On the trail with a truffle-hunting dog, and why we should save elderly plants and animals
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This is a Science Podcast for January 3rd, 2025. I'm Sarah Crespi. First up this week, newsletter editor Christy Wilcox takes us on a hike with a truffle dog. These animals can be used to find non-culinary truffles. These are the kind that you don't eat. We hear about how Rye the Dog is helping researchers inventory these shy fungi.

Next, freelance producer Ariana Remmel talks with researcher Keller Kopf about the underappreciated value of Earth's old animals. What do the wisest elephants in a troop or the oldest fish in a school bring to their species that the youngest don't? So, Christy, I don't know how long you've been talking about truffled hogs, but when did this start? How did you come across this story in the first place? This started originally with a preprint. So I

Heather and Hillary Dawson, who are sisters, had put up a preprint about using truffle dogs to find, you know, rare non-culinary truffles. I think about pigs finding truffles when I hear truffles. The problem with a pig is that they love truffles. So they will find them, but you're going to have to stop them from eating the truffle if you want the truffle.

Maybe the best part of this story is that you actually got to go on a hike with a truffle dog. You just don't live that far from the researchers and the dog. We realized that there would be potentially the opportunity for me to actually meet Rye and to go out and see what this all looks like. And I, of course, was always up for the opportunity to meet a good dog. Where's your truffle? Rye, where is it? Rye, where is it? Come on.

Rye is a truffle dog, but he doesn't just find culinary truffles, the kind you eat. He also hunts for non-culinary truffles. Why are the researchers interested in these other kinds?

People are very, very motivated to find the culinary truffles because they make a lot of money. They're really tasty. But there are hundreds of species that do the same sort of life cycle that have this underground fruiting. And we know very little about them. One of the really, really bare spots in something like the IUCN's Red List, what life on Earth is threatened, what needs to be conserved.

Fungi in general have far less attention than plants and animals, but underground fungi have even less. We know so, so little about them, but these they're very important because they form these intricate ecological relationships. They rely on these animals digging them up. That's why they smell good. That's why they taste good. Well, some of them.

but also they are underground because they are associating with tree roots. And some of these relationships are really important. I mean, if you get rid of this wood wide web, this underground network of fungi, you lose some plants just outright. And then others, you know, are really struggling. Right now we're going through this transition of we don't know anything about fungi until we actually have the tools to figure them out.

Because prior to the molecular revolution, we were pretty clueless about a lot of what they were doing in the ecosystem. That's Heather Dawson. She's a PhD student at the University of Oregon and one of the truffle researchers who took Christy truffle hiking. Good boy. Where is it?

Traditionally, to do these surveys, you literally have people going out there with rakes and they just rake away a certain area. We have a few truffle researchers out there who are pretty darn good at finding them with a rake, but most of us find it really hard.

to explore truffle diversity. And I've just kind of been landed in this fantastic position because using a dog, you don't really have to guess, you know, you just let the dog wander around and to them, you know, we look for mushrooms with their eyes. You've got to have a good eye, right? To see a truffle too. They're not obvious. I saw some of the stuff that Rye found and

She would pick it up and she would sniff it and she would put it in front of Rye and say, you know, is this your truffle? And I'm looking at it. I'm like, that's truffle. That's a rock. And it's like a...

Piece of dirt? What are you even talking about? There is nothing there. And then you cut it open and it's got these beautiful, like, rippling waves in it. It's like this alien life form growing underground that looks like a rock until you cut it open and it has this marbled or hollow interior and it smells funny. Some of them smell delicious. Some of them smell absolutely atrocious. People are like, oh, aren't you tempted to eat them? I'm like, rotted onions? No, thank you. Yeah.

This is Hilary Dawson, Heather's sister. Hilary is a postdoctoral researcher at the Australian National University.

Is that a rock? Right, that's a rock. Boy, where's your truffle? One of the big advantages of a dog is that they are just so much more efficient. You're not having to look around to see if there's a ripe truffle. If there's a ripe truffle, they know and they'll tell you. Another thing that the dog can do is it can indicate absence, which we can't really confidently say as rakers. The dog will tell you, there's no point. So there's actually less disturbance

disruption of the habitat because you're not having to rake in these areas where there aren't any truffles to begin with. Also, they're only finding the ripe ones. So they don't start producing that odor until they are ripe and mature. They don't want them to find them before the spores are ready to go. Then they just get eaten and they don't get any benefit from it. And that is really important when trying to identify them and trying to distinguish between species. Is Rye, this dog that belongs to this researcher,

Is he especially good at smelling truffle? Does he have like a special skill set or a special training or did he go to truffle school? Well, all of our dogs go to truffle school. Usually if a truffle dog finds a truffle that isn't a culinary truffle, people are like, oh, no, you don't get a reward for that. That's not what I'm looking for.

