The preceding chapter broached the idea that viewing human nature as a manifestation of our reproductive strategies provides the basis for a science of value and a liberal ethical philosophy. My aims in this chapter are, first, to explain how modern evolutionary theory justifies the assumption that the ultimate value in life is reproduction (the continuation of life), and second, to point out some of the implications that flow from this assumption. But to do this it is necessary first to show why evolutionary theory is incomplete without a thoroughly integrated theory of development (and vice versa), and why it is only when evolutionary and developmental perspectives are combined that questions about the phenotypic representations of reproductive value, including our subjective experiences of it, can begin to be answered. A large part of this chapter is devoted to the argument that life history theory is the best candidate for integrating evolutionary and developmental perspectives.