The Scientist Who Scans Fathers' Brains: The Parenting Checklist You NEED Before You Have Babies!

**Steven Bartlett** (0:00)
You've discovered something about the brain I think is quite surprising.

**Darby Saxbe** (0:03)
So we found that in fathers, the brain is actually shrinking, and I'll explain why. But also there are studies that find that both men and women who report having had more kids have markers of a younger looking brain age. And then also typically men, when they do this show about a 25% drop in testosterone. The next studies of single women have found that, you know, if you show them a series of body types, dad bod is the most popular.

**Steven Bartlett** (0:29)
And that's proven by science. So if I go out and get a dad bod, you're telling me the science says I'm going to be more attractive.

**Darby Saxbe** (0:33)
Yeah, go for it.

**Steven Bartlett** (0:34)
Let's see what my fiance says. The other thing that's worth talking about is the ****. Have you done any studies on that?

**Darby Saxbe** (0:40)
Yes. That is one of the most robust findings in parenthood research. My lab found actually that...

**Steven Bartlett** (0:46)
Wow.

**Darby Saxbe** (0:47)
So I've always been really interested in families and becoming a parent is one of the biggest transformations that you can experience. But I'm concerned about the declining birth rate. I think that we've managed to market it as an undesirable choice.

**Steven Bartlett** (1:01)
According to the CDC and Pew Research data, the US total fertility rate just hit an all-time recorded low.

**Darby Saxbe** (1:07)
Yeah. I mean, the transition to parenthood could be really challenging. You are sacrificing yourself. It can be very isolating. You're losing your sleep. But becoming a parent, you are benefiting from this sense of connection and purpose. You will rediscover your priorities in a way that will ultimately bring a lot of value.

**Steven Bartlett** (1:23)
So if all goes well, next year, you will be a dad. And I would like you to give me some advice on becoming a father based on all the research that you have.

**Darby Saxbe** (1:30)
So great fathers are made not born. There's a lot you can do.

**Steven Bartlett** (1:33)
I'm going to write it down.

**Darby Saxbe** (1:34)
Love it. So first...

**Steven Bartlett** (1:39)
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Dr. Darby Saxbe, you've discovered something about the brain that I think is quite surprising to a lot of men and women as it relates to what happens to a man's brain when they become a father. And I've got the report here in front of me, but I have a model brain over there. Could you explain to me what exactly it is that you discovered?

**Darby Saxbe** (2:32)
Yes. So we found that in fathers, and this is similar to what's been observed in mothers, the brain is actually losing gray matter volume. So it is shrinking. So if I had stronger hands, I could probably squish this brain and make it look tinier.
But the parts of the brain that are shrinking the most are in what we call the mentalizing network. And that's a part of the brain that helps us understand other people's feelings and intentions. Those areas are kind of concentrated around the midline of the cortex, which is kind of what we're seeing here.
And then you also see volume reduction in the visual areas, which is the back of the brain, which is really important for understanding. When you look at an infant's face, what kinds of emotions it's trying to tell you.
And so we see changes to those parts of the brain in new dads. In moms, we see changes to these same parts of the brain. We also see changes in moms to what's called the subcortex, which is this part of the brain that kind of controls our gut feelings and our sense of reward and is really strongly linked with our hormones. So moms are kind of changing all across the brain. Dads are mostly changing in this top layer, the cortex, which kind of controls our higher order thinking, reasoning and executive functioning.