Why this lab studies the speed of bug pee and other curiosities

The physics of insect pee

0:00Hey, I'm Flora, and you're listening to Science Friday. In a lab in the Rocky Mountains, you can find a group of scientists, hard at work, trying to find answers across biology, physics, and engineering, from the hydrodynamics of insect pee, to the physics of sheepdog herding, to designing robots that resemble squid, and hearing aids that only cost a dollar. These questions may seem unrelated, but they're glued together by one scientist's philosophy about how science should run, and how to make the most of the lab's time.

0:37Bioengineer Dr. Saad Bamla runs the Bamla Lab at the University of Colorado Boulder. Saad, welcome to the show. Thank you, Flora. Happy to be here. I want to give people a flavor of your work, so let's start with insect pee. Why did this particular question whet your appetite?

0:55Where do I start? I was initially interested in how the sharpshooters actually suck the fluid out from the trees, the xylem fluid, and I thought it was a great fluid dynamics problem. And as I was watching this bug, I quickly realized it was constantly peeing, like these most perfect spherical droplets. It's like the most beautiful pee in the world. And I was like, all right, what goes in must come out, and let's see what's this.

1:30I guess it's on an all-liquid diet, right? It is. It's basically feeding on water, so it has to constantly feed and then constantly pee. I think as with most of the questions that we kind of go on these rabbit holes and adventures on, it wasn't clear to us. We were just kind of poking around, and we made some high-speed videos, and I wanted to understand how it was flicking these droplets. And the initial thought would be that it would be kind of the simple study.

2:03And this is where it got interesting, because one of the PhD students, one of my first PhD students in the lab, Elio Chilita, when he was analyzing the data, he kept telling me that the droplet was moving in air faster than the stylus, which is the kind of object that was kicking the droplet. And I just didn't believe it, because it didn't make sense if you threw a baseball, and in air you measured the speed of the baseball as 100 miles an hour. But if your finger that was flinging this baseball moved only at 50 miles an hour, it just wouldn't make sense.

2:35Where would that extra speed come from? And that was the puzzle. What did you find out?

2:41After figuring out that we were indeed recording everything correctly, and there was no mistakes in our MATLAB scripts, as we were analyzing any factors missing, we realized that unlike a baseball, which is rigid, the droplet is squishy, and the surface tension was acting like a spring and storing energy, and this bug was timing it such that additional energy was stored in the deformation of the drops, and it was giving it a boost, and we called it super propulsion.

3:12And I think that made it even more interesting, because it gave us a principle out of it that we could now use in engineering systems, and that was so satisfying, but it wasn't planned at all. But why do insects need super propulsive pee? So it's because it's feeding on xylem sap, so after photosynthesis it's rich in sugars. And so these bugs, these sharpshooters, are feeding on the xylem, which is a very frugal diet. It's as if you and I would just survive on diet soda all the time.

3:43We would have to drink a lot, and we'd have to conserve our energy to do all the other things a living system does, mating, moving around, flying. And so if they can save energy in any aspect, especially one that they're doing over and over and over again, so if you watch this bug, it's constantly peeing like this. It's going on. So during super propulsion, what it allows it to do is save a little bit of energy, because it's storing energy in the surface engine, the droplets, so it gets some kick for free, and it can fling it away farther.

4:14Otherwise, those droplets, if they don't go as fast and as far, will contaminate either the organism itself or its friends, which are all feeding together, and collect in a pool, and biologists and ecologists hypothesize that it could attract predators. Fascinating.

Encoding time in music

4:32I mean, so this is one example of one study, but you study so many things. When we met recently, you were telling me about research about music, which feels, you know, completely unrelated, and I know that's in early stages, but what's the question you're tackling? I think with all of these things, sometimes I feel like Alice in Wonderland, we're basically taking kind of this meandering walk and, you know, smelling a flower here, observing a patch of moss somewhere else, and the goal always is we're keen.

