Famous pair at San Diego Zoo meet just once a year
                                
                                
                                    (Newser) -
                                    Suggesting that quality does best quantity, two of the most reproductively successful pandas in captivity meet—and mate—but once a year, the AP reveals. Since 2003 the San Diego Zoo's Bai Yun and Gao Gao have produced three cubs, a great feat for the endangered species. The youngest is...