The Scientist Who Scans Fathers' Brains: Parenthood Shrinks Your Brain, And Drops Testosterone 25%!

The Diary Of A CEO

  • Aug 24, 2026
  • 1:28:59
  • Full Episode

What actually happens to your brain, and how fast or slow do you age when you become a parent? Dr. Darby Saxbe reveals the surprising science of the "parental brain" and how fatherhood physically reshapes a man's mind, why dads lose grey matter, what really happens to testosterone, and why the "dad bod" might be nature's design.

Dr. Darby Saxbe is a professor of psychology and a leading researcher on the neuroscience of parenthood. She is the founder and director of the NEST (Neuroendocrinology of Social Ties) Lab at the University of Southern California, where her pioneering work studies how the transition to parenthood changes the brains, hormones and relationships of both mothers and fathers. Her research has reshaped how scientists understand fatherhood, men's mental health, and what it really takes to raise a child.

00:00:00 Intro 00:02:33 Role Of Fathers In Parenting 00:06:30 What Happens To The Brain When You Become A Father? 00:09:29 Why Testosterone Drops When Men Become Fathers 00:11:42 Should Men Be Worried About Lower Testosterone? 00:15:59 What Fatherhood Can Change In A Man’s Personality 00:19:20 The Upsides And Downsides Of Parenting 00:21:50 What Happens When We Make Parents Fight? 00:24:08 Why The Birth Experience Can Shape Your Relationship 00:27:45 Are People Waiting For The Perfect Time To Have Kids? 00:31:04 Why Fewer People May Be Choosing Parenthood 00:35:33 Ads 00:37:54 Do Parents Actually Have Healthier Brains? 00:45:22 What Does Daycare Really Mean For Children? 00:47:37 Why Mothers Become The Default Parent 00:49:30 Maternal Gatekeeping And Weaponized Incompetence 00:52:24 What Really Happens To Relationships After A Baby 00:54:47 Why Fathers Can Experience Postpartum Depression 00:57:05 Can Your Personality Predict Whether You’ll Divorce? 01:01:11 Why Women’s Ovulation May Be Harder To Detect 01:03:26 How Can You Increase Your Chances Of Conceiving? 01:04:23 What Every New Father Needs To Know 01:05:11 Ads 01:06:28 How Should Parents Divide Baby Care? 01:08:32 What Couples Should Do Before Having Kids 01:14:03 How To Protect Your Relationship After Having Children 01:16:02 Is The Dad Bod More Attractive? 01:19:14 What Does Your Childhood Teach You About Parenting? 01:21:08 How Divorce Can Affect Children 01:21:25 Are Humans Really Meant To Be Monogamous? 01:22:47 What Are The Biggest Concerns About Modern Parenthood? 01:24:32 What Systemic Change Could Transform Parenting?

She explains: ◼ Why a father's brain physically shrinks when you become a dad ◼ Why testosterone drops in new fathers ◼ Why the "dad bod" may signal a more attentive hands-on father ◼ Why men experience postpartum depression ◼ Why raising a child was never meant to be done by two people alone

Follow Dr. Darby Saxbe: X: https://x.com/darbysaxbe NEST Lab: https://www.nestlab.ca Her research: https://dornsife.usc.edu/nestlab/

Her book ‘Dad Brain: The New Science of Fatherhood and How It Shapes Men's Lives: https://a.co/d/03Qhspxt Join her US based ‘Daddy Stroller Social Club’: https://daddystrollersocialclub.com

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Brief Summary

Dr. Darby Saxby discusses brain changes in fathers and the societal impact of declining birth rates.

Key points

  • Surprising Brain Changes in Fathers. Research shows that fathers experience brain shrinkage, particularly in areas related to empathy and social cognition.
  • The Importance of Fatherhood. Fatherhood is increasingly recognized as central to men's self-concept and values.
  • The Importance of Relationships. Men's well-being is best predicted by the quality of their relationships, not wealth.
  • Fighting During Pregnancy. Negative conflict behaviors can lead to more difficult birth experiences for mothers.
  • Cultural Shift Needed for Parenting. We need to reframe the conversation around care to make parenting more desirable.
  • The Role of Oxytocin in Parenting. Oxytocin, the bonding chemical, may contribute to neuroprotection.

Episode highlights

Tension

45/ 100Some tension

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