Testing whales’ hearing, and mapping clusters of extreme longevity
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Visit our website at www.science.org and search for Frontiers of Medical Research-Women's Health, the icon school of medicine at Mount Sinai. We find a way. This is the Science Podcast for November 22nd, 2024. I'm Sarah Krespi. First up this week, a fight over where the world's oldest people live. Freelancer Ignacio Omigo talks with me about debating blue zones.

regions of the world where people appear to have extreme longevity. Next on the show, producer Kevin MacLean talks with researcher Dorian Hauser about catching wild whales and giving them hearing tests. The results of these tests could be used to better protect whales from human-made noise in the ocean. Where on the face of the earth do you think that people live the longest? Maybe you've heard Okinawa, maybe you've heard Sardinia, maybe you've heard of the

What makes these types of places or these people that live in them so special? Could it be their genes, their diet, their daily habits, or could it be bad accounting practices and statistical flukes? This week in science, freelancer Ignacio Amigo wrote about the reality of these so-called blue zones, regions in the world where clusters of people seem to have extreme longevity. Hi, Ignacio. Welcome to the Science Podcast. Hello. I'm really happy to be here.

Yeah. So do you live in a blue zone? Is that why you decided to write about this topic? I wish. A lot of those blue zones are really beautiful places, but no, I live in Madrid, Spain. So where's the closest blue zone to you? Well, the closest blue zone to me is probably Sardinia in the Mediterranean Sea. It's an island off the coast of Italy. But recently there's a region in northern Spain that was a candidate for becoming the next blue zone. What would make something a blue zone? What

What would qualify this part of Spain to this, this

this title? So the idea of the Blue Zones is that these are places that have an unusually high number of centenarians. That is the people that are older than 100 years old. Those centenarians have to be validated. Someone actually has to go there and check the birth certificates, death certificates and other records that you could sort of track the life of these people just to make sure that they're actually as old as they

as they claim to be. And that becomes like the numerator. And then you divide by the number of births and you say, oh, this rate, this rate is high, right? It's a metric called extreme longevity index. And the way it works is you look at the number of centenarians living in a particular place and you divide it by the number of people that were born in the same place.

a hundred years ago. That way you sort of get the probability of becoming a centenarian if you're born in a particular place. And that way you also, the number doesn't get mixed up by people leaving the place or people coming into the place. This is something that kind of started up in the nineties in Sardinia, and then it's expanded out globally through the work of different researchers. And you kind of track three people important to this in your story. Can you kind of introduce us to these, these characters?

Sure. So the first person is a Belgian demographer called Michel Poulin. He was already, before starting working on Blue Zones, he was already an expert in age validation of this process of actually confirming the age of very old people. He started working in Sardinia in the early 2000s. There was a

research project that had found an unusually high number of centenarians living in the island. And people thought that the records there were probably not very good quality. And so Michel Poulin visited the island in collaboration with a local scientist there, and he validated all the centenarians and confirmed that a part of the island had actually a very high number of centenarians.

And while they were doing the research, they started marking in a map the places where they could validate centenarians. And after a while, the map was full of blue dots that cluster around a certain area. And that's how the name Blue Zone emerged. Okay, so that's the demographer. That's the person who does the record checking. Who else do we need to meet? Okay, the second character is an American writer and explorer called Dan Budner.

Putner was already quite interested in longevity when he came across the work of Michel Poulin. He had done some work in Okinawa, which at the time had a reputation for being one of the places with the highest longevity in the world. He then partnered with Poulin and they started traveling the world, trying to find other places that could have longevity.

high longevity. He wrote a big story for National Geographic. It was a cover story. It got a lot of attention. And then he wrote a book as well. And the book was a bestseller. So on top of wanting to know where the blue zones are, we also obviously want to know why they are. Is there anything genetically different about people from these regions? A lot of them are islands. We know the islands offer isolation and you can get something called a founder effect where you have a limited population and they might have more genes in common with each other.

When the work started in Sardinia, that was basically the idea that the researchers had in mind. Sardinia had a relatively isolated population. And so they thought that because of this isolation, people would have very low genetic diversity. Those are the perfect conditions to try to identify genes that are linked with longevity. They haven't been able to pinpoint one of them or a few of them and say, hey, you know, these are the key genes.

