No matter how hard we try, remembering anything that happened to us before the age of, say, 3 or 4 years old feels impossible. Even memories before 7 years old feel hazy and fragmented.

Our brains just aren’t built to store specific memories from our first few years, something known as “infantile amnesia.”

And chances are, even the earliest memories we think we have might just be amalgamations of stories we’ve been told, images cribbed from old family snapshots and home videos, or scenes we’ve borrowed from movies or TV shows.

So does it really matter if it happened, if we can’t really remember it?

Yes, science says. Even if we don’t have a specific memory of what happened when we were babies, those experiences leave lasting impressions on us of being safe and being loved, which shapes how we form relationships later in life. But whether babies are able to encode and store permanent memories is still an open question.

Columbia University cognitive psychologist Tristan Yates put babies in MRI machines and showed them a series of images, and found that the babies tended to stare longer at an image they’d been shown before, suggesting that they remembered seeing the image the first time.

“We are showing that they’re able to form some memories,” Yates said. “The hippocampus is capable of forming specific memories over a few minutes, but now we need to start doing the research that can get us at longer durations, that can get at more complex memories.”

One theory for infantile amnesia is that an infant’s brain is prioritizing learning general skills, like how to walk or talk or eat, or learning to detect patterns like a bedtime routine, rather than storing specific memories that aren’t necessary for survival.

Noam Hassenfeld spoke with Yates and Dr. Dana Suskind, a professor of surgery and pediatrics at the University of Chicago, on the latest episode of Explain It to Me, Vox’s weekly call-in podcast.

Suskind studies early childhood development and the important role that parents and caregivers play, and she told Noam about how our early childhood experiences can shape us.

Below is an excerpt of their conversation, edited for length and clarity. You can listen to the full episode on Apple Podcasts, Spotify, or wherever you get your podcasts. If you’d like to submit a question, send an email to askvox@vox.com or call 1-800-618-8545.

You started out as a cochlear implant surgeon and now you’re working on childhood development. How did that happen? What’s the connection there?

It actually makes a whole lot of sense. When I first started our pediatric cochlear implant program at the University of Chicago, I started implanting cute little kids who all look like they had the same potential to thrive after implant surgery, and found very quickly that I could implant two children who looked very much the same, who had parents who loved them equally, with the same technology, but they would have very different outcomes, with one of them really thriving after surgery in terms of language learning and trajectories, and others barely able to communicate. 

It was that experience and seeing these huge differences in outcomes after the same surgery that led me into this incredible world of childhood development and the importance of the early years and the importance of parents.

Humans come out with brains that are literally only one-third the size of adult brains. That’s very different than any other species. It’s why the puppy can start feeding itself pretty quickly and start walking, whereas the human infant is helpless. In those first three years of life, 85 percent of the physical brain is built during those periods of time. 

A million new neural connections happen every second. The environmental input, the input from parents and caregivers — every serve and return, every touch, every gaze — literally is helping shape and strengthen the neural connections that happen in our brain. 

The brain isn’t being just built for your child’s vocabulary development or their literacy ability. It’s building their social brain, their ability to relate to and connect to the rest of the world. The relationships and the expectations for relationships are built in those early years.

Tell me if this is maybe an oversimplification, but I’m a parent of a young son; he’s a little over 7 months old. And I feel like what I’m doing when I’m raising him is building the structure of his brain, or building the architecture, and all the other stuff, all the specific things, are going to fill in all the rooms of the big building that we’re constructing together. But he’s not going to start filling those in with specific ideas or specific memories until later on in his development. 

The analogy you make is exactly right. I think of building the physical brain — if you were thinking about it through a computer lens — as building the hardware, the firmware, the memory, the RAM. I think of K-12 as really important, but I think of those as software updates. But these early years are building that infrastructure.

“I want you to not strive for perfection, because the one thing that AI has shown us is that humans don’t grow from perfection and frictionless existence.”

