In this episode of Tiny Show and Tell Us, we cover an aurora-like phenomenon — STEVE (Strong Thermal Emission Velocity Enhancement) — and how citizen science led to its discovery and unforgettable name. Then we talk about convergent evolution in tenrecs, a fascinating family of animals endemic to Madagascar. Some look identical to hedgehogs, some are similar to opossums, and others look like moles.
Transcript of this Episode
Sam Jones: Welcome to Tiny Show and Tell Us, the bonus series where you write in with your favorite science news or factoid, we read your email aloud and then dive deeper. I'm Sam Jones and I'm here with my co-host Deboki Chakravarti.
Deboki Chakravarti: Hi Sam. I'm excited to talk to you about our listener submissions today because I think they are a lot of fun. So before we kick things off though, a reminder that we are looking for you guys to write to us. Email tinymatters@acs.org or fill out the form linked in the episode description. Okay. Let's get started.
Sam Jones: Our first Tiny Show and Tell Us submission is from listener Leo. And Leo wrote in saying, "A mysterious aurora phenomenon was seen all across the country last night, even far up north, and it's called ... STEVE? I was wondering if you might have some more scientific insight on this weird phenomenon with a weirder name and why we're seeing STEVE." So this was fun.
Deboki Chakravarti: I'm excited. I have no idea where this is going.
Sam Jones: So STEVE, S-T-E-V-E is an acronym for Strong Thermal Emission Velocity Enhancement.
Deboki Chakravarti: I love that it's STEVE. It's fun.
Sam Jones: So both auroras and STEVE are caused when high energy particles from solar activity, for example, solar storms are swept into Earth's atmosphere by solar winds. So Earth's magnetic field then directs these energetic particles along magnetic field lines toward the planetary poles. Auroras form when these particles release their energy in the form of light. I think most of us have at least seen images of auroras before. So they generally look like this glowing green, blue, red ribbon in the sky, and you typically, typically have to get pretty close to the North or South Pole to actually see them. Except as you might remember this year, we've had them much further away from the Poles, and that's because the sun is currently at its solar maximum, meaning it's at the peak of its 11 year activity cycle, which means more frequent and intense solar storms that send charge particles toward Earth. Unfortunately, it didn't go quite south enough to see it in DC, but just very, very cool.
Deboki Chakravarti: We missed it. We heard about it because I think we could have seen it here, and we just completely were just like, "We got to sleep."
Sam Jones: That's fair.
Deboki Chakravarti: It's funny, I remember way back we did our travel episode and we had gone to the Arctic Circle and had driven around in northern Norway to try to find the aurora, and then this past few months we're just like, "No, we need our sleep."
Sam Jones: Yeah, that's fair. You have a new baby. Sleep is important.
Deboki Chakravarti: It's valuable. It's precious.
Sam Jones: Yes. Okay, so those are auroras. Let's talk about STEVE. So STEVE is formed by the glow from a fast moving stream of super-duper hot gases along magnetic field lines called the sub auroral ion drift. And so it looks like this really short-lived purple streak across the sky, and it can be observed at much lower latitudes than auroras typically. And so Ari Remmel, a journalist who did the research for this episode, found a nice summary from space.com in one of the articles where they say, "Visually, STEVE appears to be a mauve or magenta streak across the sky, whereas the aurora usually appears as green ribbons. Physically, STEVE is created by heated gas that glows, whereas the aurora is created by charged particles that glow." So very, very similar but not identical.
And so although scientists have been aware of the sub-auroral ion drift that causes STEVE for decades, it was actually members of the Aurora Chasers Facebook group who first documented its visual appearance around 2016. And the first study about STEVE wasn't published until 2018 in Science Advances and it was titled New Science in Plain Sight: Citizen Scientists Lead to the Discovery of Optical Structure in the Upper Atmosphere, which I thought was really cool. Yay for citizen science.
Deboki Chakravarti: Yeah, that's really awesome.
Sam Jones: So according to the CBC, the Canadian Aurora Chasers who photographed the phenomenon called it Steve. It didn't stand for anything. They just called it Steve.
Deboki Chakravarti: Oh my...
Sam Jones: And you might be wondering why. And apparently in the animated film Over the Hedge, which I haven't seen, but the animal characters in it discover this mysterious hedge and they decide to name it Steve in an attempt to make it seem less scary. And so that was the inspiration for naming this thing Steve. And then after the fact they were like, "Oh, it stands for Strong Thermal Emission Velocity Enhancement."
