Science Friday - Living With Wildfire, 7,000 Steps A Day Okay, Kids’ Mars Questions. Sept 17, 2021, Part 1

Episode Date: September 17, 2021

Scientists Potty Train Cows To Lower Greenhouse Gasses Scientists have known it for a long time: Cattle are a major source of nitrogen emissions, contributing to the global warming crisis. Alternatives have been tossed around for years: from eating less meat to feeding cows seaweed. Now, a new study out of Germany and New Zealand has a more outside-the-box solution: potty-training calves. Scientists trained cows to pee in just one spot—dubbed the “MooLoo”—so their urine can be cleaned before it seeps into the environment. Most calves got the hang of it within 20-25 pees. Joining guest host Umair Irfan to talk about this and other science stories of the week is Roxanne Khamsi, science journalist based in Montreal, Quebec. With Worsening Wildfire Seasons, How Can We Learn To Live With Them? It’s another record year for fire in the American West, with more than two million acres already burning in the state of California, and the Dixie Fire alone well on its way to a million acres—if it gets that big, it would be the second “gigafire” on record, after 2020’s August Complex fire. As climate change and human habitation collide in worsening fire seasons, what is the long-term outlook? Guest host Umair Irfan talks to fire scientist Crystal Kolden about the way fires are changing as we change the landscape, and what coexisting with fire can look like—including learning from the time-proven burning and forestry practices of Indigenous peoples of the West. Do I Really Need 10,000 Steps A Day? Scientists Say 7,000 Is Fine You’ve probably heard someone say that they have to “get their steps in.” But does the number of steps you take in a day actually matter? For years, there was a mythology around the health benefits of walking 10,000 steps a day. But it turned out that number wasn’t based on actual data—it grew out of a marketing effort in Japan from a pedometer company in the 1960s. Now, Amanda Paluch, an assistant professor of kinesiology at the University of Massachusetts Amherst, has published a paper—based on actual data—to help answer this question in the academic journal JAMA Network Open. Mining data collected by the CARDIA cohort study, they compared the overall health outcomes of people who walked less than 7,000 steps a day, those logging 7,000 to 10,000 steps, and those trekking over 10,000. They found that people who walked over 7,000 steps a day had a significant decrease in mortality, compared to people who took fewer steps. They’re still trying to tease out exactly what health benefits the steps may bring. Paluch joins guest host Umair Irfan to talk about the research, and what you should know about how walking might improve health. NASA Scientist Answers Kids’ Questions About The Mars Rover It was big news last week when the Mars rover Perseverance collected its first rock samples. And just in time, we invited young listeners in our audience to ask research scientist Katie Stack Morgan of NASA’s Jet Propulsion Laboratory some of their most pressing questions about the Mars 2020 mission. Questions like, “How do samples get back to Earth from Mars?” And, “How does Perseverance dust itself off … if it can?     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 Omer Erfahn. I'm a science reporter at Vox and a regular guest on this show. This week, I'm hosting the program while Ira is away. Later this hour, we'll talk about how we can learn to live with wildfires, and why scientists say 10,000 steps a day may not be the right benchmark for fitness. But first, the COVID-19 pandemic has rippled throughout American political life. Case in point, a new report says that more than half of states have rolled back public health powers during the pandemic. While this has obvious effects for our current pandemic, these rules could also have consequences for the future of public health in this country. Joining me now to talk about this story and other science news of the week is my guest, Roxanne Chamsie, a science journalist based in Montreal, Quebec. Welcome back, Roxanne. Thank you so much, you Merritt. It's great to be here. Let's start with this news about states rolling back public health measures.

It seems contrary to logic given the state of the pandemic, but of course politics have been an undercurrent throughout this ordeal. Why are these rollbacks happening and how are states justifying this? Well, yes, I completely agree with you. And I think it is fascinating that this is happening right now, given the pandemic that we're in. And what happened was Kaiser Health News did a review of all these recent legislative changes. And they found that 26 states, which is a lot, it's more than half, have pushed through laws that permanently weaken the government's authority to protect public health. So we're talking about, you know, at least 16 states have limited the power of public officials to do things like order masks and. quarantines or, you know, insist on isolation. And there's other measures with regards to vaccine passports and vaccine mandates. So this is an example of politics colliding with public health. And it kind of couldn't come at a worse time. So what is the rationale behind this? Well, I think that's a really good question. I think obviously there's a large contingency of

people that believe in their rights are being infringed upon. But at the end of the day, the public health officials are really concerned about the long-term effects of these changes. And some of these changes are really not inconsequential. So in Arkansas, for example, legislators banned mask mandates in places except for private businesses or state-run health care facilities. So, I mean, that is like a big impediment to stopping the spread of SARS-Co2, the COVID virus. The rationale is unknown to a lot of scientific minds. I think it's definitely an example where people with a lot of public health expertise are scratching their heads and frankly leaving some of these positions because of frustration. And you mentioned the long-term effects here. Like, could this have effects beyond COVID?