At the end of the day, it’s your attachment with him, being the perfectly imperfect parent. I want you to not strive for perfection, because the one thing that AI has shown us is that humans don’t grow from perfection and frictionless existence. So feel okay every time you misstep, misunderstand and repair, because that is, for him, building the understanding of, “I can be loved by another human who missteps but is able to repair.” He is starting to understand how to expect to be treated. 

That’s why it’s almost like you’re building the relationship map for him that’s going to allow him in the future to have expectations of how he’s going to be treated and loved by an imperfect human: building that strong bond, showering him with rich language, that back and forth, looking at him as a conversational partner from day one. 

It’s interesting you brought up AI and friction. What do you think this idea of a more frictionless existence is going to start meaning for kids?

I had a book that just came out on this called Human Raised, and that’s a lot of the argument of the book. Children learn from imperfect parenting through friction, through the productive struggle. And we’re seeing that friction that we’ve always looked at as a bug in the system — like, “Oh my gosh, I wish this was a more frictionless existence with the other humans in our world” — what we’re finding is that it is key for relationships development, learning to have relationships, and actually even learning. 

That’s why, writing an essay with an LLM — you don’t remember it at the end of the day. There’s something about what happens in the brain that we’ve discounted on the friction side of things. So I actually think in some ways friction should be the word of the year, and we need to embrace it a little bit more. We don’t need to friction-max, but we do need to see the power of the friction.

It sounds like even if my son is going to forget all of this, maybe on a deep level it’ll stick with him. But should I still have a nice big 1-year-old birthday party?

Heck yes. Because you’re doing it partially for you — and the grandparents, let’s be clear. Those are wonderful moments that they do remember at some level. My son, who’s now 20-something in medical school, was obsessed with Thomas the choo-choo train. I still have the box of the Thomas the choo-choo train. 

He may not remember exactly that birthday party and the cake that I worked very hard on, but it’s even fun to talk about it now in his twenties. So yes, do enjoy every moment. Don’t get obsessed, like everything has to be perfect, but those are memories for everyone.

Of all the extinction-level threats vying for our attention, AI, climate change, and nuclear war tend to get most of the airplay. But Annie Jacobsen thinks biological war should be near the top of our mental list of doomsday scenarios, too.

She should know — Jacobsen has carved out a unique niche as America’s foremost reporter on the ways we could end the world. Her bestselling 2024 book Nuclear War: A Scenario terrified readers and experts alike, and has been optioned by Hollywood. 

It was while conducting dozens of interviews with high-level government sources for Nuclear War that Jacobsen was told repeatedly that biowarfare should be her next focus.

She took their advice. Her gripping new book Biological War: A Scenario follows a similar ticking-clock format that shows, step by step, just how a humanity-threatening man-made biological catastrophe could play out. (Spoiler alert: not great.)

The result feels like dystopian science fiction, albeit the kind that comes heavily footnoted with government studies that come to similarly grim conclusions. The fact that tech CEOs are also sounding the alarm that advanced AI could make creating killer germs even easier only adds to the growing sense of anxiety. And this book has also been optioned by Hollywood for a TV adaptation. 

Jacobsen sat down with Today, Explained host Noel King to talk through the plot of her nightmare scenario, why we’re still developing biological weapons despite the clear risks, and what needs to happen to avoid disaster. Below is an excerpt of their conversation, edited for length and clarity. There’s much more in the full podcast, so listen to Today, Explained wherever you get podcasts, including Apple Podcasts, Pandora, and Spotify.

How does your book start?

The inciting incident in the book is an accident at a Biosafety Level 4 lab, shorthand BSL-4, in Siberia called Vector. And it’s an actual BSL-4 lab, the highest classification. … And there was an actual accident, an explosion there in 2019. 

In that real-life incident, a deadly pathogen was not released that we know of. But of course, in Biological War: A Scenario, a deadly pathogen is released. And it’s a form of pneumonic plague, which is a nightmare pathogen and sits at the top of the Tier 1 select agent list of the CDC. And so in the first act of the book, I show the scrambling of the intelligence community and the Defense Department, trying desperately to determine if something got out and what it is. … The release of the pathogen widens, and so once you have escape. You do not have mitigation, which has to happen in the first 24, 48 hours. Now you have a situation which is unstoppable.

