Today you’ll learn about controversial research by NASA suggesting that extinction-level asteroids may have hit Earth more often than we thought, how scientists are working to create electricity out of thin air, and the effects of using exclusively male mice in scientific research.
Today you’ll learn about controversial research by NASA suggesting that extinction-level asteroids may have hit Earth more often than we thought, how scientists are working to create electricity out of thin air, and the effects of using exclusively male mice in scientific research.
Species-Ending Asteroids
Air Into Electricity
Female Mice
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Find episode transcripts here: https://curiosity-daily-4e53644e.simplecast.com/episodes/species-ending-asteroids-air-into-electricity-female-mice
[SFX: INTRO MUSIC/WHOOSH]
NATE: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from Discovery. Time flies when you’re learnin’ super cool stuff. I’m Nate.
CALLI: And I’m Calli. If you’re dropping in for the first time, welcome to Curiosity, where we aim to blow your mind by helping you to grow your mind. If you’re a loyal listener, welcome back!
NATE: Today you’ll learn about controversial research by NASA suggesting that extinction-level asteroids may have hit Earth more often than we thought, how scientists are working to create electricity out of thin air, and the effects of using exclusively male mice in scientific research.
CALLI: Without further ado, let’s satisfy some curiosity!
[SFX: WHOOSH]
NATE: James Garvin, the chief scientist at NASA's Goddard Space Flight Center and a team of researchers have presented findings that suggest that serious asteroid impacts have happened more often and even more recently than we thought.
CALLI: Oh, good. That's a happy thought.
NATE: Well, let's talk about the research and see how you feel.
CALLI: All right. Sure. Go on.
NATE: Dr. Garvin and his team looked at four known impact craters in different parts of the world. They wanted to know if their official measurements were accurate so that they could create high resolution maps of the area.
CALLI: Well, why wouldn't they be accurate? Can't you just aim a satellite at the crater and measure it?
NATE: In theory, sure. In the intervening years between the impact and now, forests have grown and erosion has happened. And, you know, things change. So what Dr. Garvin was looking for was evidence that the outer rims of these craters were actually beyond what we can see today.
CALLI: Oh, that makes sense. So how do you measure something you can't see?
NATE: You need a new pair of glasses. They used high resolution satellite data from a company called Planet and used NASA's laser satellites to measure height. The precision of the data allowed them to essentially look through the tree cover, and with the information they found, they built massive, four meter high res maps of the four craters that they were studying.
CALLI: That's a lot to just analyze some craters.
NATE: Well, that's not all. They used an algorithm that was designed to find craters on Mars to analyze the maps, which on a personal note, I think is really cool because, like, we're using space technology to get to know more about Earth instead of the other way around. Anyway, the algorithm predicted that the diameters of each crater was in fact larger than everyone thought.
CALLI: Oh, okay. So what does that mean?
NATE: To put this in context, if these new findings are proven accurate, then the energy released from these four asteroids alone would have been something like 400 or 500,000 megatons, meaning they wouldn't have been as big as the famous dinosaur killer. But they absolutely would have had an impact on climate and could have caused the extinction of certain species of plants and animals. And it also puts into perspective the resiliency of our planet that impacts this big have happened in the recent past. Shows that Earth is one tough cookie.
CALLI: Right. The Earth survived. But will we? And how soon is the next one coming? Like, does homeowner's insurance cover 500,000 megaton asteroid explosion?
NATE: You might have to ask your agent on that one. There are two primary reasons why you shouldn't let this one keep you up at night. First, is that as compelling as the research is so far, many planetary scientists remain skeptical because they say more research is needed to back up these findings. And in fact, Garvin even agrees.
CALLI: That scientists are natural skeptics.
NATE: Yeah, and that's how it should be. There needs to be on the ground fieldwork done, you know, visits to the new predicted boundaries and other studies to confirm or rule out Dr. Garvin's research.
CALLI: What is the other reason I shouldn't be too worried?
NATE: Well, they all pretty much agree that whether or not these findings are confirmed, our future risk from impacts won't actually change.
CALLI: And is it a high risk or a low risk?
NATE: I'll put it this way You probably don't need to worry about increasing the insurance on your house.
