Can Trauma Today Affect Future Children?
This story is a part of Breakthrough, a short film anthology from Science Friday and Howard Hughes Medical Institute (HHMI) that follows women working at the forefront of their fields. Learn more and watch the films at our Breakthrough spotlight.
We typically think of a traumatic event as a sudden thing—something that has a beginning and an end. Stress and trauma can of course have lasting psychological effects—and, in some cases, physical effects such as elevated blood pressure or premature aging. But now researchers are considering whether stress to an organism can be somehow transmitted to that animal’s future offspring, via epigenetic changes that modify how genetic code is expressed in the young.
Bianca Jones Marlin is a neuroscientist studying such changes. In one study, she found that if researchers trained mice to associate the smell of almonds with an electric shock, the offspring of the mice tended to be afraid of an almond smell—even if they were raised separately, by foster parents that had no experience with the odor.
Jones Marlin joins Ira to talk about her research, and her experience as a young researcher starting her own lab in the neurosciences.
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Bianca Jones Marlin is a Ph.D. graduate of the Laboratory of Robert C. Froemke at the New York University School of Medicine in New York, New York.
IRA FLATOW: This is Science Friday. I’m Ira Flatow. A bit later in the hour, checking in with science educators about how they’re teaching students during the pandemic, and the book club continues.
But first, you don’t need me to tell you that these are stressful times. And that stress is taking a toll on many of us. But can trauma today have effects on generations still to come? Researchers are looking into if and how traumatic experiences might cause epigenetic changes.
Now, those are changes in how genes are turned on and off in an animal’s offspring. Joining me now is one of those researchers, Bianca Jones Marlin, a Neuroscientist and Simons Postdoctoral Fellow at Columbia University. Marlin is an incoming Assistant Professor of Psychology and Neuroscience, and she will be opening her lab at Columbia University’s Zuckerman Institute in 2021.
And she’s the subject of one of our episodes of our Breakthrough video series. You can watch all of those at breakthroughfilms.org. Welcome to Science Friday.
BIANCA JONES MARLIN: Thank you for having me.
IRA FLATOW: Let’s start with some basics if we can. We’re taught that genes are the way that information passes from one generation to another, and traits are either nature or nurture. But this sounds as if it’s somewhere in between. Can you walk us through what’s going on here?
BIANCA JONES MARLIN: Yes. So our genes don’t change. Our genes are information coming from our parents that are passed on to us. However, epigenetic markers means epi-, above, and genetics, our genes. There are markers around our genes that say whether or not they’ll be turned on or turned off. Whether or not they’ll be read, whether or not they’ll be, what we call, expressed.
And this is really the essence of bringing in that communication and that experience from our parents. Biology has us setup to adapt to our surroundings and that’s a huge learning component, the nurture component. But what about preparing us for an experience that we haven’t come to yet?
That’s what parents are really good for. They teach their offspring to navigate the world and to live in the environment. And it seems like biology has set parents up to inform their offspring about how to navigate the environment without even having to ever meet them.
IRA FLATOW: When you say they set them up, you mean they’re passing genetic changes to their offspring?
BIANCA JONES MARLIN: By setting them up they’re passing these epigenetic markers, potentially, down to their offspring. And we say potentially because a lot of work still has to be done to really find out what exactly is happening and what’s the mechanism. But what we do see is the phenotype, which is the actual expression of these changes.
And this is not just what we’re seeing in the lab. This comes from research observed, for example, during the Dutch Hunger Winter after World War II. The Netherlands were starved of food, and those children and grandchildren of those that were starved during the Dutch Hunger Winter suffered from metabolic issues. It was as if their bodies were prepared to live in a land where there wasn’t enough food, although they had plenty of food.
And this manifested as diabetes and hypertension, which is high blood pressure. And even in some cases, schizophrenia. So it’s as if the parents said, if you were to be born in a place of starvation, we’re going to prepare you for that. And that’s an excellent component of parenthood because you don’t have to meet your grandchild to prepare them.
But what happens when the situation changes and it doesn’t become a positive trait but a negative trait? And that’s really what we’re interested in studying.
IRA FLATOW: And how is the mechanism passed from the parent to the child?
BIANCA JONES MARLIN: Oh, Ira, that’s a great question, and that’s really what our research is focusing on. How can a memory or something that occurs in the brain, an offense, be passed onto sex sells like sperm and eggs. And moreover, how is that even maintained when implantation takes place and a new organism grows? And then again for a third generation.
These are the excellent questions. And we haven’t found out the answer yet, but that’s what we’re looking for.
IRA FLATOW: It sounds almost like Lamarck was right. Was he?
BIANCA JONES MARLIN: You’re dabbling in dangerous territory.
People are really, really against Lamarckian inheritance. And by Lamarckian inheritance an example is, the giraffe was wandering in the savanna and a branch had a high tasty treat. And so in order to get that treat the giraffe wished that its neck grew longer, and it stretched and stretched its neck and it became longer. And that became a mark that was passed down through the generations.
And now, based on what we know as science has progressed, we know that that’s not the case. And people usually put Lamarckian inheritance– you can tell I’m a little bit defensive of Lamarck– against Darwinian inheritance. But we have to give credit where credit’s due because Darwin came well after Lamarck, and Darwin used Lamarck’s work to build upon his work.
And we’re doing exactly that. We’re using the excellent data that has been collected already to build upon that. Darwin said that you’re just a lucky giraffe when you’re born with a tall neck. You get to get all the treats at the top of the trees. And then all of your short neck cousins die and you get to populate the giraffe world.
And so we’re really looking at these two very stretched out dichotomies but there are bridges in between. And we’re seeing the phenotypes, we’re seeing the ramifications of that. So it really is just figuring out what the mechanism is.