You say this is now an unstoppable scenario. What is it?

A plague itself, of course, conjures up images and ideas of the bubonic plague of the 14th century, the Black Death. That killed between one half and one third of Europe. The bacteria is called Yersinia pestis. And pneumonic plague is the airborne version of plague. The problem with an airborne pathogen is that because the delivery system is the human lungs, it can move very quickly from a scientist in that lab who now has Yersinia pestis in his lungs out to the general public. And that is precisely what happens in the scenario.

How does it spread from there? The city where this BSL-4 lab sits isn’t Moscow. What happens once the pathogen is in the lungs of the people who work in that lab, or the janitor who was cleaning it that night?

That’s right. Well, suddenly it’s in everyone’s lungs, and those people go out into their community. And even though Koltsovo, the science town where Vector is located, is a small town, it is just 12 miles from Novosibirsk, which is the third-largest city in Russia. And, also, there happens to be in this scenario a group of international hunters on a hunting trip in that area who come across a dying scientist in the snow. One of them gives him CPR, being the Good Samaritan that he is. And lo and behold, those travelers suddenly are now getting on an airplane in Novosibirsk, flying home to where they reside in five or six of the continents.

What makes this form of plague so novel, so dangerous?

I pull this information from actual facts of the Soviet Cold War-era biological weapons program that we know about from Soviet defectors. And I want you to keep in mind: This is 40 years ago when gene editing was in its infancy. But there are two things specifically that the Soviet bioweapons engineers did to plague. 

Their idea was to create a super plague weapon. And one of them has never been revealed before. They were working to insert the gene for euphoria into the plague pathogen. … When you get a disease, a pneumonic-type disease, pneumonia, tubercular, you want to go home and get under the covers because you feel terrible. And when you do that, you’re infecting a lot less people than you would if a gene for euphoria had been inserted into the pathogen, which would make you feel terrific, which would make you want to go out and socialize with people, perhaps even go to a crowded disco. 

And the other thing that the Soviet scientists were working on was a way to defeat medical countermeasures, but with an added component of psychological distress. They inserted a gene into the pathogen that would be triggered by the taking of antibiotics. And that second pathogen would give you encephalitis, which is a swelling of the brain. The psychological part of it, according to the Soviet scientists, was that they wanted the last thought of the person dying of what they thought was pneumonic plague, but would in fact be encephalitist to be, “My government and Western medicine has failed me.”

Those of us who try to remain optimistic think there’s a way to stop it. In the movies, there’s an outbreak, then the government gets it under control, and okay, maybe a lot of people die, but we’re all right. That is not where your book is headed. How does your scenario end?

So in the book, I take readers from outbreak to anarchy in six days. Anarchy is what will happen according to Pentagon war gaming and pandemic planning. And this is because fear of infection becomes a secondary weapon, if you will. People begin to behave like they are about to die, which is most certainly underpinning everyone’s mind. And so after those first six days, the Principals Committee, the President’s Biodefense Committee, must make a decision. The president has to declare the Insurrection Act, which allows the military to step in as a law enforcement agency. 

“Imagine the president — with a few Secret Service outside the door, the military aide with the nuclear football — sitting alone in a room wearing a gas mask.”

What happens to the president really blew my mind as a reporter. He goes somewhere in the United States very far away from everyone. Because the idea, the goal, is to make sure that the president doesn’t get the airborne pathogen in his lungs. So maybe I’ll leave you with an image. Imagine the president — with a few Secret Service outside the door, the military aide with the nuclear football — sitting alone in a room wearing a gas mask.

In the book, the people who survive are the ones who have gas masks. Everyone else is gone.

