You pose one of the great challenges confronting philosophical ethics: explaining the rational basis of morality. If your last claim--that all moral theories include premises you have no reason to accept--is correct, then I don't see how the challenge can be met. A number of philosophers have rejected this claim, however. Kant, for example, suggested that morality is grounded by premises you are rationally bound to accept. According to Kant, simply being a free agent requires you to accept the rational force of certain imperatives, and these imperatives then provide the basis or foundation of your moral obligations. Note that If Kant is correct, what grounds morality is not any biological fact about the ways in which our brains are hardwired. Rather, it is the metaphysical nature of rational agency that lies at the foundation of ethics. Consequently, any rational agent --human or otherwise--will be bound by the same obligations that bind you and me. Of course, it is not at all clear whether...

Does it have to be a fluke that we have evolved in the way you describe? Our perceptual and conceptual apparatuses have evolved such that our perceptual beliefs largely match what is "really out there," and so why should it be a surprise (or a fluke) that our ethical beliefs match what is really good? The point of this question is merely to point out that the fact that we have evolved to think a certain way is not by itself a good reason to reject that way of thinking. That said, your concluding question is a challenging one. How can we decide what is really good or ethical? This question can seem particularly vexing if we think that the laws of morality or the "rules of life" must somehow be "out there" in the world, waiting like the laws of physics to be discovered and understood. But philosophers have long questioned whether values must be "external" in this way in order to be genuine or real. Perhaps our judgments about what matters--about what is valuable or moral or rational--are not...

The theory of evolution by means of natural selection is not really a law of nature at all, at least in the sense you suggest. That is, it does not tell us anything about what we should and should not do with "the strongest seed." The theory of evolution is a descriptive theory. It informs us that the offspring of the "fittest" parents are themselves likely to have a survival or selection advantage. But the theory says nothing about how such parents should or ought to behave. No moral conclusions follow immediately from facts about natural selection. You need a second theory--a prescriptive or moral theory--to reach the conclusion that this evolutionary pattern results in a good or just outcome. And so the conflict between the laws of morality and the theory of evolution is only apparent.