Science Friday - Why People Can’t Read Bar Graphs, First Complete Human Genome Released, Mars Book Club Finale. April 1, 2022, Part 2

Episode Date: April 1, 2022

Can You Read A Bar Graph? Bar graphs seem like one of the simplest ways to represent data. Many people assume that the longer the bar, the bigger the number it represents. Sometimes bar graphs represent an average not a total count, which is trickier to understand. And because bar graphs are everywhere, psychologists from Wellesley College wanted to determine how well people can actually read and interpret bar graphs. Turns out, one in five people in their study misunderstood the data the bar graphs intended to show. And sometimes simple-looking graphs actually make it harder to understand the data they are based on. Ira talks with Jeremy Wilmer, associate professor, and Sarah Horan Kerns, research associate, at Wellesley College’s department of psychology, based in Wellesley Massachusetts about their bar graph research and curriculum to improve data literacy.   Scientists Release The First Fully Complete Human Genome Two decades ago, scientists announced they had sequenced the human genome. What you might not know is that there were gaps in that original sequence—about 8% was completely blank. Now, after a years-long global collaboration, scientists have finally released the first fully complete assembly of the human genome. Researchers believe these missing pieces might be the key to understanding how DNA varies between people. Six scientific papers on the topic were published in a special edition of the academic journal Science this week. Ira talks with Karen Miga and Adam Phillippy, co-founders of the Telomere to Telomere Consortium, an international effort that led to the assembly of this new fully complete human genome. Karen Miga is an assistant professor of bimolecular engineering and the associate director of the UC Santa Cruz Genomics Institute, based in Santa Cruz California. Adam Phillippy is head of the Genome Informatics Section and senior investigator in the computational and statistical genomics branch at the National Human Genome Research Institute at the National Institutes of Health, based in Bethesda, Maryland.   One Last Martian Love Fest After a month of non-stop Mars science, what questions do you still have about the Red Planet? SciFri producer Christie Taylor and co-host Stephanie Sendaula interview planetary scientist and Sirens of Mars author Sarah Stewart Johnson. Plus, they take your questions about the planet’s poles, its magnetic field, and the progress of the Perseverance rover.   Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Plato. If you hate bar graphs, you are not alone. Bar graphs are one of the simplest ways to represent data. The longer the bar, the bigger the number it represents. Easy, right? Well, not so much, especially if each bar represents an average, not a total count, now it gets a bit tougher. And because bar graphs are everywhere, psychologists from Wellesley College wanted to determine how well people can actually read and interpret bar graphs. You know where this is headed, right? Turns out one in five people in their study misunderstood the data the bar graphs intended to show. Sometimes it may take a thousand words to explain a picture. Joining me now to talk more about their bar graph research are my guest, Jeremy Wilmer, Associate Professor of Psychology at Wellesley, and Sarah Horan Kearns,

research associate in the psychology department at Wellesley College based in Wellesley, Massachusetts. Welcome to Science Friday. Thanks, Ira. Thanks so much for having us. Sarah, it looks like in some kinds of bar graphs, the graph is not so intuitive, and that's what you wanted to study. What was the purpose and how did you go about studying it? So we started our paper with a joke, which is two graphs walk into a bar, and it summarizes the study question really well. One of the easiest ways to confuse people is to use the same symbol to mean two different things. So a hexagonal sign that's really, red means stop, but what if it also meant drive really fast when it rains? Those two meanings

would be really confusing. A commonplace where one symbol is used to express two different ideas is with bar graphs. So in a bar graph, a bar could represent a single number, like a count or a stack, five iguanas, three minivans. It's a single data point. Or it could represent a mean, which is a summary statistic, average home prices, average antibody response. It's more abstract, a summary representation of the data. So when we have two graphs walking into one bar, does it cause confusion? That's what we wanted to study, and we found out that it does. One in five people, a full 20 percent confuse the two.

They see a bar that represents an average, and they think it's a count. And that holds across all ages, gender, country, of origin, level of education. It was a pretty surprising finding. That is interesting. Jeremy, tell me how you tested this study and how you found out how difficult it was for people to interpret the bar graphs. So we used a really low-tech approach. We had people look at a real bar graph from a real intracite textbook, and they pulled out a pencil and a piece of paper, and we had them sketch the graph, and with its mean values, and then add in individual values. that in their best guess were the ones that would have been averaged to create those mean values.