Without a doubt. And I think that that's something that the public health officials are sounding the alarms about. So you might recall that not too long ago before the pandemic, there were measles outbreaks happening in the U.S. because of declining vaccination. And some of these health officials are worried that with measles, if it comes back in some ways, they might not have the power to enforce some of these rules that they would usually rely on in order to protect us from these outbreaks. And so we're kind of going to be operating in a little bit of a Wild West because of the rollback, which, by the way, in all 50 states, legislators have proposed bills to curb these public health powers since the pandemic began. So this is a new era and it's concerning.

Well, let's shift gears now to a historical event, but one that was long before anyone was around to see it. It turns out the asteroid that wiped out the dinosaurs altered the course of some of our most well-known reptiles that survived. Tell us about that. Yes, so this happened way before the pandemic. We're talking 66 million years ago. So before you and I were around. And this was that asteroid that came along and we believe, a lot of people believe, caused all non-bird dinosaurs and a lot of other animals to die. Kind of a massive event where 76% of plants and animals disappeared, so mass extinction,

we're talking. But what was kind of cool if you're okay with snakes is that scientists recently looked and found that a handful of the snakes that survived that catastrophic, awful event really kind of seeded the diversity of snakes that we have right now. And we have a diversity of snakes. We're talking snakes in trees, snakes underwater, venomous snakes. other kinds of snakes. So it was a real boon for the snakes that could kind of survive underground and not eat for a while when this asteroid had hit and caused the world to kind of shift dramatically. So it seems snakes were really well equipped to dodge that massive bullet.

Yeah. I mean, you might have seen the snakes on a plane movie, but snakes do better than just on a plane. Snakes do great in a catastrophic asteroid situation. And you might know this also, but snakes are so successful on Earth. They're found in every single. single continent, except for Antarctica. And I bet if there are any snakes listening to us now, they're probably plotting their adventures to that continent. So snakes are so resilient. Let's move on to a story about genetics. Cresper is now a famous technology for gene editing, and it allows scientists to find DNA inside a cell, snip it out, and then replace it. But a recent discovery shows that CRISPR isn't the only game in town. What else is out there? Well, so it's a kind of variation on CRISPR. And when scientists talk about CRISPR, they often We often call it the CRISPR CAS9 system.

So we often drop the CAS 9, and I think CAS 9 is probably mad about that, because what CRISPR does is it's a system that relies on an enzyme called Cass 9, which was found like in bacteria. And Cas9 is what helps the whole system go towards the specific sequence of DNA that the scientist want to cut around and alter. And so what scientists did is they were like curious about the evolutionary origins of this Cas9 enzyme that the CRISPR genetic editing system relies on. And when they looked, they found there's like a whole diversity of different enzymes in that family. And so they're thinking there's all these other kind of scissors that they could be using with the CRISPR system. And who knows if this could help us kind of do different kinds of gene editing or improve the efficiency of our CRISPR gene editing. So it's a kind of cool look at the variation within this editing system. And CRISPR obviously has been very useful to us, but why did these organisms devolve it in the first place?

I mean, that to me is so fascinating. So this is thought to be kind of an ancient bacterial defense mechanism. Like they want to cut up DNA of other invaders or things like that. Like this is not a friendly gene editing origin story. This is a like, let's get them and cut up their DNA so they don't get us story. So that's the evolutionary origins. It's believed of the CRISPR-Cast-9 system for the bacteria. The next story you brought us is a little bit outside the box.

Scientists have now come up with a way to make a concrete light material from blood, sweat, and tears. First of all, ew, second, why? Yeah, I don't know if you saw the movie with Matt Damon where he's on Mars, but this definitely was not part of it. he was just growing potatoes as far as I can recall. But yeah, so scientists are trying to figure out if we go to Mars, how are we going to make buildings and colonies and what's the material that we can do this with? Because they can't take concrete on the mission to Mars. It's just a little too expensive and heavy to take that building material on the way. So they've got this Martian dust once they get to Mars, but how are they going to mix it up and make it something that you can make

a structure out of? Well, as you say, gross. These scientists are looking to use our blood, sweat, and tears and urine to mix with that Martian dust. And the reason that these scientists look to that is that in our blood, and your blood and my blood, everyone's blood who's listening, there's a protein called Human Serum Albumin. And this is what they want to take as a way to create this concrete that they called Astrocrite. And they say it's just as strong as regular concrete.