5:10Kind of, I feel like I have the superpower with my glasses. I can look at a system and try to uncover some of nature's secrets, some principles in any case. So the music is one stop in this journey, where a phenomenal postdoctoral researcher in the group, Dr. Luis Gonzalez, basically asked this question, is if you listen to Mozart's symphony or any piece of music, and you listen to it as it's intended, it sounds melodious, harmonious,

5:41but what if you played it backward? It just sounds off. And so why does it sound off when you play it backward? And so encoded in there is the arrow of time, and so we're starting to ask from the laws of thermodynamics, can we ask how is time encoded in pieces of this music? How is time encoded? It's such a deep question, and it's an astrophysicist, right, who's taking this on? That's right. And so we're so well-suited in 2026 to attack a problem like this,

6:15just because we have access to tens of thousands of pieces of music going back almost six centuries, from Gregorian chants to classical pieces to Beatles and Star Wars theme music and more contemporary pieces of music, including jazz. And we can ask, why do different composers, why do different Western music genres have different tonalities, and analyze it through kind of this lens of statistical physics of thermodynamics,

6:46and we're asking if we can kind of extract a law of this cultural artifact, which is music. Is Western music similar, like Indian music, or Iranian music, or, you know, Chinese music? And how did we all come to share? How do we all figure out that we can all listen to certain types of beats and certain intervals, and there is something in our neurons that helps us appreciate music in a certain way? What is that basis? What is that neural thing?

7:16And is it different if I'm trained in Western music versus if I'm trained in Persian music? And so the problem is these things are so subjective, and we're trying to quantify it and find some variables that give us an imperfect, yet a hook and a grip onto this problem that satisfies us a little bit.

Granting yourself permission to explore

7:37This Alice in Wonderland approach to science, you know, working across many disciplines, stopping to smell the flowers when you feel like it, isn't the norm. It's not exactly the traditional path, or maybe even so encouraged. Do you ever get side-eye? I get a lot of side-eye, and I don't know whether it's... I think somebody, I think, jokingly asked, well, who gives you permission to do whatever the heck you want?

8:11I said, well, nobody, you don't need permission. I give myself permission, and often I find as humans, as scientists, it's not as if there are rules to tell us how we should be. I think some of it is self-inflicted, self-imposed. I remember a mentor, I think a well-meaning mentor, because I'm trained as a chemical engineer, they said, Saad, you should study these classical chemical engineering topics of fluid mechanics and colloidal matter and soft matter, so then you can get tenure over five years.

8:44If you go and study in the Amazon these spiders, you're not going to get tenure. And even though I was young, I kind of knew that taking risks and kind of finding your taste of science and finding kind of what smells right to you, it's a muscle. It cannot be dormant for five years. It's like going to the gym, and even though if you go to the gym and the next day, it's not as if you can see yourself stronger, but you nonetheless keep going to the gym, you have to do it repeatedly over and over again,

9:15and it's a muscle risk-taking and finding new ways of looking at things. You can't just wait for tenure to do it. And I observed, I think, some of these well-meaning mentors after they got tenure. I think they continued doing what they were doing, and I think it's a little bit of loss for science and the next generation because they perhaps censored themselves.

9:40Anyways, I feel that we have a short life, and I'm very fortunate to have been given the gift to kind of explore, and it's a shame if I don't. Where did that philosophy come from in you? I think maybe there are two strands. One is more of a humanist strand is I never thought I'd be a scientist, and I didn't know what I wanted to be.

10:13And so I feel very fortunate that I can do this as an adult because I didn't have this opportunity to play as a child, and so I want to make the most of it because I never dreamed I could do this. So I feel so lucky to be able to derive joy from observing these kind of simple things. And so I just have to do it just because I feel so grateful to be alive every day, and I can't believe my luck. And I think the second thing is that because I'm an engineer,

10:47I naively thought when I did my PhD that if I built technology and I would earn money, that would bring me happiness. And I had the opportunity to translate my technology, and I remember sitting in a parking lot with a check after I had sold and installed this instrument to a Fortune 500 company, I felt so empty and hollow. And I realized that zeros on a check did not inspire me. I thought money was great, but it's actually, we just need to have enough of it. After that, this is such a gift. It's just such a, I think it's priceless to be able to uncover

11:20kind of the secrets of the universe. And I feel like I have a superpower, and I don't know what else to say. Yeah, I mean, you know, I think people sometimes describe this mentality as childlike wonder. And as you just said, you didn't have that opportunity as a child, and I know that from watching a talk that you gave. Would you feel comfortable talking about that and how it relates to what you do now? Yeah.

11:48So I lost my mom very earlier on, and I think with anyone who's lost a parent or a close family member at a very, very young age, I think I was 12 or 13, my mind kind of blocked out a lot of things just to protect this young mind from this trauma, from this grief. And it took me a while to kind of find myself and came in young adulthood

12:19when I found myself in Madagascar for field work. And I kind of felt like, you know, the cloud lifted and the darkness kind of, my eyes opened up and I could see things clearly. And so I don't know. I know for a long time I used to feel like life was unfair because I had to go through this trauma and grief. But I'm a big believer that I think whatever happens, it shapes us. And so in any case, I get to see the world with new eyes.

