Host: Shamini Bundell
Welcome back to the Nature Podcast. This time, how your navigation skills could be affected by where you grew up.
Host: Nick Petrić Howe
And understanding how storm surges are changing. I’m Nick Petrić Howe.
Host: Shamini Bundell
And I’m Shamini Bundell.
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Host: Shamini Bundell
First up on the show, reporter Ali Jennings has been on a bit of a quest, as he’s been finding out how your childhood environment could affect your navigational ability later in life.
Interviewer: Ali Jennings
I’m walking in the woods near my house. It’s brisk and fresh, and there are buds bursting out of the branches of the trees. I’ve been lost for about 20 minutes now. But my wife assures me that she knows where we’re going. So, why do some people have a better sense of direction than others? What determines a map magician from an itinerant wanderer? And haven’t we come down this path before? Previous research has found that in general your age, sex and level of education all affect your spatial navigation ability. Younger people perform better than older people. Males perform better than females. And the more educated you are, the better you tend to navigate. But there’s one aspect of life that, until now, had not been investigated.
That’s the sound of the number 73 bus going from Oxford Circus to Stoke Newington in the city of London in the UK. I’m walking past red-brick university buildings lining the streets and students hurrying past me on the pavement. And I’m on my way to meet Hugo Spiers, a researcher at University College London, who has been investigating how people differ in their spatial navigation ability. Hugo thinks the answer might lie in the kind of environment we live in or, more specifically, that we lived in.
Interviewee: Hugo Spiers
So, the paper, in a nutshell asks a very simple question, which is, ‘Does it matter whether you grew up in a city or outside a city for your navigation ability?’
Interviewer: Ali Jennings
But answering that question is not straightforward because, when you test navigational ability, there are all sorts variables you need to account for to make sure you’re getting to the real answer.
Interviewee: Hugo Spiers
If you were to, say, test people who are living in Manhattan or living in London, you've got a lot of differences in who they are, how much wealth they have, how much education they get, what the culture is, do they think in in kilometres or miles. To really tackle the problem, ideally you do want to test people from all over the world in all sorts of different environments.
Interviewer: Ali Jennings
So, how do you go about administering a set psychological test to enough people across the world? This is where Hugo and his team came up with a surprising solution. It’s a game. I’m playing it now and I’m piloting a brightly-coloured tugboat through a corridor of icebergs. My task is to memorise a fairly wiggly route and then reach a final marker buoy. When, at last, I reach it, I’m awarded three stars by a nautical-looking octopus. The stars are in fact starfish. This is how Hugo managed to run his test on a big enough sample size. He and his collaborators designed a smartphone game called Sea Hero Quest, and it’s phenomenally popular.
Interviewee: Hugo Spiers
We were fortunate to have 4.3 million people download and play that game. We logged every 500 milliseconds where they were and what direction they're facing in these environments. And that can then piece together whether somebody is able to navigate effectively or whether they're poor at it.
Interviewer: Ali Jennings
For this work, Hugo and his team analysed the data from almost 400,000 players across 38 different countries. Each player answered a few questions about themselves before they began, and one of those questions was whether they grew up in a city or in the country. And that was where Hugo got his first key result.
Interviewee: Hugo Spiers
So, people who grew up outside cities, in rural or other mixed environments, navigate better worldwide than people who grew up inside cities.
Interviewer: Ali Jennings
Hugo had hoped to see some effect here, but didn’t know which way it would go.
Interviewee: Hugo Spiers
It seemed to me possible that cities are complicated, full of information, a labyrinth of possible streets. But overall, it seems that outside cities, even just the suburbs outside the city, predispose you to being able to navigate environments better.
Interviewer: Ali Jennings
And at the extremes, this difference can be quite striking. You can think about the effect in terms of ageing.
Interviewee: Hugo Spiers
So as we age, pretty much every year people on average get worse at navigating. And you can see that someone who's like a woman who's in her 70s who grew up in a rural setting, will be equivalent to a woman in her 60s in a city.
Interviewer: Ali Jennings
But it’s not quite as simple as city/bad, country/good. It turns out the structure of the city you grew up in matters too. Is the street layout organic, like London? Or is it a grid system, like Chicago?
