Humans invest enormous amounts of time and energy into bringing up our babies. This unique investment is a fundamental part of what it means to be human. In this episode, the second in a three-part series on family relationships, researchers Lee Gettler, Stacy Rosenbaum, and Sonny Bechayda explore how our species' approach to fatherhood may have shaped some of the most important traits that set us apart from other mammals. Leo Hornak produced this episode. Sound design by Ray Pang. Host and executive producer, Meredith Johnson. Our editor is Audrey Quinn. Theme music by Henry Nagle, additional music by Lee Roservere and Blue Dot Sessions. Sounds effects provided by Kevin Luce by way of freesound dot org Support the show! Every donation makes a difference and helps us create new episodes. Click to make a tax-deductible donation today! This episode was generously sponsored by father and daughter Bill Richards and Dana Lajoie. Additional support from the Ann and Gordon Getty Foundation, Jeanne Newman, and the Joan and Arnold Travis Education Fund. Links to learn more:

• Fatherhood, pairbonding and testosterone in the Philippines
• Fathers' care in context
• Who keeps children alive?