Cant say I agree with you there. Science will explain where morality originated from, what mutations caused certain behaviours to pass on and others to die out, what environmental factors influence our behaviours, what part of the brain controls which actions etc. These types of questions only science can answer.
Evolution may explain where the neurological/physiological apparatus that enables us to make moral judgements came from. It will not explain the origin of every individual moral notion and premise.
Sociology may show that certain upbringings and environments can predispose people to certain moral viewpoints. However, I do not think that morality is baseless and is merely the result of random mutations and sociological conditioning.
I think there is a genuine objective morality. I simply see flawed morals as failings in the judgement of the individal who holds them. These flawed morals do not demonstrate the non-existence of objective morality any more than a flawed perception demonstrates the non-existence of an objective, external reality.
For instance, what is the evolutionary origin of the idea that it is moral to force women to cover themselves up in public? What is the evolutionary origin of the belief that it is morally acceptable to hit one's wife? Or what is the evolutionary explanation of the idea that equality and liberty are better than tyranny and oppression?
Too many atheists see science as something that can answer all questions. I think they need to understand that not all things can be reduced to having a purely scientific explanation.
I mean really, moral philosophies are based on some kind of rationality and reasoning. The scientific method itself was not written by people's genes into their minds. It was devised and developed by individuals through reasoning, observation and analysis.