Science Friday - Jackson Water Woes, Giant Telescope Mirror, Shark Sex. March 12 2021, Part 1

Episode Date: March 12, 2021

What Went Wrong With Jackson, Mississippi’s Water? Residents of Jackson, Mississippi have been dealing with a water crisis since a storm rolled through town on February 15th. The city’s water system was damaged, leaving thousands of residents without running water at home. People have relied on water distribution sites to get by, and even those who can still use their taps are on boil water notice. Impacted residents are largely low-income, and the limited access to water has raised worries about staying safe during the COVID-19 pandemic. Even before this fiasco, Jackson’s water system was in need of a change. Boil water advisories were common, and many of the city’s pipes date back to the 1950s. Water service is expected to be restored this week, but getting the taps running again will just be a Band-Aid: A true overhaul would require millions, if not billions of dollars. Mississippi Public Broadcasting reporter Kobee Vance joins guest host John Dankosky to discuss what’s happening in Jackson, and why its infrastructure was particularly vulnerable to this crisis.   Spinning Glass To See The Stars Last weekend, a giant furnace built under the east stands of the University of Arizona football stadium began to spin. That furnace contained some 20 tons of high-purity borosilicate glass, heated to 1,165 degrees C. As the glass melted, it flowed into gaps in a mold. The centrifugal force of the spinning furnace spread the material up the edges of the mold, forming the curved surface of a huge mirror, with a diameter of 8.4 meters. The piece is just one of seven sections that will eventually form the 25-meter primary mirror of the Giant Magellan Telescope in Chile. It’s not a fast process—it will take several months to cool, and then another two years to measure, grind, and polish. When that’s complete, the surface of the mirror segment will be accurate to within twenty-five nanometers. Steward Observatory mirror polishing program project scientist Buddy Martin says that when it’s complete, the Giant Magellan Telescope should be ten times sharper than the Hubble Space Telescope—if it was positioned in Washington, DC, it would be able to make out a softball in the hand of a pitcher in San Francisco. Martin talks with SciFri’s Charles Bergquist about the mirror production process, and the challenges of working with glass on massive scales. Watch a video and see photos of the process at scienefriday.com.   It’s Time To Rethink Shark Sex—With Females In Mind Sharks, rays, and skates—all fish in the subclass Elasmobranchii—are a beautifully diverse collection of animals. One big way they differ is in how they reproduce. They lay eggs, like traditional fish, and let them mature in a select corner of the ocean. Or, they might let the eggs hatch inside their bodies. But they can also give live birth to pups gestated like mammals: with an umbilical cord and a placenta in a uterus. It doesn’t end there. These fish, like many other members of the animal kingdom, have two uteruses. Females are capable of reproducing asexually, without help from a male. As genetic sequencing has advanced, researchers have been finding another curious pattern: Many litters of pups will have more than one father, a phenomenon known as multiple paternity. Evolutionary ecologists seeking to explain why sharks would use this strategy of multiple paternity have hypothesized it’s one of convenience for females. In species with aggressive and competitive mating practices, like many sharks and rays, it’s possible females find it saves them precious resources to acquiesce to multiple males. But what if there’s something in it for the female, and her likelihood of having successful, biologically fit offspring? That’s the question a team of researchers sought to answer in new research published in Molecular Ecology this month, where they asked what kinds of physiological mechanisms a female shark or ray might use to wield agency in her own reproduction. The researchers also write that a male-dominated field may be more likely to miss a female-driven reproductive strategy, and push for more study of female reproductive biology. John Dankosky talks to the lead author on the research, Georgia Aquarium shark biologist Kady Lyons, about the vast wonderland of reproductive strategies in this fish subclass—and what a history of male-centered research may have missed.   What Next For The Fully Vaccinated? In the U.S., vaccines have been rolling out since December. According to the Centers for Disease Control and Prevention, more than 95 million doses have been administered which equates to over 18% of the population. This week, the agency also put out guidelines for those who have been fully vaccinated. Sophie Bushwick of Scientific American fills us in on those guidelines and also talks about research on the effectiveness of mask mandates and a headless sea slug.     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 John Dankoski. Ira Flato is away. Later this hour, we'll take a look at the water crisis in Jackson, Mississippi, and we'll dive into the reproductive lives of sharks. But first, President Biden made his first primetime address last night, just a day after he signed the $1.9 trillion American rescue plan. In his speech, Biden called for all adults to be eligible for the COVID-19 vaccine earlier than expected. I'm announcing that I will direct all states, tribes, and territories to make all adults, people 18 and over, eligible to be vaccinated no later than May 1. Let me say that again. All adult Americans will be eligible to get a vaccine no later than May 1. Biden stressed that that doesn't mean everyone in the country will have the

