A Sydney Aquarium diver uses a vacuum to clean the gravel in the Great Barrier Reef tank as a Ray Shark swims by September 26, 2006 in Sydney, Australia. The Aquarium is undergoing its annual spring clean to prepare for the school holidays using vacuums, along with sea creatures like Sea Cucumbers, Sea Urchins, Cleaner Wrasse Fish and Sea Stars to help complete the job. (Photo by Ian Waldie/Getty Images)

President Barack Obama speaks to the press in the Briefing Room of the White House April 27, 2011 in Washington, DC. US President Barack Obama released a long form version of his birth certificate after extended criticism by those who do not believe he was born in the United States. (Photo by Brendan Smialowski/Getty Images)

In this handout image provided by the City of New York, a Nissan NV200 is seen as a New York City taxi cab in New York City. The Taxi and Limousine Commission along with New York City Mayor Michael Bloomberg announced the Nissan NV200 designed by Nissan North America, Inc., has been chosen as the winner of the Taxi of Tomorrow competition and will become the City's exclusive taxicab for a decade. (Photo by City of New York via Getty Images)

A group of San Bushmen from the Khomani San community practice their hunter-gatherer craft in the Southern Kalahari desert on October 15, 2009 in the Kalahari, South Africa. One of the largest studies of African genetics by an international team from the University of Pennsylvania, published in April 2009, revealed that the San of Southern Africa are the most genetically diverse on earth, and that the San homeland could be the spot where modern humanity began. (Photo by Dan Kitwood/Getty Images)

Bonhams expert Michaela Vergottis holds a yellow Jade Chinese Imperial Sceptre on May 9, 2011 in London, England. The piece which is thought to have been taken by British Troups during the Boxer Rebellion is expected to fetch between £800,000 – 1.2 M GBP when it goes on sale at the “Chinese Art” sale at Bonham's auction house on May 12, 2011. (Photo by Dan Kitwood/Getty Images)

Newly commissioned 2nd lieutenants throw their caps in the air as a team of F-16 Air Force Thunderbirds fly over the 2011 graduating class of the U.S. Air Force Academy on May 25, 2011 in Colorado Springs, Colorado. A total of 1,021 graduates received their diplomas in front of their families and dignitaries at the Academy's Falcon Stadium. (Photo by John Moore/Getty Images)

A sign marks a railway crossing next to the troubled Kruemmel nuclear power plant on June 2, 2011 in Geesthacht, Germany. The German government recently announced it will phase out the country's 17 remaining nuclear reactors by 2022 in a policy initiative that represents a radical reversal from its previous policy and was sparked by the disaster at Fukushima. Kruemmel went into operation in 1983 but was taken offline following a fire in 2007. (Photo by Sean Gallup/Getty Images)

Demonstrators march on a Slutwalk on June 4, 2011 in Glasgow, Scotland. Glasgow's first ever sl*t walk made its way through the town center streets in a bid to raise awareness about commonly-held attitudes towards rape and sexual assault. (Photo by Jeff J Mitchell/Getty Images)