Modern Puberty, Explained

An interview with adolescent experts Cara Natterson and Vanessa Kroll Bennett.

Today I’m thrilled to be running a Q&A with puberty gurus Cara Natterson, M.D., and Vanessa Kroll Bennett, the authors of the fantastic new book This Is So Awkward: Modern Puberty Explained. I have a 12-year-old, so I practically inhaled the entire book in one sitting, but I recommend it for parents of all school-aged kids, because puberty now spans so much of childhood (more on that in a minute).

This Is So Awkward is funny, smart, comprehensive and full of fascinating nuggets of wisdom and science. Perhaps most importantly, for those of you (like me) who are a teensy bit afraid (or maybe terrified?) of puberty, it’s also a hugely reassuring read.

The book is so good that I’m running a giveaway for paid subscribers this month that will include this book as well as developmental psychologist Aliza Pressman’s wonderful book The Five Principles of Parenting, which comes out later this month. If you’re a paying subscriber, take the two seconds it takes to enter!

Okay, now onto our fascinating conversation. Among other things, we talked about how puberty has changed in recent decades, why some signs of puberty can be deceiving, why conversations about puberty tend to focus on girls, and why adolescents (sometimes!) make questionable decisions.

Melinda: Let’s start with a big question. How has puberty changed since we grew up?

Cara: Puberty starts earlier, it lasts longer and it happens with a cell phone. Those three elements are what really mark the biggest differences, generationally, between puberty then (ours) and puberty now (theirs).

In terms of starting earlier, the average onset of puberty used to be between 11 and 11-and-a-half. Now it is between 8 and 9 for girls and between 9 and 10 for boys. So it is starting earlier. This is real. There are hormonal impacts that are then impacting the physical shifts in the body — breast budding, penile and testicular growth — and also the emotional shifts in the body, like moodiness.

It also lasts longer. How do we know? Because you can look at a middle marker, like [average age of the] first period, and see that that shift over the same time frame has gone from 12-and-a-half to 12-and-a-quarter. So a three month differential in the first period, versus a three year differential in the onset of puberty itself. Puberty is stretching like taffy. The way we would describe it in a room to 100 parents — who would then collectively gasp and almost fall out of their chairs — is that it has essentially doubled in length. It was a sprint for us; it is a marathon now.

The cell phone aspect has very real physical, social and emotional implications. There's a lot of data about [phones causing] loss of sleep, causing stress. We know that the stress response means cortisol levels go up in the body. What we also know is that high and sustained levels of cortisol tip the body into puberty earlier — this is not the only cause, it is one of the causes. So the cell phone of it all shifts the physical onset. It also deeply impacts the emotional and social experience.

Vanessa: When we think about how earlier puberty plays out, in reality, not just in the science, but in terms of in households and schools and communities — one of the biggest challenges of modern puberty is that kids look a lot older. Many kids appear to be much older than they actually are. The incongruence between how a kid appears and the developmental stage in which they truly are in terms of brain development and socialization skills and how they pack their backpack or not — that disconnect is really really hard for adults to manage because they're looking at a kid and they're like, this kid looks 14 or 15, but that kid is really just 11. And how do we remember to treat kids the age they actually are? I think this is one of the biggest places where the rubber meets the road in terms of modern puberty. It's true in classrooms, on sports fields, and in families and extended families.

The other big implication that we talk a lot about is that this isn't a girl-only conversation. When you tell people you're writing a book about puberty, they assume it's a book about girls. It's like, yeah, because men magically spring from the earth fully formed. But also because people fear girls becoming sexual and they wrongly assume that a kid who has breast buds at 8 or 9 is going to want to be sexually active at 8 or 9. But that's a much later part of pubertal development. Wanting to be sexually intimate with somebody else is part of puberty, but it's not an early part of puberty.

So the intersection of our society's fear of sexuality, particularly girls’ sexuality, coupled with girls looking older, coupled with kids of all genders looking older, creates this anxiety for adults. And can cause them to either, like, flip out or shut down because they're so scared and worried — so they don't talk about any of it. And obviously, you've read the book — you know that we would hope for neither of those paths, but, instead, a path of informed ongoing communication.