With Heather, that was what she was looking for. She was totally game. So she was always rewarding for the different truffles. And that helped Rye generalize and remember. And now he remembers. He has found more than 50 genera of truffles. Wow. And thousands, thousands and thousands and thousands of truffles. So how common is a non-culinary truffle dog that helps with scientific research? They're not that common right now, but...

If you can have a, if you're a mycology research group, a fungal dog, a fungi finding dog is exactly what you want for a lot of these things. I feel like we need a dog bureau with like working dogs that have different jobs they go to during the day. The key is really tapping into the mycology community there and saying like,

I know you were looking for culinary truffles, but if you find something, let us know. And that's exactly what happened with these other researchers, Ben Lemond and Matt Smith in Florida. They had someone who had a truffle dog who found just a truffle at a dog park and was like, this isn't what she usually finds. It looks weird. And so she sent it to the researchers and then they described it and it was a new species.

A new native species of truffle. They actually named it, so tuber is the genus, but it's tuber canarevelatum for revealed by dog. That's my buddy. Rye, Rye. Come here. Let's talk about your trip to the woods with a truffle dog. What was that like? When you arrived, what was the first thing the dog did? The first thing he did was go pee. Okay. But then he's just out and he starts digging. And I'm like, wait, what?

And she goes over and he found a truffle. In view of the car? In view of the car. It was constant. He found dozens of truffles. So tuber canadum, that was the primary truffle that he found because it was just the perfect season. He found probably 30 of them. At a certain point, she actually stopped rewarding him for finding them. That's just a tuber. Is that really what you're looking for? That's boring.

That's boring. That's boring. Can we find something better? So they're collecting data. They're getting numbers. They're getting varieties. You know, what can they do with it? So they comparing it to, you know, what people have done with rakes or pigs. So a lot of this data is really trying to get some idea of are they actually rare or are they not being looked at?

but also like just the taxonomy, the number of species. A lot of the truffles that have been collected were collected by truffle researchers doing this a long time ago.

before there was sequencing readily available. So they're in an herbarium. Many of these are described, many are undescribed, but they are not sequenced. And so a lot of fungal research today is really based on what do we find that matches other sequences available. Ultimately, my goal, of course, is to figure out what all of these different truffles are.

But the first step is really getting them sequenced, getting them publicly available and really broadening our understanding of what's out there and having that molecular data to do so.

Was it fun? Did you enjoy it? Oh my gosh, it was so much fun. It was like hiking but better because we're just going around and he's finding all this cool stuff and there's like so many little things that happened while I was out there. There's a good boy. It smells like barely anything to me. Goudy area. It's probably an oak one. I'll

Let's see what it looks like inside. One of the places we went to, one of the oak forests, had all these holes throughout it. And they were like, oh, that's a truffle dig. That's a truffle dig. And she had a hunch that it was this genus Elaphomyces. They were, you know, 20, 30 centimeters deep. That's something that you're not going to find with a rake, ever. You're not going to dig that deep. Ray, where's your truffle? Pretty much always Elaphomyces when they look like that. Ray, where is it? Find it.

And honestly, rodents love alaphomyces. They're often really thorough about getting all of them. It doesn't seem like the most appealing trouble to me, but they're obviously hugely appealing to be digging that deep. So we need to know what's out there, how they're related, what their jobs are.

how at risk they are, and then we can, you know, evaluate conservation. But it's a lot of steps. It's funny because you said you mentioned the ecology there. That's the other thing is like we know they associate with tree roots, but we don't know exactly how important different species are for different trees or what their specific role is. And one of the things that RISE actually helped with was just for the Oregon black truffle, which is one of the culinary species.

This is a species that people find all the time, right? Because they're trying to eat them. And we still didn't even know whether or not it actually has this partnership with the tree root or how important it is. And part of the reason was you have to find it in association with the roots and you have to collect all of that. One of the researchers from Florida, Ben, came out and met with Heather and Rye and went out with them. And he was able to get enough of these root tips in

in association with the fungi to actually demonstrate that, yeah, this is a mycorrhizal fungus. It is playing an important role and that's work that's going to be published soon. But like, he couldn't find enough without a dog. You seem really jazzed on this. Are you going to get yourself a truffle dog? I,

I have been considering. So one of the things Heather told me, and she swore up and down, is that any dog that is reward motivated can be a truffle dog. Oh, there you go. And my dog, Aria, will do just about anything for a piece of dehydrated salmon. So I am wondering if I can train her to be a truffle. And Heather also said at any age, they don't have to learn as puppies because my dog is

She's not as sprightly as she used to be. That sounds fun, though. It's fun. Fun little.

play date with your dog to go find truffles. You know, we'd go on hikes and she would find cool stuff. I love it. I love that. I don't know. I'm considering it. Hiking for science, walking your dog for science. It sounds great. Exactly. I know there's probably plenty of audio of this, but Rye is a very good boy. He's such a good boy. Okay. I'll definitely find some tape of you guys just telling him he's a good boy. You're a good boy. All right, Christy, thanks so much for talking with me about truffle dogs.