CALLI: Okay. I won't build a bunker either then. I might still build a bunker.
[SFX: WHOOSH]
CALLI: Are you upset about your recent electricity and gas bills? Australian scientists have discovered something that might give you energy for less money. It's called air.
NATE: So wonderful commercial. Thank you. Are you saying that scientists have discovered air?
CALLI: I am saying that scientists have discovered an enzyme named Huc that converts air into energy. Enzymes, if you don't know, are proteins that help create a specific chemical reaction. And Huc is almost like a natural battery that might literally be able to power devices out of thin air.
NATE: That does sound pretty impressive. How did they figure this out?
CALLI: A research team led by Rhys Grinter found Huc and common soil bacterium. Their most recent work showed that many bacteria actually already use hydrogen from the atmosphere as an energy source in places with poor nutrients. So, for instance, this usually happens in Antarctic soil, volcanic craters or the deep ocean. They identified Huc as an enzyme that does this in the bacterium called Mycobacterium Smegmatis. But the weird thing is, unlike those other enzymes, Huc turns hydrogen into gas, into an electrical current.
NATE: That's insane. Isn't hydrogen something like 0.00005% of the air we breathe?
CALLI: It is. And that's what makes Huc such an interesting enzyme for this project. It's important to note that there is a very small amount of hydrogen in the air we breathe. What Huc does is use that hydrogen to create an electrical current, almost like a hydrogen scavenger, because it's able to track down that trace amount of hydrogen in the air. This is weird because most other enzymes just can't do this. The team used a number of methods to figure this out. For instance, they used an advanced sort of microscope to figure out how Huc structure works at an atomic level. They also used electrochemistry to show how Huc can create electricity with even the smallest concentration of hydrogen.
NATE: Wow. Okay. But why this bacterium?
CALLI: So mycobacterium smegmatis was discovered back in 1884 by a doctor named Sigmund Lustgarten, who was researching skin diseases. I know that makes M. Smegmatis sound scary, but surprisingly it's not really linked to skin diseases. It lives in the soil, is pretty well studied because it's a good model to use when studying something like tuberculosis and it doesn't cause disease. And the best part is that when you need to study bacteria, you need to be able to change its genomes. Those methods already exist for M. Smegmatis, meaning that the extraction of the Huc enzyme is a lot easier than it would be for many other bacteria.
NATE: No kidding. Wow.
CALLI: But the thing that makes Huc good to continuously generate energy is that you can store it for long periods of time in less than ideal circumstances. For instance, Ashleigh Kropp says you can freeze husk or even heat it up as high as 80 degrees Celsius, which is 176 degrees Fahrenheit. And it will still have the power to create energy. Which means that no matter where you are, you can create energy out of thin air. Because of Huc status as a natural battery.
NATE: That sounds pretty awesome, honestly. So what's next for the Huc team?
CALLI: The research isn't very far along yet. The team knows Huc can generate energy, but haven't put it to practical use yet. Still, there's so much potential here to create small air power devices that could even replace solar energy. The bacteria that creates enzymes like Huc are very common and can be grown on a wide scale too, which means this is a potential sustainable energy substitute. So the next step for the team is to scale up production of Huc. Because once Huc is being produced in large enough quantities, the sky is the limit, quite literally.
[SFX: WHOOSH]
NATE: Here's a pretty broad statement for you: scientists don't understand women's brains.
CALLI: We're not meant to be understood.
NATE: Well, it turns out there is a very interesting reason why.
CALLI: Sure. Is it because we are, let's say, too complex, too complicated for any unwitting scientist to get their head around? Do we outsmart the tests?
NATE: No. It actually has everything to do with mice.
CALLI: Mice.
NATE: Mice? Yeah. Let me explain. Scientists have used mice in behavioral and neurological experiments in studies for decades. And for the whole history of these studies with mice, they've used male mice almost exclusively. But a new study from Harvard Medical School suggests that this may have been a really harmful error.
CALLI: For any sane person, At least on the surface. That sounds like a terrible mistake. Why on earth would they only test on male mice?
NATE: There are a few reasons, but if you'll let me oversimplify it just a little bit.
CALLI: Oh, please.