shots by then, but he wants everyone to be able to get in line. Sophie Bushwick is here to fill us in on Biden's plan, new CDC guidelines and other news of the week. She's the technology editor at Scientific American, and she's based out of New York. Sophie, welcome back to Science Friday. Thanks so much for being here. Thank you. So how does President Biden plan to speed up this vaccination process? President Biden has been giving estimates of how much vaccination would be available since the beginning of his term. He pledged to have 100 million vaccinations in the first 100 days and is on track to achieve that goal. So the latest goal seems to be that all adult Americans will be eligible to receive their vaccines by May 1st. And he has said previously that by May, there will be enough vaccines

in existence having been produced for every American adult who wants one. Given the fact that states are vaccinating at different rates right now, they've all got different priority groups. Does this seem attainable? Well, I think changing the eligibility might be attainable. But I think the speed with which those shots will get into arms is going to depend on a lot of factors. Like you said, the vaccination plans vary from state to state. And the infrastructure in place to give people vaccines also differs. So I am, I think cautious optimism is probably good. I don't think people should expect that as of May 1st, they'll be able to have an appointment to get their shot. But I think that we can hope that very soon afterwards people will be able to start making those appointments.

Anything else in his speech about the pandemic that stuck out to you? The idea that Americans might be able to celebrate the Fourth of July together in groups, in larger gatherings than we've been having for, you know, over a year is a pretty inspiring goal. Again, that's a goal. I don't know. I can't read the future, but it is definitely something to aspire to. All right. We'll make those barbecue plans, I suppose.

also this week, the Centers for Disease Control and Prevention released guidelines for people who have been fully vaccinated. What are those guidelines proposed? So those guidelines suggest that people who have been vaccinated have more freedom than they might have had since the beginning of the pandemic, but that they shouldn't throw all caution to the wins yet. So people who have been vaccinated can gather indoors with other vaccinated people without masks and without maintaining social distancing. Also, the CDC suggests that if you you've been vaccinated, you can meet with unvaccinated people, as long as those people are from a single household and everyone in that household is at low risk of severe COVID-19. So you might be able to gather

with a single family. Grandparents might be able to visit their grandchildren, but they're not necessarily saying go to a giant party filled with unvaccinated friends. And the other thing is that they still suggest for things like travel that you avoid unnecessary travel. They're still suggest that you avoid large groups and those types of precautions and that you wear a mask and maintain distancing with people who are unvaccinated still. So it's not complete normalcy, but it's starting to move in that direction. Do we still know any more about whether vaccinated people can transmit the virus? There's some preliminary data that suggests that transmission goes down a lot with people who've been vaccinated, but that is still preliminary. And so there are even differences

from different epidemiologists and infectious disease specialists about what it's safe to do. Some have said, you know, go ahead and it should be okay to eat in restaurants indoors and to travel, as long as you're wearing a mask and trying to maintain distancing. While others have said, well, don't jump into it yet. Let's give it a little bit more time and get more results. So there are different levels of caution depending on who you speak with. There was a study out by the CDC looking at the effectiveness of these mask mandates. What did it find?

The CDC found that in states and counties that had mask mandates, the rate of transmission of COVID-19 and the rate of deaths from COVID-19 went down starting about 20 days after the mandate was put in place. So that means that mask mandates still work. There's been a lot of pushback, though, and some of what the CDC has said. I know people in the restaurant industry are worried that there's a message getting out there, that gathering in restaurants might still be a cause of spread. Right. So in the same report where the CDC looked at mask mandates, they also looked at indoor dining. And they found that in counties that had opened their indoor dining, they saw an increase in the rate of transmission of COVID-19 about 40 days after the restaurants were allowed to open. And then another 20 days after that an increase in the death rate. And so their findings indicate that indoor dining could be a cause of spread. And yes, the restaurant industry has pushed back against that. conclusion. This is sort of more of the same of what we've kind of seen throughout the pandemic, where the CDC and some other public health professionals have encouraged people to be more

cautious and to lean towards not opening things like indoor dining and towards having mask mandates, while often on the other side businesses have kind of pushed back through worries that they are going to suffer economically from conclusions like that. So let's move on to some other non-COVID science news this week because we have a lot of it. Your next story looks at smart devices that are being used to monitor health. A team of researchers looking at kind of hacking smart speakers for this. Tell us more. Right. So your smart speaker does a lot for you. Maybe it can measure your heart rate as well. Just the way that bats use echolocation to notice where things are in space. This study rests on similar physics rules. They have a smart speaker release

an inaudible sound, and when that sound bounces back to the speaker, it can detect objects nearby. And the idea is that because there's multiple microphones on a speaker pointing around, it can actually sense small changes, including the changes caused by a heartbeat on a person's chest. So for this study, they had people sit just a couple feet from a smart speaker, and the smart speaker could detect their heart rate. And even if there was an irregular heart rate, the smart speaker was also capable of detecting that, which is pretty exciting because irregular heart rate, it can cause a stroke, it can cause other physical problems. So being able to detect it early without having someone required to go into a doctor's

