-[woman wailing]
-[nurse 1] Come on, push. Give it a good push, Rachel. Good push. [nurse 2] Push down! Push down! Push down! -[overlapping chatter]
-[Rachel continues wailing] [nurse 1] Well done. Now look who we have!
Look who we have! A little girl! [Rachel] Oh, my-- [groans] [sniffles] I waited so long for you! [crying] Well done. [nurse 1] Well done, Rachel. Let's take off this sheet. You okay? -[nurse 1] Look at her. She's perfect.
-[baby crying] [nurse 1] Wow! Oh, my baby! -Hey!
-[nurse 2] Well done. -[nurse 1] She's perfect.
-[nurse 2] She is. She looks like her. [nurse 1] I'm just going to switch
the towel. Thank you. Hello, pretty. -Where have you been?
-[baby mewling] Where have you been? It's over. -[Rachel] It's Willow.
-Willow. Willow. [baby crying] [father laughing] [woman 1] When we look at a baby... you can't help but wonder... [man 1] What is going on inside? [woman 2] Where does its personality
come from? [woman 3] How do they become who they are? [man 1] As a scientist and a new parent, I realize that babies are born
totally helpless. But they're going to grow up to be
masters of the universe. How does that happen? What's exciting right now is we have so many new ways
to answer those questions. [woman 4] We realize now
that even the very youngest babies already know more and learn more than we ever would've thought possible. [blowing raspberry] I'm gonna forget about that. 15 BABIES
FILMED OVER ONE YEAR 36 WORLD RENOWNED
SCIENTISTS REVEALING HOW
WE ALL BEGIN [woman 5] Isn't it amazing that the answer
to what it means to be human lies in the smallest, youngest creatures? [woman] Cheeky boy! Our babies. Da-da... Da-da! [mewling] LONDON
UK That's for Mummy. Mummy's gonna be happy to see you. Let's see. Let's see Mummy. Let's see. Which way? Down there. [Adam] Ah! Hello! Who's that? -[girl] Hello.
-Go and give your Mummy a hug. [gasps] Oh. Hello, darling. RACHEL -Babe.
-Where's the babe? Don't know. Who's that? [Rachel] It's Willow. [Adam] Are you gonna show Willow
what you bought her? [gasps] What have you bought Willow? -What's in there?
-[Adam] You gonna give it to Willow? [gasps] Aww! [Adam] Good girl. -Aww, that's very kind.
-[Adam] Good girl. [Rachel laughs] [Adam gasps] Who's this? Who's this? Gentle. Gentle. Gentle. -[Rachel gasps]
-Good girl. [Adam] That your sister, give her a kiss. TEL AVIV
ISRAEL The Beatles... Sergeant Pepper The relationship with our parents
is the most meaningful experience. It has such a huge impact
on how a baby develops and experiences the world. Okay. "My Father's Eyes." [Ruth] I was 22 when Estie,
my oldest daughter, was born. She was placed on my chest... and I think at that moment
I felt what it means to love. [speaking in Hebrew] [Ruth] Then, being a scientist,
I wanted to understand what's happening in the brain
when we fall in love with our babies. [speaking in Hebrew] What is the biology of bonding? [Ruth] Back in the early '90s,
we didn't have a full understanding of how the bonding
between mother and baby develops. IDC HERZLIYA In my research, I came across several scientific papers that described
the importance of the hormone oxytocin to bonding in mammals. [Ruth] And that really opened my eyes. So I wondered if oxytocin
would be involved in the bonding I experienced with my own children. In 2001, we started the first study to test the role of oxytocin in parent/infant bonding. [speaking in Hebrew] [mewling] [speaking in Hebrew] [Ruth] This was a real adventure. We recruited about 80 mothers, and we traveled up and down
the country to collect the samples throughout pregnancy, and in the first month after childbirth. And what we found was that oxytocin levels in mothers rise during pregnancy, and they stay high throughout pregnancy and right after childbirth. [speaking in Hebrew] What we also realized, that when mother and infant
touch each other a lot... the oxytocin levels in both go higher, and this makes you want to engage with the baby more. The brain gives the mother
the sense of intense reward. [speaking in Hebrew] [baby bubbles] [Ruth] So the higher the oxytocin
the mother had, the more she bonded with her infant. [speaking in Hebrew] [laughs] But I always knew
that this is only half of the equation. Give me a kiss. [Ruth] I began to wonder
what's going on with fathers. See how red they are? [Adam] Did you know
you're four months old today? -[Willow laughs]
-Yeah. [Adam] That's better.
