AILSA CHANG, HOST:
Time now for our science news roundup from Short Wave, NPR's science podcast. I'm joined now by Regina Barber and Nate Rott from the show. Hey to both of you.
REGINA BARBER, BYLINE: Hey.
NATE ROTT, BYLINE: Hey, Ailsa.
CHANG: Hey. OK, so as usual, you guys have brought us three science stories that caught your attention recently. What's in store for us this week?
BARBER: Hurricane-induced evolution in lizards.
ROTT: A new way to check the authenticity of certain artifacts.
BARBER: And new research that could link extreme heat to a range of health emergencies, beyond heat stroke and dehydration.
CHANG: Whoa. OK, super relevant right now. But I want to start with these lizards who apparently are evolving because of hurricanes. What?
BARBER: Yes. So this story is set on these two islands in the Caribbean. These islands were walloped by Hurricanes Irma and Maria about a decade ago. And researchers wanted to understand how these hurricanes might have affected populations of lizards that live there. They're called Silver Key anoles.
ROTT: And in particular, they wanted to know why the surviving lizards from these hurricanes seem to have shorter fourth toes on their hind feet.
CHANG: (Laughter) Shorter toes on their hind feet - what's up?
ROTT: Well, the researchers think that these shorter toes might have given the lizards a selective advantage during these hurricanes, where they endured these incredibly strong winds.
BARBER: Yeah, it's physics. It turns out the shorter toe gives the lizard more leverage to hold on to the branch better than a longer toe. And at Princeton University, evolutionary biologists tested this out. They put lizards in front of a fan to simulate tropical storm force winds.
CHANG: Oh, my God, poor lizards.
(LAUGHTER)
ROTT: Yeah, we asked one of the researchers, Shane Campbell-Staton, if the lizards seem annoyed by this.
SHANE CAMPBELL-STATON: So they are as annoyed as you would expect from, you know, somebody blowing a bunch of wind in your face. You know, but the trials themselves are actually very short. A net catches them.
ROTT: So the lizards were totally fine. And it turns out that the lizards with the shorter toe were able to cling on for a half a minute longer than ones with longer toes.
BARBER: But what's really cool about this study is that researchers were able to confirm a specific gene that was linked to making these toes shorter - like, showing that these hurricane force winds likely shaped the genes of subsequent, like, generations of these lizards, something they wrote about recently in the journal Current Biology.
CHANG: Wait, so, like, why did these scientists even get obsessed in the first place about the toes of these lizards?
ROTT: Well, so by teasing apart all the genes at play here in follow-up research, they're hoping that it'll give geneticists a deeper understanding into how, you know, multiple genes interact with each other and the environment to drive changes in animals. And it could help researchers understand how other animals might be able to adapt to rapid changes in the future.
CHANG: Ah, OK. All right.
ROTT: There you go.
CHANG: From lizards to artifacts.
BARBER: Yeah.
CHANG: Let's go.
(LAUGHTER)
ROTT: Yes.
BARBER: Yeah.
ROTT: OK, so this study is looking specifically at clay artifacts, like pottery figurines, which, Ailsa, if you've ever been to a museum, you know they hold a pretty important significance in human history.
CHANG: Yup.
BARBER: And one of the issues that museums and law enforcement agencies face today is that people will sometimes sell forged or fake clay antiquities.
CHANG: Yeah, like, they'll claim a piece of pottery or some figurine is thousands of years old when it's totally not.
BARBER: Yeah, exactly, Ailsa. And to be clear, this isn't new.
YOAV VAKNIN: There was fraud of statues already in the Roman period, so it's something that goes back a long time.
ROTT: That's Yoav Vaknin. He's a postdoctoral student at the Scripps Institution of Oceanography and the lead author of this new study, which describes a new way to determine whether something is legit or not.
CHANG: Interesting. OK, tell us how this works.
ROTT: Magnetism, Ailsa.
BARBER: It's physics again.
ROTT: Yeah.
