How the immune system can cause psychosis, and tool use in otters

This episode explores the relationship between autoimmune disorders and psychosis, and the fascinating tool use behaviors of sea otters.

1. Autoimmune encephalitis can cause severe psychiatric symptoms and is often misdiagnosed as a psychiatric disorder.
2. Steroids and immunotherapies can effectively treat some forms of autoimmune encephalitis, potentially reversing symptoms.
3. Sea otters use tools to access calorie-rich prey, which helps them manage energy expenditure and dental health.
4. The use of tools by otters is influenced by their upbringing and dietary specialization.
5. Research into otters' tool use offers insights into evolutionary biology and animal behavior adaptations.

1: Introduction to Autoimmune Psychosis

Exploring how autoimmune disorders can lead to severe psychiatric symptoms mistaken for other conditions. Rich Stone and Sarah Crespi discuss the impact on patients and the potential for treatment. Rich Stone: "It's horrifying when you see them, and you can imagine what it's like for their families."

2: The Science of Otter Tool Use

Discussion on how sea otters use tools to open hard-shelled prey and the benefits they gain from such behavior. Chris Law: "They're one of the few animals to actually use tools, which is pretty cool."

1. Recognize Symptoms: Understanding symptoms of autoimmune encephalitis can lead to early diagnosis and treatment.
2. Explore Wildlife Behavior: Observing animal behavior can provide insights into evolutionary adaptations.
3. Support Research: Contributing to medical and wildlife research can help advance our understanding of complex conditions and behaviors.
4. Monitor Health Changes: Pay attention to sudden changes in health or behavior as they could indicate underlying autoimmune issues.
5. Educate on Autoimmunity: Sharing knowledge about autoimmune conditions can help reduce misdiagnosis and improve treatment outcomes.

On this week’s show: What happens when the body’s own immune system attacks the brain, and how otters’ use of tools expands their diet

First on the show this week, when rogue antibodies attack the brain, patients can show bizarre symptoms—from extreme thirst, to sleep deprivation, to outright psychosis. Contributing Correspondent Richard Stone joins host Sarah Crespi to discuss the hunt for biomarkers and treatments for this cluster of autoimmune disorders that were once mistaken for schizophrenia or even demonic possession.

Next on this episode, producer Katherine Irving talks with Chris Law, an evolutionary biologist at the University of Washington and the University of Texas at Austin, about how sea otters gain energy benefits (and dental benefits) when they use tools to tackle tougher prey such as snails or large clams.

People

Joseph Dalmole, Rich Stone, Sarah Crespi, Chris Law, Katherine Irving

Companies

Icon School of Medicine at Mount Sinai

Books

None

Guest Name(s):

Rich Stone, Chris Law

Content Warnings:

None

Icon School of Medicine at Mount Sinai
This podcast is supported by the Icon School of Medicine at Mount Sinai, one of America's leading research medical schools. Icon Mount Sinai is the academic arm of the eight hospital Mount Sinai Health System in New York City. It's consistently among the top recipients of NIH funding. Researchers at Icon Mount Sinai have made breakthrough discoveries in many fields vital to advancing the health of patients, including cancer, COVID and long COVID, cardiology, neuroscience, and artificial intelligence. The Icon School of Medicine at Mount Sinai we find a way you listen.

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This is the science podcast for May 17, 2024. I'm Sarah Crespi. First up this week, when rogue antibodies attack the brain, patients can show bizarre symptoms, from extreme thirst to sleep deprivation to outright psychosis. Contributing correspondent Rich Stone joins me to discuss the hunt for biomarkers and treatments for a cluster of autoimmune disorders that were once mistaken for things like schizophrenia or even demonic possession. Next, producer Katherine Irving talks with researcher Chris about how sea otters gain energy benefits and dental benefits when they use tools to tackle tougher prey.

Joseph Dalmole
So the story begins in 2005, when Joseph Delmole at U Penn encountered a 26 year old woman in the ICU of Philadelphia hospital. He's a neuro oncologist. He was called in just to consult because the ICU doctors were at Wits end. She had come in with symptoms that included inappropriate laughing and paranoia, combative behavior.

