Darby Saxbe

And that is not at all unique to humans.

Like bird males drop in testosterone, rodents, primates, like biparental mammals.

You see these reproductively linked changes in testosterone.

Seems adaptive.

Yeah.

Brain structure changes.

So the brain loses gray matter volume.

And that has been seen in both moms and in dads.

And so there's this conserved kind of parental brain that seems to be streamlining, getting more efficient.

I think what's happening for men is more like an experience-dependent plasticity.

Whereas for women, it's more like you have this hormonal cascade that is potentiating some of these changes.

Yes.

I wrestled with this with my editor when I was writing this book because I'm like, I want to sell men on parents.

Yeah.

It's like, wait.

You know, but I think there are some benefits later in life.

But so the testosterone actually does really tie into reproductive strategy.

So like some of the early work was on birds.

Birds show high testosterone at the start of a breeding season because they need to be out there looking for mates.

Right.