IRA FLATOW: This is Science Friday, I’m Ira Flatow. How you all doing today?

A little later in the hour, a look at new recommendations for screening pregnant women for depression. We want to know, were you treated for depression during your pregnancy? We’d like to get you to call in if you can. Did you struggle with undiagnosed symptoms? Give us a call at 844-724-8255. That’s 844-724-8255. We’re going to get to that in just a few minutes.

But first, schizophrenia. It affects about 1% of Americans. Doctors know that patients usually develop symptoms in their ’20s, that a combination of environmental and genetics may play a role. But, the root cause of the disease still remains a mystery.

A new study out in the journal Nature now is one step closer in determining the origins of the disease. Maggie Koerth-Baker is here to tell us about that story and other selected short subjects in science. She’s a science journalist and author. She joins us from a Minnesota Public Radio. Welcome back.

MAGGIE KOERTH-BAKER: Hi, thanks for having me.

IRA FLATOW: Tell us about the findings, pinpointing something called synaptic pruning.

MAGGIE KOERTH-BAKER: Yeah, so this is the first major insight into the biology behind schizophrenia, and they’ve tied into this natural developmental process in your brain. You’re born with more connections between your neurons then you’ll ever have again.

Over the course of your childhood, your brain is kind of going through this process of trimming out connections that are redundant or that you just don’t really end up using. This is why it’s a lot easier to learn a language when you’re really young than it is to learn a language when you’re in your ’20s or ’30s. Because the parts of your brain that make the connections between language easier to learn have actually gotten pruned out as you don’t use them.

What they have found is that in early adulthood there’s a lot of this pruning happening in the prefrontal cortex. It’s the side of planning and strategic thinking in your brain, and the genes that accelerate the pruning process in this area are associated with the higher risk of schizophrenia.

That props up what we already know, which is that people with schizophrenia seem to have fewer connections in the prefrontal cortex than healthy people do. So, it seems like something’s going haywire with this pruning process and taking out a lot of connections that shouldn’t be taken out.

IRA FLATOW: But, we don’t know what that is yet.

MAGGIE KOERTH-BAKER: We do not know what that is yet.

IRA FLATOW: To be determined. Let’s talk about a planetary alignment happening. This is exciting. What should we look for? The planets are lining up.

MAGGIE KOERTH-BAKER: Right, so if you go out because between now and February 20, if you go out about 45 minutes before dawn, you will be able to see Mercury, Venus, Saturn, Mars, and Jupiter all at once. This is pretty cool, particularly because you don’t need a telescope to do this, although binoculars might help, especially for Mercury.

It’s just a coincidence. You have these various speeds and orbits of all these planets, and every so often they just to get into just the right place that you can see them all at once. It’s sort of like the astronomical version of going to Four Corners and standing in four states at once. You can do that right now.

IRA FLATOW: Yeah, well, can’t do it in the afternoon? I mean, you have to get at like 3 o’clock in the morning or something for this, right?

MAGGIE KOERTH-BAKER: Yeah, 45 minutes before dawn. It’s nuts.

IRA FLATOW: You’re way up the Minnesota. Have you been able to see it? Did you get out there?

MAGGIE KOERTH-BAKER: You know, Ira, I have a six-month-old, so if I have 45 minutes before dawn I am not doing it voluntarily.

IRA FLATOW: Well, I’m here and I’m gearing up for 2017 when there’s a total solar eclipse available all across the country. So, I’m putting that on my calendar.

MAGGIE KOERTH-BAKER: Yeah, that’s going to be really cool. That will be the first time in 38 years.

IRA FLATOW: Yeah, you know I’ve been counting down five years, four years. It’s now next year. Next year in the summer. I think summertime or spring, it’ll be great.

Let’s talk now of the growing use of neurobiological evidence in courts. It Sounds fascinating.

MAGGIE KOERTH-BAKER: Yeah, Emily Underwood had a really interesting story in Science this week that documents the rise of neurobiology in the courtroom. Most of this has been defendants using neuroscience to effectively, say my brain made me do it. There were 250 of these arguments that happened in 2012, and that’s double the number of those kind of claims since 2007. It’s been used for robbery, fraud, drug possession, murder.

What’s interesting here is that it’s rising in popularity, even though it doesn’t really seem to be all that effective. Insanity requires you to prove that you had a complete lack of understanding of the difference between right and wrong, and neuroscience evidence doesn’t really seem able to prove that.

I also think it’s personally really interesting, because it’s kind of tying into this big issue right now with science in the courts in general. A lot of forensics is being discredited. Things like bite marks and hair analysis. That’s presenting some really big questions about the ability of courts to understand and make effective use of scientific evidence.

It turns out that judges and juries don’t seem to have a lot of skill at being able to tell whether something is scientifically plausible.

IRA FLATOW: Yeah, they’re even calling into question fingerprinting and whether that’s reliable enough, and how skilled the expert has to be in the interpreting the fingerprinting.

MAGGIE KOERTH-BAKER: It’s a really interesting time of change, I think, in this field.

IRA FLATOW: Finally, another idea about the great mystery of why the zebra has its stripes. There was a famous poem about that years back.

MAGGIE KOERTH-BAKER: This is from a piece of the Atlantic by Ed Yong, and its exploring this research about why zebras have stripes. I think, like a lot of people, I learned in grade school or from children’s books that zebras have stripes as camouflage. That they’re hiding from lions and hyenas.

It turns out that this is an idea that, even though it’s repeated a lot in education, isn’t actually something that comes from evidence. It’s not something that had ever been tested. It isn’t something that we knew because of science, it’s just something people had sort of assumed.