It's a way to take what's in one's head and make it nice and concrete so you can see it. One in five people put all of the dots inside the bar as if everybody's below average, or as if there's a stack of data representing a single number rather than an average that's in the middle of the data. So if they were to do it correctly because it's an average, there should be some dots above the graph and some dots below the, the bar. Yep. And they didn't do that and they didn't understand that. Right. Yeah. And so why did a fifth of the people make the same mistake? You have any idea? I think it's because they don't grasp the mean. So mean just means average. But if we're talking about one of my previous examples, which was antibody response, two people get a vaccine. One body produces a lot of antibodies and the other

not so much. And so if you look at just the data points, you can see those two separated points. But if you look at the average of those two, it's some point in between them that actually isn't one of the data values at all. And that abstraction can be confusing about the actual data. And is that what made you want to study bar graphs because it is confusing? So there are a lot of graphs being thrown at us every day. And when people and even organizations are trying to make evidence-based decisions, using the data that they've seen, if two people look at the same graph and come away with wildly different understandings of the data, when they try to apply the facts to the issues

that they're trying to address, they'll be talking about two entirely different fact patterns. And how can you have an evidence-based decision without, essentially without any evidence? You don't have an agreement on what the evidence is. One of the reasons that bar graphs of mean values are so ubiquitous in education and in science and other areas is that they feel simple. They're just representing showing us a single number. But in fact, they're also very abstract. There's this push and pull where abstraction often confuses people, but simplicity is often helpful. So we wanted to see basically which one of those two things won in terms of understanding.

Well, what if you did away with the bar itself and just put all those dots on the graph instead? Do people understand that better, Sarah? Yes, they do. And in fact, that's one of our strong recommendations is to show individual data points in whatever graph that you use, be concrete. Well, wouldn't it be better then to do away with the bar itself, Sarah, and just show all those scatter points on the graph? Yes, I really think that it would. at the very least, I think that we should step back from using bar graphs to represent means. And so what graph would be better? So here's a little thought experiment. Imagine two flocks of

birds, hundreds of birds in each flock, and imagine that the two flocks are crossing over each other and weaving in and out. The entire time we're looking at those flocks that the human visual system is very expert at guessing roughly how many birds are in each flock, separating the two flocks, even when they're overlapping with each other, having a sense of where the center bird is in each flock. These are things we do effortlessly and very easily. I think we can do the same thing with our graphs. We create a couple flocks of birds, a couple collections of data points, show people every single one of those data points. Remember, especially in human data, each one of these data points represents a human being. And I find with my students,

once they see all the data, their minds just start churning. They, oh, well, what about that one? that one. Oh, look, you know, I wonder what that person was thinking or doing. But can we go overboard sometimes? I've seen some really complicated charts and maps and graphs where it looks like people are trying to be more artistic and creative than actually helping us understand what the data says. Do you find that true? Yeah, well, this is where science meets art. There are certain design principles that are well known to take even relatively complicated things or relatively information-packed things and make them very understandable. We can think about a Google map. Just think of the large number of pieces of information that are in a Google map, yet we can read it very easily. We just have

to carefully design things to take advantage of the human visual system's strengths and not to push on its weaknesses. Yeah, because I know that you're a big advocate for data literacy, and you've included data literacy lessons in your undergrad psychology classes. How do you go about teaching them to better understand how data works? So I take these methods we used in this study right into the classroom. I have the students take their predictions and hypotheses and draw them on paper. The first step is comparing them to each other and noticing, oh my gosh, my prediction or my interpretation differs from the three or four people sitting around the same table.

And then we look at the real data and we compare all of their guesses about the data to the real data. And that's where real learning happens. I think the most important thing that I can give to my students as a professor of psychology is a real direct understanding of what real human data looks like. Interesting. How early do you think kids should be learning about graphs? Maybe we shouldn't wait until they get to high school or college? Well, even now, graphs are taught in elementary. If you think about it, you've got the ice cream graph where everybody who likes chocolate has a little cone and it's stacked up and everybody who likes vanilla, right?

And those are count bar graphs. The problem comes in when abstraction causes confusion. So even when they're really young, getting students working with individual data, fiddling around with graphs, having children develop good intuitions about data. Interesting. Jeremy, I know you've created something called the show my data.org. What is that all about? So show my data.org is designed as a free open access suite of data visualization tools that allow it to be really easy to make best practice graphs really quickly just by copy pasting from any spreadsheet, a Google sheet or an Excel workbook. Looking at the data in a spreadsheet, it's easy for one's eyes to glaze over. But being able to copy. you paste it into a forum where you can examine the individual data points is really useful and educational. And I hear that you've hired a couple of quality control agents to determine your 7 and 11 year old kids to see if that's working out?

Yeah, that's right. Yep, Patrick and Donnell, they are my prime research and development team. They're great critics. They tell it like it is. And if it works on Patrick and Donal, then I think it has at least a fighting chance of working on my college student. Love it. Sarah, what's next for your research? So actually, we're in the process of finishing up research on another paper coming out that discusses people's understanding of data and uses the same drawing method. We wanted to investigate what other misunderstandings people had about bar graphs and the data that comprises them. And we found that in this study, people don't have good intuitions about the distribution, how even or uneven the data is, or about really extreme values.

