Animal experimentation

Instead of using human subjects for our experimentation, we use the creatures that have a "lower quality of life" than humans. The morality of this has been debated since the beginning and I still can't decide which side I stand on.

On the one hand, the experiments have definitely benefitted us, especially in medical research as well as psychological research. We've developed several new treatments for diseases through genetic research involving animals that were previously thought to be intractable defects. AIDS research is also making progress with the help of our furry friends.

But are the benefits enough to justify it? I mean, it's not like the animals have a say in the matter. Who are we to decide that they should be the ones to die through this experimentation when they get little to no benefit from it in the end? All these diseases that animal experimentation is helping us find treatments for are human diseases. We're the ones with the problems, so we shouldn't drag every other life form on the planet into it. They've done nothing to us and we should return the favor.

The main argument that justifies using animals for experimenting is that animals have a lower quality of life than humans. I would agree with this to an extent. But then there are the severely mentally subnormal humans and anencephalic infants (infants born without a brain) that would arguably have an even lower quality of life than most animals. Yet it's still generally considered immoral to test on these people. Why is that? Is it because they have human parents? Is it our own inability to accept one of our own as less than a monkey?

Which brings up another question. How do you define the quality of life? What gives one species a higher quality of life than another? And if you go for the whole evolution theory, then really the only thing that separates us from them is a few random mutations in the DNA.

So I think I disagree with most animal experimentation, but at the same time I'm not sure I'm entirely willing to give up all the medical benefits it gives us. Any thoughts?