office is a pretty interesting application. So that is pretty cool. As with anything with smart speakers, a little bit scary, but these are early days, right? This isn't going to start happening, you know, pretty soon. Right. Again, the person had to be sitting in front of the smart speaker. This is a very specific application. but the researchers have suggested that maybe if they continue to develop this line of work,

you could have the smart speaker monitoring your heart rate while you're sleeping. Maybe it could pick up whether you've got some sleep apnea. There have been studies in recent years that use a lot of surveillance for health, and they use clues about changes in your environment to see how healthy you are, but also what you're doing. So on the one hand, this seems like it could be a privacy disaster if it is implemented in an incautious way. but on the other hand, it does seem to have some implications for monitoring someone's health without requiring, you know, you don't have to have anything touching you, you don't have to

be in a doctor's office. So it is an interesting, it does have some potential to keep an eye on. That's so cool. All right. I want to make sure we have time for this last story. Let's talk about the headless sea slug. You got to tell us about this. What's happening with sea slugs losing their heads? Two species of sea slug can completely lose their head. In fact, it seems like they, themselves sever their own heads from their bodies, and then they regrow an entire body from the neck down. What? So hold it. They purposely take their own heads off. The head survives and the body survives? That's right. So the body itself survives for a pretty long time for weeks, but it does eventually die. The head can survive, and also within a few weeks, it regrows its body, a new body

identical to its old one, and then it goes on its merry way. So, well, first, First of all, why would it want to detach its own head? I mean, what would be the reason to get rid of a perfectly good body? So one reason might be to evade predators. We do see other animal species that are able to regrow limbs or tails when they lose them to predators. And the scientists think that in those cases, you know, if a bigger animal bites you or is trying to grab you, the ability to ditch one of your limbs or even ditch your entire

body and then regrow it could help your survival. And another possibility is, you know, parasites. If a slug's body is just filled with parasites, it might say, ugh, this body is so messed up. I need to get a new one. And then it just severs its own head, regrows the body. It has a fresh parasite-free body to keep going on with. How long does this process take to regrow an entire body?

The body was regrown in about three weeks. But this only seems to work with younger slugs. When the slugs get older, they seem to lose the ability to do this. As it's regrowing its body, though, how does it eat? I mean, how does it stay alive? It doesn't have any way to take in food, right? Now, this is really cool. The slug actually steals the parts of plants that allow them to gain energy through photosynthesis.

It has the ability to power itself through photosynthesis for the first few days while its wound heals. And then researchers think it does eat a little bit to help it gain the energy it needs to regrow that body. So, okay, this is fascinating. are there any other animals that we found that are able to do this particular thing, regrow an entire body? And how is it doing this? What allows the slug to regrow in this way? As far as we know, this is the only animal that can regrow its full body. We do know that other animals can, like starfish, can regrow limbs.

There's animals that can ditch their tails. But regrowing the whole body, this is about 80% of its total mass that it's regrowing is, this is the only feat of its kind that we've seen. And we think that they're doing it. stem cells. So stem cells are cells that can be, um, become any other type of cell. And the researchers at the moment suggest that that could be the mechanism that they're using, but they have to study it more to learn exactly what's going on. That is so cool. And I have to say, though, I saw one of the pictures on your site of the head crawling around the body and it kind of creeped me out. That, I can't

look at that video clip. My shoulders go right up around my ears. There's something about the way the head bumps into the body that it used to be attached to and then moves away that just freaks me out. Yeah, don't look at that right before you go to bed. That's all I have to say. That's all the time we have. Thanks so much, Sophie. Thanks for having me. Sophie Bushwick is the technology editor at Scientific American. When we come back, we'll talk about Jackson, Mississippi's water crisis. While the end is in sight for this particular crisis, more than a Band-Aid solution is needed. We'll be right back after this short break. This is Science Friday. I'm John Dankoski, and it's time to check in on the State of Science.

This is KERNNO. St. Louis Public Radio News. Iowa Public Radio News. Local science stories of national significance. Jackson, Mississippi has been dealing with a water crisis for the past month. In mid-February, a winter storm blew through the state, and Jackson's water infrastructure was not prepared for the frozen temperatures. Thousands of residents were without water for weeks.

Now the end is in sight. The city says it should restore the remaining lines this weekend. But how did this happen and how does Jackson keep it from happening again? Here with us to shed more light on the situation is Kobe Vance. He's a reporter for Mississippi Public Broadcasting in Jackson, Mississippi. Kobe, welcome to Science Friday. Thanks for joining us. I'm glad to be here.