That looks so much better. [gasps] You leave daddy's ear alone! Ooh! That's a good pinch! Have you been practicing? [toy whining] [mewling] [Adam growls playfully] [Adam] That's what the tiger did. Dad. -Dad, Daddy.
-Yeah. [Adam] Step. That's it. -[Rachel] She's walking on her own!
-That's it. [Rachel] Good girl! -[rooster crowing]
-[Rachel] Ooh! Dakota, you're getting so big on me
so fast. Mommy doesn't want you to grow just yet. Slow down. Slow down. [Destiny] As soon as she came out,
it was just like, "Oh, this is my baby." Look. She is so precious, and it was
an instant love connection of love that you've
never experienced before. [man] Yeah, this is better. It's actually
when she lays her head sideways, I know that's when she's going to sleep. 'Cause she's not moving,
she's not trying to climb no more. She's getting real comfortable. But this is me and Dakota's thing
right here. Just on my shoulder,
walking back and forth. Once she relaxes her arm, then I know, "Okay. No matter what I do,
I'mma get at least a half an hour." [car horns honking in distance] [Ruth] For the next study, we wanted to see if there's an impact on the level of oxytocin in fathers. [woman] So this is our lab. I'm gonna ask you, um,
to spit into these tubes, about one milliliter. [Ruth] So we recruited 80 couples. And we measured oxytocin in fathers, in the first months,
right after the child's birth. Great, thank you. [mechanism clicking] [device beeps, powers up] And when we looked at the results... it was really shocking. Mothers' and fathers' level of oxytocin
were identical. [Ruth] And that was a huge surprise. We know for over a hundred years that mothers get a surge of oxytocin during pregnancy, childbirth, and nursing. -And here we go!
-[baby laughs] But how do fathers get so much oxytocin? [Ruth] We discovered that
the more you do with a baby... and really lift your sleeves,
and take care of the child, and wash it, and feed it, engage in a parental role... the more your oxytocin system will activate. Papa! [Ruth] And this is amazing. Fatherhood is biological. [woman laughs] It's as deep as motherhood. [birds squawking] [Destiny] Okay. Don't open it all the way. -It goes to the back of one of these?
-Yeah. [Dakota cries] [Shawn] And this is the pump, this side? [velcro ripping] [Destiny] Look, you see that other box
at the other end? That's the actual pump down there. [Destiny] I had always been planning
on going back to work. Her pediatrician yesterday informed us that to spread out the feedings
every two to three hours, and, um, just try to find another way
to comfort her and console her, and also to give her time
to allow her to self-soothe. -[Shawn] And to wait till she finishes.
-So that way, we're not... you know, just using me all the time, 'cause then I'll never be able
to go to work. I'm not looking forward to pumping,
even though I want you to feed her, but it's just like a bittersweet...
new chapter. If you want me to try it
before it goes to your-- the real one, make sure it's good... Well, go ahead
and take one for the team, then. Excuse the six pack. [Destiny] Let me see! [pump whirring] Oh, it is doing something. Wait. -[pump whirring]
-[chuckles] Hold up! -[Destiny laughs] Let me see!
-Hold up! [Destiny laughs] Hold up. Daddy's gonna burp you. She'll probably be ready for a nap. Me too. [Destiny scoffs] [pump whirring] Dakota, I want you to still want milk
from Mommy too. Can you do both? Can we make a deal? Yeah? [snoring] So the time is now 12:25 a.m., and Dakota... has decided to... use me as a pacifier. -[mewls, coughs]
-And she won't really sleep. [Destiny] And Shawn is snoring away... like a little baby. [snoring] Sleeping peacefully... while Dakota and I... nurse away. [Ruth] We all know that
when the baby cries at night, it's usually the mom that hears it. And maybe the dad will get up,
change the baby, but it's the mother
who is not able to sleep. When we looked at mom's brain, we found that the oxytocin surge at birth
activates a very primitive structure. The amygdala. This is the amygdala. You see it in both sides of the brain. It makes us vigilant. It makes us worry about the infant. And once the mother's amygdala is open, it stays like this forever,
no matter how old your child is. [Ruth] When we look at dad's brain,
we saw quite a different story. It's about a quarter
of what you see in mom's. But not every family has a mother. [car horns honking] I've been a parent for the past... eleven hours. [chuckles] And this is the other parent. I am so tired. He's the most beautiful boy in the world,
in the universe. Oh... -[Isaac] He's been a good boy tonight.
