Thanks for starting us off, Hannah. I want to focus particularly on your first question, as I fear you conflate some things that might need more careful distinction.
First, ‘nature’ isn’t the same as ‘biology’, nor is ‘nature’ simply creation as it appears to a narrowly scientific method. While biological processes are an integral part of nature, nature isn’t reducible to them. As a natural reality, for instance, sexual relations are more than just a biological fact.
Second, there seems to be some equivocation here over the meaning of ‘nature’. ‘Nature’ as it functions in discussions of natural law, for instance, is not simply what can be observed to exist or occur in the natural world (let me introduce you all to the homosexual necrophiliac duck), nor does it just refer to the typical form that things take (e.g. people being right-handed), or to our personal desires, instincts, and interests divorced from a wider reality and moral order.
‘Nature’, as it functions within most forms of natural law, has directivity as an integral element and not just something appended in the form of positive command or personal volition or determination. For instance, in saying that the eye is an organ of sight, we are saying that it is natural for the eye to be able to see and that an eye that cannot see is not a good eye, even though blind eyes can readily be found within the world.
As human beings, we are person-bodies embedded in a larger natural world and moral order in which we participate. We have both forces at work within us that are greater than us and natural orientations towards expression of, participation in, and realization of realities that exceed ourselves. The natural order beckons to us from both within and without. Living according to natural law is more of an art than a matter of speculative science. It involves deepening our acquaintance with and honing the directivity of the natural order that is already incipient within and operative upon us, through the feedback loop of participation in and reception of a natural reality that exceeds us. It also involves recognizing that we are not just brute creatures of instinct and need to act in accord with the personal and moral character of human nature (for example, recognizing that as we are personal beings, we cannot approach sexual relations in a purely animal fashion without morally injuring ourselves). In such a manner we pursue the flourishing of our nature in unity with other persons and the created order more generally.
Nature—as a force that is other and greater than ourselves, yet which is at work within us and which places constraints and demands upon our behaviour—is threatening for many. We may wish to cut ourselves off from its operations, exercise control over it, and autonomy over against it (C.S. Lewis’ The Abolition of Man is worth reading on this, especially the third chapter). The only nature that will be acknowledged is the ‘nature’ that surfaces in our private desire. And, as we are living in a world that hasn’t been perfected and which is broken and sinful—where persons can experience an unchosen predilection for the most wicked acts, for instance—our own natures viewed in such detachment are hardly a reliable source of moral norms.
Finally, I think you might be eliding explanation, description, and prescription. Natural description would readily seem to support the notion men are the physically stronger sex and that, despite overlap in the bell curves of male and female strength, sex is easily one of the most crucial variables underlying strength differences in humans. Evolutionary psychology is one discipline that seeks to provide us with explanations for this fact (whatever their merits might be). Neither, however, provide us with the prescription that men must be stronger, although their observations and explanations may inform our moral and social practice.
I think Jem’s piece on evolutionary psychology misrepresents academic forms of it (the first comment beneath it raises important objections, I think). Evolution’s mechanism of natural selection centres the importance of processes surrounding reproduction—mate selection, successful mating, the bearing of offspring, the rate of offspring survival, their reproductive success in particular environments, etc.—as an explanatory tool for the different forms of species. Men and women are implicated in these processes in very different ways. As in other species, we should expect sexually divergent forms, behavioural tendencies, and social outcomes to accompany the contrasting parts that men and women play in the central species task of bringing other human beings into the world. Maleness and femaleness is a primary example of the way that we are confronted by a natural order that exceeds us, an otherness operative and present in our most intimate selves, an otherness with which disciplines such as evolutionary psychology seek to acquaint us.