Interviewee: Hugo Spiers
If you grew up in a highly organised, griddy city, your navigation skills will adapt to griddy environments. You'll be better at navigating more griddy places. On average, a lot of the world isn't that griddy, which puts you at a disadvantage worldwide. So, people who grew up in convoluted, complicated cities with wiggly streets, they ended up benefiting in that they are better adapted to that.
Interviewer: Ali Jennings
The overall complexity of a city’s layout can be reduced to a single value called its entropy. The lower a city’s entropy, the lower its layout complexity, and the worse people growing up here are at navigation. What Hugo also finds interesting is that it’s only the environment we grow up in that matters, not the environment we live in as an adult. This makes Hugo think that there may be a critical period in our development where our environment determines our future navigational ability.
Interviewee: Hugo Spiers
We don't know when the most critical period is. It could be all the way from your early childhood experience up into your early adolescence. It could be your adolescence, when you start leaving home. It could be when you start being more independent that's absolutely critical. We don't know and we would love to find out.
Interviewer: Ali Jennings
I certainly don’t remember the city I grew up in being particularly easy to get around. So, why should growing up in the countryside make you a better navigator?
Interviewee: Hugo Spiers
So, I think growing up in the countryside and other mixed environments is giving you exposure to having to keep track of your path bending in different directions as you travel, and that seems to benefit your capacity to navigate those sorts of environments. Most environments we encounter are somewhat disorganised.
Interviewer: Ali Jennings
Hugo hopes that this work will also have medical applications. Navigational ability is known to decline in those with dementia. Being able to better test it could help doctors diagnose dementia and diseases like it. And Hugo also has plans for more research.
Interviewee: Hugo Spiers
I'd love to know how people perform from traditional communities that navigate, who spend every day walking tens of kilometres, and then how do they perform? So, there are lots and lots of questions out there. And of course with brain data it would be nice to link this together with what's actually happening in the brain that underlies these biases we see. There’s so many different directions and it's a very exciting time, yeah.
Interviewer: Ali Jennings
And if there’s one thing Hugo’s research has done, it’s explained how my wife – who grew up in tiny, country village – can always find our way home.
Host: Shamini Bundell
That was reporter Ali Jennings. For this piece, he spoke to Hugo Spiers from University College London here in the UK. To find out more about navigation, check out the paper in the show notes.
Host: Nick Petrić Howe
Coming up, we’ll be hearing how storminess and flooding have changed over the decades.
Host: Shamini Bundell
‘Storminess’ – did you just make that up?
Host: Nick Petrić Howe
No, that’s the actual scientific term, Shamini. Laughs.
Host: Shamini Bundell
Nice.
Host: Nick Petrić Howe
The amount of storms. Right now, though, it’s time for the Research Highlights with Dan Fox.
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Dan Fox
Boa constrictors are well known for squeezing the life out of their prey, but what hasn’t been understood is how they continue to breathe while they constrict, until now. Boa constrictors breathe by expanding and collapsing their ribcages, a technique that seems at odds with the snakes’ constricting ability. Now, scientists have found that while one part of the boa’s body is occupied squeezing its dinner, they simply breathe with another part. Using a blood-pressure cuff, researchers were able to constrict portions of the bodies of boas and observe the movements of the snakes’ bones. They saw that when a region of the snake’s body was immobilised, the animal shifted its breathing to other spots along its length. The results may help to explain another long-standing mystery: why are there so many types of snake? Snake species outnumber other long, slender vertebrates tenfold, and the researchers believe that evolving the ability to breathe with isolated parts of their lungs while squeezing and then swallowing prey whole increased the variety of animals snakes could eat. This let them live in a wide range of habitats, where they diversified. Swallow that research whole at the Journal of Experimental Biology.
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Dan Fox
For trees, the secret to long life is simple: live as far away from humans as possible. Researchers mined a database for information about the age and location of nearly 200,000 trees. At about 4,900 years old, two bristlecone pines in the mountains of southwest United States are the world’s oldest trees, followed by a 3,600-year-old Patagonian cypress in Chile. The team counted 30 trees older than 2,000 years, and found that 27 of them are located on high mountains, probably because human activity is limited in these remote regions. The analysis also revealed that of the 95 studied tree species represented by individuals at least 500 years old, about 70% are endangered by human over-exploitation of natural resources. Warming temperatures also threaten the survival of extremely old trees, leading the authors to call for new conservation strategies. Read that research in full in Conservation Biology.
