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- [00:00]
Capital One Bank Spokesperson
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- [00:31]
Dr. Samantha Meem
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It's breathable, hypoallergenic and surprisingly machine washable so it's easy to care for. People love waking up with smoother hair, calmer skin and no sleep lines. Plus, Blissey makes the perfect gift and you can even complete the set with matching sleep masks, silk bonnets and crease preventing scrunchies. Blissey is offering 60 nights risk free plus 30% off when you shop@blissey.com unwind your skin and hair will thank you. Hey, before we dive in, if you're enjoying Curiosity Weekly, do us a massive favor, hit that subscribe button, leave us a review and share the show with a friend. Word of Mouse is like the gravitational force that keeps this whole thing orbiting. So help us spread the science. Ninety percent of people are right handed, so in this episode we're celebrating the 10%. And just in time for international left hander on August 13th. We'll start by looking into one of the oldest puzzles in human biology. Why are so darn many of us right handed? Then we'll talk with Dr. David Carey about why the left and right halves of our brain don't do the same thing. And how your dominant hand ties into that whole picture. And finally, because we can't resist, we're talking about handedness in dogs. It turns out our best friends have paw preferences, too. We'll even tell you some simple at home tests you can try with your own pup. Welcome to Curiosity Weekly. I'm Dr. Samantha Meem. Most humans are right handed, about 90% of people. And that holds up across cultures. For a long time, scientists couldn't really figure out why. Well, we may finally have an answer to that question. And it surprisingly has more to do with our legs and our brains than it does our actual hands. The majority of primates, our closest relatives in the animal kingdom, are far more evenly spread when it comes to handedness. Humans are the only primate species on the planet that are overwhelmingly dominant on their right side. This led researchers from the University of Oxford and University of Reading to investigate where this shift happened in the timeline of human biological history. And the best way to do that was to go straight to the apes themselves. Using data from over 2,000 monkeys and apes across 41 different species, the team tested a bunch of different theories about what causes dominance in one hand versus the other. They used a statistical framework called Bayesian modeling. That doesn't just say yes or no. It tells you how confident you should be in different explanations. Basically, the model is a way to quantify uncertainty. The researchers looked into factors like diet, body size, social structure, habitat, movement patterns, and tool use. In every single case, humans stood apart from the other primates. As a group, they split roughly evenly between their right and left hands, while humans skewed right handed. But eventually, two traits of our evolutionary history tipped the scales. Walking on our hind legs and the size of our brains. And they seem to play slightly different roles. Our upright gait is tied more to how strong our hand preference is, while our big brains are tied more to the direction, mostly right. Once the researchers plugged those traits into the model, humans no longer stood apart. Their extreme right handedness could finally be explained within the same framework used for every other primate. So these two things appeared to be what pushed humans into the extreme 90% right handedness that we see today. The theory is humans began to walk upright, which meant that our hands were now free to do other things. Our brains grew, and with that growth came something new. The two halves of our brain started dividing up the work, like having language mostly controlled by one side of the brain instead of being separated across both. And it seems to researchers like that reorganization one hemisphere taking the lead on things like language and movements from our dominant hand. That's what cemented our right hand dominance. The theory brings up a lot more questions, the big one being why has left handedness persisted all this time in such a minority of people? Well, we might need to wait to find out the answer to that big question, but this research puts into perspective just how much of an anomaly we are when compared to our animal cousins.
- [05:47]
Capital One Bank Spokesperson
With no fees or minimums on checking accounts, it's no wonder the Capital One bank guy is so passionate about banking with Capital One. If he were here, he wouldn't just tell you about no fees or minimums. He'd also talk about how most Capital One cafes are open seven days a week to assist with your banking needs. Yep, even on weekends it's pretty much all he talks about in a good way. What's in your wallet? Terms apply. See capitalone.com bank capital1na member FDIC
- [06:17]
Dr. David Carey
Then I thought, what if I've scaled businesses? What if I scaled my philanthropy? What if I did as much in one year as I've done in my whole life?