-Yeah. Having him in my arms and feed him, I don't know how to say, it was like love at first sight, but... it's this kind of love
that you know that, no matter what, it will never end. It's... It's... It's impossible to describe with words what you're feeling. [woman] Hi, baby. [Josh] Who is changing you? Who is that? AJ? Yeah! -[AJ] Hi, squishy butt. Hello.
-[Josh] Look at how happy he is. [Isaac] We started exploring
surrogacy in the UK, and we learned about the option
of going for surrogacy in Canada, because in Canada
you just put your case up for any woman
that wants to carry your baby, and they actually are the ones
that choose you. The whole story changes
from the very beginning. [Isaac] What is it? The umbilical cord is out now!
He has a bellybutton! -He has a bellybutton!
-[Josh] Aww! [Josh laughs] [AJ] In Canada, it is illegal to get paid
for surrogacy. But I think that,
because of how intimate surrogacy is, money cannot be the reason to do this. And I wanted to help. I mean, I can't do much,
but this is something that I can do. Those baby noises when they're eating,
when they're like, "Hm." [Isaac] Tonight, at five, he was like... [Isaac imitates mewling sounds] [Isaac] AJ gave us the ultimate gift
of being able to form a family. Now she's part of our family. Her family is part of our family as well,
and she will forever be. [Josh] Father and son,
both of them sleeping. So cute. [Ruth] In 2010,
we recruited a unique group of parents where there was no mother. [singing children's song in Hebrew] [Ruth] We had 48 gay couples who were living in a partnered,
committed relationship and had a child through surrogacy, and had the baby
from the first day of life. [kids' music playing in background] [Ruth] We videotaped in the home,
the baby interacting with the parents, and we took it to the lab to code it. We also measured oxytocin levels. And we scanned father's brain. And when we analyzed the results, we were in for a big surprise. When fathers are primary caregiver, they had amygdala activation
just like mothers. [Ruth] We had no idea
that we would find that. Looks like a hungry duck. One, two, three. [laughs] Ooh! [Ruth] Pregnancy, childbirth, and nursing activate the maternal brain. But also,
it's activated to the same extent by committed caregiving. [Ruth] So it doesn't really matter
whether you are the biological parent or a committed caregiving parent. It's a choice. It's a choice to be a parent
to that infant. [indistinct chatter in background] [Josh] So I'm taking Eric
to get his vaccines. I'm just a little bit worried
because everybody told me they hurt, but I'm trying to push that down. Hi. [laughs] -Nice to meet you.
-[woman] Nice meeting you. I'll take you through everything now. You have to know what is going to happen
after we've given the vaccines. -You are seeing my face already!
-[woman] Okay. I don't know who is going to suffer more. -Him or me.
-Oh, really? -I'm already suffering. I hate injections.
-Turn a little bit to the side for me. I need to get into these muscles here. -[Josh] Okay.
-Okay? [crying] -[woman] Sorry, sorry.
-[Josh] I'm really sorry, my love! -It's okay, my love. It's okay. Well done.
-[woman] Sorry, Eric. [Josh] All the time,
I'm worried about Eric. You know, probably more than I should. -[Eric crying]
-It's okay, it's okay. It's okay, it's okay, my love. [Josh] Every sound that he's making, I was all the time waking him up
to check what's happening. [woman] Okay. He is my baby, you know? [woman] Well done. We're done. Having Eric made our lives more stressful, but it's a good stress. [distant police siren wailing] [seagulls squawking] [man] I came to the psychology department at Harvard University in 1968. Back then, everyone was doing hard science studies. Visual perception, learning, memory. [Ed] But I was really interested
in what's going on between mothers and their infants. And that had never really been... been looked at before. I actually had one of my professors put
his hand around my shoulder and say, "This emotion stuff is not
what you want to be doing." And somehow, I resisted that,
because I wanted to ask, "Is the baby born
ready to engage in social relationships?" Or is the baby just... sort of passive? This led me to the development
of the still face experiment. [film projector whirring] [Ed] We had mothers playing
with young babies, three, four, five months of age. And if the infant got really excited, the mother got really excited. Then we asked mothers to stop reacting to the baby
for about two minutes, to see what the baby would do. The babies immediately picked up
that the mother wasn't reacting the way she typically did. They would smile at her. Eventually, the babies might cry. But they would keep on trying to get back into a relationship. Oop! [chuckles] [baby cooing ] [laughs] [woman] Ooh! [Ed] It was clear that the baby is born with the capacity to engage in social interaction. [laughter] [Ed] It's something that's built in
and critical to us. -You guys are supposed to be working out.
