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Hello, welcome to the latest dose of science news from New Scientist. I'm Rowan Hooper and joined again by Chelsea White, now back in New York. Hey, Chelsea. Are you missing the fog and the crumpets of London town? I do miss you all in the London office. Oliver Twist. Yeah, but fall in Manhattan is my favorite time of year, so I'm glad to be back.
On the show this week, we're hearing from a neuroscientist who scanned her own brain 75 times over a few months and measured how it changed in volume depending on whether or not she was on the birth control pill. We're also hearing some... for once hopeful news on climate change as the overall amount of heat energy being gained by the planet has fallen from a record set in 2023. That's coming up, but first we're starting with ancient crime.
I think everyone is fascinated by crime stories when a famous old case is solved. And in this story, we have a very cold case. an 800-year-old account of a body being stashed in a well inside an ancient Norse castle way back in 1197. Rowan's been hearing about it from our Australia reporter, James Woodford. Rowan? In 1938, a body from that well was recovered, and in 2014 and 2016, more of the body was found, and now researchers say they've cracked the mystery of well man.
as he's been, of course, called. Okay, James, you're going to be Sherlock for this. I'm going to be Watson. Tell me the evidence that links the body in the well and the saga. Hey there, Rowan. Can you just indulge me for a minute while I read a little bit from an ancient Norse saga? Oh, yeah. Go ahead. Okay, this is from the Sveris saga, 182. verse Old Norse text recording the exploits of King's Fair Sigurdsson who rose to power in the second half of the 12th century.
And it concerns a raid that took place in 1197 at Sversborg Castle near Trondheim, Norway. And I'm not going to try and do this with my Viking accent. But here goes. The Bagels seized all the property in the castle and then burnt every building of it. They took a dead man and cast him into the well. and then filled it up with stones.
Before they left the castle, they called upon the townsmen to break down all the stone walls, and before they marched from the town, they burnt all the king's longships. After this, they returned to the uplands, well pleased with the booty they had gained in their journey. The Vikings are always pleased with their actions, aren't they? They're not contrite or anything, are they? What happens next, James? Now we fast forward to 1938, just a mere 800 or so years.
And although not much is known about the events surrounding the recovery of a skeleton from the same well that was mentioned in the saga, what we do know is that... At that time, remains were retrieved from the well and it was assumed to be the well man from the saga. The technology did not exist last century to prove that. And then as you mentioned at the beginning, in 2014 and 2016, more remains were recovered by archaeologists.
And their studies confirmed that the skeleton was from a 30 to 40 year old male. And then since then, the gene technology required to study the skeleton. has become more accessible to researchers and this week a Norwegian team has revealed some really astonishing results. Firstly they radiocarbon dated the remains and found it was the right age for that battle way back in 1197, then DNA analysis has suggested that the man most likely had blue eyes.
and blonde or light brown hair, they also believe his ancestors were from the southernmost Norwegian county of present-day Vest-Agde. And as Michael Martin... at the Norwegian University of Science and Technology in Trondheim says, a big surprise is that the raiders who attacked the castle most likely threw one of their own into the well.
The most surprising thing to us, the research team, was in regards to the wellman's ancestry. It had previously been assumed that the attacking army from southern Norway had thrown the body of the dead man in the well to... Basically to poison the local drinking water source for the local people and the local army there in middle of Norway. They had already burned down all the buildings and destroyed the castle.
But we found the man in the well's ancestry traces back not to the local area around the castle, but to the very southernmost counties of Norway, where the attacking army had actually been raised. So if you can imagine doing such a cruel and violent act, could you imagine using the body of one of your own allies rather than the body from the opposing side? That was the real shocker for us.
So in this kind of way, the ancient DNA analysis has added some new details to a story that has been told for nearly 900 years. And it's enriched it with details about the backstory of a minor character that we couldn't have known otherwise from simply reading the historical text. What a great example of how new technology and science is shining a light onto...
stories from the past, James, isn't it? It does remind me actually of the Richard III case here in Britain. A few years ago, they found a body under a car park in Leicester and DNA analysis of that supported... the identification of that skeleton as Richard III, the last Plantagenet King of England. So, James, is it case closed? Look, the researchers say that they are confident.
that the skeleton is the same man who got a mention in the ancient saga, but of course they admit it's impossible to prove beyond any doubt. However... The circumstantial evidence is certainly very strong. So I'd say cold case closed. As we all know in the past year or so we've seen some extreme warming.