But the treatments were not working. Antipsychotic medications had no effect. Antibiotics didn't help. And as she got worse and worse, she couldn't recognize family members. She developed severe facial twitches, lapsed into a coma, had to be intubated. She had trouble breathing. The only physical abnormality, it seemed, was some mild breathing inflammation and a teratoma. A teratoma is a rare kind of germ cell tumor, and this teratoma was in her ovary. So what connection could it possibly have to her? Brain? Inflammation, the symptoms she was having? So Dalmol was stumped. Unfortunately for the woman, they gave her steroids to try to tamp down the brain inflammation. She got better, she steadily improved, and within a year, she had a clean bill of health. So she was giving back her life. And it dawned on Delmo that there were three other young women with similar symptoms who had been referred to him in previous months that also had these benign ovarian teratomas. So, stunning coincidence, perhaps, but he suspected that antibodies generated by the immune systems were attacking the teratomas and then mistakenly also taking aim at proteins in the brain. That was his hypothesis. So he set out to search for these new kinds of antibodies, and he found them. He found in the spinal fluid from these women never before seen antibodies that were targeting brain tissue. So it was a new kind of autoimmune disease.

Sarah Crespi
This week in science, contributing correspondent Rich Stone wrote about autoimmune encephalitis. Basically, this is when the immune system targets the brain, causing symptoms from seizures to psychosis. Researchers think this has been overlooked as a cause of some mental illness and are now trying to find the best biomarkers and treatments. Hi, Rich. Welcome back to the podcast.

Joseph Dalmole
Great to be with you, Sarah.

Sarah Crespi
Yeah, so some cases of autoimmune encephalitis sound pretty extreme. And you say that caregivers for people with this type of psychosis that can be caused by autoimmune encephalitis are traumatized. And you even mentioned that instead of being treated as a psychiatric condition in the past, it was treated with exorcism.

Joseph Dalmole
One of the forms of this disease. And there are 18 different forms, one form. If anti NMDA are encephalitis, the patients tend to be teenagers. A lot of them are women. They present with extreme psychosis. So they're fine one day and then suddenly they're psychotic the next. And as one neuroimmunologist I talked to for the story said, it's horrifying when you see them, and you can imagine what it's like for their families, for their caregivers. So, as it turns out, looking back in the literature, there were cases of people who underwent exorcisms who clearly had the constellation of symptoms that would fit anti NMDAR encephalitis. And moving forward to more recent times, there were a few patients who, after the discovery of disease, who had gone through exorcisms, were treated with immunotherapy and got better. One scientist, even going back to literature, found that the patient who inspired the novel the exorcist had symptoms that certainly seem to fit anti NMDAR encephalitis.

Sarah Crespi
Is it likely that the person doesn't have a family history of schizophrenia or psychosis. Is that one thing that they consider when diagnosing a patient with this?

Joseph Dalmole
Absolutely. In fact, an absence of family history of schizophrenia and then sudden onset psychosis is really a hallmark of anti NmDAr encephalitis.

Sarah Crespi
Ironically, it's almost like good news if you have this, because maybe it can get treated.

Joseph Dalmole
It is good news. I mean, there are, of course, caveats. There are 18 different autoimmunencephalitis diseases, all targeting different proteins in the brain. Some are more treatable than others. But the fact is that if you can catch this illness early and treat relatively simply with steroids or with second line drugs that are available, you can often bring people back to functional ability to get their, to work again in their jobs. Some are even cured entirely. But in the past, before it was known that these were autoimmune conditions, they were assumed to be entirely psychiatric psychogenic illnesses. Patients were treated with antipsychotic medications, and those often made their conditions worse.

Sarah Crespi
So how common is autoimmune encephalitis? Do we have a sense of the rate of diagnosis at this point?

Joseph Dalmole
They're all very rare. The most common is called anti NMDA receptor encephalitis. And that's essentially a rate of one to one and a half per million people.

Chris Law
Yeah.

Sarah Crespi
And the rest are even more rare?

Chris Law
That's right, yeah.

Sarah Crespi
Okay, so, and to test for it, are you looking for antibodies in these people to say, oh, there's an antibody in this person, so we know that they have this disorder?

Joseph Dalmole
Often treatment decisions are taken, especially with anti NMDA receptor encephalitis. The patient presents very classic clinical picture. Now, it's known that this is the clinical picture of this disease. They can be treated even before confirming tests is done to show that they have the auto antibodies in their CSF in the cerebral spinal fluid. Other autoimmune encephalitis is much more difficult to diagnose, and you really need to pinpoint which auto antibody is involved and then treated accordingly. You don't want to make presumption in these cases that a person has an autoimmune disease and then treat them with immunotherapy before you have some level of confidence that that's the case. Often, borderline cases may present with some of the symptoms of autoimmune encephalitis. If they are treated with immunotherapy and they don't get better because it's not an autoimmune condition, it really raises false hope in the patient. And their families that this is a treatable condition.