-[Ed] And if a relationship gets disrupted it has a very powerful emotional effect... [baby mewling] ...on be it a baby or an adult. [Willow crying] I'm sorry, Willow. We're nearly home. [Rachel] We've just been out
with the two of them. [Willow crying] [Rachel] And now both are crying
in the back of the car, and I can't do anything about it. Not far now. Oh, God. [Adam] Stressful for Mummy. She was foaming at the mouth,
she was crying so much. -You forgive me?
-[Adam] Look at your mummy. You forgive me? -[Adam] You looking at your mummy?
-[tsks] What a horrible... [sniffles] What a rubbish end
to a nice little afternoon, eh? Are we friends again? Do you forgive me for letting you cry? I didn't have a choice, darling. Oh, I'm sorry. Silly car. [Rachel] Who's got a nice little bath? [mewling, hiccuping] Having water on your head? [Rachel] Hair, it gets greasy
really quickly as a baby. Yeah? Is that nice? Hey? [car horns honking] Hi. [woman 1 laughs] Hi. I barely made it. You made it just fine. [woman 1] This is nice.
It's like a more... Yeah. [Ed] Stress is inevitable.
You really can't avoid it. So does a good relationship between
the parent and a baby help the baby cope with stress? Hi. Nice to meet you. Hi. Oh, you're smiling. -You can see just his little eyes pop out.
-[assistant] Nice to meet you. [laughter] What? What did you say? We have set up a new way
to use the still face experiment where we look at the amount of stress
that the infant experiences. -Can you say hi?
-[Ed] Hi, sweetie. There's Ed. Say hi to Ed? Thank you so much for coming in
and helping us. [assistant] So we will take
several measures of both you and your baby. [Ed] The first thing we do is we take a sample of the baby's saliva and look at the level of a stress hormone
called cortisol. The higher the level of cortisol, the greater the level of stress
for the infant. Okay, let's go to the other room. Okay. I want to get this around you
for a bit, okay. [assistant] You can stop playing, and I'll tell you when to do
the still face. [Ed] Let's see how he'll react. [singing gently in Spanish] Do you have tootsies? Uh-oh! I'm stuck. You got me. [Ed] The still face experiment
helps us to see what goes on in regular interactions
between the mother and the baby. Shall we do "Wheels On the Bus"? ♪ The wheels on the bus
Go round and round... ♪ [Ed] What we see there is that they're matching one another,
they're dancing coordinated. ♪ All through the town ♪ [mother coos] [singing in Spanish] [whispers] Have her do the still face. Uh, please start the still face. [assistant] Remember,
no touching, no talking, and sit back in the chair. [Ed] As soon as we start, the baby sees something has changed. They know it right away. [baby wailing] [screeching and wailing] [Ed] Babies try to elicit her response. [crying] [Ed] They may start to fuss, even cry, when she's not responding. [crying continues] -[assistant] She's complaining a lot.
-There you go. [Ed] But eventually,
they bring their hands up to their mouth and comfort themselves. -Okay.
-[assistant] Okay. Have her resume.
-[assistant] Great job, thank you. Uh, you can start playing again. [mother] Okay, you're going back
to the fingers. -[crying]
-Oh! [mother laughs] You're not supposed to cry now! [assistant] She's complaining.
"What did you do to me?" [baby crying] [Ed] And it doesn't take long for the baby and the mother to figure out
ways to reconnect after the stress
of the still face experiment. [blows raspberry] All right, again! [blows raspberry] Ah! Oh, you got me. [Ed] And that's really important
for the infant. It means that the infant is able
to trust this person to fix, to repair, after something has gone wrong
in the interaction. When we look at the levels of cortisol
during the experiment... we find that where an infant has
positive experience with their parents, the infant is less stressed
during the still face and shows lower levels
of the stress hormone cortisol. [assistant] Okay, thank you.