Temperature records have been smashed all around the world. And this year is on course to be the hottest on record, with an average global surface temperature more than 1.5 degrees above pre-industrial times. Yeah, and this has led to fears that global warming is accelerating. and that there may be flaws in climate models that mean those models are underestimating how much warming we're in for. I don't know about you, Chelsea, but I've certainly seen some pretty terrifying claims.
and assertions being made on social media, real doomster stuff. But in a rare bit of good news, it's looking like those fears are unfounded. Michael Lepage is here. Michael... Actually, what are you doing here with good news? Yes, I know it's very unusual, but very happy to go against the usual. Yes, so this is all about a key measure of global warming known as energy imbalance.
the energy imbalance has been rising fast. And in the first part of 2023, it spiked to record levels. That's what led some people to suggest that the climate models are getting it wrong. But the good news is that since then the energy balance has fallen sharply. Well, that's good to hear, but can you go into a bit more detail about what that energy imbalance is?
Yes. So when people talk about global warming, they usually refer into the surface temperature, that's the temperature of the air a couple of meters above the land or sea. That's obviously what we care about, because we live in this thin layer of air. But it's just a small part of Earth's climate system.
So there's the rest of the atmosphere and the oceans and the land surface too. So how do we tell how much this entire climate system is warming? Well, to do that, we need to look at what's called its heat content, how much energy it's got, and whether it's gaining or losing heat. energy. So basically, if the earth radiates or reflects as much energy to space as it's gaining from the sun, then that heat content stays the same.
But now, because rising greenhouse gas levels are blocking heat emissions to space, the planet is gaining more heat than it loses. That's the energy imbalance. So it does sound quite tricky to measure, Michael. How do they do that? It's not easy. It's done mainly using instruments on satellites. So these instruments measure how much sunshine is reflected immediately, say by clouds or by ice. They also measure how much of the heat energy rate.
radiated from warm surfaces actually manages to escape into space. And so if you compare those to how much sunshine is hitting the planet in the first place, you can work out what the energy imbalance is. Now we've had these instruments on satellites since around 2000. And since then, the average energy imbalance has nearly doubled, which is obviously not good. That means the planet's been gaining much more heat over time.
And then last year, we had this record spike, which is what really alarms some people. And if it had kept going up from that level, it would really been bad news indeed. But the data over the last few months show that the energy imbalances. has fallen and is now down to levels more in line with what we're expecting. So I asked Ben Sanderson at the Centre for International Climate Research about this. Here's what he said. Given the way that the numbers have evolved in the last year.
It no longer looks like there's anything dramatically wrong with the models. It now looks like, you know, the observations lie within the model distribution, but it's just they lie on one end of the model distribution. So it's not the sort of potentially dramatic issue you might... some people would say once a year ago. And I saw a nice quote from Gavin Schmidt the climate scientist at NASA basically warning against a real extreme doomster narrative and he said
There's a big difference between tracking the increasing impacts that climate change and habitat loss are having and buying into a notion that everything is spiralling out of control and we no longer have agency. That, in my opinion, is not justified. That was what... Gavin said. Past, present, future is the History of Ideas podcast with me, David Runciman, exploring ideas from politics to philosophy, from science to fiction, where they come from, what they mean, why they matter.
We have series on the great political fictions, the great historical what-ifs, the history of bad ideas, and much more. How ideas change and explain our world. Twice a week, every week, wherever you get your podcasts. past, present, future. So Michael, why has the energy imbalance been rising and why has it now fallen? So this is something a lot of climate scientists are trying to work out and there are a lot of uncertainty still. But the long term trend since 2001.
done is obviously partly to do with the fact that greenhouse gas emissions have been rising over that time. But that doesn't explain it all. So it's it we think it's also partly to do with the fact that we are cleaning up air pollution now. aerosol pollutants like those that come from coal powered fire stations can reflect sunlight back into space. So if you clean up the air pollution, you get more sunlight reaching Earth's surface. So
That's the sort of reason for these long term changes. Now, these short term changes, this big spike in a subsequent fall, those are probably more likely to do with the phenomenons known as La Nina and El Nina. So prior to 2023, we had this La Nina. that lasted for an unusually long time.
And during a La Nina, these cold ocean waters spread across the surface of the Pacific. So surface temperatures fall, or at least don't go up much. Now, if you've got a cooler surface, that's emitting less heat up into space, which means... that the Earth is losing less energy and the heat imbalance gets bigger.
basically the reason for the spike then after that we had this el nino and then that in an el nino you have these warm waters spreading across the surface of the pacific that means the surface gets warmer you've got more heat emitted more gets back into space and the heat imbalance
fours so that's pretty much in line with with what we expect um this is not to say we can all just go on holidays on on flights and burn oil and not worry about anything anymore is it no no not at all so we're not this is
basically saying yes this is evidence that the world is warming in line with what the model projections are saying and if that's true there's still a huge amount to worry about i mean you just have to look at all the extreme weather disasters happening around the world to see that but this
Fall in the heat balance does mean that some of the more alarming scenarios, this idea that there's going to be a rapid acceleration in global warming, those scenarios are looking a lot less likely. So in that sense, it is good news.