They've been some candidates here and there, but none of them by itself does much. So if it's not in their genes, maybe it has something to do with diet or daily habits?

Boudinier in particular did a lot of work trying to identify what are the main elements that are common to some of these blue zones that they were identifying in terms of lifestyle. In his book, he talks about nine things they have to do with keeping a balanced diet,

Doing some regular exercise, but not in the gym. It's more like exercise associated with your own lifestyle. Moving naturally, you know, walking rather than driving. He also mentions drinking moderate amounts of alcohol. So looking at this list, it's all pretty safe bets, like get exercise, eat a balanced diet, be

be happy if you can, like low stress. Yeah, exactly. Be happy. And most of this stuff would not offend a public health person who was just like here daily recommendations. The alcohol thing might be a flag though, right? The alcohol thing was a bit more controversial.

There was a big meta study published quite recently, I think it was last year, that found that there is no safe amount of alcohol. Even just one or two glasses a day can increase the risk for some pathologies, particularly cancer and particularly women. That's also well in line with the most recent recommendation by the World Health Organization.

So we've had the demographer and the explorer working to identify blue zones, investigate what might be behind them. But they actually ended up parting ways. Can you talk about what caused the separation? So Dan Buettner, at some point, he trademarked the concept blue zone. It's the title of his book. And he trademarked the concept. He says that as the term became a bit more popular, he started seeing people misusing it, using it to promote racism.

things that he didn't believe in. And he says he trademarked the concept to try to protect it from these misuses. He also started a company. The company's plan is sort of to try to implement some of these lessons from the Blue Zone. So he created a company that works with municipalities to

to sort of shape the public environment, to sort of nudge people towards these healthy options. He started all these business ideas without telling Michel Poulin or some of the other people involved in this project. And that started a conflict. The scientists were not so worried about profiting from the concept, but they were a bit taken aback by the idea

Putner's enthusiasm in trying to sort of expand the number of blue zones. I think it's time to introduce our third person here. We've been talking about the demographer and the explorer and how they came up with this idea, spread it around the globe. Someone commercialized it, which caused some rifts. And then as this idea got more popular and more well-known, other people started to question the validity of this because it does kind of seem odd. And they're

there's no genes and some of these lifestyle interventions seem pretty basic. So...

Let's talk about this Australian researcher who is based in London now. This person called Saul Newman is a scientist. A few years ago, he started looking into longevity papers and then he actually published a couple of papers flagging big errors in some high-impact journals. And about five, six years ago, he wrote a paper which he published as a preprint, so it hasn't been peer-reviewed yet.

He published the preprint with a lot of data that he's been pulling out from actually public sources.

that exposes a lot of errors and problems with longevity studies and particularly with research around centenarians. For example, he's identified some signs of errors in big databases used in longevity research, databases of centenarians or supercentenarians, people that are over 110. What? Yeah, there are some people that are over 110.

And so, for example, in some of these databases, he's seen that there's an unusually high number of people that are born the first day of the month or multiples of five and things like that. And that sort of indicates that probably those dates were forged. He's also sort of collected a lot of real world data that shows that a lot of the things that

Butner and others are saying about the blue zones are actually at odds with reality. And probably his best example is Okinawa, which is one of the regional blue zones. Butner's explanation of why people live longer there has to do with the diet that people eat, again,

Again, all these recommendations of, you know, people eating less meat and not drinking a lot of alcohol and things like that. But the problem is that if you look at the numbers in Okinawa today, Okinawa ranks really high in alcohol consumption, ranks really low in exercise. And so basically,

So basically everything that's been said about Okinawa is at odds with what the real numbers say about Okinawa today. So we have problems with the records. We have problems with the way these people are living their lives. Like it doesn't comport with what we say an extreme longevity population would be doing. But why this is, you said this is a few years old, this preprint, and it's not published. Do we know why? Well, what Newman says is that every time the paper is

is submitted to a journal, the editor sits on it for months and months, and then the paper is rejected. And he thinks it is because the paper is being reviewed by experts in the field who have no interest whatsoever in publishing a paper that sort of debunks all of their work. Right. What do our demographer and explorer think about Newman's work debunking or trying to debunk a lot of this Blue Zone stuff?