And one of the major findings from that new piece of work is that often people, when they're thinking about the spread of the data, they imagine that there's no overlap between two different groups. So imagine two different treatments, for example, for some sort of illness. And so people will see two different means, and a lot of folks will imagine that every, single person who got the treatment did better than every single person who didn't get the treatment. And in most domains of life, that's a little too over-optimistic. There's some folks who got the treatment who did a little less well, and there's some folks who didn't get the treatment who ended up doing just fine. We think one of the implications of that new piece of research is to

help people to more carefully and accurately gauge. What is the benefit? And for how many people is this a benefit? Again, thinking at the individual level about individual human beings. Yeah, very good way to wrap it up. And I want to let our listeners know if they want to see some examples of the bar graphs used in the study, they can go to our website, Science Friday.com slash bar graph. Thank you both for taking time to be with us today. Thanks so much, Ira. Thanks so much for having us. Jeremy Wilmer, Associate Professor of Psychology at Wellesley College and Sarah Horan Kearns Research Associate in the Psychology, Department there at Wellesley in Wellesley, Massachusetts. We need to take a break, and when we

come back, did you know that two decades ago when scientists announced they'd sequenced the human genome? There were actually pieces missing, and now they think they've got the whole thing. Why the missing matters. Stay with us. This is Science Friday. I'm Ira Plato. Two decades ago, scientists announced a monumental scientific achievement. They had sequenced the human genome. But what you might not know is that there were gaps in that original sequence. About 8% of the sequence was completely blank, and a lot of that used to be dismissively called junk DNA. Well, now after a year's long global collaboration, scientists have finally released the first

fully complete assembly of the human genome. Researchers believe these missing pieces might be the key to understanding how DNA varies between people. Six scientific papers on the topic were published in a special edition of the journal Science this week. And joining me now are my guests to talk about it. Karen Miga, assistant professor of biomolecular engineering, an associate director of the UC Santa Cruz Genomics Institute, and Adam Philippi, senior investigator at the National Human Genome Research Institute, that's at NIH in Bethesda, Maryland. Welcome to Science Friday. Yeah, thanks so much for having us. Thanks, Ira. Pleasure to be here.

Nice to have you. Let me begin with this question of this telomere-to-telemerer consortium that you have founded, an international effort that led to the assembly of this new fully complete human genome. Dr. Meaget, tell us the significance of that name. Your listeners may recognize that the telomere is at the end of our chromosomes. And so we chose telomere-to-tele-mere to really illustrate that we were trying to complete an entire chromosome in one assembly end to end. Not just broken pizza pieces. Exactly.

Yeah, and it's been really wonderful because it really does create a full view of a human chromosome for the first time, which is exciting. So let's get into this. What's on these newly sequenced parts of the human genome, Dr. Miga? Right. So the new sequences represent essentially regions of our genome that are known to be important for fundamental cellular processes. When we talk about regions like the Centromere,

which is pretty exciting for my own research, we know they're responsible for how our chromosomes are transmitted every single time our cells divide. So changes in these sites in our genome could actually cause errors that could lead to all kinds of health outcomes. In total, we're talking about 200 million bases, so it's a lot. That is a lot. That's a large percentage.

We said 8%. Could you make a whole new genome out of that kind? of material? Well, I think when we talk about a chromosome's worth, 200 million bases is about the size of one of our largest chromosomes. We look at the information that's their third largest, so it's slightly bigger than chromosome three. Now, are these parts of the genome that scientists use to refer to as junk DNA? Is that what you have actually identified? I think it would be hard to consider the sequences in these regions to be junk. I think that word, Ira, you'll probably agree with me, is probably outdated and it's just used as a way to explain processes we don't yet understand.

How dumb was that? I really think that these regions are misunderstood. They don't fall in our standard textbook definition of how genomes are organized. They do have genes in these regions. We do have these standard organizations, but they're really enriched with a unique kind of structure where you have a sequence that's found in a head detail, head detail orientation for millions of bases. And why our genome is arranged in this way in the corners of our genome, I think remains an unknown. And this has been your life's work, hasn't it? It has. I've been passionate about satellite DNAs since graduate school.