In fact, when they add the urea, which is a part of our urine to the mixture, they say it's potentially even stronger. So pretty gross, but also yay, I guess. I don't know. And presumably we're bringing some of the raw materials inside our own bodies? Absolutely. And I looked at the paper where they were proposing this and they said that people could donate twice a week. So I'm imagining they're thinking about hooking up the human beings to donate the plasma. Obviously, it's a way to get maybe a little bit more out of more female astronauts in space since we're donating blood by accident every month or so. So, yeah, there's probably a lot of ways to get blood from people in space. And if it builds you a house on Mars, I think people will serve their arms up and say, let me donate. So turning astronauts into

biomaterials factories. That's so fascinating. Let's move on to another story that I hope listeners will bear with us is also about bodily functions, but not of humans. Scientists have found a way to potty train cows. What's going on here? Yes. Okay. So before we talk about what they did, let's just pause for a second to appreciate that there's about 1.4 billion cows on Earth, which is a lot of cows. And they emit a lot of, like, wasteful products while they're hanging around doing their thing. And what happened was there were these scientists that did an experiment in Germany that they called the Moo Lou experiment, kind of playing on the word Lou that the Brits use. And they had these cows. They had 16 calves, so like, you know, young, cute little cows.

And 11 of them were successfully taught to use this Mulu system, so to pee in the place that they wanted them to pee in just 15 training sessions, which the scientists are like, oh, they're smarter than little toddlers that are trying to be body trained. And the reason that they wanted to do this is that, you know, when cows excrete either poo or pee, some of that can mix together and kind of contribute to global warming because it like releases this thing called ammonia, which has a nice. nitrogen compound that can get into the atmosphere or get into the systems that will contribute to global warming. So they wanted to basically sequester the urine, and they did that by getting these calves to pee where they wanted them to pee. And what did they do with the pee after they collected it? So once they had that pee, they basically treated it and neutralized it, so that it posed less of a risk. So they kind of chemically addressed some of these ways in which the urine could mix with other things potentially. But really just taking it aside,

and putting it someplace where they could neutralize it is like a huge boon. You know, countries like the Netherlands are considering curbing the amount of cattle that they allow because of this problem of urine and the feces contributing to global warming and things like that. So the Netherlands has what they're calling a nitrogen crisis. And if you can take that urine, which has nitrogen and sequester it and neutralize it, perhaps it gets around that problem. And how easy is it to potty train a cow? I mean, if you're asking me, 15 training sessions is not that many. I'm sure when my parents potty

trained me, it took a lot longer. We're talking diapers, right? So 15 sessions, not too long, pretty doable. And they think that this is maybe a window on how we might be able to work with animals in a way to solve environmental issues without compromising their animal welfare because, you know, they gave these cows, these calves, a treat when they peed in the right place, a little food treat. And if they didn't pee in the right place, they'd. kind of burst them with a little bit of water. So these weren't really drastic ways of training them. It was just kind of a nice way to, almost like how you train a dog to go pee outside instead of on your carpet. So could we potentially see bathrooms installed in pastures and

stockyards in the future? I think that that is not an unforeseen possibility. And I mean, why not? They deserve it. They're doing so much for us. Yeah, I think we all deserve a little bit of comfort. That's all the time we have for now. I'd like to thank my guest, Roxanne Hamsey, a science journalist based in Montreal, Quebec. Thanks so much for joining us. Thanks, Umair. It's been great. After the break, as fire seasons get worse and longer in the American West, what are the options for coping in the long run? Why one scientist says we can and should learn to live with fire. This is Science Friday. I'm Omer Erfant, sitting in for Ira Flato. Wildfires are a fact of life in states like California, but as we've seen over the recent years, they're changing in dangerous

sways. Last year, a record 3.2 million acres burned in California, while nearly two million more burned in Oregon and Washington. This year, California has seen another two million acres burned, and the season is far from over. The Dixie Fire, north of Lake Tahoe, has by itself burned over 900,000 acres in northern California. If it makes it to a million acres becoming a gigafire, it will be the second on record ever to do so, right behind last year's August complex fire. Meanwhile, the Caldor fire south of Lake Tahoe has topped 200,000 acres. Research is increasingly clear that wildfires are burning hotter, fire season is lasting longer, and fire risk is increasing in places that aren't used to it. Meanwhile, more people are in harm's way. In California, 11 million residents live in high

wildfire risk areas, and the state's population is growing. All the while, humans are making these risks worse, through building practices, poor forest and wildland management, and climate change. So if climate change and other human factors are worsening wildfire risks, what can we do about it? Should homeowners pull up stakes and retreat, or can they hold their ground and adapt? My next guest is someone who thinks a lot about these questions. Dr. Crystal Colden, a fire scientist at the University of California, a Merced. Welcome back to Science Friday, Crystal. Thank you for having me back.

