...what genes are? (with Carla Easter, PhD)

Ever Wonder? / July 21, 2021

...what genes are? (with Carla Easter, PhD)

Dr. Carla Easter, Director for Education, Outreach and Visitor Experience at the National Museum of Natural History
Image attribution
James Di Loreto/Smithsonian Institution

Carla Easter, PhD

This summer, we opened a brand-new exhibit called Life! Beginnings in our World of Life gallery. Life! Beginnings invites our guests to discover how humans and all living creatures reproduce, develop, and pass on their genes to bring new life into the world.

At its core, reproduction is all about passing on genes to the next generation.

Do you ever wonder what genes are?

And how much do our genes tell us about who we are, where we come from, and what we might become in the future?

To try to answer some of these big questions, we spoke to Carla Easter, PhD, from the Smithsonian National Museum of Natural History. She served as a scientific advisor for Life! Beginnings, and has spent much of her career helping the public learn about genetics. We had a fascinating conversation about our complicated and often misunderstood relationship with our genes.

Have a question you've been wondering about? Send an email or voice recording to the podcast team to tell us what you'd like to hear in future episodes.

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Perry Roth-Johnson (00:06):

Hello, this is Ever Wonder? from the California Science Center. I'm Perry, Roth-Johnson. This summer, we opened a brand-new exhibit called Life! Beginnings in our World of Life gallery. Life! Beginnings invites our guests to discover how humans and all living creatures reproduce, develop, and pass on their genes in order to bring new life into the world. Reproduction is all about passing on genes to the next generation. But do you ever wonder what genes are? And how much do our genes actually tell us about who we are, where we come from and what we might become in the future? To try to answer some of these big questions we spoke to Dr. Carla Easter at the Smithsonian National Museum of Natural History. She served as a scientific advisor for Life! Beginnings and has spent much of her career helping the public learn about genetics. We had a fascinating conversation about our complicated and often misunderstood relationship with our genes. Check it out. Dr. Carla Easter, you are the Broh-Kahn Weil Director for Education, Outreach, and Visitor Experience at the Smithsonian National Museum of Natural History. Carla, welcome to the show.

Carla Easter (01:16):

Thank you so much for having me. I'm very excited to be here.

Perry Roth-Johnson (01:20):

Yes, and Devin Waller cohost of the show is here with us. Hi, Devin.

Devin Waller (01:24):

Hey, Perry, great to be here. And hi, Carla. Thanks so much for joining us.

Carla Easter (01:27):

My pleasure.

Perry Roth-Johnson (01:28):

So, I want to start with some super basics. You know, make sure we're defining some terms. We've heard of the Human Genome Project. You know, it's been roughly 20 years since that project, uh, wrapped up. What is a genome?

Carla Easter (01:41):

Yeah, no, that's an excellent question. So, we'll just start with the basics. Genetics typically refers to individual genes, right? So, you study a particular gene. There is a gene where a variant or a change or a different version of that gene brings about a particular, um, result, right? So just to simplify things, you know, you have variants that may cause you to have curly hair, right? You know, a variant that causes, you know, freckles, right? Again, being very simple. But when we think about genomics, it's really about the scale. We're talking about multiple genes and all of those other genetic elements within an organism that are part of its genetic makeup. So, it's not just the individual genes. It could be those areas that don't necessarily encode proteins because that's typically when we define a gene, although we are starting to rethink what a gene is. But all of those things within the genetic makeup of that organism is its genome. So, I kinda like to describe it to people. It's the difference between, you know, thinking about a gene as potentially a city where if you bring it up a scale, a genome is like an entire country.

Perry Roth-Johnson (03:13):

Oh, okay.

Carla Easter (03:14):

Right? So, you have these very discreet areas, which are the genes, but a genome is everything that surrounds, and that gene is part of. So, when we think of genomes, it's really, it's the whole thing that makes an organism an organism.

Perry Roth-Johnson (03:36):

I like that analogy. So, like, you might have a human genome. That's like one country, and then you might have a genome for dogs, that's a different country.

Carla Easter (03:44):

Exactly, exactly. And, oh Perry. That's so cool you did that because in those particular countries you'll find similarities, right? So, for every genome you can find something similar, pretty much across every genome. There's something that is similar between us and dogs, between us and amoeba, between us and plants that might be very small, but just like with every city, you will find similarities between those cities, but then very distinct things. Like we know that Washington D.C. is different from Paris, but they both have a subway system. Right? So it is, and that's really kind of cool because that's what allows us to compare genome to genome are those similarities.

Perry Roth-Johnson (04:37):

Okay. So we talked about genes, individual parts, genomes collection of genes, but these other two words came up when you were talking, genetics and genomics. How do those relate?

