IRA FLATOW: This is Science Friday. I’m Ira Flatow. Later in the hour, why a scientist peeled starfish off rocks and chucked them into the ocean. Trust me, he did it for a good reason.

But first, there’s been a heated energy in this year’s political race that we really haven’t seen before. Remember the Dean scream that ended Howard Dean’s try for the presidency in 2004? Well, you know, this year, that would have been considered a peep.

Donald Trump told the New York Times editorial board that if his events get a little boring, all he needs to do is mentioned the wall, and the audience goes nuts. What’s the cause of all this audience arousal?

Maggie Koerth-Baker is here to tell us about that, and other selected short subjects in science. She’s a science writer based out of Minneapolis. Welcome back.

MAGGIE KOERTH-BAKER: Hi. Thank you.

IRA FLATOW: So there’s something called emotional contagion here?

MAGGIE KOERTH-BAKER: Yeah. So this is kind of how we humans automatically and unconsciously influence each other’s feelings. And it’s based around mimicry of external expression. So you watch other people’s gestures– their voice, their facial expressions. And you end up sort of mimicking those without really intending to. And the more you mimic those, the more you change your internal feelings.

So this happens all the time. You’ve probably experienced it if you’ve ever gone out to coffee with an anxious friend and came away from the experience feeling anxious yourself, even though you didn’t have the same reason to feel upset. But it also happens in the workplace with your boss. And it’s something that can also happen at political rallies.

Now, we tend to talk about this in the context of peers influencing one another, or somebody at the top influencing the people at the bottom– you know, the leader influencing the followers. But it turns out that it’s a little bit more complicated than that. And the experts that I spoke to for a story that I wrote about this at FiveThirtyEight this week told me that followers can influence their leaders, as well.

And that was really interesting to me, because FiveThirtyEight had done a documentary about the Dean scream that you mentioned.

IRA FLATOW: Right.

MAGGIE KOERTH-BAKER: And in that documentary, Howard Dean was talking about how, throughout the campaign, he just kept having these moments where he knew that he was supposed to kind of tone down his excitement. And he couldn’t, because whenever he did, the audience didn’t look all that interested. And he wanted to feel the energy from them. And he wanted to feel the excitement. And so he would get excited. And then they would get excited. And then he would get even more excited. And the next thing you know, he’s being painted as somebody who doesn’t have the temperament for the presidency.

IRA FLATOW: Well, how long ago. How close it really was to now. How different things really are. How long does the contagion last? Do we still feel it once we leave the rally or the ballpark or wherever this stuff is happening?

MAGGIE KOERTH-BAKER: You can, definitely. And what’s interesting about this is it’s not just about what you feel. It’s about what you do with those feelings. So emotional contagion is you picking up feelings from other people. But then those feelings shape the choices and the decisions you make later.

And there’s been a lot of studies about this, how it functions top down. But despite the importance that it has, obviously, to these political rallies– to interactions even with your boss in your office– there’s only been a couple of studies that looked at it from the bottom-up influence– the way the followers influence leaders.

IRA FLATOW: Yeah. Because you hear people up on stage saying, I get my energy from the audience.

MAGGIE KOERTH-BAKER: Right. And that’s exactly what that is.

IRA FLATOW: Yeah. Go to any talk show and be in the audience for the warm up. And that’s exactly what they’ll tell you– scream loud, because they get their energy from it.

MAGGIE KOERTH-BAKER: Yeah.

IRA FLATOW: Well, let’s move onto another topic. I understand that DARPA is– you know, they always turn to the crowd to help them invent things. And they want people to weaponize a vacuum cleaner? Household items?

MAGGIE KOERTH-BAKER: So, they’re looking for a few good MacGyvers. After years of having terrorists in the Middle East, creating these improvised bombs that are used for roadside explosives, DARPA is trying to get out ahead of the threat of off-the-shelf technology by inviting private citizens, companies, experts to figure out how everyday technologies can be used to kill innocent people.

So they’re looking at commercial software, open-source code, readily available materials like vacuums, toasters, RC cars. And they want you to kind of bring them some ideas of how you might use these items to build something that could be a weapon. It’s similar to the way that a company will hire hackers to break in through their security before an actual bad guy does. You know, it’s all about preventing surprise.

IRA FLATOW: Yeah, well, all you have to do is do a bad home canning job on somebody’s fruits, and you got botulism all over the place.

MAGGIE KOERTH-BAKER: Right. Yeah. So a vacuum, two avocados, and a cigar, and you might be able to help the Defense Department.

IRA FLATOW: What could go wrong here? I mean if thousands of people are sending in cheap ways to make bombs, and everybody learns about that, what could go wrong here?

MAGGIE KOERTH-BAKER: Well, I think that part of it is the Defense Department saying that everybody knows about these things already. And that it’s not actually a big secret. I think probably all of us who ever thought about terrorism have sat around and thought, well, if I was evil, this is what I would do. And the Defense Department is just trying to take those sort of off-the-cuff ideas, and see which ones could actually be feasible in the real world.

IRA FLATOW: Let me move on to an interesting story about European storks– are finding new nesting grounds in landfills?

MAGGIE KOERTH-BAKER: Yeah, so the historically European white storks are migratory. They flew to Africa in the winter. And they’d spend the colder months there. But humans have really changed their pattern.