Absolutely. Christy Wilcox is our daily newsletter editor. You can find a link to Science Advisor and the story that we talked about at science.org slash podcast. Good boy. We'll find a next Virginia movie. Okay, find one. Stay tuned for a discussion on why it's important to protect the oldest plants and animals with producer Ariana Remmel and researcher Keller Kopf.

Though we often dwell on the downsides of aging, growing old has its benefits too. In the animal world, older individuals are often the largest and most experienced members of their ecosystems, helping their species reproduce and sharing knowledge with youngsters. But Earth's old animals are in decline, causing a cascade of consequences for terrestrial and aquatic environments across the globe.

This week in science, Keller, Kopf, and colleagues wrote about the underappreciated value of Earth's old animals to biodiversity and why we need to consider longevity conservation in wildlife research and management. Hi, Keller. Welcome to the Science Podcast. Hi, Ari. Thanks for having me today. So that we're all on the same page here, what do you mean by old when talking about animals? Old is a relative term depending on the species that you're talking about.

So what might be old for a mouse, for example, would be two years. But for an African elephant, a 20-year-old individual might be considered young.

So what we're talking about are older age classes, particularly of long-lived species like elephants, whales, but also species that aren't so long-lived like pack-hunting carnivores, wolves, for example, as well. They don't tend to live very long, but older individuals of those species provide important ecological functions.

What are some of those ecological functions? Why are older individuals important to their species and ecosystems? This is exactly what we've tried to pull together in our paper that was recently published. And it turns out that across a wide range of animal taxa, those benefits vary. So if you're a cold-blooded animal, an ectotherm,

often the advantages are associated with increasing reproductive output with age. And the reason for that is that older individuals of ectotherms tend to be larger. So they grow throughout their life. And unlike a lot of mammals, as ectotherms get bigger, the mothers actually produce more eggs. And in some cases, they produce exponentially more eggs in terms of the number of offspring produced per gram of body mass.

We often hear the adage that with age comes wisdom. Does that apply to some of the long-lived animals that your team looked at in this study? Yes. Increasing experience with age and the ability to transmit that knowledge to other individuals of your species appears to be important for a wide range of animals. This is something that

is called cultural transmission. So while animals can't communicate in the same way that we can as humans, they do it in different ways. And they often lead by example, leading migration pathways or finding particular spawning areas, for example. This is a common strategy that

migratory birds employ. And we're also learning more about aquatic animals that use cultural transmission to learn about the habitats that they're using and the places that they need to go to

survive during extreme drought periods or extreme flood conditions. This knowledge built up over a lifetime is often held by the older individuals. Your paper looks at some of the ways that humans have contributed to the decline of older animals. And I wonder if you can tell me a little bit about what those impacts have looked like in both aquatic and terrestrial ecosystems.

In aquatic environments, humans have been harvesting fish for a very long time period. Since commercial fisheries have been developed and expanded over the past century, we selectively harvest these large, old individuals. And the models that we use as fishery scientists to determine whether or not that fishery is sustainable actually rely on the removal of those

older individuals, and then expectations about faster growth or more young recruiting to that population when you harvest those old individuals. And it turns out that while those assumptions hold under some conditions, there are a lot of benefits of these older individuals that we didn't actually know were playing out. It's something that's happening particularly in the fisheries world in terms of the harvest of large old individuals.

But also on land, hunting, poaching, as well as different other types of anthropogenic pressures can systematically remove these older individuals. And we're seeing that in places around the world, whether it's in Africa, trophy hunting male lions or poaching of African savannah elephants. It's happening both in aquatic and terrestrial environments. What happens to these animal communities when the older individuals are removed?