We are coming in. It's really a pretty amazing finding, and it speaks to the effect of parenting on how the infant will be in the world. [crying] -[crying]
-What's wrong? [Ed] Every parent struggles to find out... "What does my baby need now?" But if you keep on trying, you'll find out the answers. [laughing] [Ed] Trust your baby to tell you what it is that he or she needs and trust your own instincts about how to be responding. That's how the two of you... fall in love with one another. [mewling] [woman] Yeah. Mommy's coming. [Dakota crying] It's gonna be a big one. [Dakota crying] [woman] Oh. Oh. Probably needs her diaper changed, and... [Destiny] It's just crazy. It just doesn't feel good,
especially because she's fussy over there now. I want to, like, hold her and,
you know, talk to her, but at the same time, I have to prepare
for the showings tomorrow. [woman] I know,
and it will always be like that every day, for like... [Dakota crying] [Dakota screeching] [Destiny] Ooh. This is the last one. One, two, three, four, five. Mommy is coming. -[woman] Okay.
-What address was this one? [muttering softly] Liberty. [Destiny] It's very, very... very... difficult. And it's like... it's hard for me
just as much as it is for her. You have feelings that
she just can't experience yet, like guilt. [laughs] Your little chunky cheeks. I'm giving you the strong pat,
that's why, jelly. You like the strong pats. [crying] [mewling] -Hi, pumpkin.
-You know what? I'm gonna let you guys do this. Come here. Hi. Hi! Here I am. Hi! -[squeals happily]
-Yeah! Say, "Hi, Mommy." Mwah! Mwah! Mwah! What was all the fuss about? What was it about? Did you want to tell me a story? Yeah? [mewls softly] [Dakota mewling] Did it? And what else? [Dakota mewling] Really? Is that what happened? Were you giving Daddy a hard time? Hm? Yeah? That's your job, right? We gotta give him a run for his money. -[mewling]
-Yeah! [distant ship horn blowing] [indistinct chatter] [woman] Is this the first time
you guys have done it without me? -'Cause, have you done it at camp?
-Yeah. -I think so.
-I forget. -I'm not sure.
-I think he did. Okay. [woman] As a parent, I'm faced with
constant dilemmas every day. I really want my children to be
adventurous and courageous, but I also really want to keep them safe. [Anne] Patricia, yours is on, right? These are real choices. [kids laughing] So I've wondered, what kind of impact can these parenting choices
have on the baby's development? [kids laughing] [Anne] A newborn's brain is developing
quite rapidly in early life. [Patricia] Whoa! I wanted to design a study that would allow us to look at if parenting would affect
the infant's brain during this unique period of life. [Anne] When we first started
looking at this, to my knowledge, there wasn't much on just differences in parenting and the infant's brain. So we really needed scans
of babies' brains right after they were born, before they'd experienced really
any parenting styles. And then fortunately we had
this great opportunity to take advantage of a much larger study... the Growing Up In Singapore
Towards Healthy Outcomes study. In this study, these babies had already been scanned
within the first few weeks of life. So we had a sort of baseline
for brain development. We needed to follow those babies
to six months... take another scan of their brain... and also observe differences in parenting style. -[Anne] Hello.
-Hi. -I'm Anne, one of the GUSTO scientists.
-Hi, I'm Nina. -Hi, nice to meet you.
-Nice to meet you. -This is Nathaniel.
-Hi, Nathaniel. So we brought in the moms and babies
when the babies were six months of age, and we observed the parenting behavior
in the laboratory. You go down on the mat? [Anne] What I'm really looking at is how attentive and responsive is a parent to the infant's signals? Hello. How are you? Great? Are you having fun? Stretch. We had 20 babies... and we rated the mother's behavior
using a system of descriptive cards. Do they respond
to what the infant is doing? -[woman] Oops!
-[baby crying] [woman] Oh, no, no, no. [Anne] So for example,
we might see a baby cry. Does the mother quickly offer comfort? [baby crying] [woman] Ooh! Oh, sorry. [Anne] If the baby is reaching
for something, does she let the child choose, or does she choose? You like this? These interactions are really small, and sometimes they're really quick. But over time, they add together to complete a picture of what the relationship is like. [birds chirping] [breast pump whirring] [Destiny] I'm gonna stop at 55. [cell phone ringing] This is him. Hello? Good morning. So you're up. No, you're gonna go
straight to the property? I know, I'm gonna text you the address. Okay, perfect. -Okay, bye-bye.