(LAUGHTER)
ROTT: So when you take a piece of raw clay and you put it in a kiln, the iron-bearing minerals in that clay will align with the Earth's magnetic field.
CHANG: Whoa.
VAKNIN: Kind of like you can imagine a needle of a compass but on the atomic level.
BARBER: And when that clay starts to cool, the larger particles get locked into that position, creating kind of a permanent record of the Earth's magnetic field at that moment.
CHANG: Wow. So it's, like, unique to that particular time and place on Earth, and scientists can use that data to date the pottery.
BARBER: Unfortunately, no, because...
CHANG: Oh.
BARBER: ...The objects have moved from their...
CHANG: Darn.
BARBER: ...Original position. But...
ROTT: Yup.
BARBER: There are these smaller particles that don't get locked into position, and their magnetic signatures never really settle, so they move with the Earth's magnetic field over time.
ROTT: Yeah, and the secondary magnetic signal can be erased by reheating the object. And what Yoav and his colleagues discovered is that it takes hotter temperatures to erase it in old objects than it does in new.
CHANG: Huh. OK, so you could theoretically test to see if an object is old or authentic versus new and forged just by reheating it?
ROTT: Yeah. They tested old artifacts, and they found that if it takes above 112 degrees Celsius to erase that secondary magnetism, the object is indeed more than 1,000 years old.
CHANG: Oh.
ROTT: Now, I will say, Ailsa, you need very specialized equipment to do this, but the method, described in the proceedings of the National Academy of Sciences, could be used by museum curators or others to determine if artifacts are indeed legit in the future.
CHANG: Well, speaking of heating or reheating...
BARBER: Yeah.
CHANG: Let's get to our final topic. Let's talk about these health issues linked to extreme heat.
BARBER: Yeah, more on the serious news here. We know that climate change is linked to more frequent and more severe heat waves, but we still don't know the full impacts of those heat waves on human health. So researchers in Chicago analyzed almost a million ER and urgent care visits over the past 12 years. And they did this to find which diagnoses were correlated with periods of extreme heat in the city, basically going in without a preliminary idea of what they're looking for, just running through the data and looking for patterns.
ROTT: Yeah, and what they found wasn't just, like, your typical culprits from heat, like dehydration or heat stroke. Really hot days were also associated with things like higher diagnoses of kidney failure, of skin rashes, of swelling, of mental and behavioral disorders, assault and, Ailsa, even traffic accidents.
CHANG: I mean, I feel like that kind of makes sense because when it's really hot, people kind of go out of their minds, yeah?
ROTT: I mean, yeah, totally. So, like, researchers told us that, like, some of these more mental- and behavior-related diagnoses, they might be due to heat stress. Like, let's listen to one of the researchers on this project.
ABEL KHO: We do know from prior literature that when it's hot out, people are under a lot of stress - mental, physiologic stress - and behaviors change. People are out more.
BARBER: So, that's Dr. Abel Kho. He lives in Chicago, where he's a professor of medicine at Northwestern University, as well as a practicing physician, and he was part of the team that did this research. They recently published a paper with these findings in the journal Science Advances.
CHANG: OK, got it. So now that they found these associations, what do you do with them?
BARBER: So Abel and the other experts we talked to said, it's important to note that these are looking at associations, not causality. Maybe that's the next step - like, figuring out why extreme heat might exacerbate these health issues and how to deal with it.
ROTT: And Ailsa, I want to just plug really quick - speaking of extreme heat studies, NPR climate correspondent Alejandra Borunda has been working on a huge project with Boston University scientists to investigate undercounted heat-related deaths across the country. I highly encourage people to listen to it, look for your county and track the number of heat-related deaths near you at npr.org.
CHANG: That was Nate Rott and Regina Barber of NPR's science podcast Short Wave, where you can learn about new discoveries, everyday mysteries and the science behind the headlines. Thanks to both of you.
BARBER: Thank you, Ailsa.
ROTT: Thank you.
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