And so I was really lucky to be able to pair up with such an amazing scientist like Adam Philippi to make this dream come true because he's really kind of the other side of this, where I've been focusing so much on the satellite DNAs and the biology of these unique genetic elements, having that type of mastery over assembly really brought us to where we are now. Well, let me talk to Adam. Dr. Philippi, why did it take so long to sequence this final 8% of the genome? After the human genome project finished in 2004, the holes that were left were the most repetitive bits of the genome. So, you know, imagine you have a puzzle, and there's a bowl of skittles over in the corner of that puzzle, and that's the hardest bit to put together

because all of the Skittles look the same, those types of repeats make jigsaw puzzles hard, just like they make putting a genome back together again, difficult. And so it was those repeats that had us interested from a computational perspective and gave us a big challenge in putting this back together again. So the reason that they weren't done originally is the technology just wasn't up to the task

back in the early 2000s. We could only read small bits of the genome at a time, and when the puzzle is made of small pieces, it's a lot harder to put together than when they're made of big pieces. And so for this project, we came in with new sequencing technologies that have been developed over the last decades. They can read up to a million bases of sequence at a time compared to in the early 2000s, where we were limited to a few hundred bases. Now, knowing what we know now, if you have the total sequence, how does this move us forward in learning about DNA?

Well, now that we've figured out how to do it and we can reconstruct these repetitive regions for the first time, it allows us to do that again now for many more human genomes. Or if we have a patient coming to the clinic, we can sequence their complete genome, line it up against this new complete reference sequence, and we're able to get a more comprehensive picture of all of the potential variants that they have within their genome. And then over time we'll be able to link those newly discovered variants to potential disease associations, for instance.

Is there one disease out there or one treatment that was waiting for their this total sequence to be unraveled, do you think? And now it's in the crosshairs. The one I would probably point to first are the so-called Robertsonian translocations. These occur in one in a thousand births, and it's a fusion, essentially, of two different chromosomes. And we've revealed for the first time five entirely new chromosome arms, and they are directly related to this type of chromosomal anomaly. And a lot of our collaborators that are interested in these translocations now have

the base precise sequence that they can look into and try to understand how these form and what the potential repercussions could be. Will it also tell us how we're different from other animals, other primates close to us? Yeah, absolutely. In fact, these repetitive regions are some of the most dynamic, the most variable regions of the genome compared to our nearest primate relatives, the most variable between individual humans. So we have some hope that there'll be very exciting discoveries within these regions that might hold the key to what makes our genome uniquely human. It's kind of a contrast to how we think about function with everything having to be deeply conserved. In these regions, which we know are

functional or are placed in these critically functional regions, they're, as Adam mentioned, extremely dynamic and in many cases, human specific. So it's kind of in contrast to what we're used to thinking about in terms of how we think about evolution and conservation. Now that we have these new tools you're talking about, how far out are we from each one of us? getting our own individual genomes mapped. That's definitely the goal of this consortium is to help develop the technology to a point that a project like this to get a complete human genome can be replicated and become routine. And I think within 10 years, it will be routine to have your complete diploid genome as just

part of your medical record. At a cost of what? So for the original human genome project, just to put things in perspective in today's dollars, I think it was around $5 billion. and a 10-year-plus effort of this project, we estimate, maybe a couple million dollars from start to end. But the technologies that we developed along the way and the technologies that have come from industry and elsewhere

have driven this number down so that if we were to redo this project today, we could probably get it done in a month for tens of thousands of dollars. But the trajectory of technology advances just continued on this exponential pace for 30 years. and I think within the next 10 years, we can easily get it to under a day and very likely, you know, this mystical $1,000 genome. In addition to this economic benefit of making it more affordable and more scalable, but I think that in the process of moving in that direction, we're giving the research community time to study these sequences and balance it with the benefit, going back against that statement that this is junk DNA, now providing the genomic community and the research community with these sequences for the

first time, hopefully they'll see why it's so useful to have this type of comprehensive variant scan. Interesting. Dr. Philippi, I know that part of this research is that your team has mapped some missing pieces in the Y chromosome. What was missing and why is this such a big achievement? So in the papers that are coming out this week, we actually didn't describe the Y chromosome. The particular cell line that we chose to sequence initially has two copies of the X chromosome. But in the year that followed since we completed that genome, we moved on and got a different cell line that had a Y chromosome and replicated the same effort for this particular one. There's 50% missing in the current Y chromosome reference to date from the Human Genome Project in 2004.

A lot of that is this highly repetitive DNA that Karen was mentioning earlier. And it's important for the same reasons that we've completed the rest of the genome. This is filling in all of the missing pieces in the puzzle. And now we can look at those regions and identify the variance and understand the functional consequences of the sequence in those regions. And the Y chromosome has passed paternally, right? So that's quite important to know about. Yeah, that's correct. It's commonly used in genealogical studies because of that fact.