Well, they obviously disagree with him. I think the main element for disagreement, and I think it has to do with the fact that in the blue zones, the ages of all these centenarians has been validated. So actually, it's not just the records that Newman has accessed from his computer. People have actually gone there and checked the records and validated the age of those really old people.

And so basically what they say is that, okay, there might be some issues that the Newman's flagging here, but actually the reality is that they don't apply to the blue zones. In what refers to sort of the lifestyle, what Boudinard and the others say is that in the last decades, those places have become sort of Westernized. So

more ultra processed food, more driving. And so what defenders of the Blue Zone say is that, yeah, this was real a few years ago. And what we're seeing now is that the Blue Zones are actually disappearing because of this malign influence of Western lifestyle. Some of this research is 20, 25 years ago that they said, oh, this is a Blue Zone. Are they

Are they still making these super old people? No, not anymore. At least that's not the case in Okinawa and Nicoya, which is another blue zone in Costa Rica. We've got already papers by demographers saying that blue zone effect is fading out. Are we making new blue zones? When Bündner and Poulin sort of part ways, they kept using the term blue zone for their own research.

And so Poulain since then has added Martinique, which is an island in the Caribbean, as a new blue zone. He's validated a very high number of centenarians and he says that that's a new blue zone. As some of the other blue zones are disappearing, it looks like at least they're finding new ones. On the other hand, Boudinard

claims that actually Singapore is the new blue zone. So it's the first one that Budner claims on his own without the work of a demographer validating the term. And what Budner says is that this region is very different. He calls Singapore an engineer longevity blue zone. So a place where

Through public interventions, the government has been able to sort of increase the longevity and the number of centenarians in the island. So what is your takeaway from all of this? Do you feel like there just needs to be more research or, you know, what do you think is going on here? That's a very good question.

I think there's probably a mix. In some cases, there might be a high concentration of centenarians. I think Saul Newman's criticism, the broad criticism to the field of demography, I think he raises some really interesting points that people should be addressing more seriously.

I think the validation process itself can probably help solve some of these record issues. So, yeah, I wouldn't put this expression in English when you... Throw the baby out with the bathwater? No, we say in Spanish, we say something like, I wouldn't put my hand on the fire for this or I wouldn't like, you know. What made you decide to write about this? What caught your attention about this story? A

A few months ago, I started seeing in Spanish media news about this region in northern Spain, in Galicia, in actually my region where I'm originally from, about this place that could become the new Blue Zone.

And so I thought it was interesting. I started reading a bit more and then I started coming across these interesting characters and these sort of controversial science and this tension between the work of demographers and scientists. And at the same time, how that was also being turned into a profitable business. And yeah, I thought it was an interesting tension there between all of these elements of

science marketing business. Yeah, absolutely. You went and visited this potential blue zone. What was that like? I visited this potential blue zone in Galicia with a local researcher and we visited a person who is 101 years old. She's called Armenia. I was there when the researcher was sort of doing an in-depth interview to Armenia to also try to understand a bit

what her life habits being, trying also to identify the elements in her lifestyle that made her live so long. Did they ask her, you know, about her age or like what she remembers, you know, about 100 years ago? I mean, I guess she could remember a few things from 100 years ago. Yeah. So during the interview, the researcher asked her also about her

old memories which you remember from the old days. And yeah, it's really humbling to be next to someone who's lived more than a century and was telling us about what it was like to be a child during the Spanish Civil War in the 30s. And a lot of the things that she said actually made a lot of sense in the context of what we know about the other Blue Zones. They lived in very tight communities.

They farmed their own food. They had their own animals. They had farms where they could feed themselves. They didn't need to buy almost anything. And they had a very strong sense of community as well. Like everyone helped each other. And that's some of the things that people say about the Blue Zones and what makes them so special. So in that way, it was well aligned to what we've heard from other places. Do the demographers have an idea of how long a Blue Zone lasts?

How long do you keep making 100-year-olds? Is there a time limit on that? What we do know is, for instance, in Sardinia, when they sort of described the first blue zone in 2004, they included in that blue zone a number of municipalities.

And what they've seen over the years is that some of those municipalities are no longer blue zones or they don't have the high number of centenarians that they did a few years ago. But other municipalities actually now have a high number of centenarians.