Melinda: The point that you just made and make over and over again in the book — to treat kids the age that they are, not the age that they look — it's such an important message. Related to that, you also explain that there are a number of physical changes that that often coincide with puberty, like hair growth and acne, but that actually aren't manifestations of puberty. Can you talk a bit more about that?

Cara: You said the exact right word, which is that they coincide with puberty. So the adrenal glands — a gland is just an organ in the body that sends a hormone from one place to another to do its job — sit on top of the kidney. The adrenal glands are where cortisol is produced. They are also the home base for what are called the adrenal androgens, which are cousins of testosterone and estrogen. When they go out into the body to do their thing, they are the root cause — no pun intended — of hair growth everywhere, and then also increased sweat — thicker, oilier sweat. The sort of epicenter of acne and body odor.

The adrenal androgens are released around the same time that the sex hormones are released — estrogen, progesterone, testosterone — but they're not part of the feedback loop from the brain (the pituitary gland) to the ovaries or the testicles. It’s the sex hormones that are going to make you go from being sexually immature to being sexually mature. The two hormonal paths are very separate. They do interact with each other; the hormones that make you sweaty and break out are certainly impacted by the hormones that make you ovulate, and that's because they're all distinct cousins, but the paths themselves are very distinct.

In our broader modern definition of puberty, which is an umbrella that includes anything and everything that's touched by the sex hormones, that make you sexually mature, you have to include this path. It’s called adrenarche, and we talk about it as part of puberty. The world sees it as part of puberty. But when you really go down to the nitty gritty, it really doesn't involve the sex hormones at all. Growing hair does not make you sexually mature and smelling badly does not make you sexually mature. They’re coincidental, parallel processes.

Melinda: So it goes back to this idea that just looking at an adolescent, you're not necessarily going to understand where they are in puberty.

Cara: There are some very young kids who have hair or body odor — 6-year-olds, 5-year-olds — and there are some very old kids, 18, 19, 20, who don't. And parents sometimes worry on either end of the equation, which is totally understandable. But when they go to the doctor, the doctor is like, “Don't worry.” And so the question becomes why? And the answer is because this is not part of the path through puberty. It is truly a parallel path.

Vanessa: On the flip side of what is puberty is very, very, very slow penile and testicular growth that's really, from day to day, not visible to a caregiver for two reasons. One, because it's so subtle and so slow, and two, because usually when boys become private is around the same time that they start changing. Often, adults, parents, don't know that their boys are in puberty because they’re private and it’s so slow — whereas with breast buds, I mean, I like to joke that you could be wearing a down vest and your breast buds would poke out of your vest. You can see breast buds poke out of anything. A suit of armor. So there's also that disconnect in our society because the earliest sign of female puberty is so visible, and the earliest sign of male puberty is so not visible, that people assume actually that they're happening at very different points.

Melinda: I want to unpack another aspect of puberty science that you discussed in your book and that kind of exploded my brain. I know, and have often said, that the prefrontal cortex doesn't fully mature until the age of 25. But I had no idea that myelin played a role in that. Can you explain what myelin is and how it plays a role in adolescent moods and decision-making?

Cara: This is one nugget of information that parents should definitely pass along to their kids. Because they deserve to understand why their decision-making, even when well intended, doesn't always work out that way. And this is not to excuse bad behavior, but rather to explain to kids who really want to get it right what the heck is happening in their heads.

Myelin is the insulation material that covers the nerve fibers in the brain. It is made from fat cells. It is laid down one cell at a time in a very predictable order, bottom to top, inside to out. So the first place to get myelinated is the base of the brain. The last place to get myelinated is the prefrontal cortex that is all the way out, underneath the forehead. About halfway up and halfway out is the limbic system, the famous limbic system that is in charge of all feel-good-motivated — what most people think of as bad, but doesn’t have to be — decision-making.

