in a rage room in Moscow, Russia on January 27, 2016. The Debosh stress relief service gives its customers an opportunity to smash the rage room up with sledgehammers and bats to relieve stress and tension. (Photo by Artyom Geodakyan/TASS/Barcroft Media)

Clowns sit in the pews and hold hands across the aisle of the All Saints Church during the Grimaldi clown service in Dalston, north London, February 7, 2016. The Clowns International 70th annual service brings together professional clowns from Britain and Europe in a service of remembrance to the famous British clown Joseph Grimaldi, who died in 1837. (Photo by Peter Nicholls/Reuters)