Do non-human animals have self awareness?

I presume you're asking about animals on Earth. Otherwise I'd be inclined to answer "Almost certainly!" given the vastness of the universe and the mind-boggling number of planets that astronomers estimate are out there. You've asked a question that's at least partly empirical, so as a philosopher I'm not especially well-equipped to answer it. But some who are better-equipped have answered "yes": see this link .

Is torturing an insect less immoral than torturing a non-human primate?

I take it that being tortured implies the experience of pain or other suffering (physical or psychological) or, at the very minimum, the frustration of the victim's desires. Now, insect brains are surprisingly complex: according to Wikipedia, there are 100,000 neurons in the brain of a fruit fly, and as many as 10 million synapses; no doubt there are many more in mantids. But are insect brains complex enough that insects can experience pain, suffering, or frustration? I don't think anyone knows. But the answer may well be no , in which case your question would rest on a false presupposition. But suppose an insect can be tortured. If a case of torture is otherwise gratuitous, then its degree of immorality probably varies with the suffering that it causes. It seems highly likely that at least some nonhuman primates can suffer to a greater degree than insects can, making it worse to torture them, all else being equal.

I read somewhere that a human being's DNA is almost the same as a rat's. (I think the percentage of similarity is 90%.) In other words, we're animals. If I saw a group of grey squirrels killing a group of brown squirrels in a park, I wouldn't judge the actions of the grey squirrels as "immoral." I would just wait for a biologist to give me some explanation. (There is a limited supply of nuts in the park; the grey squirrels have a mutation in their brain that makes them overly aggressive; etc.) So when one group of human beings commits genocide against a different group of human beings, why do we label it as "immoral" when we wouldn't do the same for squirrels (considering that humans are merely animals in the end.)

The knowledge that human beings are animals didn't, of course, await the discovery of DNA. We've known it for millennia. But your question puts enormous weight on our being merely animals: the word "merely" is being asked to do all the argumentative work. I take it you're suggesting that anything that's merely an animal can't act immorally. It's open to someone to reply that either we're not merely animals or else some mere animals can act immorally. Indeed, if there's anything we know of that can act immorally, it's an animal -- rather than a plant, bacterium, or fungus. The capacity to act immorally arises from ongoing self-awareness, rational agency, the ability to reflect on one's actions, and the like -- features possessed by some animals (including but probably not limited to our species in this vast universe) and lacked by other animals (such as squirrels). On Earth anyway, the ability to philosophize seems to be restricted to human animals. Why not, then, the ability to act...