Sarah Crespi
You mentioned in your story there's actually a project in New York where they're going to be testing many, many people for this.

Joseph Dalmole
That's right. Researchers at Columbia University are going to be working with the New York State mental health system, which is a 3000 bed system across 14 different wards. And they're going to be looking for auto antibodies and other treatable conditions in these patients. Patients who may have been languishing for years in these wards presumed to have a psychogenic illness. They may be able to identify a handful of patients who can be treated successfully with immunotherapy and basically give their lives back to them.

Rich Stone
Wow, this is a really fascinating mechanism because basically the immune system is targeting very specific proteins in the brain. In the case of the NN, the NMDA type that we've been talking about, that's a receptor. It's on many kinds of neurons, but there are high concentrations in certain regions. And so if the antibodies are targeting those regions and blocking those cells actions, you can end up with this suite of symptoms that point to those receptors being blocked. But there are many other possible places that antibodies could be targeting in the brain.

Does that give us a bunch of different symptoms depending on the target, the kind of autoimmune syndrome that's happening?

Joseph Dalmole
Yes. Some overlap in symptoms. Some of the autoimmune encephalitis do involve psychosis, others do not.

Their memories affected most prominently. Some it's sleeping patterns are disrupted. Probably the grimmest of these diseases, the one with the worst patient outcome, is one that affects sleeping patterns. It really screws up the patients ability to sleep. And this particular autoimmune encephalitis is usually fatal in these patients.

Icon School of Medicine at Mount Sinai
We've mentioned steroids and there are some other treatments we're going to talk about. Do those stop the symptoms? Do they reverse and prevent further degradation? Or does it depend on the target of the antibody?

Joseph Dalmole
That's right. It's because of different mechanisms of what happens after the auto antibody attacks the receptor or a protein in the synapse. What happens with anti NMDA receptor encephalitis? What makes it more likely to have a good outcome is that the receptors that are attacked are absorbed into the neuron. But then the neuron can later make new receptors and you can recover function. There's another. The second most common is the anti LGI one, encephalitis. LGI one is a protein in the synapse. The auto antibody latches onto it and it disrupts the function of different receptors on either side of the synapse, and it leads to a permanent deficit in function. So LGI one patients can have some of their life restored to them, but they often face deficits. Sometimes it's memory deficits, and other patients, it's different kinds of neurological deficits.

Sarah Crespi
We kind of know what some of the mechanisms here, what is triggering the body to have immune reaction to the brain, because it is kind of a protected space most of the time.

Joseph Dalmole
Yeah, I mean, there are a lot of nuances, these relatively newly discovered illnesses. The first one was discovered only 2007, and there's been 17 more that hadn't been discovered since then, practically one a year. The mechanisms are still being puzzled out. But the blood brain barrier, yes, it usually protects you from this, but for whatever reason, sometimes an immune cell called the b cell, it will sometimes pass through the blood brain barrier and generate auto antibodies. Within the brain, there also is a mature form of b cell called plasma cells that stay in the brain for a long time. They can last for months in brain tissue, and they are generating auto antibodies as well. So it's, for whatever reason, some people are vulnerable to the development of autoimmune encephalitis and that the triggers are still being discovered. So they know, as I said, some cases it's the teratomas, these rare germ cell tumors. Sometimes it's a viral infection. So that's a whole area of research right now.

Sarah Crespi
What's special about a teratoma?

Joseph Dalmole
I don't think they really know. I don't think scientists really know why it's special. But the fact is that these antibodies respond to both the teratoma and then to particular receptors in the brain. And this explains just a certain subset of autoimmune encephalitis cases. There are other triggers. For example, herpes simplex infections can sometimes lead to encephalitis. And then as a sequel to that, patients sometimes will develop autoimmune encephalitis after they had the viral version of the disease. So that explains a subset of patients. Other triggers, though, are unknown.

Rich Stone
What about this idea that some researchers you spoke to suggested that a subset of immune targets, or maybe a milder level of inflammation, might be the cause for some psychiatric diseases, such as OCD or depression?

Joseph Dalmole
This is provocative and controversial. A lot of researchers, such as Joseph Delmo, other colleagues of his, are quite skeptical of this line of research. But there are neuropsychiatrists, primarily, who have been finding auto antibodies in people with a range of psychiatric conditions, depression, OCD, bipolar disorder, possibly in postpartum depression.