IRA FLATOW: Is there this ability for traumatic effects to be inherited? And if that’s true as you say it is, can we fix it?
BIANCA JONES MARLIN: Ideally, it would not serve us well to say we found a way that a body holds offense and you can pass those offenses on for generations, so everyone’s angry. But in order to understand what’s happening so that we can fix it, we first have to understand what’s going on. And so as cool as that question is, I want to do the due diligence of saying I can’t jump to that conclusion until I figure out what’s happening beforehand.
And that can help lead us in the direction of figuring out how to fix this. And how to remedy when our environment does change and our epigenetic markers say that we have to interact with the environment in a certain way but it’s not beneficial to us.
IRA FLATOW: Well, let me put it in just the opposite context. What if we live in an environment that’s happy and healthy and very giving to us? Can we pass those changes, those epigenetic changes that might happen there, also to our kids?
BIANCA JONES MARLIN: I wish you could join our research team, you’re asking all the excellent questions. And once again, that’s a question that we want to answer. And it would be so cool to see that positive traits can be passed down. But we also want to be careful with the way we’re saying positive and negative.
Because based on what biology is doing it’s not negative, for example, someone who is an offspring of someone who is starved, to respond to the environment by saying, I’m going to take in food and hold that food in so therefore I may be more likely to be obese or have diabetes or have hypertension. That’s not necessarily negative. It could be positive if the environment was still poor. And so the positive component really just has to do with what’s important.
IRA FLATOW: I was watching the Breakthrough film that profiles you. And you seem to have had a very interesting childhood that influenced the direction you’re taking in your research.
BIANCA JONES MARLIN: Yes. I only realized in retrospect why my interest in parental behavior and maternal behavior and how trauma can be passed down is so strong in my scientific heart. I had the blessed opportunity to grow up in a really dynamic home. My biological parents were foster parents, so I had foster brothers and sisters and adopted siblings.
And being able to grow up in the same home and have the nurture component be very similar and yet the nature component be so different, as well as a prior experience component, really, I think, motivates my research. And by that I mean, although we ate the same food and slept in the same rooms and went to the same schools, my siblings went through traumatic experiences that caused them to be in foster care. It’s very rare that you’ll be in foster care for coming from a happy household.
And my siblings really had to sit with a lot of ghosts of their past. Of either things that happened to them or even happened to their parents. And it was so hard to navigate being a high school, junior high school student, when you’re sitting on all of that trauma and offense to your being. And so I really do think it motivates why I think the work is so important that I’m doing now.
IRA FLATOW: You’re early in your research career. Do you have any advice for other people who might not be sure of their career path yet?
BIANCA JONES MARLIN: I do. I think my main piece of advice– and I say this with hesitancy because I don’t want to sound handwave-y, but I really think it’s proven correct. And I think it’s follow your interests. And I know it sounds very loose. It’s not an actual, like, make sure your resume is– the margin is 1.5.
And science is a lot of work. We spend a lot of time in lab, we spend a lot of time in deep, dark dungeons and basements of microscopes, and if you’re not enjoying the end goal, then it can be really hard. Science is going to be hard regardless. But at least there’s a light at the end of the tunnel that you think the work that you’re doing is interesting and you believe in it.
And so finding work that you believe in, that you will stand for, and that you are willing to put your time and energy to makes it more enjoyable. And therefore, makes for better science.
IRA FLATOW: If I had a blank check in my back pocket, which I don’t have yet–
BIANCA JONES MARLIN: Oh, no. [LAUGHS]
IRA FLATOW: –what would you do with the money? How would you spend it?
BIANCA JONES MARLIN: Oh, I’m excited to answer. I want to make sure I answer clearly just in case anyone listening does have a blank check. To make sure that it’s a good answer.
And so, the brain definitely interacts with something called neuromodulators. These are chemicals that are released from the brain or from the body. They’re endogenous to us which means they come from our body. And they really help aid in learning, they really strengthen synapses, and they’re particular to the environment.
So one of my favorite ones happens to be oxytocin. It’s released during eye contact, hugs, soft touch, orgasms, with love, breastfeeding with a child, and it helps to create bonds. I would love to see when neuromodulators are released while we’re looking at the brain in real time. So when a mother’s interacting with her child, but when the mother’s interacting with her child and a stressful counterpart comes in, maybe she’s in an abusive relationship.
How these neuromodulators are working in the brain at the same time, which is very hard to do because we’ve always focused on one neuromodulator, to see how it’s changing the brain. And so ideally, the blank check would look like this. I can image the whole brain. I can look at different neuromodulators, they’d I’ll be tied to different color.
So I can see where neuromodulators are released from, where they’re targeting, what they’re doing, all in an experience. So we’re not just parsing out the animal smelt this, or the rat smelt that, and it looked at this, and it heard this. We’re seeing all of these things in concert and how it’s changing all the areas of the brain.
Because we as scientists can only do so much to look into one particular part of the brain. But the brain is working in concert, and so much is going on that we can’t see. Having the ability to look at how neurochemicals, neuromodulators, are working at the same time would give us so much insight into how we navigate our world.
So that’s my blank check request. If it could be a request.
IRA FLATOW: Well, I wish you great success in your career and whatever you’re doing over there Columbia. Thank you for taking time to be with us today.
BIANCA JONES MARLIN: Thank you, Ira.
IRA FLATOW: Bianca Jones Marlin is a neuroscientist and Simon’s Postdoctoral Fellow at Columbia University. She is the subject of one episode of our Breakthrough video series, terrific series.
And this season we gave you short portraits of women in science who were trekking on volcanoes, looking for ancient birds, hunting for distant galaxies, and a lot more. You can watch all of those at breakthroughfilms.org.