Why does it matter? This is the example we use: Think about your cell phone charger. You have a wire in there, and the wire is covered with a piece of white plastic. When you plug your charger into the wall and the other end of your phone, it is the insulation covering the wire that allows the electricity to flow faster from the wall to your phone. And when you touch the wire you don't get a shock. None of the energy is disseminated. Same thing in your brain, which is electrical. If you cover a neuron with myelin, then the electrical message can travel faster — it turns out it's 3000 times faster — and it doesn't get dissipated. It doesn't start to trigger other neighboring neurons.

Why is that significant? Because [adolescents] have prefrontal cortices; they can access them and use them. But the messaging to and from their limbic system happens so much faster when the limbic system is myelinated, and the prefrontal cortex isn't, that it's not a fair fight. When they are in a circumstance with someone who does not light up their limbic system — and there are three examples of those people on this Zoom right now — then they can give their brains time to send a signal to the prefrontal cortex. It's easier for them because their limbic system is not highly engaged, and the message, while slower to the prefrontal cortex, gets there.

Now they're in a store with their friends and someone says, “Let's shoplift.” What part of their brain is engaged in that decision tree? Usually, it's not the prefrontal cortex. They usually cannot give themselves the time that it takes to let a message crawl to the consequential part of the brain and make a better decision.

Now — every single one of us knows the good kid, the kid who always makes the right decision. What is that kid doing differently? Well, that kid is using their prefrontal cortex. How? They're giving themselves time. They don't make what we call an impulsive decision. But it is not necessarily easy to be that good kid who uses their prefrontal cortex, because it carries with it a lot of responsibility. If you've got the kid who's always on the right side, there are conversations to be had with that kid about what it feels like to be in those situations and how they manage other kids. Because that can feel heavy.

Melinda: What can we do, if anything, to the help other kids — the ones who maybe don’t always make the right decisions — access their prefrontal cortex?

Vanessa: Part of it is giving them skills to buy time. Count to ten, do five burpees, text me, text a friend who's not there. Giving them realistic strategies. I can feel like, why should we even bother having these decision-making conversations with our kids if the limbic system is going to win every time? But it won't win every time if we help them begin to build an awareness of what's happening in their brains, and also some problem-solving and refusal skills. Parents, when they get stressed and worried, they just want to tell their kids what to do or tell them what to say in a tough situation because they’re worried. That's how our stress comes out. But we really encourage parents to, like, ask a kid “Well, what would you say or how would you handle it?” Or, “What language would you use?”

If we think about kids’ brains as being under construction, and someone's pouring wet cement, we get to be a hand print in that wet cement. They won't always go back and revisit that hand print, but that hand print is there and it stays with them. I think parents lose hope that they can't have an impact, but they can.

We have a neuroscientist who we love, Molly Colvin, who's based out of Mass General. She talks about the opportunity available in working with kids whose brains are under construction — the elasticity, the opportunity where there’s a great chance for them to incorporate the ideas and the language. Just as it's a challenging part of working with kids, there's also a great upside to it. People shouldn't lose heart. There's a lot of amazing ways their brains can bring on information and incorporate and gain new skills. But, like everything, it's thousands of conversations. And having conversations with kids about decision-making is exhausting and frustrating and disheartening at times. But we don't want people to lose heart.

I'll give you a perfect example. Ever since my kid turned 13, I would say to him over and over: “You can always call me. I'm always here, no matter what time of day, no matter where you are, no matter what you've done or someone else's done.” And he would say to me, “yeah yeah yeah yeah yeah.” And he would never call. And literally just last year I had dropped him off at college and I was still in the city where he goes to college, and it was two in the morning and my phone rang. And something had happened to one of his friends. And he was like, “What do I do? I need your advice. How do I handle that?” And we talked it through and the next morning he texted me and he said, “You know, Mom, you've always said to me that I can call you, you're always there, and I think I finally understand what that means. And I finally believe you.”

We can't give up. We have to keep trying and someday, somehow, somewhere, they will really understand what we've been trying to tell them.

Melinda: That's a really powerful example.

