"G.C. Williams' "lottery theory" claims that parthenogenesis is akin to buying 100 lottery tickets with the same number. All the tickets can win, but chances are that all will lose. Sexual reproduction is like buying 100 tickets with different numbers. Only one number can win, but there is a better chance of having a winning ticket. Sexual reproduction does not produce as many individuals as parthenogenesis, but there is a better chance of at least a few individuals surviving."