And look, we hope we never get to that, by all means. But yes, the Pentagon has issued 1.7 million gas masks to its military personnel. And that is a spooky thought in and of itself, coupled with the idea that the military is predominantly male. There’s something like 17 percent women in the military. And so, unlike the Nuclear War scenario in which I had science-based nuclear winter theory to work from, in Biological War, nothing has been written on the science record about what it might be after. And so the one imaginative part of the book is the very end where I write about biological twilight. … And it is a very, very ugly world.

Let’s back up. We did outlaw biological weapons at some point, right?

That’s right. Very mysteriously in 1969, President Nixon just unilaterally declared that the arsenal was going to be destroyed. At the same time that all of the nations of the world were working to sign this treaty called the Biological Weapons Convention Treaty, which would outlaw bioweapons. Soviet Russia at the time signed it but immediately began work on an illegal biological weapons program that was colossal. And this went without notice, without any idea really by the CIA and the Pentagon all the way until 1989, when one of the Soviet scientists named Vladimir Pasechnik had a crisis of conscience and he defected and he told British intelligence all about the program.

Where have we seen biological weapons used?

Maybe the most important example of a biological attack in the past, certainly here in the United States, are the anthrax attacks, which occurred right after 9/11. Weaponized anthrax was sent through the mail to US senators and a number of media outlets. So five people ended up dying; 22 got sick in four states. But that really kicked off what can be considered the biological military-industrial complex, if you will, which led to this buildup in BSL-4 labs around the world today. There are 110 BSL-4 labs around the world. There are more than 3,500 BSL-3 labs.

Your book has a map of where those labs are, which I found weirdly comforting, mainly because I don’t live too near any of them. If one of these things is going to be released, either accidentally or deliberately, where is the threat coming from? A rogue nation? Terrorists?

Certainly, bad actors getting a hold of a biological weapon was the great concern of the post-anthrax situation. And that is why so much emphasis was put on bioterrorism. Now I avoided that specifically in the book. … And I didn’t even have an attack. Rather, I had an incident. I had a lab leak because I have learned in the decades since that really is the greatest concern. So many of these BSL-3 and 4 labs are in places without a lot of security, including in countries where there are wars going on.

Could somebody be making a biological weapon in a basement somewhere, off books?

Absolutely. And another disturbing document I came across, unclassified in the Pentagon, was a threat spectrum that showed weapons of mass destruction in terms of destructiveness. And of course, nuclear weapons sit at the far end of the spectrum. They are the most destructive. But very close behind were biological weapons. And even more startling was the notion that biological weapons present the greatest overall threat. 

Nuclear weapons have an extremely high barrier for entry. You have to have fissile material. … You have to have a weapons delivery system like an ICBM or a submarine. … That creates a situation where most nuclear weapons, all nuclear weapons, if you will, are in the hands of a command-and-control system within a nation. 

Biological weapons have no such barriers. In fact, the barriers for entry are getting lower literally by the day. You now can have a situation where someone with very limited knowledge of biology can create a biological weapon in their basement with the use of computational systems like an AI system, for example.

Your book reads like a thriller. How much have you exaggerated? How much have you novelized in order to hold our attention?

Everything in the book is based in science fact, meaning all of the facts, all of the figures. I write a hundred or so pages of notes in the back of the book for readers to be able to answer the question that you are asking me. … In the notes, you can find that answer.

Did any of those people give you good recommendations for how to avoid a disaster scenario, or at least how to avoid these things proliferating?

Well, you know, the ticking clock scenario that I write has an even more urgent ticking clock, which is the public’s pressure on lawmakers to absolutely do something about this nightmare scenario before it happens. Look, we have a world right now where you have the CEOs of the largest AI companies in the world admitting publicly that the lane of bio mixed with AI is of their top concern. You don’t hear that about nuclear. You hear that about bio.

How do you sleep through the night?

Anyone who knows me personally can vouch for the fact that I am an optimist at heart. I really believe that information is king. Once you know things, it gives you a lot of power. Perhaps that’s whistling by the graveyard, but that’s what works for me.

Do you have a biohazard suit?

I do not. I do not. But I do have a few gas masks. I must tell the truth.