Traditional views of human nature focus on the supernatural, defining us as creatures with souls, minds, and spirits that transcend our physical attributes. In this provocative book, distinguished scientist and historian Elof Axel Carlson argues for a different understanding of ourselves based on our biology--cellular organization, genetics, life cycle, evolution, and our origins as a species. This interpretation does not negate our capacity for imagination, spiritual and emotional yearnings, or aesthetic appreciation for art, music, and literature. Carlson challenges educators, the media, and public policy makers to integrate the evidence from science more fully into our understanding of ourselves.