Let's talk first about why Jackson was so devastated by last month's storm. What's the water infrastructure like in the city? This is a city where things like boil water notices are really common. For one, in January, there were about 40 boil water notices issued in the city alone. So, you know, the city has problems that have existed for decades. Looking back, you know, there are pipes in the city that have been in the grounds for possibly 100 years. They're made of cast iron, and the mayor is describing them as peanut brittle. When repair crews go out to, you know, try to take them out of the ground, patch holes,

their hands might go right through them. And then as they finish repairing a pipe, they may look down the street and see another break. And so the city has been dealing with this for decades, and it has become a problem that has exceeded what they can do within just one administration. Wow, that sounds really bad. So what exactly happened then to this really old, brittle infrastructure during the storm? Well, starting on Valentine's Day, Mississippi had a winter storm that swept across the state. It also impacted Texas, which led to many power outages. But here in Mississippi, while power was still relatively fine, water in Jackson was hit hard.

Monday morning the roads were frozen over, pretty much halting interstate traffic throughout the state. Now that prevented delivery trucks from getting to Jackson that had chemicals that were needed to be used into plants for treating water. Then the water intakes from the reservoir and the Pearl River froze, and that limited water intake as well from the city. And so as residents began to continue to use water in their homes, because everybody's home and they can't leave, water storage in the water towers and the other storage tanks around the city began the drain. And so eventually you had a complete loss of water pressure across the entire city. Some residents may have had like a trickle of water, but many had none. And so boil water notice was issued at that time. And, you know, we're going on our fourth week now.

Some residents still don't have water. Kobe, it's my understanding that Jackson has one of the fastest shrinking city populations in the entire country. Is part of the issue here just disinvestment in the city? A lot of it has to do with white flight. In the 80s, around half of the residents in Jackson were white. And then since then, it's dropped to about 16%. And in a state that has a storied history with racism,

it's no surprise to hear that politicians lost interest in the city as soon as the white residents begin to leave. And so since then, funding for the city has begun to plummet. Neglect has just been growing and growing and growing over the past few years. The remaining residents who still don't have water are expected to get it back sometime soon. But is this going to be a real fix to this long-term problem? The city has requested $47 million from the state legislature. But that might not be enough to fix all of the problems in the water system. Mayor Shokwe Antar Lamumba says that the city

has so many problems, it would take $2 billion to accomplish all the goals the city needs to make. And that's including roads, transportation, other infrastructure, including water. So let's talk quickly about how people have been getting by these last few weeks. How have they been getting water? Well, thankfully, the National Guard was deployed, and they began to use water tankers to help provide non-potable water. The city has provided bottled water at several locations periodically. Sadly, I don't think it's been every single day, but they've been trying to keep residents, at least some supply of bottled water that they can use. A lot of residents are spending their own money to be able to just, you know, go to a local grocery store to buy. some. Now, and also as the city begins to continue to build up water pressure again, they are getting water back to the residents that are furthest from the treatment plants. And so, you know, as all

these are happening, bottle water is still the largest need in the city right now. And thankfully, it looks like residents are getting what they need as of now. Of course, all of this is happening in the middle of a pandemic, too. I mean, are people worried that the crisis is going to lead to a spike in cases? Absolutely. The city leaders, the mayor, health officials, in the area, they're all concerned because you can't wash your hands, you can't shower, you can't do basic things, you can't even wash your clothes for many residents. I mean, if you wouldn't want to drink the water, would you want to wash your hands with it? If you can't drink the water, would you want to shower in it? And so that's become a major issue is just people finding ways

to stay healthy. The National Guard was handing out large bottles of hand sanitizer at the beginning, but those supplies were limited. And so now residents are just trying to find ways to protect themselves the best they can. Kobe Vance is a reporter for Mississippi public broadcasting in Jackson, Mississippi. He's been covering this water crisis. Thank you so much for your time. I really appreciate it.

Thank you for having me. Turning now to a giant optical engineering project, here's CyFrize Charles Bergquist. Hi, Charles. Hey, John. I know you're always up for a good game of Name That Sound, and I have a fun one for you. Oh, Name That Sound is one of my favorites.

Okay, well, here it comes. Any guesses? Well, it's a beautiful sound if you listen really closely. I can imagine it being part of a sound installation in an art gallery, but, you know, it could also just be a vacuum cleaner. Close, but it's actually sound recorded last weekend of about 20 tons of glass, getting heated up to 1165 degrees Celsius in a giant rotating furnace located underneath the east stands of the University of Arizona Football Stadium. I think if you listen very carefully, you can hear that part. That's exactly what it sounds like now. Now that you say that.

This thing, it looks something like if you turned the designs of your standard fairgrounds carousel with the horses, turned it over to a bunch of science fiction art designers. It's this big, rotating, red cyberpunk-looking thing. And if you listen carefully to the whir, you might be able to decode that it's spinning at about five revolutions per minute. It's all part of the slow process for casting a giant mirror. Wow. So there's a lot there.