These scientists kind of set out to see what you would actually see of a zebra’s stripes with the vision that large predators have. For instance, humans can clearly distinguish a zebra’s stripes from almost 600 feet away, but if you’re a lion, you have to be between 100 and 250 feet from the zebra. At that point, they could smell the thing already anyway, so it really wouldn’t be that effective as camouflage.

So, we’re kind of left with this space where we don’t really know why zebras have stripes. There are a number of different theories, including it could be defense against biting flies. It could also be something that helps the animals cool off, because of temperature differences between the white and black stripes create little currents of air over the surface of their skin. But, we now kind of have to admit, we don’t know why these stripes exist.

IRA FLATOW: So, they’re not for camouflage. At least that’s what this research shows.

MAGGIE KOERTH-BAKER: Yeah, apparently not.

IRA FLATOW: All right, well we’ll tackle that after we get clues on how the camel got it’s hump. So, we’ll get back to you on that one. Thank you, very much. Maggie Koerth-Baker is a science journalist talking to us from Minnesota Public Radio.

And, now it’s time to play Good Thing, Bad Thing.

[MUSIC PLAYS]

Because every story has a flip side. This time we’re talking about the winter weathercast. Right? Every day here on the weathercast there’s a wind chill factor and you think you know what that is. It’s an attempt to tell us what temperature feels like outside, as opposed to merely what the thermometer says. But is the wind chill factor accurate? And, just how did it get started?

It has a surprising history, and here with that is Joseph Stromberg. He’s a science writer in New York, and his story on wind chill recently ran on the Vox.com welcome to Science Friday.

JOSEPH STROMBERG: Hey, Ira, thanks so much for having me on.

IRA FLATOW: What is a good about windchill?

JOSEPH STROMBERG: Windchill, essentially, is good at one thing– which is what it’s designed to do– which is to tell people the risk of frostbite on exposed skin when they’re outside. The idea of windchill actually goes back to the 1940s when you had a pair of Antarctic explorers who did experiments treating bottles of water outside their hut.

Then, in more recent decades the National Weather Service updated the formula and, essentially, it’s supposed to tell you how prone you are to frostbite. It’s 35 degrees outside with a windchill 20, in theory, that means that your risk of frostbite is the same if it were 20 degrees with no wind at all. And the formula is pretty good at that.

IRA FLATOW: How did this originate? What was the idea, and who did this first?

JOSEPH STROMBERG: OK, so you had Sipel and Williams who were two Antarctic explorers– they were Americans– and, basically, the idea that wind made objects lose heat faster than otherwise was known for a while, so in their experiment they tracked how long it took bottled water to freeze. Based on that they came up with this formula.

The formula kind of exaggerated the effect of wind, so over the decades people updated it, but over time no matter how much it was calibrated it still this takes into account two variable, which is the ambient temperature and the wind speed outside.

Over time, meteorologists started to use it and the public picked up on it and interpreted it as, OK, windchill is what it feels like to be outside. But, that’s not really what the formula is meant to do. It wasn’t designed to do that, even to the present day.

IRA FLATOW: So, that’s really what’s bad about it, then. We misinterpret what it’s for.

JOSEPH STROMBERG: Yeah, I mean, in isolation it’s not a terrible formula, but there’s all sorts of other things besides temperature and wind speed that affect what it feels like to be outside. If you’re in sunlight, obviously, that makes you feel a lot warmer than if you’re in the shade, or it’s dark out. The degree of humidity, whether the wind is steady or whether it’s gusting. All these things make a pretty big difference.

As it happens, the most recent windchill formula, which was released in 2005, makes all kinds of interesting assumptions. It assumes that your face is totally uncovered and you’re walking into the wind at a steady rate for the entire time you’re outside. So, even if you just took shelter behind a bus stop, that’s going to change what it really feels like you.

The formula doesn’t take into account humidity or sunlight, whether you might actually have your face covered up. All sorts of things like that.

IRA FLATOW: And there’s not even an international standard on windchill, is there?

JOSEPH STROMBERG: There’s not. The current windchill index, which is a National Weather Service approved, and it used a lot of countries. But there have been attempts to improve on it. You have private weather forecasting companies like the Weather Channel and Wunderground. They have their own proprietary feels like formulas.

There was a consortium of European scientists a few years back that created something called the UTPI, which is an attempt to improve upon it using the variable that talked about, like solar radiation, humidity, and trying to calibrate it to actually match what it feels like for us to be outside. But they haven’t really caught on.

IRA FLATOW: Yeah, I’ve seen then the other feels like index. The Real Feel, things like that. There is an attempt to try improve because it just doesn’t tell you what you need to know.

JOSEPH STROMBERG: There certainly is, but it seems like windchill, for whatever reason, has kind of stuck. It’s one of the statistics that in the public imagination we give some kind of authority to.

IRA FLATOW: All right, Joseph, thanks for filling us in on that.

JOSEPH STROMBERG: Thanks, so much.

IRA FLATOW: Stay warm. Joseph Stromberg is a science writer, and his story on windchill recently ran on Vox.com.

Copyright © 2016 Science Friday Initiative. All rights reserved. Science Friday transcripts are produced on a tight deadline by 3Play Media. Fidelity to the original aired/published audio or video file might vary, and text might be updated or amended in the future. For the authoritative record of ScienceFriday’s programming, please visit the original aired/published recording. For terms of use and more information, visit our policies pages at http://www.sciencefriday.com/about/policies.