Used to build family trees and anybody that's used 23 and me and any of those other services will have benefited from that. Karen, why is this part so important? Or the Y chromosome. I think that's a huge question. I think we haven't quite figured out what it means to lose a giant amount of tandem repeats that exist on the Q arm, half of the chromosome. I do know that as we age, you know, these parts of our genome that are typically repetitive, they change in the way our cells regulate how they're organized. And over time, the Y chromosome is sometimes lost.

So it does offer some new insight, something about these particular sequences. all the proteins that are binding to them present a huge unknown for people to start thinking about what it's doing in the cell and how it could be influenced with the gain or loss of a Y. On these very large tandem repeats on the Y, it's not just those tandem repeats that we've added, but also added a number of genes nearby and around those tandem repeats, increasing not only the sequence content, but the genic content of the Y as well. Adam, you started this project to complete the human genome back in 2018, but the second half of the project, the computational end, took place during the

pandemic. And in fact, a big breakthrough happened right in the middle in the spring of 2020. Can you tell us about that? Yeah, we were in many ways fortunate that all of the sequencing and lab work that generated the data for this project happened before the pandemic. And so we were sitting on that data spring of 2020 when COVID outbreak hit. And postdoc in my lab, Sergey Nirk, who, was leading the computational analysis, came to me with kind of the early look at that data, trying to assemble it for the first time. And when we looked at it, you put it up on his screen and showed me and kind of everybody in the room saw that and thought, wow, we actually have a chance at succeeding here. It gave us the clearest picture we had seen to date. And so we kind of rounded up

all of our colleagues that were experts in this genome assembly process and worked over the course of that summer for about three months. And didn't really expect to complete every chromosome. I would have been happy if we just got five done, but come August, all of it had snapped together. We had all of the chromosomes complete and ready to validate, and it was just a tremendously exciting summer and gave us something positive to focus on during those difficult times. Do you think that everyone working from home and focused on this project, because it was a worldwide project, right? Did that perhaps get you to where you could get to the endpoint faster? Yeah, it's always tricky to speculate, but I usually have a,

a busy travel schedule, and I was home in my basement every day working, and so I definitely could focus a lot more on the work at hand and not be diverted with all of these other administrative tasks, travel tasks. And also just all of the collaborative tools, you know, we were on Slack and Zoom all day long talking to each other kind of constantly. It definitely helped make progress fast. I'm Ira Flato, and this is Science Friday from WNYC Studios. Dr. Miga, how many scientists internationally worked on this project?

Well, when we look over our author list in the main paper, I think we're approaching 100 scientists in total. When we started, it was just more or less Adam and myself asking, is it possible and just starting to sequence and work together? But when we opened the consortium, it was really a grassroots effort. It was an open door anyone could join, and we soon had contributors from around the world. Now, I understand you published the Complete Genome via a preprint server last summer, are scientists already using it in the lab? For sure.

I mean, we've had hundreds of people already download our preprint, siding our preprint. So I think that this is really demonstrating the utility of our work and the fact that there's going to be new discoveries that will be made and announced in the future. This kind of philosophy of the group to be very open and inviting to everyone has given us those new directions and it's also given us a lot of confidence that what we're looking at is correct

because we've had, Karen mentioned, hundreds of people looking at every corner of this genome over the past three years. And that gives us a lot of confidence that we've done it correctly. I remember when the project was first announced 20 years ago, when they talked about, hey, we've got the human genome figured out. The scientists were saying, well, wait a minute, that was actually the easy part. the difficult, the real work is going to come into figuring out what the functionality is and how we apply it. Dr. Philippi, do you think this is where we are again? What comes next?

Yeah, exactly. We've spent 20 years digging into what was produced by the Human Genome Project and have just scratched the surface of that. And now we're at this again where we've got another 8%. And we've been looking at the same parts of the genome for the past 20 years. So this represents a new 200 million bases to be investigated. And so, yeah, we're starting over with this. It's a brand new unknown sequence, and the same excitement will repeat itself now in another 20 years of digging into this new sequence. And Dr. Miga, what do you hope this new sequence will bring? I hope that these new sequences will bring some new insight into what these repetitive sequences are contributing to in terms of how our cell functions, how it contributes to cell identity in early

development and how it contributes towards human disease. I think that there's so many open questions here, and I think they've just had a roadblock because of the lack of a reference genome. And in fact, many scientists and researchers around the world probably already have data now that they could just map to our reference genome without even doing another experiment and start to find new discoveries and new information, just because they've been ignoring it for so long. It's so hard to portray for we on this side of the microphone to portray the excitement that must be going on with scientists who have completed this. Would I be correct in assuming that? Well, it's been the most exciting point of my career for sure. Same. This is really great. This is the most joy I've had in my career.