We're still learning about what happens when that removal occurs. But one thing that does appear to happen is their populations become more unstable. So they have a greater range of variation over time. And this can be a problem for populations because the stability that those old age classes provided

allowed them to persist through a wide range of environmental conditions. And this has a lot of implications, we think, for climate change and the ability of species to resist extreme climate events, but also in terms of long-term sustainability of fisheries. Atlantic cod is a very clear example where we have good evidence that older individuals provide really important benefits

biological functions for those populations, particularly in terms of the number of offspring that large females produce. And then those populations in particular have been harvested intensively over long time periods. And one of the major outcomes of that harvest has been the depletion of older age classes. And

It does appear that the selective removal of those older age classes is one of the major contributing factors as to why those populations have not recovered following collapse. There's likely to be a wide range of other reasons why those populations have not recovered, but we think this is

may be one of them. What are some of the outcomes to the ecosystems as a whole when older individuals are pulled out of these populations? The loss of these old individuals not only impacts their population and those species, but because of their roles and ecosystems, it can also impact the stability of those environments and the food webs that they affect. In some of these species,

They also change their diets as they grow old. So larger, older individuals of many fish species feed at higher trophic levels and feed on different food items. So we're changing the dynamics of how these environments work. But fundamentally, we think that the loss of these old individuals affects the

the stability of those ecosystems in the long term. Like old growth trees and forests, these old individuals and their populations provide stability for the environments in which they live. So when thinking about how we manage wildlife and fisheries, you

You and your team introduce a term called longevity conservation. Can you tell me a little bit more about what that means and what that might look like? Yeah, what we're calling for there is the protection of older age classes of individuals. Often in natural resource management or conservation, we're focused on species and their abundance, the abundance of individuals generally.

or the areas where they occur, their spatial distribution. But less often do we actually consider the age structure of those populations. This can lead to situations in a wide range of species where the oldest age classes have been completely eliminated from those populations.

And we have large numbers of young individuals. If you think about it in terms of large old trees, you could have an old growth forest, for example, where you've removed all of the large old trees and potentially you have a large number of young individuals, but it doesn't necessarily mean that those populations are healthy. And thinking about it in an animal context, think, for example, the consequences of if we removed trees,

older age classes of human beings and we were left only with age distributions of humans that were younger than 25 years old or something. So it would be a very different society. And we're saying that the removal of those old individuals can play out in a wide range of different ways because of the negative consequences for biodiversity, but also the benefits that people derive from these old individuals. We're calling for the protection of those older age classes. So

That's what longevity conservation is. And in terms of where to from here, we think that dedicated policy directives are needed to protect those older age classes. For example, when it comes to fisheries, there are different types of overfishing that fisheries scientists evaluate for. And we try to avoid so that we can have populations that are harvested sustainably

providing food for people in the long term. One of the things they don't assess for is longevity overfishing, the depletion of old age classes. And because we're learning more about the negative aspects of removing these older age classes, we're calling for longevity overfishing to be something that's actually evaluated by fisheries managers and avoided where possible.

So that's an approach that we're suggesting. Also in terms of biodiversity conservation, organizations like the IUCN, the International Union for the Conservation of Nature,

When they assess whether or not a species is threatened, they have a range of different criteria. And these criteria are often based on the overall abundance of individuals, but they don't consider the age classes of those species. So similar to the old growth forest example that I talked about before, you can have almost the complete elimination of old individuals of these long-lived species and those populations being considered healthy in terms of assessments of fishing and a

assessments of whether or not those species are at risk of extinction. And we do know that the depletion of these old age classes is a contributing factor to the listing of particularly some of these very long-lived species. What's at stake for biodiversity and conservation moving forward if we continue to neglect these older animals in our research and management priorities? For the species themselves,

The loss of those older individuals we know is a contributing factor to population decline and in some species is likely to have been a contributing factor ultimately to their listing as a threatened species. So potentially extinction is one important outcome from the loss of these old individuals.

But we also stand to lose services that these populations provide, particularly when it comes to fisheries production and the sustainability of that in the long term. So those are the two important outcomes that we do stand to lose. Thank you so much for taking the time to share this research with our listeners. Thanks, Ari. I really appreciate the opportunity to talk about it.

Keller Kopff is an ecologist and lecturer at Charles Darwin University in Australia. You can find a link to his team's paper titled, "Loss of Earth's Old, Wise, and Large Animals" at science.org/podcast. And that concludes this edition of the Science Podcast. If you have any comments or suggestions, write to us at [email protected]. To find us on podcasting apps, use the search term "Science Magazine."

or you can listen on our website, science.org slash podcast. This show was edited by me, Sarah Crespi, and Kevin McLean. We had production help from Megan Tuck at Paji. Special thanks to Ariana Remmel for their work on the Oldest Animals segment. Our show music is by Jeffrey Cook and Wen Kui Wen. On behalf of Science and its publisher, AAAS, thanks for joining us.