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Interviewer: Nick Petrić Howe
Climate change is causing flooding of coastal areas around the world, costing tens of billions of dollars each year. And things are getting worse. This flooding is caused by so-called ‘extreme sea levels’ – exceptionally high water levels, which are caused by tides and a combination of the gradual increase in the average height of the sea – the mean sea level –and storm surges – the water level above this average point when things are stormy.
Interviewee: Francisco Calafat
All sea-level research shows that sea-level rise, and by this I mean the sea-level rise caused by ice melting and ocean thermal expansion, has made extreme sea levels more likely across the world for many decades now. There is almost unanimous consensus on this, okay. The debate is basically over in this respect.
Interviewer: Nick Petrić Howe
This is Francisco Calafat, a sea-level scientist from the National Oceanography Centre here in the UK. While the effect of mean sea levels on extreme sea levels is pretty well resolved – average seas levels are rising and that is causing more extreme sea levels – the same cannot be said for storm surges. Past research has suggested that storm surges aren’t really changing over time, but Francisco isn’t so sure.
Interviewee: Francisco Calafat
Either the trend is zero, or the data are not enough to detect the trend.
Interviewer: Nick Petrić Howe
So, Francisco set out to get some definitive answers – are storm surges not increasing and so not having an impact on extreme levels? Or has there simply not been enough data to find any trends?
Interviewee: Francisco Calafat
In our paper, we argue that it is the latter.
Interviewer: Nick Petrić Howe
To get to this point, Francisco and his team had to analyse a lot of data, gathered from tide gauges all around Europe from 1960 to 2018. But it has been tricky. The data are sparse and even gappy, which explains the lack of statistical power in previous studies. So, they developed a model to fill in the gaps. Their model exploits the fact that extreme sea levels that occur close together tend to be similar. These extrapolated data points, added to the huge amount of data they already had, allowed them to start running analyses that turned up some answers.
Interviewee: Francisco Calafat
We found that, contrary to the prevailing view, trends in storm surge extremes and sea-level rise both made comparable contributions to the overall change in extreme sea levels.
Interviewer: Nick Petrić Howe
Now, this comparable effect of storm surges is an average across western coastal Europe, but it does vary from region to region. For example, in northern England and Scotland, storm surges were trending upwards, whereas further south, in places like France and Spain, they are going down.
Interviewee: Francisco Calafat
So, we were also interested in the causes of these changes and particularly the role of climate change, and determined that the trends in storm surge extremes were mainly driven by the influence of natural climate variability, but the trends also include contributions from human-induced climate change.
Interviewer: Nick Petrić Howe
To be clear, as Francisco explained to me, climate change was making average storm surges worse everywhere. But its contribution was less than that of natural variability, which meant that some places were seeing less storm surges despite climate change. In any case, for a long time, coastal planning has not really accounted for a change in storm surges. Increased sea levels, yes, but a change in storm surges, not so much. So, Francisco’s results may suggest that authorities haven’t done enough in some locations to stop the worst impacts of coastal flooding.
Interviewee: Francisco Calafat
The emphasis should be on cost-effective adaptation plans that can, say, balance protection costs with the expected damage from an extreme event, and I think that our study is a significant step towards achieving this aim.
Interviewer: Nick Petrić Howe
That was Francisco Calafat from the National Oceanography Centre here in the UK. To find out more about changes in storminess, check out the paper in the show notes.
Host: Shamini Bundell
Finally on the show, it’s time for the Briefing chat, where we discuss some of the articles that have been featured in the Nature Briefing. Nick, what have you found this week?
Host: Nick Petrić Howe
So, this week, I was reading an article in Science, and it’s about someone who was completely paralysed but was able to communicate via a brain implant.
Host: Shamini Bundell
Ah, so we’ve covered some elements of this topic before with people using brain implants and brain-computer interfaces and things to communicate with the outside world. How does this one work?
Host: Nick Petrić Howe
Well, this one may be different from the others we’ve done before because this was a person who was completely paralysed. They weren’t able to move their eyes. They weren’t able to move any muscles at all. So, they were on a ventilator, and this was just from sort of neuronal firing that they were able to determine things. So, the way this one worked were two tiny implants were put into a part of the brain that controls movement, and then they were able to, after a while and through a lot of practice, make a tone go up and down, and based on that tone, they could answer ‘yes’ or ‘no’ questions. And later on, after a lot of practice, they were able to use this tone going up and down in pitch to be able to spell out words.