There's a rotating furnace, and it's under a football stadium. But I guess I should ask you first, what's this mirror for? So this is one of six identical curved mirrors that will eventually get installed in the giant Magellan telescope. That's a huge optical telescope being built in Chile that's planned to see light not till late this decade. So you say a giant Magellan telescope, like how giant is it? The primary mirror is 25 meters across. And there's no real process for making a mirror that big. So that's why they have to do it in pieces.

These six curved mirrors are arranged like flower petals around a central point. And each of those mirror segments is 8.4 meters across. That's like 27 feet for the metrically challenged. Wow. So they pour molten glass into a bowl shape to cast this? So that was my first guess. that maybe they somehow carved it out of a large chunk. And it turns out both of those ideas are completely wrong.

If you go to our website at ScienceFriiday.com, you'll see a video of people preparing for last weekend's melt by stacking hundreds of these hexagonal boxes into a giant circular mold. I talked with Dr. Buddy Martin, project scientists for the mirror polishing program at the Stewart Observatory at the University of Arizona in Tucson, about just how this mirror casting process works. If you imagine starting with a solid disk of glass that's 28 feet in diameter and more than 2 feet thick, first you would carve out the top surface to make it concave.

It's nine inches deep in the center. And then you want to make the mirror much lighter than it is so you would grind out the hexagonal cavities in this disk. well all that grinding would be prohibitively expensive and very risky so we melt the glass and cast it in that structure the boxes will form the cavities of the honeycomb and in order to get the curved top surface the optical surface we spin the furnace while the glass is molten so that the centrifugal force will push it out and up the sides of the mold to give us that concave surface, which is approximately the curvature that's necessary for this telescope.

So the key components of the glass structure here is it needs to be strong, it needs to be stiff, and it needs to be lightweight? Right. Stiffness against the wind and stiffness against gravity are the two most important features of the mirror. That's what makes a good telescope mirror, because if it doesn't have that, it won't be able to hold its shape accurately in the telescope. You can polish it to a very accurate shape in the lab. But in the telescope, it's going to hit hit by 20 mile per hour winds. It's going to be pointed in different directions as the telescope points to different objects around the sky. And so gravity is trying to bend it also.

I understand you're using a kind of glass called borosilicate glass for this. That's the same material I might find in my kitchen measuring cups or a pie plate or something like that. Exactly. And it's used for baking dishes. For the same reason, it's used for mirrors. And that is that it doesn't expand very much with changes in temperature compared with other types of glass like plate glass. It expands very little. And that's a valuable property for a telescope mirror as well as a baking dish.

We get this borosil glass from the Japanese company O'Hara, and one of the reasons it's perfect for our application is that they melt the glass in one ton clay pots and then carefully break each ton of glass into a few hundred small pieces so that they have such pristine fracture surfaces that they melt together with no trace of the individual blocks. And that's a difficult thing to achieve when you melt pieces together. The peak heating process took place last weekend, but I understand the glass is still going to be very warm for some months to come. Why is that? At that point, the glass is solid. It's not going to change its shape so we can stop the furnace rotation. But it's still soft at the atomic scale. The atoms will finally get locked in place at about 500 degrees C.

And it's essential that the mirror is very uniform in temperature while that's happening. So we achieve that by cooling it very slowly, two and a half degrees C per day for about a month. Another month and a half, we'll bring it down to room temperature around June 1st. And we'll take apart the furnace, take apart the outer parts of the mold, and get our first good look at this mirror. This is Science Friday from WNYC Studios. I'm talking with Dr. Buddy Martin of the University of Arizona about manufacturing a giant telescope mirror. I was reading that once this is cool, it'll take something like two years to polish it.

What's going on there? Yeah, that's right. Well, that's all about improving the accuracy. The mirror comes out of the casting operation with the surface accurate to say two and a half millimeters. meters on average. And over those two years of grinding and polishing, we're gradually going to improve the surface to an accuracy of 25 nanometers. So that's an improvement by a factor of 100,000.

And it just takes time to gradually improve the surface. I don't have a good feel for what 25 nanometers or a millionth of an inch is. and I'm not sure anybody does. So I like to think of it as if the mirror were expanded to the size of North America, 3,500 miles in diameter. In that case, the average hill would be just 17 millimeters, 2 thirds of an inch tall, and the average valley, two-thirds of an inch deep. That's how smooth this mirror has to be in order to form images that are as sharp as nature allows.

And that's why it takes two years to polish it. How sharp an image is that compared to what we have available today? If you allow me to stick to this continental description of things, if the telescope were located in Washington, D.C., which nobody would want to do. But suppose it were there, then it could resolve a softball in, San Francisco. It would see that as distinct from the arm that's holding it. Sharpness or angular resolution of a telescope scales with its diameter, and that's a fundamental

property of light related to the wave nature of light. So that's what I mean when I say images as sharp as nature will allow. Some of the most spectacular images that any of us have seen are made with the Hubble Space Telescope, which is two and a half meters in diameter. Well, the GMT is 25 meters in diameter. So its images will be 10 times as sharp as those of the Hubble Space Telescope. So when I think of my mirror at home, it's got this reflective surface. Can you tell me about how that ends up on this mirror? Most mirrors at home say bathroom mirrors have the reflective coating on the back of the mirror. It's protected that way.

