The first step in addressing this question, I think, would be to start with Marx's concept of species essence. Essentially, humans differ from other animals in that we are not "at home" in nature. We cannot, like a bird, or squirrel, for example, walk or fly into a wooded area and immediately have everything at our disposal for our survival. We must create a means of production, even individually, in order to survive. We must make things. Make shelter, food, clothing, and so on. What capital does, and how it differs from other systems of production, is that when it is socially constructed to be the dominate mechanism in which a society, and social relations operate on: capitalism--what humans have done, it would seem according to Marx's view, is create a system that becomes something entirely detached from the thing in which it was created by. Capital becomes an inhuman, alien force that is exerted on society, ruling it, while humanity worships it. Capitalism requires everyone and everything to change and act in ways that are not necessary, natural, or even in our own long-term self-interest.