Dad Brain The New Science of Fatherhood and How It Shapes Men's Lives

By: Darby Saxbe, PhD

Published by Flatiron Books, 2026-06-09

A groundbreaking scientific exploration of fatherhood that explains the biology of caregiving and redefines what it means to be a “good dad”

Over the last decade, researchers have discovered that having a child profoundly transforms our brains, hormones, and sense of self. Most studies have (understandably) focused on mothers. Until recently, the transition to fatherhood has been overlooked.

Now, in Dad Brain, University of Southern California Professor Darby Saxbe draws on her field-leading research on families to revolutionize our understanding of fatherhood. As Dr. Saxbe explains, across both animal and human societies, fathering behaviors vary widely. Male birds and fish are exemplary dads (Nemo’s father was no outlier; clownfish dads are particularly devoted), but involved fathers are rare among mammals. Human fatherhood is considered “facultative,” an optional but very useful adaptation. That’s where nonbiological factors such as love, obligation, culture, religion, and complex reproductive strategies come in, influencing the ways fathers respond to the needs of their children.

In Dad Brain, Dr. Saxbe takes readers on a fatherhood world tour, from hunter-gatherers in the Congo to contemporary suburban dads, and into her lab at USC, where she investigates how caregiving alters men’s biology—including their brain architecture and hormone levels. Ultimately, she offers powerful evidence that great dads are made, not born. When men devote time and care to their children, their physiology adapts to set them up for success—and they can discover a richer and more connected life.

In the tradition of bestselling books such as Hunt, Gather, Parent and The Anxious Generation, Dad Brain blends science, culture, and personal narrative to offer an illuminating, research-based understanding of fatherhood that will become a must-read for all parents.