Chen Ruolin of China performs a jump during the mixed team event final at the Aquatics World Championships in Kazan, Russia July 29, 2015. (Photo by Stefan Wermuth/Reuters)

A child looks at a polar bear swimming under a water in its enclosure on a hot summer day at Prague Zoo, Czech Republic, July 30, 2015. (Photo by David W. Cerny/Reuters)

A woman dressed as a Viking drinks local red wine during the annual Viking festival of Catoira in north-western Spain August 2, 2015. The festival re-enacts past Viking raids in the area and is celebrated annually on the first Sunday in August. (Photo by Miguel Vidal/Reuters)

Pakistani laborers transport the front portion of a vehicle using a handcart at a road in Peshawar, Pakistan, Monday, August 3, 2015. (Photo by Mohammad Sajjad/AP Photo)

Chantel Sydnor participates in the annual Sturgis Motorcycle Rally in Sturgis, South Dakota, August 4, 2015. This year marks the 75th anniversary of the rally expected to draw hundreds of thousands of motorcycle enthusiasts from around the world for events throughout the week-long festival, according to organizers. (Photo by Kristina Barker/Reuters)

A devotee covered in motor oil poses for a pictures during celebrations honoring the patron saint of Managua, Santo Domingo de Guzman, in Managua, Nicaragua August 9, 2015. (Photo by Oswaldo Rivas/Reuters)

Students from Vida Nueva School present their dinosaur robot built with recycled materials during the annual robotics fair supported by the Bolivian Education Ministry in La Paz, August 10, 2015. (Photo by David Mercado/Reuters)

In this July 25, 2015 photo, youth eat a cooked pig's head as they wait for the start of carnival in Santiago, Cuba. (Photo by Ramon Espinosa/AP Photo)