Thank you both for taking time to be with us today. And I hope you'll come back and tell us about these exciting times when they happen. Happy to. Thanks so much for having us. Yeah, if you're still here in 20 years, Ira, we'll be back. It's a date. Okay. We'll meet here. Thank you both for the work you're doing for taking time to be with us today. Karen Meaga, assistant professor of biomolecular engineering, Associate Director of the UC Santa Cruz Genomics Institute, and Adam Philippi, senior investigator, head of the genome informatics section at the National Human Genome Research Institute

that's at NIH in Bethesda, Maryland. After the break from the poles of Mars to its magnetic field, you had questions, and planetary scientists Sarah Saras. Stuart Johnson had answers. We'll wrap up our Martian book club when we come back. Stay with us. This is Science Friday. I'm Ira Plato. The time has come to close the book on Mars literally. Of course, I'm talking about our book club discussing the search for life on the red planet. We've been reading The Sirens of Mars. And back with me one more time is our own Mars rover,

Christy Taylor. Hey, Christy. Hey, Ira. All right, all good things, as we know, must come to an end. And so what have we learned this month? Yeah, Ira, we have learned a lot. We have considered how finding life that no one's seen before may be harder to find than the kind of life we already have on Earth. We looked at the history and perhaps present of water on Mars. And we peered deep into meteorites, which are the only pieces of Mars that we can actually study in a lab.

At least until we can send the mission to get samples back, right? Right, exactly, Ira. And we had one last Mars Lovefest last week. Listeners got a chance to ask planetary scientist and Sirens of Mars author Sarah Stewart Johnson, all of their many questions in a live Q&A that we held on Zoom. Co-hosting this Q&A with me was Stephanie Sondala. She's a programming and outreach specialist for Library Link, New Jersey, and she recommended this book in the first place. Ah, so it's all her fault. Exactly. Stephanie and I started by going over some of what we had loved about reading Sirens of Mars. Like how Mars has, over the years, been kind of a reflection of anxieties on Earth, from an astronomer who obsessed over it during the trauma of World War I, to how climate change is perhaps motivating the current crop of billionaires to their sort of quest to colonize. And then there's the fact that the geology of Mars, unlike Earth, has remained mostly unchanged for billions of years.

Here's Stephanie talking about that. Something that stuck with me, which Sarah may talk about too, is how Mars is kind of frozen in time. So it's just like this relic of the past. And just like the concept of that, like thinking about that. It's just so fascinating to read about and want to learn more about. And Sarah, let's talk about the story of our exploration of Mars, which is what you cover in this book so well. What were some of the major shifts of understanding that scientists had to have in order to get where we are today? You know, we just started with this total blank slave.

We just had just this point of light in the sky. And like even the ancients knew there was something. something really special and different about Mars. It wasn't just its color, but it had this crazy sort of retrograde motion where it would sort of every couple of years backpedal and go the different way against the rest of the background of the fixed stars. And it was a while before Mars was really understood as this world, like a place you could scrape your knee, just like the earth. We start off with kind of amazing ideas of what this world might be because in 1965, It was the first time we ever saw the surface of another planet, and we get these images back,

and they're covered in craters. And all of a sudden, there's just this staggering disappointment that Mars is just like the lifeless moon, you know? And unfortunately, we didn't stop going to Mars. We kept sending these missions, and it's sort of been climbing up from that kind of Nidear ever since with all kinds of new discoveries that are just tantalizing and incredibly exciting, especially around the search for life, which of course is the piece of it that I'm most interested in. That's such a great answer, Sarah, too. And I had a few questions, but I see a few people asking similar questions.

Sarah, what do you think of the future of Mars exploration is? What do you think about billionaire interest in Mars colonization? Do you think it's helpful in a long run or should we be concerned? So I'd love to hear your thoughts about that. So when I think about the future of Mars exploration, you know, it's just this question of like, you know, will humans go to Mars? I do think that will happen. When will that happen? I really have no idea. Like, you know, it's always been one of these things that's been like 20 years away. But I think that the stage is set for really rapid progress. Like there are huge technological challenges. You know,

like the radiation environment's incredibly punishing, like long time space travel. You know, the moon. You can get there quickly and get back a couple weeks. It's a business trip. But Mars, you are out deep, deep, away. And if something happens, there's nobody that can come rescue you. And so it's just very hard. But I think that the sort of technological leap from when we had nothing before Sputnik to the Apollo program, that was 12 years. And I think that the technological leap from where we've been with the moon to going to Mars,

I think it's smaller than that. So I think that if we decided we wanted to go, like we could do it rapidly. It's a tricky thing. And I feel kind of up to minds about. I think that there are ways that human exploration can go in tandem with robotic exploration. But honestly, I spend a lot of time thinking about the next 10 years, the next 20 years, like all the things that I really want to do with robotic exploration before humans arrive, while we still have this kind of pristine planet.