Vanessa: I literally started crying when I got the text. I was like, “Oh my God, thank You, Lord.” Finally, he heard it. I've probably said it to him hundreds and hundreds of times — every night before they go out, the same thing. Every time they walk out of the house. “You can always call.” Hundreds of times. And finally, he could hear it.

Melinda: Okay, last question. You’ve both raised kids who've gone through puberty. What’s the one thing you know now that you wish you knew when your kids were younger? Or the one thing you really want parents to know?

Cara: I’m going to answer as someone who is very solution-oriented. I'm a tactician as a parent. But I have learned to turn that off. Puberty is not something to solve for. The hurdles of their puberty are different from the hurdles of our puberty. Some might look and feel familiar. But so often — and this is a piece of advice we give in lots of different ways, but it is so real for me — they just want you to listen. They don't want you to talk. For those of us who are talkers and solution-oriented, the best gift that I have learned to give myself — I wish I had done it sooner — was to shut up. Just zip it and get comfortable with the space and the quiet and just wait for them. And sometimes it's a matter of minutes and sometimes it's days or weeks. Each of us have had so many experiences like that with our various kids, where it's the silence that brings the most interesting, most bonding conversations. That’s what I wish I had understood going into this — that it's not a problem to be solved.

Vanessa: For me, I think the desire to be the perfect parent and not get it wrong —  recognizing that I'm going to mess up over and over and over again and I have to take do-overs over and over again. And the incredible power of my kids witnessing me admitting a mistake, apologizing for anything from forgetting to fill in a permission slip to really hurting their feelings. The incredible connection it creates with kids when we own our humanity and our fallibility. The permission it gives them to be fallible and to make mistakes in this incredible pressure-filled world to be someone who really, truly, honestly says to them, “It's okay to make a mistake and you know how I know it's okay to make a mistake? Because I own my mistakes.”

I was so excited to become a parent and then when I became a parent, I was always rushing — the shoes needed to be tied perfectly, we needed to be on time. It was always this desire for everything to be all sewn up tight. And when you get to this stage of life, there's absolutely no way that can happen and things are going to fall apart in a million different ways. My best moments with my kids — because my kids, I have four between 13 and 21 — the best best moments are those moments when the shit has hit the fan and there's arguments, or the kitchen’s a mess, or we're lost on a road trip — everything is falling apart and we come together in laughter. That is honestly when I feel closest to my kids and I think they will tell you they feel closest to me. I just wish I had known that earlier and been better at it earlier.

Cara: Vanessa, you and I share this experience of — we have we talked to so many people and we realize, “There but for the grace of God.” So much of what happens during adolescence is luck and timing and circumstance and privilege and so I think that's made us both deeply appreciative parents when things are flying off the rails and going right.

I'm sure parents email you all the time asking how to do things right or the best way. And one thing that Vanessa and I like to talk about is that we have really different styles of parenting. And we have really different kids. And we really respect each other's parenting styles. It's awesome to look at someone else's parenting and glean some really great tips, but also just to look at their parenting style and say, “That's so cool that that works that way in their house.”

We have basically lived together for the past eight years. We knew each other pretty well before then, but now we really understand each other an order of magnitude better. And that is the theme that has come up over and over and over again. The way our kids communicate with us is different. Our rules, our way of sharing what the rules are, where our comfort zones are. And yet, we still fully respect the way the other person chooses to go through it.

So I would say, the first step is to shed the judgment of other people. The follow-up is to learn how to to see other ways of doing this thing that we are all making up as we go along. I think it is so freeing to see the journey of parenting that way. It also makes you better at the comebacks because when you screw up, it helps to acknowledge and then try something new when you're able to respect how other people do it. You get a glimpse into maybe another way. “Oh, Vanessa did it this way and it looked like it really worked out in her house. I'm going to try it.”

Melinda: I really appreciate that. That’s what I write about now more than anything else — that there's so much pressure on parents these days. There's so much shame-based, fear-based parenting advice out there that's like “You have to do it this way. And if you do it any other way, you're going to screw up your kid for life.” And it’s not true! There are so many ways to be a wonderful parent. There are so many ways to raise fantastic kids.

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