So climate change has warmed up southern Europe. Invasive American crawdads are turning out to be something that the birds like to eat. And our trash piles are also providing a really nice place to find food. And so storks in Portugal and Spain are now sticking around all year.

Back in 1995, you had about 1,100 birds living in Portugal. And now it’s more like 14,000. And 80% of them are hanging out in landfills.

IRA FLATOW: Wow. And finally, I understand that researchers found a tiny T. rex. But we shouldn’t get too attached to it just yet.

MAGGIE KOERTH-BAKER: Yeah. So this is something that I’m researching for a story next week. Researchers announced on Monday that they had identified a new species of dinosaur called Timurlengia euotica. And it’s about the size of a horse. And it’s kind of this middle stage of development between T. rex going from something that was very tiny to something that was very big.

But here’s the catch. So I got to digging around in this research on dinosaur naming. And it turns out that there are a lot of reasons to be skeptical of just about any newly-named dinosaur species. So from about 1820 to 1980, the error rate for new dinosaur species was 50%.

And we don’t know how high it is today, according to University of Bristol paleontologist Michael Benton, because there hasn’t been enough time for scientists to go back and really reevaluate the more recently named species. So about half of the dinosaurs that are getting named, there’s a decent chance that they aren’t actually new species.

IRA FLATOW: Wow. Stay tuned, in other words.

MAGGIE KOERTH-BAKER: Yeah.

IRA FLATOW: Yeah. All right. Thank you, Maggie. Very interesting stuff.

Maggie Koerth-Baker is a science writer based out of Minneapolis. So we’ll see you next time.

MAGGIE KOERTH-BAKER: Thanks a lot.

IRA FLATOW: And now it’s time to play Good Thing Bad Thing. Because every story has a flip side. And if you’ve spent much time by the sea, you know that, given a chance, barnacles seem to find a home on everything. They’re on jetties, they’re boats, and whatever. Well, add to that the plastic debris in the middle of the ocean.

Joining me now to talk debris-riding barnacles is Dr. Mike Gil, one of the authors of a study on barnacles on plastic waste, published recently in the journal Scientific Reports. He’s a postdoctoral fellow in the Department of Environmental Science and Policy, University of California at Davis.

Welcome to Science Friday.

DR. MIKE GIL: Thanks a lot, Ira. Appreciate it.

IRA FLATOW: It’s hard to say, yay, floating debris! But there’s some good out there.

DR. MIKE GIL: Well, you know, I would argue that it’s kind of challenging to pull some good news out of this study. But I would argue that the study, as a whole, is a good thing in that shed some new light on a pressing, but poorly understood topic in environmental science, which is understanding how all this plastic debris is interacting with nature.

And as you alluded to, what our study revealed is that the smooth surfaces of many of these pieces of plastic debris appear to become more attractive homes to a greater diversity of animals if these barnacles first step in and colonize the debris. And I’m referring to a specific kind of barnacle, known as a gooseneck barnacle. It gets its name from the fact that it has this long, extended stalk that forms the base of its body.

And so you could think of these barnacles as being functionally similar to trees in a rainforest in that they produce a tremendous amount of structural complexity on an otherwise structure-free, flat surface. And this structural complexity provides nooks and crannies and hiding places for other animals to then come in and occupy– and in turn receive protection from things like predators and high winds and waves that could knock these animals off of their new plastic homes floating at the surface of the ocean.

IRA FLATOW: So you’re building like a whole new ecosystem out there where didn’t exist before. So what could be bad about this?

DR. MIKE GIL: Well, so the negative is actually closely related to what I just described to you. So superficially it may sound like a good thing, that barnacles make plastic garbage a more attractive home to more animals. Until you consider the fact that some of the species that will end up on this debris will use the debris like a luxury cruise liner to cross vast areas of open ocean, and ultimately end up in new coastal ecosystems.

And we know that when foreign species enter new ecosystems, they have the potential to become invasive– meaning their populations could grow out of control and have dire consequences for the local plants and animals, and ultimately the local economy, that may be based, in part, on native species. And so ironically, it’s the diversity of animals that we find on these floating plastic islands, these artificial ecosystems, that could potentially compromise the biodiversity along natural coastal ecosystems that we value tremendously for economic reasons.

IRA FLATOW: You know, when cruise liners dock, the passengers love to get off and shop. So that’s what you’re afraid of happening here.

DR. MIKE GIL: Exactly. Yep.

IRA FLATOW: And so their efforts to provide a habitat, perhaps– you know, there have been, I should say, efforts on oil rigs and subway cars and stuff dumped into the oceans. Is that a bad thing?

DR. MIKE GIL: Well, the species we’re referring to that are typically colonizing these plastics aren’t the kinds of species we’re worried about being endangered–not things like creating an artificial reef in a shallow-water system. This is more a combination of what we call obligate rafters– species that only persist on rafting pieces of debris– in combination with a random assortment of animals that came from shallow-water systems, and basically hitchhiked on top of these pieces of plastic to arrive at wherever the plastic takes them.

IRA FLATOW: Mm hm. All right. Quite interesting. Thank you very much for taking time to be with us today.

DR. MIKE GIL: Absolutely. My pleasure.

IRA FLATOW: Michael Gil, a postdoc fellow at the University of California Davis.

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