So how would you put these fires this year in context compared to some of the record-breaking seasons we've seen in the past? Are they par for the course, or are they still surprising in some ways? They're surprising in some ways and not so in others. There is a tendency to focus on how big the fires are, because that is one of the statistics that people understand and it's readily available. For fire scientists, often what we're more interested in is looking at how fires are burning across different landscapes between forests and shrublands and grasslands and trying to figure out what are the things that are outside of the normal range and what are the things that are within the normal range? And this year's fires have certainly surprised us with some of the types of fire behavior we've

seen, some of the burning that we've seen, particularly at high elevations. And the thing that is not surprising in many ways is how these fires have grown larger, because this has been projected by many of our fire climate models for quite a few years. Is there an example that stands out in your mind about how these fires have been behaving in unusual ways? I'll use the Dixie fire and also the Caldor fire, which of course threatened the South Lake Tauqua region. And those fires were both fires that burned over the Sierra Nevada Mountains this year. And prior to 2020, there had never been a modern wildfire that burned up and over a mountain range. And last year, the East troublesome fire burned over the Rockies in Colorado.

That was a first. And then this year, we saw our first Sierra Nevada fire that burned over the crest, being the Dixie Fire, followed shortly by the Calder Fire also burning up and over the crest. So this is really, you know, something that we noticed that was unusual. and, you know, one of the key things is that we have seen really active burning at night and at high elevations, where historically we have not seen that active fire behavior. And that is really indicative of how dry it has been this year. How dry the vegetation is, how warm and dry it stays at night. And that is producing this really active fire behavior that simply exceeds the capacity of fire suppression resources. So we can't simply look at the number of acres burned.

We also need to consider the ecosystems, the timing of the fire, and the nature of the burns themselves when evaluating these places. Yes, if our goal is to prevent wildfire disasters and specifically things like loss of life, loss of homes and infrastructure, and loss of some of the really critical facets

of ecosystems that we highly, value, things like having clean water come out of these forested watersheds or certain species like giant Sequoia, which are currently being threatened by fires in Sequoia National Park. If we really want to prevent those types of disasters, we have to separate how fires are burning to produce those disastrous outcomes and how they are burning in other places and maybe even still doing a lot of ecological good. And one of the things that I and many of my colleagues, have tried to showcase is that even on these really large fires like the Dixie Fire, there's a lot of actually beneficial fire being reintroduced in a lot of these forests

in places where it was excluded for over a century. And these forests are fire adapted. So much of that acreage is actually beneficial. And we have to recognize that in order to be able to say, all right, what we want, is to minimize, not the fire itself. And a century of trying to put fires out has taught us that we simply can't do it. And it's actually really detrimental to ecosystems to try and do that. But rather, we want to support beneficial fire and minimize and mitigate those fire disasters. To your point, though, about protecting homes, you know, a lot of people who are watching this from afar

seeing wildfires occurring, you know, year after year in very similar places, A lot of people are asking, you know, should we even be living there to begin with? Shouldn't people retreat? And, you know, often hear about this idea of a managed retreat in the context of coastal areas and sea level rise. But do we have to do something similar with fire or is there more to think about here? I think that fire is much more complex when we're talking about managed retreat. When we're looking at California and we're talking about a place where there is already another major disaster that befalls, Californians, which is earthquakes. And we don't ask people to no longer live on fault zones in

California, right? We basically stemming from the 1906 earthquake in San Francisco have figured out how to engineer and mitigate a lot of that potential earthquake damage, such that subsequent earthquakes in 1989, in 1994, we did not have the level of destruction that was seen in 1906. When we talk about wildfire managed retreat in a place like California or really anywhere else vulnerable to fire, does it make more sense to just tell everybody to move somewhere else where there's another disaster or it's far too expensive for them to live? Or does it make more sense to say, okay, can we engineer and mitigate this environment, these homes, this community so that the wildfires that we know are going to burn don't have. as disastrous of outcomes. And I think what we have seen

the last few years is that we can do that. Last week, we saw people evacuating South Lake Tahoe as the Caldor Fire approached. That's a major tourist area, and it looked like it was under serious threat. But it seems that area's defense has held,

and since then the fire has been better contained. What happened? And can we learn from this? But I hope people take away from watching what happened in South Lake Tahoe the last few weeks, is that they engineered a positive outcome. The reason that that success occurred was due to the many, many years of work that have occurred in the forest just around the edges of the city.