When asked about this, the demographers say that the blue zone is moving. And they think that that's a really interesting fact. Like, you know, these blue zones are not static. They can sort of move around. If you ask Saul Newman, the guy who's been criticizing the blue zones, he will tell you that the scientists are just moving the goalposts. All right. Thank you so much, Ignacio. This has been super fascinating. Thanks, Sarah. It's been great. And yeah, thanks for having me. Thanks.

Ignacio Amigo is a freelance science writer based in Spain. You can find a link to the story and a map of the contentious blue zones at science.org slash podcast. Don't go anywhere. Up next, we have producer Kevin McLean and researcher Dorian Hauser talking about giving hearing tests to wild juvenile minke whales.

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The ocean has always been a sound-rich environment. From the muffled sloshing of surface waves, to snapping shrimp, to the whale songs that carry for miles and miles. Many species use underwater acoustics to communicate, to echolocate, to evade predators, and to hunt down their next meal. But humans have introduced all kinds of noise into the mix too.

To understand what bothers animals underwater, we need to know what they can hear. And in order to know what they can hear, we need auditory testing in all the species that our noises reach. And we have to consider the specialized ways that they use sound.

Dorian Hauser and his colleagues conducted a first-of-its-kind hearing test on a species from a taxonomic group whose auditory abilities have been difficult to characterize, baleen whales. Hi, Dorian. Welcome to the Science Podcast. Hi, Kevin. Thanks for having me. Appreciate being here. Great. Yeah, it's great to have you. Now, Dorian, I was first wondering if you could just lay out the problem that we have in our oceans a little bit. What

What kinds of issues have we encountered in the past when it comes to various noisy activities that humans have going on at sea? Well, I think the interest in ocean noise began about 40 years ago, primarily with the oil industry and thinking about how

Seismic surveys associated with that might affect the large whale communications, but it was in the 1990s when there was mass strandings of whales associated with Navy sonar activities that really put a spotlight on it. Since that time, there's been a lot of investigative work trying to understand just how sound can affect marine mammals, many of which rely on their hearing more than they do any other sense.

And we know that they can have their communication interfered with by masking, which is when one sound covers up another sound. You can call it the cocktail party effect when you have trouble listening to someone at a party because of all the noise.

It might directly affect their hearing, possibly causing a temporary threshold shift, which is the rock concert effect. You know, when you go to a concert, come back and you do not hear as well as you did when you went in, even permanent threshold shifts. And then possibly changes in behavior of the animals as well, forcing them out of areas they might normally use as habitat or interrupting important activities such as foraging or socializing. Yeah, and I should be clear, you know, we're not just talking about bothering animals. It really affects their survival, right?

It potentially can. Again, highlighted by the strandings of whales with sonar activity. That was a mortality event. Wow. Yeah. Now, you and your co-authors also pointed out that regulation of noise in the oceans has been, I guess, hesitant to regulate noise impacts for baleen whales in particular because of a lack of information.

This study is sort of the first direct measure of that hearing range, but what are some of the ways that hearing has been estimated for baleen whales? And what are some of the limitations of those approaches? Yeah, I guess a better way to characterize it is the regulators have not been hesitant. They've just been very cautious in their approach. Because we have no direct estimate of hearing on baleen whales, they've had to extrapolate from other marine mammal species for which we do have

curing estimates, but there's a big divergence between those marine mammals and the baleen whales. So it's an assumption that is obviously wrong to some degree.

We also have to make estimates about not only the frequency range at which they can hear, but the sensitivity they have. We just don't understand how sensitive those animals are to those frequencies that they can hear. Why were you interested in knowing this in baleen whales in particular? Was it just because we haven't been able to get that estimation in the past? I think for people who study baleen whales and how they utilize sound,

understanding what they hear has been a holy grail for decades. But it's almost impossible to deal with because it was long assumed that you could not hold an animal long enough to teach it to behaviorally respond to perform a hearing test, which is something that is done with smaller marine mammals, dolphins, corpuses, seals, sea lions, and the like.

