Too many folks confuse relative mores (societal and cultural norms and practices) about things like consensual sexual behaviors or modes of dress or diet or regulations regarding uses of intoxicants, with morality.
I do believe there is an absolute moral code for humanity.
It is this: What is harmful to yourself, you ought not do to others.
It was sighted by Jesus as the primary moral imperative (Mathew 7:12). Although he may just have been cribbing off of Rabbi Hillel (who, if we trust bible scholars' timelines, died when Jesus was about 12). Rabbi H said the same thing Jesus would later say (that is the summation of all the law and the writings of the prophets). It's in the Mahabharata. Buddha says it, Lao Tzu says it, and Confucius says it. There are Islamic versions, Shinto Versions, Native American versions and versions from a variety of ancient Greek and Roman philosophers. For instance, Thales, the father of Greek philosophy, said it 7 centuries before Christ. If nothing else, even if it doesn't represent an absolute morality, such an impressive consensus should allow us to use it as if it were an absolute moral standard. Especially as it requires no eternal threats, nor promises of heavenly reward in order to operate, just enlightened self-interest.
Game theory shows that using a strategy based on a such a code leads to viable long term success: http://en.wikipedia.org/wiki/Tit_for_tat
Moreover, evolutionary biology and game theory mathematics overlap, and show that such behavior can confer adaptive benefits on a population: http://en.wikipedia.org/wiki/Evolution_and_the_Theory_of_Games