Host: Shamini Bundell
And was this sort of using machine learning so they had to train the algorithm to understand what their different brain patterns meant, like ‘yes’ or ‘no’?
Host: Nick Petrić Howe
No, so this was actually the person who was paralysed training over time with this machine to actually be able to meet the targets that the researchers set. They would basically ask them to match certain tones and they would do that, and over time they were able to develop a system whereby they could actually work out what letters and things they were looking for. And they were able to spell out some quite sweet things like, ‘I love my cool son.’
Host: Shamini Bundell
Ah, so, from this guy’s perspective, what was he thinking about? How was he controlling the device?
Host: Nick Petrić Howe
So, the researchers originally asked him to just use any method possible to try and change the tone and, once they were able to develop a system where he was able to communicate, he told the researchers that he was trying to move his eyes, and that’s what he was using to change the tone. Now, it was quite slow. So, he was able to do one character per minute, and average writing speed for a person is about 40 words per minute, so many, many more characters per minute. So, it was very, very slow, and it wasn’t always accurate as well. So, out of the 135 days he had this device and they used it in the study, only on 107 was he able to get about 80% accuracy, so he wasn’t always able to produce like intelligible sentences. But still, for someone who is unable to move any muscles at all, this is a huge step in being able to communicate with their relatives.
Host: Shamini Bundell
So, if this particular person was completely paralysed, how did they sort of set up the experiment initially and kind of get them on board with the trial?
Host: Nick Petrić Howe
So, he had a disease called ALS, which progresses over the years, so once you have a diagnosis of ALS, you know that the disease is going to progress in a certain way and you’re going to lose more and more control. So, back in 2018, when he still had control over his eyes and was able to communicate using a camera that measures eye movement to type, he joined the programme and consented to the research then. Since then and since he’s lost the ability to communicate, his wife and his sister signed written consent to say they’re happy for this to go forwards, but there are still ethical questions as well, like what if he’d changed his mind or something like that, but it seems that they took as many steps as they could in this particular case.
Host: Shamini Bundell
So, you said the trial is over now, but is there a way that this particular person could keep using this system?
Host: Nick Petrić Howe
Yeah, the research team is committed to maintaining the device for as long as he wants to use it. However, the only problem is that his ability to spell out words has decreased. He can now only answer ‘yes’ or ‘no’ questions. And there’s a couple of reasons this could be, like it could be that scar tissue around the implant is blocking some of the signals, and it could also be that there’s been some amount of cognitive decline as well. In any case, some of the researchers who were interviewed for this article were quite excited because it represents quite a big step forward for people being able to communicate with their loves ones when they’re completely paralysed.
Host: Shamini Bundell
Oh gosh, yes, well, I mean I’m sure we’ll be chatting about this again in future, as there seems to be lots of different work on this kind of topic and lots of different methods being used, which is really interesting.
Host: Nick Petrić Howe
Definitely. But what have you found for us to talk about this week, Shamini?
Host: Shamini Bundell
So, I have a National Geographic article here from the Briefing that is all about an aquatic kind of dinosaur. I was wondering, a bit of a challenge for you, Nick, whether you could name any aquatic dinosaurs.
Host: Nick Petrić Howe
Erm, okay. I’m not as much of a fan of dinosaurs as you, so maybe I’ll struggle with this, but is this avian dinosaurs or non-avian dinosaurs?
Host: Shamini Bundell
Well, I was kind of hoping to trip you up a little bit there because obviously, if you’re talking about birds, there’s quite a lot of aquatic birds.
Host: Nick Petrić Howe
I was going to say penguin. Penguin is my answer.
Host: Shamini Bundell
Yes, ducks, penguins, waders, divers, all those sorts of things, but in the non-avian dinosaur world there aren’t many. So, a lot of the big, pre-historic aquatic creatures, like mosasaurs and ichthyosaurs and plesiosaurs, sort of classic, ancient sea-monster-type shapes, they weren’t in fact dinosaurs. But the one non-avian dinosaur group that we think was aquatic are the spinosaurids, and this particular article is about a new spinosaurid find that adds even more evidence that they could have been living a really quite surprisingly aquatic lifestyle. But no one’s quite sure and no one’s really sure how it would have worked either because they’re just very unusual.