And it was unlikely, at least, that you could capture one to use other techniques such as auditory evoked potential methods, which is what we utilize for this study that we'll talk about here. The approach you described in this paper is, as you said, this auditory evoked potential test. You mentioned it's been done in a lot of different species, other marine mammals. How does it work? I think most people don't realize they've had experience with it, especially in the

pretty much nowadays have their hearing tested through this method soon after they're born. And it's fairly simple process in which you play a sound and then you measure the voltages that the brain produces when it hears the sound. So we want to apply that technique same

Same technique that is used in humans to whales. We just have to learn how to adapt it for this species. Yeah, so is it you have to attach electrodes in order to monitor that activity? You have to attach something directly to the animal? Yeah, so you actually physically have to have access to the animal. We do use surface electrodes, so they're embedded in suction cups so we can stick them on the animal and record the voltages produced by the brain at the skin surface of the animal.

This procedure is commonly used in smaller cetaceans like dolphins and porpoises. But to be able to temporarily hold and test a baleen whale means you have to be very, very selective about the animals that you're targeting for this purpose, which is one of the reasons why we targeted the minke whale. Yeah, yeah. So you were working on minke whales. What I gathered from the paper and the bit that I do know about whales, they're certainly...

one of the smaller baleen whales, but it's still a whole whale. Can you, I guess, maybe talk a little bit about minke whales and why they were the target and how you're able to do this? The minke whale is certainly one of the smaller species of the baleen whales. And we specifically targeted adolescents. They're three to five meters in length. This is a size that we have tested in other cetaceans.

belugas can get up to that length. Some of the largest dolphins can also get to that length. So we have done tests on this size of animal before and we're confident that we could do so. But they need to be small because we need to have a favorable brain to body mass ratio. That is, we can't have a small brained animal with a giant layer of blubber around it that prevents us from being able to record the signal at the surface of the animal.

The other reason was accessibility. These adolescent minke whales are known to migrate northward in the late spring and early summer to get to the Arctic, and they hug the coastline of Norway. There's a region in Norway, Lofoten, where there's a lot of rocky islands that scattered along the coastline. And this gave us an opportunity to create a temporary catch and release area where we might corral an animal into it, hold it for the purpose of doing the hearing test, and then release it back to the wild.

Oh, man. It sounds like a really intense process to plan out and you really got to get it right, I think. Intense is a good word. Yeah. So...

you know, you've talked about where you were doing this, I guess, what were you, what were you expecting to find when you were, were doing that? I know that, that part of it is, you know, doing this for the first time on this type of animal. So I'm sure there's a little bit of, you know, refining the process and getting, making sure that, that it works properly. But what were you, what were you thinking that you would find in doing this?

That's a good question because we came at it with the idea that because of the size, we had a pretty good probability of having success, but we didn't know for sure. This has never been done. These animals do not have the same auditory system of say a dolphin or a porpoise, which is built for echolocation and they give very large neural responses

to sound when we played it to them. So we expected these animals to be probably more like a seal or a sea lion, which don't have those specializations. We based our predictions on the range of frequencies they might hear based upon anatomical modeling. There has been some work in the past that has suggested these animals might hear up to as high as maybe 32 kilohertz.

So we went in with an expectation that that might be exactly what we find. But it would be good because that would then validate the anatomical models, which would be useful for other species. So once you've been able to corral one of the animals to put the electrodes onto it, then what happens next? How does the test actually work? There's a process by which we corral it into a modified salmon farm, which is a giant ring for holding fish.

When the small whale is in there, we can then pull the net up underneath it and place it in this hammock for testing. We put the electrodes on it. We place a sound source about a meter to two meters in front of it. And then we play various types of sounds. To start off with, we use very broadband sounds, things that hit a lot of frequencies on the ear at the same time, like a clap or a click.

These tend to give us a very robust response from the brain. And if we can capture that, then we can move forward to trying to test more tonal signals, getting to more frequency-specific hearing sensitivity and addressing the hearing range of the animal.

And for that, we use tone pips, which are just very small bursts of tones. And we repeat that over and over until we can capture the signal from the brain and average it out from the noise that the brain produces on its own. And the brain is a very noisy place. So you have to spend some time to try and capture these signals.

The animals we've worked with so far, we held them between 30 and 90 minutes before we let them go. But that's been sufficient over four years now to get some really good information on these animals. And so what did you find in terms of what they were able to detect or to hear? I think the most surprising thing was that the frequency range of hearing was much higher than we thought it was going to be based upon anatomical modeling.