These are preliminary findings that suggest there may be a link. But these other antibodies, it's not certain that they're involved in the disease process. That's where all the controversy is. They might essentially be red herrings that could mislead people into thinking that psychiatric conditions could be treated with immunotherapy. So it's very controversial. Delmo and others are quite nervous that clinicians especially don't jump to conclusions and start assuming that people who come in with a particular psychiatric illness might necessarily benefit from immunotherapy.

Sarah Crespi
Can we just walk through some of the treatments that are available now, and then we can talk about what research is being done to kind of firm these up?

Joseph Dalmole
The good thing is that the first line therapies are tried and true techniques that have proven to be effective in a lot of cases. So, for example, there's plasma pheresis, where you take the blood, patient's blood, you circulate it outside of their body. You do that to purge plasma of antibodies. A second approach is to infuse an immune protein called PhytG that prompts the body to sop up all kinds of auto antibodies. And then a lot of patients get high doses of steroids, such as cortisone. And that can really work for a subset of patients. There are second line treatments, which are monoclonal antibody treatments, and the one that is used most often is called rituximab.

Sarah Crespi
So, yeah, and you mentioned there are some clinical trials going on right now for these drugs.

Joseph Dalmole
People have been using rituximab without being able to point to clinical trials showing a that's better than the placebo. They need to have more rigorous trials just to prove the efficacy. That's ongoing now. Then there's a huge trial underway that the NIH is backing. It's at 40 sites around the world, and it is a different monoclonal antibody called in a bilismab, that targets a different antigen on cells. It's in clinical trials now with results expected in 2027.

Sarah Crespi
Thanks so much, Rich.

Joseph Dalmole
You're welcome. Thank you.

Sarah Crespi
Rich Stone is a contributing correspondent for science, and he's the senior science editor for the Howard Hughes Medical Institute's Tangled Bake Studios. You can find a link to the story we discussed@science.org.

American Association for the Advancement of Science (AAAS)
Podcast Stay tuned for a chat with a researcher, Chris Law and producer Katherine Irving, about the pros and cons of tool use amongst otters.

Icon School of Medicine at Mount Sinai
Before we get to the next part.

Rich Stone
Of the show, id like you to.

Icon School of Medicine at Mount Sinai
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Katherine Irving
One of the most adorable sights for any sea otter lover is watching them pop up out of the water with some tasty clam or snail to eat. Some of these otters have figured out how to use tools to help them crack open those tough shells. But scientists were never sure how helpful those tools actually were. This week in science, Chris Law and his colleagues finally have a little bit of a clue as to what these tools are doing for the otters. So, hi Chris. Welcome to the podcast.

Chris Law
How's it going?

Producer Katherine Irving
So, according to the paper, it seems like it's been known for a long time that otters use tools. So what did we already know about sea otter tool use?

Chris Law
Yeah, so it's known that sea otters use tools to break open hard shell prey like clams, nails, crabs, and all those hard shell invertebrates that they eat. It definitely is pretty neat that they're one of the few animals to actually use tools, especially since it's a non primate tool user, which is pretty relatively rare. So pretty cool that they're just right in the backyard in the Mario bait. It's also been known that otters at least in the Monterey Bay, exhibit variation. So some individuals will actually use rocks or use tools to break open a prey, whereas others don't. And some previous work has found that it might be tied to their diets. So, like as a snail specialist or individuals that specialize on snails, they'll tend to use tools where something like a urchin specialist won't tend to use tools.

Producer Katherine Irving
How does an otter become a specialist in one particular prey item? Is there something that might predispose them to do that? Or do they kind of just figure it out on their own?

Chris Law
Otters tend to become specialists based on what their mom is feeding. So if a mom is a snail specialist, that pup will tend to grow up becoming a snail specialist and so forth. Sea otters typically prefer urchins and abalone, because those are prey items that are calorie rich and don't really require much force to break them open once they bring them up to the surface.

But unfortunately, in Monterey Bay, those prey items are typically gone due to various reasons, whether it's cr's eating them all or humans impacting those distributions. So they're forced to really specialize on different prey items that might not be as preferred. And that tool using behavior actually facilitates that ability to specialize on, on different prey.

Producer Katherine Irving
And why is it in particular that otters, as opposed to other animals, use tools?