Carla Easter (04:50):

Yeah. So typically, when I think about genetics, it's the study of genes, right? So, it's that idea of understanding the working of genes. And again, you have people that specialize in particular aspects of genetics, it might be human genetics. It might be, you know, um, dog genetics, right? But again, I think genomics again, that whole, the study of that entire organism’s genomics. I think in recent times, because we have the technology now to decipher genomes that oftentimes those two things, genetics and genomics, sometimes become interchangeable. I think when I was a graduate student, because we didn't have the capacity to decipher genomes the way we do now, right? You could sequence individual genes, but with the Human Genome Project and that technology, you now can decipher entire genomes. I think those two terms, genetics and genomics, are becoming a little bit more interchangeable.

Perry Roth-Johnson (06:00):

Got it.

Carla Easter (06:01):

Right? It's very often that people who do study a particular gene will oftentimes think about the context in which that gene sits within a genome and the other factors that might be affecting that particular gene. So, I think the entire field of genetics, which is really where we kind of started all of this when we think about Mendel and all of the early pioneers in genetics. I think we're seeing that transition because of the technology for us to think much more holistically and to talk about genomics, next to, or as part of genetics, much more than we have been able to in the past.

Perry Roth-Johnson (06:48):

Makes sense.

Devin Waller (06:49):

You were a scientific advisor for the Life? Beginnings exhibit, our new exhibition about how humans and other living things reproduce. And fundamentally reproduction is all about passing on genetic information from one generation to the next. Several of the interactives in the exhibit explore how genes are passed down and how genes and the environment interact to help make us who we are. So from your perspective, as a molecular geneticist and an educator, why is the topic of reproduction and especially when we're talking about genetics and heredity, important for people to learn about?

Carla Easter (07:30):

Yeah, you know I think that's such a, you know, it's such a cool thing to think about in some ways. It's like the essence of being an organism, right? What is your goal? To pass on your genes, right? That, that when we think about the very basics of it. But I think one of the reasons that I think it's important for us to understand that process is to also understand that even by virtue of passing your genes on to an organism, that there can be differences. So, for instance, if I could reproduce, you know, by myself and, you know, create a clone, even that clone would be different, right? Even if they got all the genes that I gave to them, they would be different because the environment in which they're growing up, the environments in which they're existing would be affected, would affect their being. And so again, this idea of being able to pass our genes on, we also have to recognize that there are also factors that are, that are involved in what the outcome of those expressions of our genetic makeup are.

Devin Waller (08:49):

What is it that you hope that, you know, our audience, our guests, and especially our younger scientists take away from the exhibition?

Carla Easter (08:56):

One of the things that I hope people understand is how the environment and the changing environment impacts, you know, organisms around us. You know, even, um, even to the point of having impact on organisms’ genomes, so to speak, right? How quickly organisms can adapt to a changing world, right? You know, we don't adapt very quickly, genetically. Um, so I think people understanding, number one, their connectivity to everything around them. That there is the fact that we are all by virtue of being organisms on this planet, we are all interconnected. And then secondly, that those connections are in some ways impacted by our environment and that there is not this idea that everything is so ingrained in stone. You know, this idea, they call it sort of essentialism that you are your genes, and nothing can be changed. I want people to take away that that's not always true. That there are things about us that can be changed or that everything is not so hardwired into our genetics, that there is a fluidity to that. But again, I think most importantly, our connectivity to every other organism on this planet and every other person. You know we are unique in our own ways, but there are more similarities than differences between any two humans on the planet.

Devin Waller (10:25):

Yeah. So, you've had a lot of experience teaching genetics to the public. What has surprised you most about how people tend to think about genetics?

Carla Easter (10:34):

Oh yeah. I think going back to this idea that people are so, they're so tied to their genes, right? That everything is so tied to their genetic makeup. I often find that really interesting, right? That, that people don't quite understand the nuances around genetics and genomics and the fact that, you know, everything can—as I said, there's a fluidity to this. You know that there is a constant interplay between our environment and our genetics. You know, I think about things like diabetes, right? The idea that, you know, if people were in the best situation, if they had the best diet, got all the exercise that they needed, even if they potentially had the predispositions to be diabetic, that may not manifest itself because everything in their environment was perfect. But again, given a situation where we don't always get as much exercise as we need, you're under constant stress, you don't have the right nutrition. And, you know, then, you know, these things sort of played themselves out and no one can deny that there is an interplay between someone's genetics and their environment. And then I'm also surprised by people who think that we're so different genetically, right? That they have this idea that people are just so different. That to the point that they don't see the similarities between any two humans, and they feel like it is so, you know, tied into their genes. So again, I think it's the extremes, right? The people who think, uh, you know, that nothing can be changed because of their genes. And then the people who think that we're just so different.