But for a telescope mirror, you can't afford to let the light go through the glass. We usually think of glass as an optical material because light goes through glass and we make lenses out of glass. But for a telescope mirror, we're just using glass as a structural material that can be polished to a very precise and accurate surface. The whole purpose of this huge piece of glass is to hold that layer of aluminum up. It's only four millionths of an inch thick, about a thousand atoms thick. And the mirror's job is to hold that reflective coating in the right shape at all times through all perturbations that will occur in the telescope.

This mirror is the sixth of seven. Are there five others sitting in a warehouse somewhere? They're not all in a warehouse. There are two of them in a storage facility in Tucson. and we are polishing the third one now, hope to be finished with that, you know, sometime this calendar year. The fourth and fifth are in various stages of fabrication in the mirror lab, and this was the sixth that was cast this weekend.

Since it does take us three or four years to make one of these mirrors, it's important that we can work on more than one mirror at a time. We're typically working on three or four mirrors simultaneously at different stations and at different stages in the manufacturer. And when does the seventh mirror get made? I understand that it will be cast in 2023, roughly two years. Well, good luck with finishing mirror number six and best wishes for mirror number seven. Buddy Martin is the project scientist for the mirror polishing program at the steward of of the University of Arizona in Tucson. For Science Friday, I'm Charles Bergquist.

Coming up after the break, sharks take some unusual steps in the process of becoming parents. We're going to take a look at shark reproduction under the sea. This is Science Friday. I'm John Dankosky. Next, we're going to talk about baby sharks. And as a bonus, we're not going to play that song for you. But we are going to tell you about some things you might not know about baby sharks and their relatives, baby rays. First of all, did you know they're called pups? Yeah, they're born in litters, just like dogs or cats. Pretty cute, right?

And it often takes a long time to grow them. Most female sharks are pregnant for at least a year, though sometimes as long as three years. And yeah, that's the other thing. Many sharks and rays gestate mammal style with umbilical cords, placentas, and uteruses. And yes, that's uteruses, plural. We're going to spend the next few minutes

talking about these and other shark reproduction wonders with my next guest, Dr. Katie Lyons. She's a research scientist at the Georgia Aquarium in Atlanta and lead author on new research looking at one very specific reproductive mystery, which we will hear all about. Welcome, Katie to Science Friday. Thanks so much for being here. Thank you for having me. It's such a pleasure. So Katie, to get started, before we get to this new research that you've just published, everything I just talked about is pretty cool to think about. But maybe you can start by telling us what else sharks and rays,

have going on reproductively. Oh my goodness, so many things. So I am going to bias this conversation a little bit towards the gestating animals. So moms are pregnant, just like you would see somebody on the street. We'll be a little biased against the egg layers, but they're really cool too. So we have a range of these reproductive characteristics. So females can gestate and just basically lay an egg in their body and not provide any extra nutrition. And we have all the way to the other end of the spectrum where females will continuously ovulate eggs and those babies can eat those eggs like you would have eggs for breakfast every morning, all the way to interuterine cannibalism, where it is a literal hunger game inside the female's body where siblings eat each other and the ones who make it are the

ones who make it. So holda, talk a little bit more about that. I mean, that sounds both incredibly frightening but also probably efficient, right? If you are eating all your brothers and sisters, you're probably coming out pretty strong. That's what we would assume would happen is those genes from that particular embryo are the ones that are going to make it out into the greater population. So it's incredibly energetic, of course, for both mom, but it limits the number of offspring that she can produce. So if she's not going to be able to produce many offspring, that's going to limit her overall reproductive fitness. So the whole goal of biology, the meaning of life isn't 42, it is to pass on your genes. And so if she has less opportunities to do that, that could have

some important consequences. So she's going to want to make sure that those offspring are as fit and ready to go as they can be. There can be up to 300 pups for a mature whale shark, but you can have a single pup, like in a cow nose rate. They only have one pup per litter. As I mentioned early on, two uteruses? Tell us more about that. Yeah, so it's actually fairly common across the animal world, but they have two, a left and a right. They can have pups in both. There are some species that have a completely vestigial uterus, so they have two, but they only really use one. So they have all kinds of cool things going on. And some sharks can reproduce asexually, too.