And there's a lot of astrobiology and a lot of experiments that I'd love to see completed in the near term. We have a question from Susan now. and she says, I worked on a photosynthesis experiment that went on the first Mars lander, and she says she wants to know what happened to it. Yeah. So what Susan's talking about are these Viking landers that landed on Mars in the 1970s. First time we touched down on the surface of Mars.

And there were these biology experiments, these three life detection experiments that were part of those missions, like both of those landers. And all of these experiments taken together were sort of broadly interpreted as, you know, something was going on in that soil that was causing these sort of chemical reactions, but nothing that was indicative of life. And then the real kicker was there was also a chemistry experiment that was along for the ride that was a gas chromatograph mass spectrometer. And it was looking for organic molecules, the kind of building blocks of life as we know it. And it found none, like just none whatsoever. And it was so perfect. perplexing, because, you know, how could you have life without the building blocks of life as we know it? And it was years, decades, until we really understood what was going on with those signals that there were these particular types of salts called perchlorates that were in the Martian soil. And it's something I wrote about in the book. And it's almost like you're dry cleaning the samples when you heat up the soil samples in combination with these really reactive oxychlorine salts. The signals can really disappear, kind of evidence. And so that's kind of where things ended up. So we now have gone back to Mars. We found all of those

building blocks of life, all those organic molecules with a curiosity rover. So that was very exciting to definitively see those. Thanks, Sarah. And that kind of follows up a question from Kevin, who asked, what happened to the magnetic field? There is no more magnetic field at Mars. So do you know what happened to it or do you have any insight on it? Early on, March did have. a magnetic field. And so we get that from having a dynamo, from having convection in the core. And that's why we have a protective magnetic field here on Earth, which we are very grateful for because it protects us from the solar wind. It protects us from having our entire atmosphere sort of sputtered away. But on Mars, we think sometime around, say, 3.9 or 4 billion years, that early dynamo kind of shut

down. And so Mars is this planet that's smaller, had less heat of accretion, you know, like it may have just kind of gotten cold enough that that convection just sort of shut off. But without that protective magnetic field, the thick atmosphere that we think was present on early Mars just began to be sputtered away to space. And that's why now Mars has this very, very thin atmosphere. We have another question from James, who has a question, another Mars science question. about the poles of Mars. James, go ahead. Yeah, I understand that the space agency do some radar work found the potential water under the poles. Are there any ideas about doing some drilling and sampling to see if it in fact is water in a liquid form and if anything living in it? Yeah, that's a great question,

James. And so there were these detections, these radar reflections that were picked up a couple of years ago in the south polar layered terrain, these under-subglacial briny potential lakes. And it's so exciting to think about a body of liquid water that could be on the surface of Mars today, especially in the context of looking for extant life or still living. But if this does get borne out, that this is indeed an underground subglacial lake, we've done like really interesting work, like in Antarctica and sublacial lakes and there are thriving microbial communities. And I've been a big proponent of the idea of drilling on Mars and getting down into the subsurface and looking for traces of life and potentially extant life as well. So we have the Rosalind Franklin Rover. It's going to drill down

two meters into that basaltic rock, not at the pole, but we'll at least get below a lot of that radiation damage at the very top of the surface. But then JPL, The Jet Propulsion Laboratory has been working on some really exciting concepts for doing deep drilling. And maybe one day we can even drill as deep as those really exciting potential subglacial lakes. Yeah, thanks, Sarah. And I think this kind of ties into what you were just saying earlier. What do you think Mars can teach us about Earth? And that's kind of something I kept thinking about as I was reading the book.

And there's so much to learn from Mars and learn about ourselves in the process. Oh, Stephanie, I love that question. And also, you know, Mars really is all past, you know, like so much of the history of our planet has been lost because of erosion, because of plate tectonics. It's almost like we've swallowed our deep geologic past plate by plate and it's gone. There are just a few very small elk crops of really ancient rock. But on Mars, because, again, a lot of these geologic processes just slowed down. And we don't think there was potentially ever play tectonics on Mars.

We have like just this incredibly perfectly preserved record. And so what were the conditions like when life got started here, even if there is no life on Mars? But then also understanding just kind of how these two planets that started off so very similarly, you know, these are two planets that had thicker atmospheres that were warm and wet, at least period, they had just very, very different paths and sort of understanding more about that. I just think is just really incredible and intriguing. And I think we can just learn so much about ourselves by study in Mars. So your book was written before the Perseverance Rover was under construction. So what are you hoping it finds? So we probably won't know for another decade or so. But the Perseverover landed and now is in this campaign to collect all of these samples

that a couple of dozen of those and we'll bring them back to Earth. And it'll take some effort. You know, we've got to send a fetch rover and then we'll have a vehicle that I'll sort of bring them back home to Earth and then we'll sort of ferry them out to different laboratories. My hope is that we can look into these samples and again find these traces of ancient life. And there's a lot of other stuff that we'll potentially find from these samples. you know, kind of geocrinology, understanding the timing and the history of Mars. There's a lot of fundamental geology that will discover no matter what.