NATE: It mostly comes down to bias. Mostly, the scientists have always just assumed that the hormone cycle of female mice would influence the consistency of their behavior. In other words…
CALLI: Oh, my God. They thought they'd be too hormonal.
NATE: Yeah, basically. And believe it or not, they had some cause to believe this as the hormone cycle in mice fluctuates fairly dramatically. And if you're trying to study behavior or neurological functions, you want a mouse of some consistency, Right? But the new study changes everything.
CALLI: I'm already furious. Please go on.
NATE: Before we talk about the findings of the study. Let's talk about mice. Professor of Neurobiology in the Blavatnik Institute at Harvard, Sandeep Robert Datta was a co-lead of the study, along with Rebecca Shansky of Northeastern University. Datta says that most of our understanding of the relationship between genes and neural circuits and then between those neural circuits and actual behavior comes from research done using mice. And there's a reason for that.
CALLI: I'm guessing it's not because mice are cute.
NATE: That's just an added bonus for the scientists. It's because mouse brains and human brains are surprisingly similar, both in organizational structure and genetically. In fact, Dutta considers mice, quote, the flagship vertebrate model for understanding how the brain works.
CALLI: Uh huh. Just not female mice.
NATE: Well, yeah. Studies have been coming out showing that in most, if not all, biomedical research, female mammals have just sort of been forgotten. And Dutta and Shansky and their team wanted to understand whether or not that bias was justified. So the study, the study, they put a female mouse in a five gallon bucket for 20 minutes and recorded its every move. They swabbed the mouse to measure its estrogen and other hormone levels and then repeated the test with the same individuals several times.
CALLI: What were they looking for with this bucket challenge?
NATE: Here's where it gets interesting. They used an AI technology called Moses to break down the mouse's behavior, its body language, its rearing up, stepping, pausing, turning, and so on. They were trying to assess something they call exploratory behavior, which is one of the basic things they look at in just about any study on mice behavior.
CALLI: Okay. What did they find?
NATE: The mouse's estrus status had almost no effect on their behavior, but it gets even better when they did the same tests on the males. What they found turned 50 years of bias on its head.
CALLI: Please tell me the male mice were more hormonal than the female.
NATE: Well, no, but they were less consistent. Both male and female individual mice showed a lot of differences between each other. Datta said that he got to know each individual so well that he could identify them by their personalities. So they were individually unique, but the females were each consistently unique. Their individual behavior stayed pretty constant, regardless of their hormonal changes. But not so much with the males.
CALLI: So let me get this straight. The males were actually more moody than the females?
NATE: I don't know if I would put it that way, but sort of, yeah. In fact, the researchers said that not only should future experiments be conducted with a mix of female and male mice, but also that if you could only include one, you should use females. And that has huge implications.
CALLI: I can imagine that assuming females weren't useful, test subjects led to some really bad research.
NATE: And some bad outcomes for human women. Drugs developed using only male test subjects might not be as effective for female patients or might even have unforeseen harmful side effects.
CALLI: So problem found and solved?
NATE: Sadly, it's not that easy. Bad habits are hard to break in. All while the recommendation is to use a mix of male and female subjects in studies, there's no rule forcing researchers to do so. It's going to take a pretty big cultural leap to solve this problem once and for all.
CALLI: This is the most ridiculous problem I've seen science face in a long time.
[SFX: WHOOSH]
NATE: Let’s recap what we learned today to wrap up. NASA scientists took new measurements of recent large meteor strikes and suggested that the impacts were much larger than we previously thought. If this is supported by further research, it means that we’ve been bombarded more frequently, and by more massive impacts than we ever knew.
CALLI: Upset about that electric bill this month? Soon, you might be able to generate that electricity yourself - with AIR. An enzyme has been found in a form of bacteria known as Mycobacterium smegmatis that has the ability to convert the very small amount of hydrogen in the air we breathe into energy. The work is still in its early stages, but the team is confident that if they can harvest enough of the enzyme produced by this bacteria - well, the sky’s the limit.
NATE: Turns out science has been ignoring half the population for quite some time now. A new study from Harvard reveals that tons of scientific studies use male mice as test subjects exclusively. Male mice are potentially less predictable than female mice, the study found, so now there is a push for equal gender representation in mice-based research in order to better understand the female body.