Yeah, and I think the point, just to go back again to what Gavin Schmidt said, like that... we still have agency here and that's what we always say you know we let's not buy into this doomsterish scenario of spiraling out of control we do still have absolutely what we do matters enormously Next up, health reporter Grace Wade has been speaking to a neuroscientist who scanned her own brain dozens of times and found that it shrank while she was taking birth control.
Grace, this sounds a little startling, maybe. Is it actually concerning? What's going on here? Hey, Chels. Well... Until this study, no one had studied the brain before, during, and after taking hormonal birth control. And we should say right away that the volume of this neuroscientist's brain only shrank a little when she was on the pill, and we don't necessarily know if that's a bad thing. Okay, that's good to know.
But the point is that we've had hormonal birth control since the 1960s, yet have only recently started to study its effects on the brain. Previous studies have shown differences in brain volume between women who take hormonal contraceptives and those who don't, but very few studies have looked at the brain in the same person. So Karina Heller at the University of Minnesota decided to scan her own brain.
I had a chat with her about the study, and she told me she'd used hormonal contraceptive for a long time and went off it, and that's what prompted her to scan her brain. Here she is talking about it. three to four months, I noticed some changes. I broke out a lot. And then I also experienced some mood swings. which I did not experience while I was on oral contraceptives. I would say I was pretty stable. I did not report any mental health issues, depressive symptoms.
where I was on oral contraceptives. But when I went off them, I noticed some changes. And then I did some research and I looked on PubMate and saw that there were just like a couple of papers. on how oral contraceptives impact the brain. And this is what got me really interested in this research. We scanned myself 25 times for five consecutive weeks with a natural menstrual cycle. So I was off oral contraceptives for about three years. So I had a natural cycle.
I would say I was not the best participant because I tend to have an irregular cycle. So sometimes my cycle is like 30 days long, then it's 40 days long. So it's kind of irregular. Then after like the five consecutive weeks, I went on oral contraceptives for about... three months. And I used like the most prescribed oral contraceptive prescribed in Germany because I was living in Germany at the time. Then we scanned.
me for another 25 times across five consecutive weeks. Then I went off oral contraceptives again, waited for another three months or two. wait for the washout period so that all of the medication would be like out of my body. And then we repeated the whole procedure. So we scanned myself for another 25 times across.
five consecutive weeks. Okay, so they did a total of 75 scans on her and found that the volume of Carina's cerebral cortex, which is the brain's outermost layer, was 1% lower while she was on birth control compared with when she had stopped taking the medication.
This is in line with previous studies that have indicated hormonal birth control may decrease volume in certain areas of the cortex. I would expect a lot of changes during pregnancy, too. Is that right? Yes. Karina spoke about a study that looked at this. Here she is. There has been a paper published very recently on a pregnant woman. So research is from the University of California in Santa Barbara. studied a pregnant woman across two years before, during, and after pregnancy. And they did...
26 brain scans on this participant, and they found that brain volume and cortical thickness was also decreasing during pregnancy. These researchers are of the opinion that this means that the gray matter is just reorganizing during pregnancy. with all these changes happening to the body and happening to the life. So here we also see that just because we see that the volume is decreasing, this does not necessarily mean that this is bad. This more speaks to
cortical brain reorganization. You know, it makes total sense that you'd get a reorganization of the brain during pregnancy, doesn't it? Right. And as Karina says, it's important that we study this. And just to emphasize that it's not a bad thing, this change in the brain, and it should definitely not be a reason to avoid oral contraception, should it? Not at all. I asked her what the takeaway is from this study. I would say that you should not be worried.
doing this study like going through the process i would still go on oral contraceptives i have been recently thinking of going on oral contraceptives again, I have to be honest, because they're just so good for your hair and for your skin and everything. And you don't have to worry about your reproductive health. So there are a lot of very positive benefits coming from oral contraceptives, and it gives a lot of women a lot of freedom. I do like that quote, giving women a lot of freedom.
Yeah, same. The other thing to remember is that this is just one study of one woman's brain. As Karina said, hormonal birth control affects people differently. Just because she experienced decreases in cortical volume doesn't mean everyone will. So you can't really generalize these findings to a broader population. Yeah, that makes sense.
But what is important is that this is a step towards understanding why some people experience side effects on hormonal contraceptives such as depression while others don't. You know, Grace, the other thing that really strikes me listening to this is that... Contraception is getting harder to access for many women in the United States. I saw a report showing almost two-thirds of women aged between 15 and 49 in the US.
They use some form of contraception, but in a dozen US states, they allow some healthcare providers to refuse. to provide contraception services. So that means there's more than 19 million women without adequate access to birth control methods. And I just think that's an important point to make when Karina has just been talking about the real importance of women's...
reproductive health. Absolutely. That's it for this week. Thanks to all our guests and thanks to you for listening. Do tell your friends about us and give us a five star rating and a review on Spotify and Apple Podcasts. And there's always more from New Scientist on our website at newscientist.com. We'll be back next week. Bye for now. Bye. This podcast is produced by OG podcasts.
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