- [06:24]
Capital One Bank Spokesperson
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- [06:30]
Dr. Samantha Meem
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- [06:32]
Capital One Bank Spokesperson
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- [06:59]
Dr. Samantha Meem
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- [07:01]
Paige from Giggly Squad
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- [07:49]
Dr. Samantha Meem
Every August 13th is International Left Handers Day, a day established in 1992 to celebrate the creativity and uniqueness of left handed individuals and raise awareness about the everyday challenges that they face in a world largely built for right handers. The first image that always comes to my mind is how most scissors are right handed. But the examples are endless. Picture L shaped desks in college classrooms, A computer mouse, manual can openers, hand saws, brass instruments. They're all designed specifically for right hand use. But it goes beyond tools and ergonomics. It even impacts the way we do neuroscience research. Most brain imaging studies are in right handed people for the sake of standardizing. But what do the brains of left handers actually look like? Left handers are roughly 10% of the population. How do these differences shape the way we process language, faces and movement? Our guest today is Dr. David Carey, a clinical neuropsychologist who studies behavioral asymmetries like handedness, footedness and sighted dominance. His work explores our physical biases and deeper patterns in brain organization. Welcome Dr. Carey.
- [08:56]
Dr. David Carey
Good morning Sam, how are you?
- [08:58]
Dr. Samantha Meem
I am doing great. To start us off, can you tell us like high level. I know we don't have a ton of imaging data on left handed individuals, but what do we know about how their brains might be different from a right handed brain? Are things on the opposite side?
- [09:15]
Dr. David Carey
You've asked the big question right from the get go. We've known for a long time, even before imaging, that there's something different in how the two halves of the brain work in left handers. And much of the early data came from studies of people with language disorders after stroke. So even back in the 1860s we knew if you were a right hander like you or me, chances are damage to the left side of our brain, which controls our right hand, our dominant hand would be the one that would produce some problems with speech comprehension production. And so after these observations were made in right handers, of course, because we're so common, people made the assumption that left handers must be the other way around. In other words, their right hemisphere is dominant for speech and language and, and that's why they use their left hand. But it became apparent after studying lots and lots of patients that left handers were often aphasic. They had these speech problems after left hemisphere damage. And then this led eventually in the 70s and 80s to people doing more detailed systematic studies to determine which half of the brain is important. So we've known that for a long time, long before imaging. What imaging has changed, I guess is that lots of People have gone back to the basics and they look for things like structural differences. Can you tell if somebody's a left hander or right hander from looking at a T1 image from an MRI scan? And the answer is, you can. The individual variation between my brain and your brain swamps any of the variability that would be accounted for by hand. So there's no sort of structural correlate, no bit of the brain that's bigger in one side or the other, anything that would really give away if somebody's left or right handed. So what we've started to do, as you rightly point out in your introduction, left handers were ignored like the plague in imaging studies, especially ones of language in early days. A small number of us though, who are interested in handing this, have started scanning them en masse so we can talk about some of those effects if you'd like.
- [10:59]
Dr. Samantha Meem
There was this long standing hypothesis that people who are left handed have more structural connectivity between the two hemispheres of the brain. And you in 2025 had a publication that kind of went against that.
- [11:13]
Dr. David Carey
Yeah, it's an old claim that goes back to a Canadian neuropsychologist named Sadner Whittleson, I think, or if not Geshwinder Galiberta, American Neurolog. But I think the logic goes like this. If my left hemisphere is dominant for language, but I write with my left hand, in some sense handedness doesn't matter in terms of the control of your hand, as you said, it's the contralateral bit of motor and sensory motor cortex that controls the hand. So that must mean in left handers, information from the language dominant hemisphere is going from the left to the right. So everybody, as soon as we had MRI scanners, everybody was looking at the corpus callosum, this big band that you can see in cross section and a sagittal section to look for structural differences. And you would think it would be bigger, in fact the majority of left handed, but it just is not. And what we did that was a bit different is we scanned people functionally while they were doing a task to let you determine which was the speech and language dominant hemisphere. What that meant is we can also control for your language dominance. So you might argue that if a left hander is left dominant for language, but yet uses her right hemisphere to control her left hand, she's one or a group of those people would be the ones with the bigger corpus callosum. But it doesn't work.
- [12:27]
Dr. Samantha Meem
I'm curious how brain asymmetry matters in a clinical context. So does handedness change how you would approach any sort of diagnosis or rehabilitation, for example, like after a stroke or brain injury?