Chris Law
It's kind of like a chicken and egg type of situation where their otters become specialists on hard shell prey inverts. Is it because of this tool using behavior, or is it because of different adaptations? And I'll say that sea otters, even without the use of tools, they exhibit all sorts of adaptations in their cranium or in their skull that allows them to eat these hard shell prey. So, for instance, they have, like, these really big molars that look very similar to us, and a lot of ancestral hominids. So they're really great for crushing these hard items, and they also exhibit these short, blunt skulls that really increases bite forces to crush those hard items. So they already exhibit all those adaptations. The tricky part is actually understanding when tool use first came to be, because you can't really see that in the fossil record, because tools don't really preserve, and they're the ocean. So who knows whether a rock is being used by an otter? My guess is that otters already were able to eat these hard items based on their cranial morphology. And this tool using behavior somehow just appeared. We don't really know when or why it appeared. So that is definitely a mystery for sea otters, right?

Producer Katherine Irving
Yeah. Some otter just saw a rock one day and was like, oh, this might be useful.

Chris Law
Yeah. Yeah. Who knows?

Producer Katherine Irving
It seems like we've known for a while that the otters use tools for various reasons. They mentioned in the paper that it's difficult to study, like what exactly the benefit is of those tools. So why has it been sort of difficult to analyze that in the past?

Chris Law
Yeah, it's just access to longitudinal data, basically following individuals throughout their lifetime and understanding what types of prey that they're consuming and their associate behaviors with those type of different prayer items. That kind of data is pretty rare to get in natural systems. We're lucky here with the sea otters in that they've been flipper tagged and radio tagged for decades. So we have these great longitudinal data sets for a lot of these individual otters. We know where they hang out, what they're eating, whether they're using tools. We're able to even estimate the sizes of those different prey items. So we have all this great natural history and life history data associated with individual otters.

Katherine Irving
So how do researchers track what kind of food each individual otter eats?

Chris Law
Because they are threatened, lots of organizations work together to basically flipper tag them. So this includes like the Monterey Bay Aquarium, UC Santa Cruz, USGS, fish and wildlife, and lots more. So they flipper tag them and then they have all these volunteers to basically go out to shore and use scopes to watch them, observe them and document what it's eating, how long it's diving for or foraging, and whether it's using tools and all that fun stuff.

Producer Katherine Irving
That sounds like a fun volunteer opportunity.

Chris Law
Yeah, I mean, it's not bad. You just hang out by the California coast and watch sea otters.

Producer Katherine Irving
In the research that you're doing, you'd speculate that tool use helps minimize trade offs between different factors when choosing prey, like tooth damage and amount of energy spent. So what are some of these factors that otters have to take into account when they're choosing a prey item? And how does tool use help intervene with those factors?

Chris Law
Imagine sticking a clam in your mouth. You would probably fracture your teeth or, like, have a really hard time just breaking that open without a tool. So that's what this behavior allows them to do, is break open these harder prey items, especially things like clams, mussels and snails, which takes a lot of force to break open. That is far greater than the amount of force they can generate with biting alone. What we found is that there's all these trade offs between those considerations in terms of what types of prey that they're eating, how much calories do those different prey species contain? And, you know, whether it's going to damage their teeth as they're trying to break into those different prey items. We were interested in really understanding what is driving this variation from more of a mechanical and even bioenergetic perspective, as in, like, why are snail specialists actually using tools and urchin specialists aren't? And is there a benefit, as in individuals that use tools frequently? Are they gaining more calories compared to individuals that don't use tools?

Producer Katherine Irving
So then once you have that data, it says, kind of in the paper, you were doing a few different models to try and figure those questions out. So how exactly do you set up and run a model on these sorts of things?

Chris Law
It goes back to that life history data that we were able to get from these individual otters. So it includes things like estimated age, sex, their location, their tool using frequency and their prey specialization. So we basically fit a variety of models to try to understand how all of those affected our variables that we were interested in, which were like amount of force it takes to break open their prey, how many calories that they were able to consume, and their tooth condition. And we were primarily focused on how this tool use frequency influenced those variables, accounting for things like sacs, age, size and location, and all those life history traits. So, yeah, a lot of coding, once.

Producer Katherine Irving
You ran those models, you kind of came across some pretty interesting results to me, at least. What kind of was the most interesting part of it for you in terms of what you found?

Chris Law
There are three things that kind of alluded to. First is that increased tool use does enable otters to gain either access to harder prey or larger prey. And this pattern is more significant with the females. Sexual dimorphism is usually an obvious source of variation within a single population, like our elephant seals, where males have evolved to become larger so that they can compete with one another for access to mates and control, basically, of the beach. In sea otters, it's probably similar, where larger males are able to basically push away competing males for reproductive success or increased reproductive success.