Devin Waller (12:30):

Yeah, and on that point, are there common misconceptions that you hear often about genetics?

Carla Easter (12:38):

People who are from a particular country, right? That they have particular genes. Or people with particular ancestral backgrounds have this gene. And the reality is we all have the same genes, right? There might be variations in those genes, but by virtue of us all being humans, we have the same genomes, right? The sequence of those A's, T's, C's, and G's that make up the DNA might be a little different, but we still all have the same makeup. That's something that we really do need to come to terms with as humans. And I think part of that is just the way we're taught genetics. We're taught that when we think about particular disorders—there's a sickle cell gene. Well, there's not a sickle cell gene. There is a gene for hemoglobin that when you change a particular, when you change a particular base pair or one of those, A’s, T’s, C’s and G’s in the DNA of that gene, the result is sickle cell. But again, you may know, we get into this idea that there's the gene for this or the gene for that. No, we all have the same genes. It's just the variation. I think it goes back to, you know, in my early experiences, working with middle school students and teaching genetics to them, we often speak like that—Tay-Sachs gene, right? We have this idea that somehow these disorders only appear as genes in certain people. And we just need to get away from that kind of thinking.

Perry Roth-Johnson (14:16):

Um, one thing I've heard you say, and others say before, is that like, there's more genetic diversity within a racial group than across racial groups. Can you unpack that for us?

Carla Easter (14:24):

Sure, sure. Certainly. So again, it goes back to this idea that as humans, we all have the same genome, right? We all have, you know, if we were going to be very basic, at the very basic level, we all have the same genomes. We just have variations within that genome. And I think through the Human Genome Project, we calculated, if we go to two humans who are not related, you could probably find something like, you know, a million to 3 million differences between them, right? And that seems like a lot, but when you're looking at 3 billion potential places where there could be differences, it's really so much. Even, and again, race is a social construct, right? Race is a social construct, because we're all Homo sapiens, we're all human beings. If you look at say individuals who are of African descent, who are in Africa... Because our human origins come from Africa, individuals in Africa, their genomes have had longer to have variation, right? And again, let me go back and say, variation is not necessarily bad. It just means certain changes. And so, if you look across the continent of Africa, you may find far more differences because they've had a longer time for there to accumulate variations. Then if you look say, you know, in individual ancestral populations that have not had as long... You know, they may have come out of Africa. They may be in Europe. You know, they created their communities. They haven't had as long to change, to have those changes come about.

Devin Waller (16:24):

Yeah, that makes sense.

Carla Easter (16:24):

So again, if you look across any two humans, and again, let's just think about it. If you just looked at their genomes, you would probably not be able to tell a racial identity. There might be particular ancestral markings or places where it might be more common for people of particular ancestral backgrounds. But let's just be reasonable. In this country, people have been so—you know, we are a melting pot of people, right? We are pulling from so many different places. That, again, it's really hard to just say that, you know, that someone who is of this race or that race, that there would be that much difference between us.

Perry Roth-Johnson (17:11):

Can, can we go back to the sickle cell example you brought up earlier? How does that fit into this whole picture of, um, genetic diversity within a racial group and across racial groups? How does all that play out?

Carla Easter (17:25):

Yeah, so, you know, we know with sickle cell disorder, you know it is prevalent among populations of individuals who are within regions where malaria is, uh, you know, more common and because it is protective, right? So, if you have what we call heterogeneity, or you have one version of the hemoglobin gene that confers the sickled version, and one version that is, I'll just use the word normal, right? I don't like to always use normal, but the version that is not sickled, then you have a protective mechanism against malaria. So, if you are in a region where malaria is endemic, right, then you tend to be protected. If you have, you know, those two versions. Well, inevitably as people move out of those areas, and again, we think about where malaria is—in tropical areas, you can find it the Mediterranean, in Africa—if you, as a group move out of those areas into areas where malaria may not be, you know, something that you have to be concerned with, you still have taken those variants with you. And it just so happens in this country, we find that more common, it is people of African ancestry who carried those variants because at one time those variants were protective. But if you looked across the world, you would find those variants more prevalent in regions where malaria is highest. And that doesn't necessarily mean just people of African descent. But in this country, because of our history of the slave trade and people coming here from those regions, we tend to think about people of African descent, have sickle cell being more common within that population. But again, if we looked across the world, that wouldn't necessarily be the case. So again, it's like you said, Perry, it's about context.

Perry Roth-Johnson (19:44):

Thank you for unpacking that because that's like such a common example. I mean, it was never really explained what that kind of nuance when I was in high school. So, thank you.