But my hope is that there's something like a smoking gun and that we can take something that is really exciting and suggestive of life, but we can hit it with everything we've got and we can build confidence that, you know, this is a real detection. I still think about like the Apollo samples that we brought back, you know, decades ago. like we're still learning the most extraordinary things from them. And once we have samples in hand, we'll have them forever. And so the chance to study these as our technologies improve, as our techniques get better, I just think it's going to be a tremendous opportunity.

Just a quick reminder, I'm Christy Taylor and this is Science Friday from WNYC Studios. Talking with Sirens of Mars author Sarah Stewart Johnson about all of your great questions about the Red Planet. I'm so glad we're talking about perseverance. I believe perseverance is currently belining for the river delta on Mars, where all the magic is supposed to happen as we speak. And we have a question about that from Glenn in Florida. Go ahead, Glenn. I was just wondering why we designed this rover to get these samples,

but not to bring them back. Why is there has to be a new mission to bring them back? Because it was so expensive. That's the simple answer. That team that sort of came up with this concept, there are these planetary scientists that got together. And their motto was go big and go home. They even had like little buttons and decals.

And this whole idea that like once we collect these samples, it will be so compelling will derive the idea of sample return. You know, there was this and they got together and they said, this is the one most compelling thing you could do for planetary science, bring back really carefully selected. samples of Mars. And to do that, you know, we've already spent a couple billion dollars just building this one rover. And there were a lot of constraints with that, you know, was built in the exact same chassis as curiosity, again, to save money. We just didn't have the

budget to do it all at once. And we're hoping to get help from the Europeans as well in terms of like bringing these samples back. But it really had to be in these three different steps to to make it feasible. Sarah, you are both the author of this beautiful book, but also a planetary scientist yourself. And we have a question about that from Shelby. Go ahead, Shelby. My question was, what are your words of wisdom

for future generations of students who are interested in pursuing a career in science and then even planetary science? Oh, my words of wisdom, I still marvel at the fact that this is my job and that I get paid to do this amazing thing. where I just wake up in the morning and I get to think about these like huge, deep questions. Like, is our life in our universe? And I think studying things that you're particularly

passionate about, I think that's really important. And planetary science, I mean, it's almost like doing Earth science like 100 years ago, you know, like you can get up to speed on sort of what's happening because there's still so much we don't know. And it's very interdisciplinary, you know, it's drawing from chemistry, from physics, from, and geomorphology, geophysics, all of these things. And biology, potentially astrobiology, is now becoming this big thing just in its own right. And I think finding that, you know, some part of science and then thinking about how you can synthesize it with other parts of science is really helpful and really what we need is to sort

of break down some of these traditional silos and bring together all of these different disciplines because places like Mars, they're every bit as complex to understand as places like Earth. then we just really need a whole fleet of people working to help us. And that's all the time we have. I want to thank all of our listeners for their wonderful questions about Mars. And Sarah, thank you so much, both for joining us and for writing this enthralling, poetic, detailed book. I feel like my perspective on the Red Planet has definitely changed quite a lot after reading it. Yeah, thank you, Sarah. You are great.

Oh, thank you both. This has been such an honor. And Stephanie, thank you so much for helping us be Mars. nerds today and for recommending this book. It is in many ways all your fault. Thank you so much for having me again. Stephanie Sondala is a programming and outreach specialist for Library Link, New Jersey, and Sarah Seward Johnson is an associate professor of planetary science at Georgetown University and author of the book, The Sirens of Mars. I'm Christy Taylor. Christy, another great book club. Thank you. What about people who want more of Mars? Yeah, for anyone who wants to learn more about Mars or learn more about the sirens of Mars, our website is still there, ScienceFriday.com slash book club. And from there, I always recommend people dip their toes into our online community. We've got some really thoughtful discussion happening there. And of course, that's the best place to stay informed about future book clubs and other treats for our SciFri bookworms.

You said it. ScienceFriiday.com slash book club. Got it. And thank you again, Christy. Thank you, Ira. And that's about all the time we have. If you missed any part of this program or you'd like to hear it again, yes, subscribe to our podcasts or you can ask your smart speaker to play Science Friday. And we are active all week on social media, Facebook, Twitter, Instagram. Have a great weekend. We'll see you next week live. I'm Ira Flato.