Deboki Chakravarti: Wowee.
Sam Jones: There are a lot of great pictures of STEVE and I will be sure to link to some great press releases that have beautiful photos as well as photos of auroras and all of that. So definitely check the references in the transcript for this Tiny Show and Tell Us. Now, you might be wondering, will we see STEVE again in the future? And the answer is probably, so STEVE, it's still a rare optical phenomenon, but that might just be because we didn't know what to look for or that we could see something very similar to an aurora that far away from the Poles. And so STEVE has exclusively been observed in conjunction with auroras, likely because they're caused by the same space weather events, but scientists are still working out how to predict STEVE, and they think that major geomagnetic storm events are probably the place to start. That would probably be the best indicator that there might be a STEVE coming.
Deboki Chakravarti: That makes sense.
Sam Jones: So in the spirit of citizen science, if you happen to get a picture of STEVE or auroras, actually NASA and the National Science Foundation have a project called the Aurorasaurus Project, and it's a citizen science project that tracks the appearances of auroras and now STEVE, and they would love for you to share your image with them. And so I'll put a link to that as well.
Deboki Chakravarti: I just love that they heard it was going to be named Steve and they're like, "We're going to figure out from here what it's going to be, what it's going to stand for."
Sam Jones: Yeah, me too. It's really fun.
Deboki Chakravarti: Well, that was really cool. I am here with something a little more earthbound. This is from listener Deb. They said, "I've been listening to Tiny Matters from the start and love it. I'm a SciShow Tangents import." Thank you, Deb. That's great.
Sam Jones: Yeah, thanks for coming over.
Deboki Chakravarti: "Here's a puzzling scientific thing I came across for a Tiny Show and Tell Us. Reading one of David Attenborough's books, I recently became aware of this weird thing. There's a mammal from Madagascar called the lesser hedgehog tenrec that looks a lot like the hedgehog, but they're not even in the same order. It's a cool example of convergent evolution. But looking more into it, the tenrec family has a lot of examples of convergent evolution with other species. Some species looking like shrews, others like moles, others like opossums. Why is this so common in this family? Are there other examples of convergent evolution at the organism level species looking a lot like other species? How similar did the niches that these species occupy have to be for evolution to end up with organisms looking so alike? There are also some species of the tenrec family that don't look like any other animals, like the lowland strip tenrec. Too cute to not mention it.
Also in the latest Tiny Show and Tell Us, you mentioned how you guys should do more plant episodes, and as a plant scientist, I would indeed love hearing more about plants on the podcast. Thank you for the great podcast." And thank you, Deb, for the great submission.
Sam Jones: Thank you.
Deboki Chakravarti: This was super cool to me because I had never heard of tenrecs before, and if you are listening and you're not driving, you're in a place where you can Google, I highly recommend that you Google tenrecs because you'll have the same response that I did where you look at it and you think that's a hedgehog. That is a hedgehog. And if you can't Google what a tenrec is, just imagine a hedgehog and you'll be on the right track. Specifically I guess the lesser hedgehog tenrec. But like Deb said, they're not even in the same order as hedgehogs. Their last shared common ancestor probably goes back to 160 million years ago. Tenrecs are actually more closely related to elephants than they are to hedgehogs.
Sam Jones: That's wild.
Deboki Chakravarti: So for those of you who are also new to tenrecs, they are mainly found on Madagascar and there are around 36 species, but they can look just like so wildly different from each other. There's the hedgehog looking ones, there's the shrew looking ones, there's the lowland streak tenrec that Deb mentioned, and they're really cool and black and yellow and spiky. Those spikes can apparently even vibrate. Some of them can vibrate at a special ultrasonic frequency. There's a lot going on.
Sam Jones: Why? I wonder why.
Deboki Chakravarti: Well, apparently some species might be able to use echolocation to get food.
Sam Jones: Whoa.
Deboki Chakravarti: Another fun fact, the tailless tenrec holds the record for the most nipples of any mammal because they have 36 nipples.
Sam Jones: That's a lot of nipples.
Deboki Chakravarti: Because they can have up to 30 babies. So when you have a lot of babies, you need a lot of nipples.
Sam Jones: That sounds exhausting.
