I think morality is completely subjective. There are no moral absolutes. Morality is simply the standard of what is right and wrong in a particular frame of reference (Einstein was on to something with the whole concept of relativity). It is determined by the values of a society. For example, in our society we place a great deal of importance on individual rights, which is why we have laws protecting people from the whims of the majority (although these laws still need improvement).
However, consider a completely different kind of society that may have evolved on a different planet, a society of sentient insect-like beings who think in terms of what is best for the collective. In this society, individual rights are not valued among its members. What is considered moral is whatever is best for the whole. And lets say that in this society, overpopulation is a constant threat to their survival because of their prolific nature and the fact that resources are limited. In this context, murder is considered a moral act (and even considered honourable) since it is necessary for the survival of the species and accepted by all as a means to ensure the greater good.
However, consider a completely different kind of society that may have evolved on a different planet, a society of sentient insect-like beings who think in terms of what is best for the collective. In this society, individual rights are not valued among its members. What is considered moral is whatever is best for the whole. And lets say that in this society, overpopulation is a constant threat to their survival because of their prolific nature and the fact that resources are limited. In this context, murder is considered a moral act (and even considered honourable) since it is necessary for the survival of the species and accepted by all as a means to ensure the greater good.