But it's been noted that in more aquatic mating species like sea otters, or increased size advantage kind of decreases because they're mated in water, and it's really hard to use a larger size to gain advantage. So this suggests that maybe there are other factors that might be contributing to sex or dimorphism as well. And one factor that contributes to dimorphism might be just allowing different sexes to target different types of food. Maybe males that are larger might be able to eat harder or more difficult things to gain access to, whereas females that are smaller might eat smaller things. But what we found here is that females use tools more frequently than males, which we found actually allow them to gain access to harder prey items that males won't even eat, which is kind of cool. So they're able to gain these novel sources of food that are either bigger and potentially more calorie rich or harder, that are also more calorie rich compared to males.

Second thing, we found that in general, increased tool use does lead to a reduction in tooth damage, which is pretty cool. If you ever look at a sea otter's mouth, a lot of the individual otters, especially the older ones, their teeth are completely destroyed just from eating all these hard items. And without their teeth, they can't eat. So then they would die. So we found evidence that tool use does reduce that damage. And then the last thing was he alluded to this, to the trade offs between tool using behavior and energetic intake. Some individuals that use tools were able to gain more calories compared to individuals that don't use tools. But then we also found that individuals that use tools a lot actually exhibited a reduction in energetic intake rate. We attributed this to alternative strategies, to maintaining caloric income in the event when all your preferred prey are gone. That first strategy is using tools to gain access to these harder clams, which are super energy rich, so they're able to gain access to those prey items. And the second alternative strategy is to gain access to hard snails, which are energy poor, but they're super abundant or like, found all over the kelp forest, so there's a lot of them to eat. So kind of those two strategies that was pretty interesting to find.

Producer Katherine Irving
One potential tool used method is to go after stuff that's super energy rich that they wouldn't have been able to get at before. And then part of it is also just, oh, I don't have any other foods, so I've got to go after this snail, even though it doesn't have a lot of energy in it.

Chris Law
Exactly.

Producer Katherine Irving
If a female teaches a male son how to use tools, does he just choose not to use them because he has other options for prey? Or how does that tool use pass down across the generations?

Chris Law
The thought is that if the mom is using tools, the pup will learn to use tools, but the mom isn't actively teaching the pup how to use tools. It just kind of watches it. But in terms of that sex difference, like when a mom is using tools and a male pup is watching its mom use tools. Whether it just stops using it, I actually have no idea.

Producer Katherine Irving
That seems so interesting to learn more about whether they have this cultural inheritance or whether they just figure out on their own that they don't need the tools or that they need them more.

Chris Law
Staff at the aquarium will notice that orphaned pups with nobody to watch these tools will kind of use that tool using behavior in a playful kind of way. They're like basically bang things against their chests, even though. So the idea is that, you know, it's wired in their system, but in order to actually develop it, they need to watch some other individual use a tool. So.

Producer Katherine Irving
So it's kind of like a combination of something that they want to do naturally and something that they need to figure out also. Like baby babbling.

Chris Law
Yeah, exactly.

Katherine Irving
So it seems like that easier prey is in a much lower supply as a result of human activity. So could it be that the tool use by the otters is somewhat a response to that effect of human presence?

Chris Law
Yeah, yeah, exactly. It definitely does help them out in terms of anthropolog changes to kelp forests and other habitats around that area. So, yeah, I guess they were, they lucked out that they were able to use tools to gain access to these different parietals more easily.

Producer Katherine Irving
What do you hope to do next to build upon what you've done here? What's next to learn?

Chris Law
It'd be super cool to be able to test to see whether this tool using behavior, is it increasing in frequency through time in this population? Are more individuals using tools compared to even a decade ago? Second, it'd be also cool to see if individuals that use tools more, do they exhibit greater reproductive success than non tool users? If they do, that would suggest that there's some kind of fitness advantage with tool use in this population.

Producer Katherine Irving
Chris Law is an evolutionary biologist at the University of Washington and the University of Texas. You can find more information about the study we just covered@science.org. Podcast so thanks for coming on the show, Chris.

Chris Law
Thanks for having me. It was fun chatting with you.

American Association for the Advancement of Science (AAAS)
And that concludes this edition of the Science Podcast. If you have any comments or suggestions, write to us@sciencepodcast.org to find us on a podcasting app, search for Science magazine, or you can listen on our website, science.org podcast. This show was edited by me, Sarah Crespi, and Kevin McLean. We also had production help from Megan Tuck at Prodigy. Special thanks to Katherine Irving for this week's segment on Otter tool use. Jeffrey Cook composed the music on behalf of Science and its publisher, AAA's. Thanks for joining us.