That's right. Yeah. So a lot of these things were observed in Aquaria, actually, because we're keeping animals here. And oftentimes it's more convenient to have a single-sex group. Females tend to be a little more chill and not as frisky as the males. And what was noticed is that in a lot of species that lay eggs, that, you know, there's no male in there. And then there'd be these little embryos developing. And people like, what's happening here? So it's, It does seem that there's a whole other complex reproductive mode going on too, where a female, maybe if she doesn't have access to that sperm, and she's like, well, I got to pass my jeans on one way or another, so we're going to find a way to do that. All right. Well, let's get back to something you just said. You talked about the males being frisky. From what we understand, the mating process for sharks and rays is pretty aggressive. Maybe we can just talk about that piece of it first. Yeah, absolutely. So as everyone probably knows, sharks don't have hands. So manipulating things is going to be a little difficult, but they do have teeth.

And those teeth can be very sharp. So you have males that will grasp on to females. So a lot of times when people are observing mating behavior or not observing it directly, but you can look at those scars on females as a cue of, oh, maybe this is around when mating season is because we see these open wounds. But in addition, males are known for being fairly aggressive. and to gang up on females in groups. So that can be a little overwhelming, as you might imagine, for a female shark or ray.

All right. So this gets us to your research, which just appeared in the journal Molecular Ecology. There's this phenomenon, as we talked about, where sharks and rays will have litters, but with multiple sires or fathers. So tell us a little bit more about that and how this plays into the research that you're doing.

So it's been going on for decades that people started looking into this. You know, you have a litter of pups and it's like, oh, let's just do some genetic testing. We kept finding that multiple paternity or having multiple fathers in a single litter is actually more of the norm than it is the exception. Some explanations for that, though, have tended to be very male biased. And that gets back to some of that mating behavior that we talked about, where you have very frisky males that might gang up on females.

And so it's not hard to see why, you know, a few. female might be mated multiple times with different males. And we could wash our hands of that explanation as, you know, yeah, sure, that makes sense. But for our paper, we wanted to flip the other side of that coin because there's a whole suite of physiological mechanisms that females are going through to actually bring that egg all the way up to a completely developed embryo that is, you know, fully functional and ready to go. You're looking at this from the female sharks perspective, whereas most research has looked in the past at male sharks,

not just being the aggressor, but also as the driver of this multiple paternity. More or less, yeah, there has been some casual nods to females, but because those explanations are a lot harder to empirically demonstrate, then the de facto explanation of late is just, well, it's because it's convenient for females just to acquiesce and let the males have their way with her. And so we were saying, hold on, she is investing a ton of energy into producing these babies. Why would she not have a stake in that? Why wouldn't she have a say in who's going to get to fertilize her eggs?

All right. So what did you find? Some really cool stuff, actually. We set up a few hypotheses, both from the male and female. perspective. And essentially what we demonstrate is that there's an equally plausible explanation that these observances of multiple paternity are having those multiple fathers in a single litter can be by female drivers. And then we go on to talk about all the cool ways that females might potentially be able to do that based on other literature, all the way from fruit flies up to complex mammals like us. What are some of these cool ways that the female sharks are controlling

their own reproduction? These are just hypotheses. So we hypothesize that this might be happening and very much advocate for a whole other field of research to really look into this to demonstrate that those are happening. But some of those ways can be through sperm storage. So I'm sure some people have heard of sperm competition where it's like the fastest swimmer gets to the egg and everything's hunky dory for that little sperm. But that all occurs in the female body. And she can actually manipulate those fluids to change the way that that sperm can move. So that's been demonstrated in other animals. So if she can alter that swimming, she's going to be able to alter who is going to be able to access her eggs. Some other things that we hypothesize is that she might be able to

regulate when she ovulates. So if she can ovulate over a long period of time, maybe if she mates with another male down the line, then she can replace that other sperm from the first male with sperm from the second male. So again, these are all hypotheses that we propose that people should look into, but they could be plausible explanations. When you talk about sperm storage, we just talked recently on the program about how bees do this. Queen bees will mate a lot of times very early on and store sperm for sometimes a very long period of time. Is it similar? Do we know how long female sharks store sperm after mating? We're not sure exactly, except that there are some species where it's purported to happen for perhaps up to a year. So definitely a huge area of research that would

be great. And a lot of that has been hypothesized in species that are more oceanic. So they might not encounter mates very often. So it's thought, okay, well, maybe she has some mechanisms to store sperm on board for when she needs it. And perhaps, you know, she could alter who gets to survive within her body and who doesn't. We don't really know, but there's just a ton of even just basic anatomy that I think hasn't really been properly addressed and giving females their full due. And for the species that have placentas, there's a way to selectively direct resources to different embryos to essentially say, here's where we want our body's resources to go. Oh, that's so exciting. Yeah. So a lot of research about that has been done in mammals. We actually

don't know a whole lot about that in sharks, and that's kind of the next paper that I'm hoping to work on, is taking that to the next level to say, okay, like, is mom able to actually control that? Because when you think about it, mom has little parasites in her body, and those little parasites, those embryos, they're going to want to maximize their resources, but that isn't necessarily in the benefit of the female if she's too weak to reproduce another season. That doesn't benefit her fitness. So that inter-euterine competition between mom and pup, I think is going to be fantastic to really dig into further. Why does it matter so much which parent has agency and reproduction me? Why is this so interesting to you? Well, again, I'm a little female bias, and that's probably