And the amount of fuel reduction work that was done, the prescribed burns that were done, and all of the treatments that allowed firefighters to work safely and be committed. batting much lower flame lengths and much less energetic fire as the Calder Fire moved towards South Lake Tahoe. That is a landscape engineering success that saved, you know, the vast majority of homes in the Christmas Valley, Myers, South Lake Tahoe area. We spoke last year to members of the Uruk tribe and other indigenous cultural fire practitioners, you know, many indigenous peoples who have lived in California and the West, conducted controlled burns as part of their cultural practices for thousands of years. So it seems there is a precedent for what you're describing. Yeah, when we look at what indigenous people have done in terms of fire stewardship and how that

is part of a larger holistic land stewardship ethic, what it tells us is that as people, we can live with fire in these landscapes. But what we see across much of the country is that indigenous groups used cultural fire in so many different ways to basically steward the landscape that they were living on, you know, and to ensure that they didn't lose their villages and the landscapes that they were utilizing for substance living, right, to wildfires. Indigenous practitioners basically came up with the first approaches to doing burns around the indigenous version of the wildland urban interface. A lot of the cultural burning that was done was basically to protect the village. So we can learn from that, right?

And we can actually empower the people that still hold that knowledge today, like the Karuk, like the Yurak and other tribes across the West. There are so many knowledge holders that would love to be able to restore a lot of those cultural burning practices. And right now there are many barriers to that happening. If we can learn from them and listen to their deep knowledge, then we can learn to live with fire in these places. Now, casting sort of a wider lens to the whole U.S. and maybe the whole world, are there any examples of fire mitigating? or fire risk reduction that have done pretty well? Are there any examples or just kind of case studies that are places that we should look to? Even within our own country in the U.S., we look at the southeastern U.S., there's a very, very strong

prescribed fire program in the southeastern U.S. They burn over 5 million acres a year there. And that has really minimized the number of huge destructive wildfires that the southeast has. When we look at places in Europe, when we look at places in Africa, where there are strong burning programs, oftentimes in combination with agricultural programs and grazing programs, what we see is that they are even under climate change able to effectively mitigate the most negative impacts of wildfires, right? and it allows wildfires to do what they have always ecologically done and be beneficial for many of these ecosystems. All the things that you're describing make a lot of sense, and I imagine if you told most people about them, they would agree with you. So what's holding us back from implementing this? What kinds of policy changes or other kinds of tactics do we really need?

There are a couple of key things that have to change. There are certain policy barriers. that make it difficult for us to utilize larger amounts of prescribed fire or even do the types of mitigation work beyond prescribed fire that we know are effective in reducing fire behavior. So as an example, in a lot of places, there are HOA rules in certain communities that are actually not very conducive to doing the type of work around homes. If there's architectural requirements that are not conducive to, you know, more of a hardened home type of neighborhood, that's a very localized barrier, right? Cost is also a huge barrier, but that's less of a

policy issue. Many communities, there would be enormous benefits from introducing things like goats. You know, they can do a substantial amount of fuel reduction, but for, you know, obvious reasons, and some of this is sort of legacy in the U.S., there are a lot of restrictions against having farm animals in your community. You know, and at landscape scale, there are a lot of policy barriers around prescribed fire because it is a risky thing, right? We're intentionally lighting a fire. And one of the really heartening things that has happened just recently, is that there are a couple of bills that have been working their way through the state legislature in California and are waiting for Governor Newsom's signature. And they are both

directed specifically at changing the liability laws around prescribed fire, such that instead of having someone be fully liable for anything that might go wrong on a prescribed fire, It instead changes the liability such that, you know, if you are doing everything right, we recognize that there is a greater liability in not doing these prescribed burns and instead waiting for a wildfire to come along. And it allows us to do more of the type of prescribed burning that we know is very, very effective in reducing wildfire disaster outcomes. I'm Omer-Refan, and this is Science Friday from W.

NYC Studios. Populations are growing and average temperature are still rising. Are we running out of time to implement these measures? Running out of time implies that, you know, there's sort of a date after which nothing we do will help. And the reality is that everything that we do now will help. And this is actually the second piece of the puzzle for how we need to change our thinking about this.

and change the way that we approach implementing a lot of these mitigation measures, which is that we need a cultural shift. We need a cultural shift in the way people look at fire on this landscape. And instead of having Californians or even, you know, Westerners in general, look at fire as something that can be prevented and that is bad all the time, right? Instead, we need to start looking at fire as something that is inevitable but doesn't have to be bad and actually can be very, very beneficial when it is occurring in a way that is not producing disastrous outcomes. But if we use more prescribed fire, we can control how much fuels on that landscape. If we introduce some of these other mitigation measures, you know, like understory brush removal and grazing, we can control the level of fuel on the landscape.