Devin Waller (19:51):

Yeah. It hasn't.

Carla Easter (19:52):

Right and again, it becomes very easy to, uh, you know, to then think about these disorders and maybe this gets back to our other question about, then it's so easy then for us to put people into particular boxes, right? That we think this disease is only, you know, because of these people or with these people. And again, it's much, it's much, it's much greater than that.

Devin Waller (20:19):

How related are ancestry and genetics? So, with, within a family, um, what's that relationship like?

Carla Easter (20:26):

Yeah, yeah. So, this is really funny. So, um, I always tell the story of my family members who have, you know, their ancestry testing done. So, they'll come back, and they'll tell me, "Oh my God, our siblings, we all had this done. And it came back a different percentage for each of us. Are we not siblings?" Then I'm always like, "No, no, you are, siblings. You're all related." But again, it's because when you think about how that's done, we have to go back to the fact that, you know, we are all sort of genetic composites of our parents. So, you know, different things get moved around in our egg and our sperm. And I'm sure that the exhibit will talk about some of those things that happen. And so, when you get your chromosomes from one parent or from another, that chromosome may not be exactly the same as what your sibling got. But again, there'll be so much similarity that we'll be able to say that your siblings. Ancestry is no different. So, what they're looking at are particular regions on those chromosomes, which are basically found more common in people who now live in particular regions of the world. And what I always liked to tell people is, remember, they're taking this information from the people who are there now, right? So, it's not as if they can take DNA from the people who lived there 200 years ago. That what they're comparing it to is that people who have lived in these places and then across particular regions of your genome, they compare that DNA to your DNA. And then they give you back what they think is your ancestral background. And again, the nuances of that can be very subtle, right? You may have a sibling who says they have, you know, 49% West African ancestry and yours might come back 45%, something like that. And so again, I always tell people, just, you know, you are still related. You just have to recognize how it's done because genetics is all about probabilities and statistics and comparisons. And again, sometimes those numbers can be a little, you know, just a little different for every person.

Perry Roth-Johnson (22:49):


Devin Waller (22:49):


Perry Roth-Johnson (22:51):

And humans are notoriously bad at like dealing with probabilities, anyway, right?

Carla Easter (22:54):

Oh definitely.

Perry Roth-Johnson (22:59):

So of course, this is confusing. I mean, I kind of reminded of some friends in grad school who were in biology and thinking about becoming genetic counselors. Is that why those jobs exist? Because you just need to unpack.

Carla Easter (23:13):


Devin Waller (23:15):

Oh, my goodness!

Carla Easter (23:15):

Yeah, because again, this, and again, I will just put the plug in for genetic counseling being one of the most up and coming fields out there. And if you have any students who are listening to the podcast who are interested in that kind of intersection between genetics and counseling and that intersection between teaching and, you know, sort of providing helpful information for people, genetic counseling is for you. Because you're absolutely right, Perry. We, as humans are not very good at understanding those sort of subtle differences, you know, like the percentages of probabilities. The other thing is that we also don't know—you know, if you got a probability of 45%, what does that mean to you versus someone getting a probability of 90%, right? It, again, it's those subtleties. It means something very different to all of us and genetic counselors are phenomenal at explaining number one where those probabilities come from, but also helping people make decisions based upon those probabilities. Because yeah, we're just, we're just, everybody's different. Right? If someone told me, I had the probability of, you know, winning the lottery and my probability was 45%, would I play the lottery? At what level would I have to have the assurance that I should play the lottery? And again, it's different for every person.

Perry Roth-Johnson (24:46):

Well, we're about out of time, Carla. I think that's a lovely note to end on. Just real quickly... where can people follow you online and find your work?

Carla Easter (24:54):

Oh, well, you know, they can always find me at the museum, the Natural History website. They can certainly find all of the cool stuff that's happening at the Natural History Museum there.

Perry Roth-Johnson (25:06):

It's been wonderful talking to you, Carla. Thanks for joining us on the show.

Carla Easter (25:10):

Oh, thank you so much. This has been just a wonderful opportunity. You both have been so lovely and so gracious. And so, thank you so much.

Perry Roth-Johnson (25:19):

That's our show and thanks for listening. Until next time, keep wondering. Ever Wonder? From the California Science Center is produced by me, Perry Roth Johnson, along with Devin Waller. Liz Roth-Johnson is our editor. Theme music provided by Michael Nickolas and Pond5. We'll drop new episodes every other Wednesday. If you're a fan of the show, be sure to subscribe and leave us a rating or review on Apple Podcasts. It really helps other people discover our show. Have a question you've been wondering about? Send an email or voice recording to everwonder@californiasciencecenter.org, to tell us what you'd like to hear in future episodes.