Deboki Chakravarti: Yeah, they are a wild group of animals. So Madagascar became separate from mainland Africa around 170 million years ago, and the tenrec's ancestor probably maybe floated over to Madagascar and got stuck on the island at some point after that. And so the diversity of tenrecs from that point onwards is an example of what's called adaptive radiation or divergent evolution, because different species evolved and specialized to different niches in their ecosystem. So it's interesting to me because both this example of divergent evolution, but they're also an example of, like Deb mentioned, convergent evolution. And this is what happens when you have animals that aren't closely related to each other, evolve similar features or behaviors.
Sam Jones: The example that I love for convergent evolution is wings. Bats and birds are not closely related, but they have very similar wing structures. And so that's an example of convergent evolution too.
Deboki Chakravarti: Yeah, that's a great example. And what likely happened here with tenrecs is that they just exhibited similar selection pressures that other animals in other parts of the world do. And so in the case of hedgehogs and hedgehog tenrecs, maybe they were both dealing with predators and they were like spines. This is where ... I mean, they didn't decide this. That's not how evolution works. But just through whatever series of mutations and selections that happened, they both landed on spines. Meanwhile, moles and mole tenrecs both evolved forelimbs that helped them dig and live underground. So I think the answer to Deb's question about why tenrecs show so much convergent evolution is that I think adaptive radiation took one ancestor into a bunch of different species that had these different niches to fill in Madagascar, and that led to them landing on solutions shared by other animals.
She's asking about how similar do these niches have to be? I'm not quite sure, but it's something like the mole tenrec that's digging underground. That's a pretty specific way of life, even if you're in a completely different ecosystem I think. So I think in that case, it kind of makes sense to me why they would end up on something similar to moles and then something like spines. I'm not sure again, how similar does the environment have to be. And there's some other really cool examples of convergent evolution. For example, I did not know this until I was going through Ariana's notes for this episode. Falcons are more closely related to parrots than hawks or eagles.
Sam Jones: Whoa.
Deboki Chakravarti: Yeah. There's also this whole phenomenon that I've heard of. I haven't learned too much more about it, but I think it's really funny and cool. It's called carcinization. This refers to the fact that crab-like body plants have evolved at least five times. And then to bring it back to plants from the houseplant world, there are succulents that we call cacti because they're pokey, they're spiny, so they seem very cactus-like. And some of them are cacti, but some of them are actually an unrelated plant called euphorbia plants. So yeah, spininess again, this shows up.
Sam Jones: Wow, that's so fascinating. I noticed also in some of Ari's notes, so Ari's a big birder. They said that the birder internet jokingly calls falcons tactical assault parrots, which I thought was hilarious. That makes them seem a lot less intimidating.
Deboki Chakravarti: But also it makes parrots seem scarier.
Sam Jones: Yeah. I always think of them being ... I mean, they're funny and so smart, but I think of them being a little more docile, but it's in there. I don't know.
Deboki Chakravarti: At the very least, I think of them being goofy. I wouldn't want to get in the way of a parrot beak, but you think of them being just silly birds.
Sam Jones: No. They've got that killer instinct in there somewhere.
Deboki Chakravarti: Amazing. Let's wrap this one up. Thanks to Deb and Leo for your contributions to today's episode. And thank you for tuning into Tiny Show and Tell Us, a bonus episode from Tiny Matters, created by the American Chemical Society and produced by Multitude. And a big thank you to science journalist Arianna Remmel, who did the research for this episode.
Sam Jones: Send us an email to be featured in a future Tiny Show and Tell Us episode at tinymatters@acs.org, or fill out the form that's linked in the episode description. We'll see you next time.
References:
- Mysterious phenomenon with aurorae seen as far north as Hamilton
- Getting to know Steve
- What is STEVE, and how is it different from the aurora?
- New science in plain sight: Citizen scientists lead to the discovery of optical structure in the upper atmosphere
- Scientists discover what powers celestial phenomenon STEVE
- NASA Needs Your Help to Find Steve and Here’s How
- Morphological diversity in tenrecs (Afrosoricida, Tenrecidae): comparing tenrec skull diversity to their closest relatives
- Convergent evolution explained with 13 examples
- The wonderfully weird world of tenrecs
- Why Do Animals Keep Evolving into Crabs?
- Is My Cactus Really a Cactus?