Descriptive evolutionary ethics consists of biological approaches to ethics (morality) based on the role of evolution in shaping human psychology and behavior. Such approaches may be based in scientific fields such as evolutionary psychology, sociobiology, or ethology with a focus on understanding and explaining observed ethical preferences or choices and their origins. On the other hand, normative evolutionary ethics may represent a more independent attempt to use evolution, alone or partially, to justify an ethical system. This project has not, according to one view, been especially successful; for example, Richard Dawkins describes how we must rise above our selfish genes to behave morally (that is, evolution has endowed us with various instincts, but we need some other moral system to decide which ones to empower or control). Dawkins has since expressed interest in what Sam Harris calls a science of morality, which starts with the assumption that "morality" refers to "facts about the flourishing of conscious creatures".