Species ethics - first questions

District 9 - an incredible, intelligent, multilayered story - is the movie of the year.

I'll quickly concentrate on a layer that I've thought quite an interesting angle into an inquiry into ethics - and if this is not too sci-fi, would like to explore this academically at some point, at least on a level of a thought-experiment.

How would our ethical system change if we were not to consider ourselves the highest species? What would an inter-species ethical system look like? What would we consider moral action towards lower and higher species if humans were only a step on a continuum of species?

There are many assumptions and beliefs in the above, begging definition, but since this is not an academic piece, I'll just pen down some ideas I have about this. This far, we have fought and argues about what is right and wrong; whether such questions can be answered; whether they can be asked at all. We have been severely handicapped by our acceptance that the naturalistic fallacy and Hume's guillotine separate the worldly from the the ethical, and that arguments of ethics are eternally doomed to either clash or descend into cultural relativism and even nihilism.

By the fact that we exist, we cannot deduce that our existence has any moral value. We can, however, say that we have the right to exist. Analyzed further, this breaks down to simply two things: that we WANT to exist, and that we have the ability to DECLARE it. Most mammals - lower species in terms of cultural complexity, technology and communication - can be deduced to want to exist as well. In fact, they display fear, warn others of danger and attempt to flee when faced with imminent doom. Of course, that is an declaration of desire to exist, since we wouldn't understand them without some kind of communication.

That's a very short introduction to some ethical dilemmas around animal rights - a loaded subject among vegetarians and carnivores alike. To escape that, I'll just place the point of observation outside the animal-human distinction, and assume that the continuum of species goes beyond that of humans - again, beyond in terms of cultural, societal and technological complexity. How should we assume our declaration of our desire to exist should be reacted to?

One answer could be based on intelligence and self-consciousness, but this approach would require us to draw a line between intelligence and non-intelligence. Are we intelligent? Not in comparison, necessarily. Are sheep not non-intelligent? Again, not in all comparisons. If it is likelier, that intelligence, like other forms of complex interaction, is not a huge, emergent leap but a spectrum (this is my stance, which I aim to argue for in entirety later).

I won't offer answers here, but you should see the perspective I'm aiming for now. Is an ethical system possible that can be accepted between species on a continuum of interacting species (eating another species counts as interaction)? What would that entail? If such a system is feasible to accept, should we accept it, or continue to assume that we are, morally, the highest species?