because I would identify as a feminist. So I'm going to bring my own biases to the table. But I think all researchers, whether they know about it or not, are going to have some bias that they come. with. But I find this reproductive aspect so interesting because as humans were rather boring, we have essentially one way that we do it. And sharks and rays have evolved numerous different ways on providing the supplemental nutrition. And so my interest is, well, how and who does it benefit? And how are they able to do this? Studying these mating systems is important because males and females have different prerogatives of what is going to increase their fitness. And so for males, it behooves them to mate with as many females as possible. Females, on the other hand, are

limited because they have a certain amount of space and a certain amount of resources they can put into the production of young. So mating with more males to a certain point is not going to benefit them because, you know, if they are only going to ovulate five eggs, they're only going to ovulate five eggs. And so for them, that cost then becomes mating with a low quality male or a concept called genomic and compatibility. And that basically is where not every sperm is going to be able to fertilize every egg. So for female, if she's mating with a genetically incompatible male, that actually has a real cost to her because she's limited and how many young she can produce. I'm John Dankowski, and this is Science Friday from WNYC Studios.

And we're talking with Dr. Katie Lyons. She's a research scientist at the Georgia Aquarium in Atlanta. We talked about asexual reproduction before. Would there be reasons you think for a female shark to find it advantageous to essentially clone herself, even if she has access to sperm from a male? Yeah, and there's some new research by one of my colleagues actually that's looking at that. So they artificially inseminated bamboo sharks, and they found that even when females had access to sperm, some of them still chose, sure, at a lower rate, but asexual reproduction still

happen. So we're not exactly sure why, but it could be, you know, maybe a female's able to say that this sperm isn't compatible with me, and I know I'm compatible with me, so I'm not going to waste my energies. We just don't know, but that could be a reason. You've said a lot here that these are hypotheses that need to be tested. So what's missing right now from the research? I think we need to completely delve into female reproductive biology from like a mechanistic standpoint. And part of this is just it's very difficult to study sharks and rays. They're caught in the wild. You don't know where they're going to be.

And sometimes they're hard to keep in human care. So there's all these things that we really don't know from a microscopic level. And so I think changing that narrative. And once we can look through that female lens, I really hope that that's going to open up a lot of research. But we really just need to start using sharks and rays' model species. And that hasn't really been done a whole lot because of their difficulty in caring for them. Does it help us understand evolution in some way? Absolutely.

I mean, considering that sharks and rays have been around for millions and millions of years, that's given plenty of time for different. lineages to go their own way and figure out what seems to be working for them. I think that there's going to be a lot of interplay between physiology and ecology, and that would be another exciting avenue to pursue this research to say, well, when is it advantageous to do this type of reproduction in this particular environment or in this social context? So I think there's definitely a larger picture that we can look at to start to understand why. this particular thing would be beneficial in this particular scenario.

One thing that you have noted in your research and in our conversation here is an awful lot of the theories that we have in ecology have come from male scientists in the past. I guess I'm wondering how much you think about how that has colored the way in which we think about something like shark reproduction. Yeah, and I think that it has in a way, and part of that has to do with things that get ingrained. So, you know, Darwin is the father of evolutionary biology and a lot of like modern science. And it's fantastic. But there was literally hundreds of years where only male voices were being heard. And female voices and females' perspectives were not. And so we're leaving out kind of

these important things that might not occur to men. Everyone's perspective is going to change the way or alter the way that they look and approach a particular problem. So if we can have a more holistic inclusion, I think that's going to make for richer science. And that's going to help us uncover things that maybe we didn't even think about because it was in the dark and our spotlight was only on this other corner. Unfortunately, that's all the time we have. Thanks so much to my guest, Dr. Katie Lyons, research scientist at the Georgia Aquarium in Atlanta. Thanks so much for joining me today, Katie. Thank you. This has been a delight. One more thing before we go. Check out our newest education resource created by Science Teacher and Science Friday Educator collaborator.

Turtle Haste. Students can learn all about infrasound and volcanic activity by exploring how sound waves are transmitted and can be used as data. Check out the resource on our website at ScienceFriday.com slash soundwaves. Charles Bergquist is our director. Our producers are Christy Taylor, Katie Feather, and Kathleen Davis. our senior producer is Alexa Lim. BJ Leatherman composed our theme music. If you missed any part of this program or you'd like to hear it again, please subscribe to our podcasts

or ask your smart speaker to play Science Friday. And if you want to drop us a line, you can find us on Facebook and Twitter. Talk to us on the Science Friday Vox Pop app. You could also email us. The address is SciFri at ScienceFri.com. Have a great weekend. Ira's back next week.

I'm John Dankoski.