Science is based on theory. If the theory can not be disproven than the theory stands. Gravity is a theory and in till gravity is disproven the theory of gravity stands. Evolution is a theory. As of yet the theory of evolution stands. Everyday they continue to dig up bones that support the theory. In till they dig up bones that disprove the theory the theory of evolution stands. Another way to look at this scentific process is this: let the answers to questions shape our understanding, instead of letting our understanding shape the answers to questions.