You've discovered something about the

brain that I think is quite surprising.

>> 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 the

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.

>> And that's proven by science. So, if I

go out and get a dad bod, you're telling

me that science says I'm going to be

more attractive.

>> Yeah, go for it.

>> See what my fiance says. The other thing

that's worth talking about [music] is

have you done any studies on that?

>> Yes, that is one of the most robust

findings in parenthood research. My lab

found actually that

>> Wow.

>> So, I've always been really interested

in families and becoming a parent is one

of the biggest [music] transformations

that you can experience. But, I'm

concerned about the declining birthrate,

and I think that we've managed to market

it as an undesirable choice.

>> According to the CDC and Pew research

data, the US total fertility rate just

hit an all-time recorded low.

>> Yeah, I mean, the transition to

parenthood can be really challenging.

You are sacrificing [music] 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.

>> So, if all goes well, next year I 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.

>> So, great fathers are made, not born.

There's a lot you can do. I'm going to

write it down. Love it. So, first