-[Shawn speaks indistinctly] -[sneezes]
-[Destiny and Shawn] Bless you. -[sneezes]
-[Destiny and Shawn] Bless you. Okay, yes. [Shawn] Destiny is finding it really hard because she's really motivated
to go back to work. But I feel like she doesn't want to be any minute away from Dakota. I guess it's the motherly instincts
kicking in. Dakota, I'm going to need you to be
a little bit more still. I feel I know what I'm doing, but I'm, like, real confident
with doing this now. Yeah, it's time for you to eat. [mewling softly] Come on. [gurgling] But it's time for you to eat. [Shawn] Dakota definitely knows who I am. I feel like, you know,
nothing could break our bond. There you go. It almost makes me feel real soft inside, like, real mushy and, I don't know, like, getting real deep into my emotions, which I don't like doing,
but she brings that out of me easily. Can I get one burp? Hm? [mewling] [car horns honking] So I just need to ask you
a few questions... -Yep.
-...before we proceed with the MRI. There's no radiation involved,
so that's why we can do it on children. -Yep.
-All right? -Ready?
-Ready. [Anne] We had looked to see differences
in parenting style. Now we needed to see
how do these parenting styles affect areas of the infant's brain? And to do that, we needed to take the babies back
into the MRI for their six-month scan. [baby crying] ♪ If you're happy and you know it... ♪ [Anne] It's really hard to scan a baby. ♪ ...and you know it
Clap your hands ♪ [Anne] Because for a successful scan
you need to stay still. [woman] Wow! And that's not something
that comes naturally to infants. [Anne] So to make it easier, babies are fed before so they fall asleep. [woman 1] Okay. Let's start the scan. Is the baby sleeping? [woman 2] Yeah. [woman 1] Okay. -There it is.
-Yes, coming up-- [woman 2] It's coming right up. [woman 2] Are you okay
with the image quality of this? [woman 1] Yes. [woman 2] Perfect. [Anne] I went to my colleague Anqi Qiu,
an expert in neural imaging, whose team processed the data. I was really excited to see
what she had found. [Anqi] Here is actually
the structural image. And now you can see red dots showing up. That's where the hippocampus is. [Anne] So this is just one baby,
though, right? [Anqi] Yes, it is. But if you look at all the scans we have, you look at individuals,
and they have a very similar pattern. This was really quite incredible. [Anne] The hippocampus, this area towards the middle of the brain, that differed according to parenting styles. The infants who had received
less responsive caregiving, their hippocampi were a bit bigger. [Anne] This was surprising, because the hippocampus
is really important to learning and to managing distress. So what it suggests is that the babies
were having to manage their own stress, because they're not getting
quite as much support from their parents. Even at six months,
these everyday differences in parenting were actually linked to observable differences
in the structure of the infant brain. [Anqi] Hey! Good job. To my knowledge, that was the first time
a group had seen this. [Anne] When a parent is attentive
and responsive, the baby is learning
that the world is a safe place, and that frees up time for them
to explore their environment. When a baby doesn't get
those same signals from the parent... [laughter] ...the baby may need to prioritize
thinking about safety and comfort rather than exploration. I'm the last person to say
that parenting is easy. None of us do this perfectly. What is important
is that the overall experience that the child is receiving
is one of attentive and responsive care. And I think, for parents,
that's reassuring. Itsy-bitsy spider
Climbed up the water spout Down came the rain
And washed the spider out ♪ Up came the sun
And dried up all the rain ♪ ♪ The itsy-bitsy spider ♪ Climbed up the spout again [squeals] [Adam] Yay! [cooing] Mommy missed you, Dakota. [Destiny] I'm comfortable leaving, and so, um, it just gives me a lotta hope. It gives me a lotta, lotta hope. [Destiny] Come on, Dakota. Come get Mommy. [Isaac] I think we're gonna
make good parents. But there's a lot of stuff
that you learn on the way. [chuckles] [Josh] Hi! [woman] Woo! [Rachel] It's not just her
being a baby now. She's a real part of our family, and she's growing into her own person. [man] Babies are the ultimate mystery. They're much more complex
than we ever thought. [man] Ba-ba! [baby] Ba-tha. [woman] Good boy! How do they learn language? Why are they sleeping so much? How is it that babies learn to crawl,
and what do they learn when they're crawling around in the world? [babbling excitedly] One of the great puzzles is, what's it like to be a baby? [theme music playing]