Host: Nick Petrić Howe
I mean, my experience with talking to various palaeontologists is there’s always a bit of debate about this sort of thing, so is this a new piece of evidence to settle the debate? Were they really aquatic animals?
Host: Shamini Bundell
It’s never settled it. I think it’s undeniable that Spinosaurus lived some kind of an aquatic lifestyle and, for a long time, the question has been to what extent and in what way? So, one example would be they could be literally swimming through the water and catching fish. Or another idea is that they could have been wading through the shallows, perhaps acting like a modern heron, perhaps standing very still and sort of reaching out and grabbing fish from the water. And there have been various bits of evidence over the years. It’s actually been kind of tricky because the original Spinosaurus fossil was destroyed in World War II. The original bones were first found in the 1910s, so it wasn’t until 2014 that a new, surprisingly complete Spinosaurus skeleton was found that actually has provided a lot more answers. And one of the reasons, I’ve got to admit, that I was particularly interested in this story was because I made a film a couple of years ago about some of the results from this new Spinosaurus skeleton, and that was about its tail and how it had very long spines on the vertebrae of its tail, this fossil, suggesting that this tail was used for swimming, which again suggests a really sort of ‘in the water’-type aquatic lifestyle. But this new paper is all about the bones and in particular about bone density.
Host: Nick Petrić Howe
Oh, okay, I see, so I’m guessing then because water gives you an amount of buoyancy, it would make the bones more or less dense if you spend more time on land versus in water.
Host: Shamini Bundell
Exactly, but there isn’t a clear-cut answer of this bone density equals this kind of lifestyle, so what these researchers have done – and this is something that has actually taken them many, many years since this new fossil has been found – was trying to compare them to as many different species and creatures as possible, so modern birds and reptiles and mammals as well as extinct creatures, trying to get museum specimens, trying to measure the density of, in particular, the ribs and femurs of all these creatures, and trying to figure out where Spinosaurus fits on this selection. And the creature that it came up closest to was in fact your pick from earlier, a penguin, who have quite dense bones useful for ballast when they’re diving.
Host: Nick Petrić Howe
Oh, well, obviously, I was prescient and thinking ahead when I picked penguin. I mean, we said the debate will never be quite settled, but does this push the side of aquatic further along, or what does this mean for science?
Host: Shamini Bundell
Well, it could mean that it’s more evidence that they really were underwater swimming, perhaps diving, to catch their prey. A lot of creatures, when they move towards an aquatic lifestyle, do increase bone density to keep them weighted down. Then again, a lot of other creatures don’t, so ducks and geese, for example, don’t have particularly dense bones. And some creatures have dense bones for other reasons, like elephants and big sauropod dinosaurs that have bones to support their weight, although those usually have sort of slightly different internal structure. But there are other elements of Spinosaurus which doesn’t seem very suited to an aquatic lifestyle. The famous sail, so they have this big sail on their back, no one’s ever quite figured out what that’s for, and this particular article uses the phrase ‘hydrodynamically vexing’ to describe this sail, which I thought was quite amusing. And people disagree, so some scientists quoted think this is still a creature that’s probably mostly in the shallows, mostly standing in the water and sort of catching prey. It seems quite likely that they were certainly not completely aquatic. They were very adept on land as well, and other spinosaurid species in other parts of the world certainly seem more land-based, and there are things from this particular fossil that are still being looked into. So, this same team who published this paper, and in fact published the paper we’ve got a video on on our YouTube channel, are now looking at their feet and hind limbs and trying to see if maybe they had webbed feet. So, we don’t know exactly what they were doing back then, but we do know that they were certainly very unusual.
Host: Nick Petrić Howe
And I doubt this is the last secret that this skeleton will unveil, so I look forward to hearing more Spinosaurus facts in the future.
Host: Shamini Bundell
All the dinosaur facts from me, for sure.
Host: Nick Petrić Howe
Thanks, Shamini. And listeners, for more on those stories and how to sign up to the Nature Briefing, check out the show notes.
Host: Shamini Bundell
And, yeah, that’s all for this week. Don’t forget, you can follow us on Twitter – we’re @NaturePodcast. Or you can send us an email to podcast@nature.com. I’m Shamini Bundell.
Host: Nick Petrić Howe
And I’m Nick Petrić Howe.