12:52And yes, oftentimes I get to do childlike things as an adult, get paid to do it. And I'm obviously much smarter, have better skills. I can lead my team and hopefully make it into useful things that others enjoy. So I'll uncommunicate that, so. And you have the courage, you've found the courage to give yourself permission to do that. Yeah. Which I don't think is trivial. Okay, we have to take a break, but don't go away because when we come back, I want to know how you know if a question is good.

13:24Of course.

Finding good scientific questions

13:25Stick around. Okay, Saad, how can you tell if a question's a good question to tackle scientifically? I think it's like piece of art. If somebody writes a poem or somebody paints a painting or even, you know, composes a piece of music, how do you know it?

13:55Of course, just like, you know, filmmakers can take classical pieces and make it palatable to modern taste and make it a blockbuster such that maybe that inspires people to go read classical literature. There is a way to think about science that we know can be made palatable to everybody. And, you know, we're scientists, we're pretty smart. We know what can be catchy and what can be attractive and package it, just like all artists, you know. Insect pee, obvious, grand slam.

14:29But I think you also know there are some things that are your own taste. It just gives you so much joy. Sometimes I feel it in my, deep in my stomach. I feel this giddiness and I just know it feels so good. And what is it? It feels like, for a brief second, it feels like you know something that nobody on the planet knows and nobody ever who lived ever knew it the way you did. You kind of uncovered a secret. It was there. You just, you know, made the final brushstrokes

15:01and you uncovered this fossil, new interesting tidbit, a new way of thinking. And then, yeah, how do you know? I don't know. It just comes and it smells good and it feels good. It's just so great. And then sometimes people appreciate it, sometimes don't. But I think I tell my team members, it just takes two to think. And if them and I care about it, that's enough. We don't need the world right now to care. But we'll polish it and we'll make it pretty and we'll share it with the world. But for a long time, for a year, three years, five years,

15:35it's just a journey that me and a team member, one or two people will go on and we are exploring. And it's just the most amazing thing. And what else? I don't know. You'd have to, I'd pay a million dollars to be able to do this. It's just a delight. I don't know any other way.

15:55I know you're a parent because we talked about this. Have you noticed anything about how your kid approaches, kids maybe, kids. Two boys, six and two. How your kids approach, you know, science or school or the natural world that stands out compared to your childhood? Um, gosh. So my older one, I took him to the Amazon with me and, you know, he caught snakes, scorpions, bullet ants. And, you know, for a five-year-old to be on the Amazon,

16:26there'd be times he'd be sitting on this huge mound of leafcutter ants and it'd be 3 a.m. And he'd be like, no, no, I just want to be here because he's, you know, poking and prodding these leafcutter ants that are, you know, just going about their business. And it was heaven for him. I couldn't get any research done because I was just worried he'd die.

16:46He's constantly telling me that he's an artist scientist because my wife is an artist. And, um, we're in Colorado now and bears are basically terrorizing us every night up in the mountains. And he's like, but dad, we need to set up cameras. And then what are they like? And what are they not like? And he's like, maybe we can make a trail and leave the honeypot there. And if you give them food, they won't bother into our trash can. It's like coming up with all these experiments.

17:16And I just love it. I just love that he can see the same thing I see. Hey, there's an interesting puzzle here. And isn't that amazing to see puzzles everywhere? It just, life just seems like an endless string of puzzles and it's just fun games out in the backyard. Saad, thanks for joining us today. Thank you, Flora. Thank you so much for having me. I really, really enjoyed our conversation. Yeah. Me too. Dr. Saad Bamla, bioengineer at the University of Colorado Boulder. This episode was produced by D. Peter Schmidt.

17:47If you liked listening, why not leave us a review? Here's the one we got from Bothered 2020 on Apple Podcasts. They write, I love the show, the episode on beavers. Ah, I'm now obsessed with beavers. Lol. Me too, Bothered. That beaver episode got me too. And if you're out there listening and you feel newly obsessed with glass-winged sharpshooters and their super propulsive pee after this interview, why not leave us a review? Thank you for listening. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman.

18:17I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman. I'm Flora Lichtman.