And if we harden our homes and communities and have that be a major investment priority for the state and the Fed, then we can actually reduce the dangers and the risks of fire to our structures and our infrastructure. And, you know, the thing is, it's empowering to think you can do something about it. I think your point that everything we do will help is a really important one. Thanks so much for joining us, and I really appreciate all the input that you provided today. Thank you so much for having me. I always enjoy talking about this topic. Dr. Crystal Colden, assistant professor studying fire science at the University of California in Merced. One last thing before we go. This fall, the SciFri Book Club is reading Rising, Dispatchez from the New American Shore by Elizabeth Rush. It's a book about climate change, floodwaters,

and rising seas, and how communities are banding together to protect themselves. We hope you'll join us in reading and discussing starting October 1st, and we're giving away free copies of the book, hosting Zoom events with scientists, and more. And if you're on the Cyfry Voxpop app, tell us a bit about your own experience. Have floods or high seas shaped your life? All that and more on our website, Science Friday.com slash bookwark. Club. After the break, do you keep close tabs on your Fitbit? Live with an eye on your Apple Watch? If you're trying to get your daily steps in, we have new research into the health effects of exercise. We'll be right back after this short break. This is Science Friday. I'm Amher Erfant. In for Iroflato.

Eight glasses of water per day. Two thousand calories of food per day. Eight hours of sleep per night. There are many numbers that are supposedly the key to healthy living. And with the rise of wearable gadgets like Fitbits, activity trackers, and smartphones, our lives are more quantified than ever. But what benchmark should we be using? Is there any scientific evidence behind these targets? Amanda Palooch, an assistant professor of kinesiology at the University of Massachusetts Amherst, decided to dig further into one of the most popular health goalposts,

the idea that you should walk at least 10,000 steps per day. She recently published her findings in the journal JAMA Network Open, and she joins us now. Amanda, welcome to Science Friday. Thanks for having me. So before we get into your study, let's talk about these 10,000 steps. Where did this mythical number actually come from? So the backstory is that in the mid-1960s, a Japanese pedometer was produced,

and it roughly translated to 10,000 steps meter. And this is really stuck in the mainstream media until now. And there really hasn't been any scientific evidence to support this 10,000 step goal. I didn't realize that number was so old. Does that mean that there was really no data to back it up at all? Yeah, there really hasn't been. In order for these studies, like how we've looked at in terms of your risk of death, you have to have a long follow-up. And also, we have to have studies where participants actually wore these types of devices. So these types of studies did not start coming around until really the early 2000s was when we started to put devices on participants. And then giving it, enough time to follow these participants to actually look at these health outcomes. Your study, however, did actually conduct a scientific assessment and look at real-world data.

So what did you actually find when you actually looked at the results? So in our study, we broke groups into those who accumulated less than 7,000 steps, those who accumulated between 7 and 10,000 steps, and those who had greater than 10,000 steps. And really what we found is the individuals who took at least 7,000 steps per day had a 50 to 70% lower risk of premature death compared to those who took less than 7,000 steps per day. It was also interesting that we saw that the risk reductions tended to level off at 10,000 steps per day. So meaning that we didn't see any additional benefit going beyond 10,000 steps. That's interesting. So 10,000 actually sort of forms the plateau of where you start seeing these benefits.

Does that mean, though, then I should adjust my Fitbit and set it at 7,000 from here on out? So if you're already at 10,000, stick with 10,000. The great message about this study is that there's benefits earlier than 10,000. So for those who are struggling to get to that level, who have really not been thinking about physical activity or feel like that 10,000 steps just is a little too much for what they can handle, just getting a little bit more can make a difference in your health. So it's really not saying that 10,000 is worse than 7,000.

It's really saying that there's incremental benefits as you increase your activity levels. And then once you get beyond that 10,000, you're not going to get much more benefit, but there's not harm in doing more than 10,000 in terms of the results that we found for this cohort of middle-aged adults. So generally, it's still good to get more exercise. Absolutely. It is 100% still good to get more exercise. So if you're getting your 10,000 steps, that is awesome and you should continue to do that. The data that you used in the study, where did it come from? Did you track people who already had these Fitbits and how long were you tracking them? So this comes from a study called the Cardia cohort study. And this study has been

around since the mid-1980s. And how this study works, it's funded by the National Institute of health, and they followed a group of young adults starting in 1985, and they followed them for risks of cardiovascular disease. And about every five years, they do data collection on these participants. And in 2005, they put an accelerometer, which is a research-grade device that measures activity. You could think of it similar to a pedometer. A Fitbit is also a type of accelerometer. So they put an accelerometer on these individuals, and we have about 2,000 participants who have this data. And then we have additional follow-up, where we were then able to follow them for death. And we have about 11 years of follow-up on these people. So we were able to see whether

