There's a few pertinent issues in your question.
First, you haven't really precisely specified "intelligent life", which may lead to some difficulties down the road in talking about this. I think it actually turns out to be very hard to reach a good definition of this term, so I am going to leave that concern aside.
Second, your exclusion of religion and culture does not seem well-justified. Here, I'm not trying to argue religion, politics, or culture with you. Instead, there's an important ambiguity that makes for some pretty disparate cases. Specifically, we need to be careful to distinguish between rules and their justifications.
A religion or culture might both tell you that murder is wrong and give a justification for why murder is wrong. Now, if it tells us that murder is wrong because the flying spaghetti monster told us its wrong, then I would definitely agree that we should skip over the justification which will definitely not prove to be universal. On the other hand, that does not mean that we should per se exclude "murder is wrong" from consideration as a universal law.
The same issue arises with culture. Each culture has taboos and ethical norms. And these norms have behind them somewhat strikingly different stories at times. But if your question is about universal rules, then who cares about the stories?
There's two or three lines that I'm familiar with that think all intelligent life has at least some common rules.
First, there's sociological and cultural accounts. James Rachels for instance provides an article that talks about cultural relativism and leaves him with a few common principles that he thinks are trans-cultural for humans:
- Some system of care for the young
- Rules about truth-telling
- Rules about life-taking
- Rules about who we have sex with and when
Anthropologists have some somewhat variant lists, but the gist is that to make a human society that survives it needs certain sustaining practices -- which could be seen as consequences of human intelligence.
Second, there's Kantian and neo-Kantian accounts that take what unifies us as rational beings to be certain capacities which in the case of our sorts of beings enable us to follow moral rules. Christine Korsgaard has a pretty ingenious account where what makes us moral is that we are committed to certain values insofar as we are committed to action.
Third, there are Aristotelian accounts of morality. The key here is that Aristotle thinks that humans and other rational creatures engage in the pursuit of ends. And that there are features of pursuing ends that will require us to behave in ways consistent with what we are and with the achievement of good function for ourselves and the attainment of our ends.