How and why human males evolved the capacity to be highly involved caregivers—and why some are more involved than others. We all know the importance of mothers. They are typically as paramount in the wild as they are in human relationships. But what about fathers? In most mammals, including our closest living primate relatives, fathers have little to no involvement in raising their offspring—and sometimes even kill the offspring sired by other fathers. How, then, can we explain modern fathers with the capacity to be highly engaged parents? In Father Nature, James Rilling explores how humans have evolved to endow modern fathers with this potential and considers why this capacity evolved in humans. Paternal caregiving is highly advantageous to children and, by extension, to society at large, yet highly variable both across and within human societies. Rilling considers how to explain this variability, and what social and policy changes might be implemented to increase positive paternal involvement. Along the way, Father Nature also covers the impact fathers have on children’s development, the evolution of paternal caregiving, how natural selection adapted male physiology for caregiving, and finally, what lessons an expecting father can take away from the book, as well as what benefits they themselves get from raising children, including increased longevity and “younger” brains. A beautifully written book by a father himself, Father Nature is a much needed—and deeply rewarding—look at the science behind “good” paternal behavior in humans.