their steps per day was associated with their premature death risk. And this cardiac study that you're drawing on, this was focused on cardiovascular health. But the benefit of the benefits you saw were declines in all-cause mortality. How does that work? Absolutely. So for this study, like you mentioned, we looked at death from any cause. It provides a nice metric to look at in terms of just your risk of premature death and indication of your health. We hope to further look at outcomes such as cardiovascular disease. And this study also has outcomes like diabetes and hypertension and obesity. And so these are our next steps in terms of what we hope to look at because this study only looks at all-cause mortality, but there could be different associations depending on the outcome you're looking at. So that's why we hope to look at these additional outcomes as we pursue this research.

And the people in this study, how representative are they? How much can we read into the results you saw in this group? So this study in particular provided a nice distribution of both black and white adults and also an equal distribution of men and women. And it comes from four different geographical locations within the United States. So it's not a perfect representation, but it does give a decent representation, particularly among black and white middle aged men and women. Of course, it's not going to extend beyond that to other race and ethnic groups. Does this then have implications for public health? Like should we be telling couch potatoes and people staying at home to start taking 7,000 steps in a day? Will we see immediate benefits if we start doing that?

So yes, I think this is kind of the main public health message, is that if you are not moving, getting to that 7,000 steps could be a really great goal, particularly for those who are inactive right now. So thinking about those incremental ways of increasing your activity. And the great thing about steps per day in terms of a public health message is we can fit steps into our daily lives. And like we've talked about, the wearable technologies, we have access to tracking our steps throughout our day. And this provides the opportunity to think about unique ways that we can fit in these steps in just our daily living. So this provides this really nice public health message that you don't need to go and get out and go run several miles if you don't have the time to do that. think about just parking further away from the store or perhaps opting for the stairs instead of the elevator

or apt for a walking meeting or even taking a few laps around the soccer field while you're waiting for your kids to finish up practice. So these are just some simple ideas that we can think about just getting in a few steps per day that could be very meaningful for our health. Now, I'm somebody who likes to walk really fast and I tell myself that's an easy way to get exercise. but your study found that the pace of walking really didn't make much of a difference. How do you make sense of that? So yes, you're right. In terms of our study did not find any clear associations with stepping intensity or pace. Now, this can't be challenging to tease out because those who step faster also tend to get in more daily steps.

We tried to account for this in our analyses and our results did show that stepping intensity or pace was not associated with mortality beyond the total. total number of steps taken. So according to our results, getting your steps regardless of the pace at which you walk them was associated with a lower death risk. It's worth noting that, again, this is just focused on premature death. And this could look different. The pace at which you're walking could be meaningful for other health outcomes. And this should be continued to look at in other populations as well. So this is kind of some preliminary evidence that we're not seeing very much in terms of the pace of what you're walking and just getting that total number of steps is more meaningful. But I think there's still some more research to be done on this topic.

Now, these activity trackers and these devices are getting more sophisticated all the time. My phone now claims to be able to measure my heart rate, my breathing, and my sleep habits. What metrics would you like to study next if you could actually measure them? So that's a great question. And you're absolutely right that these wearables technology, are really growing and rapidly. And so, you know, the accelerometer that's in these wearable devices that gets the steps per day is really just the start of being able to look at health and health behaviors. We're really interested in potentially pursuing these other metrics to see how it can maybe

give us a better representation of people's activity and fitness levels. A lot of these wearable devices and these additional. metrics still need a lot of work and perfection, which is why steps per day is a nice, clean one. It's been around for a while. So we have a lot more confidence in terms of the validity of those. But as wearable technologies continue to develop, we hope that we can combine these to better understand somebody's health from a physical activity perspective. Do you have a specific question in mind that you're looking to answer or a mystery you'd like to solve? One thing that we would be interested in and has been shown in the past is in terms of looking at somebody's fitness level.

So we have a physiological measure of someone's fitness. And so when we think about fitness, that's your ability to run faster for longer or to walk longer, those types of things. So your cardiovascular fitness, which has been tightly linked to your risk of all-cause mortality like we're looking at here. well as cardiovascular disease and other health outcomes. And as these wearable technologies grow and we get other metrics such as heart rate and those become more perfected combining physical activity with heart rate data or, for example, your electraldermal activity, which is your perspiration, getting those types of metrics in combination, we might get an idea of somebody's fitness level.