The results that we got in the third year of the study suggested that the animal's upper limit of hearing was somewhere between 45 and 90 kilohertz. Now, that seems like a lot of frequency space in which to make a decision about what the upper limit is, but it's only one octave. So when we think of it in that regard, it's not that wide. More recently, work we have done has probably narrowed it down. We think it's about up to 64 kilohertz. But this is important for a number of reasons. One, it tells us about the ecology of the animals.

Why would a baleen whale hear to such high frequencies? I mean, we don't have an exact answer, but we think it's probably because they have evolved to hear their predators, which are the orcas. Especially in this region, they are preyed upon by killer whales and killer whale echolocation clicks are in the same frequencies that overlap the hearing range of the whale. Oh, interesting. Can you place me in a,

in the range, like where do we hear and like where do some of the other species that are in the ocean hear? I don't know how much hard rock you've listened to in your life, so I'm not going to guess what your hearing range is. But when you were young, you heard up to about 20 kilohertz. The whales are hearing up to at least three times that level, but maybe two to three octaves higher than we do. And, you know, I should point out as well that that information is very important to us in trying to understand how

man-made sound affects marine mammals, because we tend to look at what the frequency range of hearing is to think about the sources that might affect them. And if we had only used anatomical modeling, we might be missing some high-frequency sources that we put into the ocean. And now we at least have a better understanding about what sources to be worried about. Yeah. How do you think this research could be helpful in terms of the sort of cautious regulatory process you mentioned? Well, I think a big part of it is just minimizing uncertainty. People have to think about what

what the different sound sources are, what the levels are that might affect the marine mammals. The regulators have to think about that and reducing that guesswork, getting us down to what is something of real concern or making sure we don't miss something that's of concern because we've excluded it. Those are the important aspects. The frequency range of hearing is just one part of it, though it's also the sensitivity at different frequencies because an animal might be able to hear something, but it might be very insensitive to that sound.

And therefore, that sound might not be a concern. Conversely, they might be very sensitive to it and therefore have a much higher response or a lower threshold to response when they encounter a sound. So I think from the perspective of managing ocean noise and trying to understand the impacts that it has on marine life, this

audiogram, we call it, the curve that describes sensitivity as a function of frequencies, the most fundamental piece of information we need to address some of that uncertainty. What are the next steps that you have planned? What do you hope that this work is going to lead to? Well, I think for the group that I work with, the most exciting part is just finding out that we can do this. Now, there are lots of different baleen whale species, and they are widely ranging in size. They're widely ranging in the kinds of sounds they use to communicate.

So even though we've tackled this first task of getting audiogram on a baleen whale, there are others that we're concerned with. Now we think because we've done this with this small species, we might have opportunity with other species that have small members of their group. In particular, we think about gray whale calves and humpback whale calves, which in certain parts of the world are known to strand.

There are often interdictions to release them and get them back into the wild. And during that process, we might have the opportunity then to test those animals' hearing as well and start to get an idea of how much does the hearing range vary across these different species of baleen whales.

With the baleen whales, I think the biggest concerns have generally been communication space, especially with low frequency sounds. If these animals are communicating across great distances by using low frequency sounds, are we causing problems by introducing low frequency sounds from shipping, transportation containers, from seismic surveys, from scientific exploration, from military activity? And if we are, we need to understand

how that's affecting those populations, particularly if they use that type of CA-BELIN for mating. There are a number of large whale species that are endangered, and we need to think about how we can best mitigate our activities to ensure that they're not impacted by them. Well, thank you so much, Dorian. This is so interesting. I really appreciate you joining us on the show. Thank you. It's great to be here.

Dorian Hauser is the Director of Conservation Biology at the National Marine Mammal Foundation. You can find a link to the paper we discussed at science.org slash podcasts.

And that concludes this edition of the Science Podcast. If you have any comments or suggestions, you can write to us at [email protected]. To find us on podcasting apps, search for Science Magazine. Or you can listen on our website, science.org/podcast. This show was edited by me, Sarah Crespi, and Kevin MacLean. We had production help from Megan Tuck at Podigy. Our music is by Jeffrey Cook and Wenkoy Wen.

On behalf of Science and its publisher, AAAS, thanks for joining us.