And so we're hoping that maybe in the future, this could be something we could look at. and it be a reliable measure. Because right now we have to put somebody on a treadmill and do these very sophisticated measurements that are rather burdensome on a participant. So if we can get a level and estimate of fitness in a wearable technology and be able to look at that with health outcomes, I think that could be very informative and meaningful for future tracking. And then people could have the access to those type of fitness metrics. Well, I would be definitely interested in seeing what you come up with. Well, thanks.

I'd like to thank my guest this hour, Amanda Palooch. She's an assistant professor of kinesiology at the University of Massachusetts Amherst. Thanks for joining me today. Thank you so much for having me. This is Science Friday from WNYC Studios. One last thing before we go. Remember last week when Ira and science reporter Kendra Pierre-Lewis were talking about the news that the Mars rover, Perseverance, had collected its first rock samples?

Kendra was pretty excited. but Ira was more measured. People shouldn't get too excited too quickly because we have no mission yet to go pick up those samples. There. I mean, we talk about them, and they're planning for it, but there's no spaceship out there in space

going to pick them up tomorrow and bring them back, I guess is the point I'm making. Turns out Ira wasn't the only one asking questions about this. How do samples get back to up the noise? That's seven-year-old listener Lucille, who was one of the young people we recently invited to ask their most pressing questions about the Mars 2020 mission and the Perseverance rover. The answers came from Dr. Katie Stack Morgan of NASA's Jet Propulsion Laboratory. Yes, thanks, Lucille.

That is a great question in something that NASA is working on right now. So Perseverance's job is to collect rock and soil samples and store them in little tubes and leave them on the surface of Mars or potentially pass them off to the next rover that we call a fetch rover, just like your dog would fetch something. This rover would fetch the samples that Perseverance collects. Then the next leg of that mission would involve taking those samples and blasting them off the surface of Mars. But then that rocket that would blast off the surface of Mars has to rendezvous and meet up with another orbiter that would be circling Mars. And so we transfer the samples from the surface of Mars to an orbiter that would then fly through space back to Earth and then go through the Earth atmosphere and land those samples back on the surface of Earth.

So the way that we would get samples from Mars to Earth is through a series of different missions. So it's not all Perseverance's job, but a series of missions, rovers to orbiters to get those samples back. So it's a pretty complex series of maneuvers we have to pull off. But each one, you know, NASA's done before. We just have to string them all together and hope that the timing is just right and gets those samples back to. But these kids had other questions, too, like Gia, age nine, who wondered how the rover stays clean on the dusty Mars surface. So how does Perseverance dust itself off if it can? That is a great question.

And the answer is Perseverance does not dust itself off. Best experience we have is with curiosity. When the rovers first land on Mars, they're looking pretty sparse. darkly clean. But over the years, and Curiosity has been on the surface of Mars now for over nine years, things get pretty dusty. And so when we take images of the deck of the rover, we can see how dusty it gets over time. But that's okay because curiosity and also perseverance actually don't use solar power. So previous smaller rovers like Spirit and Opportunity had solar panels. And so those solar panels got dusty and would need to be cleaned off intermittently. But with Curiosity,

Perseverance, they have a nuclear power source. So even when it's really, really dusty and when the rovers get really dusty, it doesn't so much matter because they can still generate the power that they need to operate. But I will mention a really neat thing that Perseverance has. It has a tool to do dust clearing, not of the rover itself, but of dust that we have on the ground. So when Perseverance drills or creates a little, has a tool that can abgrade the surface of the rock, remove the surface of the rock, it creates a bunch of fine dust. And so then we have basically a little gas puffer. They go and can actually blow that dust away. And we call it the gas dust removal tool. And it can actually blow dust off the surface of Mars. And it makes a little clean area on the surface. And so we won't use that tool necessarily on the rover itself. But we do have a way to clear dust. It's just on the ground instead. That's Dr. Katie Stack Morgan from NASA's Jet Propulsion Laboratory answering kids' questions about the Mars mission. To see more questions and answers from our live Zoom event. Go to science friday.com slash Mars questions. Oh, and for all of our educators out there, we've got

another round of the Educator Phenomena Forum coming up this November. It's a free professional development series hosted by STEM educators and researchers. To sign up for this fall space-themed sessions, go to ScienceFriiday.com slash phenomena to sign up. That's sciencefriiday.com slash phenomena. Charles Burquist is our director. Our producers are Christy Taylor and Kathleen Davis. John Dan Kosky is our news director. BJ Leaterman composed our theme music. If you missed any part of this program or would like to hear it again,

subscribe to our podcasts or ask your smart speaker to play Science Friday. You can email us too. The address is SciFri at ScienceFri.com. Ira will be back next week. I'm Omer Erfahn, senior reporter at Vox. Thanks for listening.