- [12:40]
Dr. David Carey
That's a really good question too. In the older literature on language disorders, the aphasias, the claim was that if you're left handed, you're more likely to have a language disturbance in the first instance. If you just take loads and loads of patients who come through the hospital and they've had a unilateral or a bilateral stroke of some kind. So left handers were at a disadvantage because they're more likely to be dysphasic or aphasic stories, you'd say, in America. But they recover better. This was the claim. And it's easy to kind of map that onto the notion that they're a little more bilateral in their organization. The evidence for that is pretty mixed, but, but the suggestion is out there. I don't think I would design a rehab program differently for somebody who's left handed or right handed in that particular respect. You would make different predictions potentially in left handers and right handers about what deficits they might have after left or right brain damage. For example, the really rare kind of deficit you guys have probably talked about on the show at one stage or another, prosopagnosia, this deficit where I can't recognize familiar faces anymore even though my vision is still relatively intact, that usually follows from damage to both halves of your posterior brain. But actually when you get it from damage to the right side to the left side, it's more likely to be the right side. And so we now think the right hemisphere is dominant for face perception in some sense. And there's some neuroimaging data that support that. But of course, left handers sometimes, not always will show the opposite pattern. So they're a little more likely teprosopagnosia after left brain damage. So you might look, for example, if you're a neurologist, you might, and you knew the patient was left handed, you might do a broader neurological exam than you might do normally. Because right handers like us, Sam or vanilla ice cream, right. Our brain asymmetries are mostly pretty standard. And so if I have a language problem, I might also have apraxia, for example, difficulty making movements to command or copying movements to. So you might change your exam in that regard. The claim is that in some sense, if your left hemisphere is busy doing lots of language related things, then your right hemisphere is going to become specialized for non language things. Marlene Behrman, who's at Carnegie Mellon, has a Nice model of this, which is you weren't born, Sam, with a bit of your brain that knew how to read. Reading is a relatively new invention, culturally speaking, it's probably nine or 10,000 years old. Our brains have been evolved for about 200,000 years. There's some reason to believe that these circuits that you're born with that are going to suck up speech like a sponge when you're a little girl or a little boy. These regions are left hemispheric if you're a boring right hander like us. But then when you learn to read, it makes sense for the visual regions of your brain that become specialized for letters and words to build that circuitry in the same side as your speaking brain. Now it turns out those bits of the visual brain, a place called your fusiform gyrus, they like foveal vision, right? We need our fovea in order to read properly, but we use our fovea also when we're recognizing faces on learning basis. And so the idea is as you learn to read, face processing gets pushed over to the other hemisphere because of crowding. So this is part of a general idea in neuroscience and neuropsychology that's been around for God, 100 years, which is there's complementary hemisphere specialization. If you're a vanilla ice cream right hander like you or me, you're left dominant for speech and language, but you're going to be right dominant for things like face processing, some aspects of emotion processing, aspects of processing, the emotional aspects of speech. So if your partner said, great job on the dishes last night Sam, versus great job on the dishes last night, Sam. The linguistic content is handled by the left side of your vanilla brain. But that emotional content telling you that that person's being sarcastic, that is coming from the right side and that we've known for a while. So this is an old, quite attractive idea. It turns out not to be perfectly true, but that if one side is doing language, the other side does a lot of non language things. It doesn't always have to be that way.
- [16:45]
Dr. Samantha Meem
We've talked a lot about handedness so far and that gets a lot of the attention. But in your research you also look at things like footedness and sighting dominance. How do these other asymmetries relate to to handedness? And can someone be right handed but left footed?
- [16:59]
Dr. David Carey
They can, and in fact I'm an example of it. So I'm a right hander, I'm a boring right hander. I turn out to be left eyed for sighting. Although I don't see very as well out of my left eye than my right eye. I also turn out to be left footed for kicking. Now that's complicated in my instance because I destroyed my right knee playing basketball around the time I started playing football. So it's hard to know if I was born left footed or not. Now again, if this was just which eye you saw better with, what should happen is about half of us should be left eyed and about half of us should be right eyed. But it's not true. About 65% of us or so are right eyed. And you're more likely to be right eyed if you're right handed than if you're left handed. Now fitness is even more dramatic. About 80% of us roughly are right footed. And that's just weird because if you think about it, we're bipeds, we're walking around on these two feet, our brains are doing incredibly complicated somatosensory and motor control things all the time. We're running, we're playing, we're twisting, we're not falling over when we throw balls or catch or do anything else. Yet when people kick a ball, they have a really strong preference and that's quite surprising. And you are definitely more likely to be right footed if you're right handed. There's no question. And I don't think that's planned and I don't think that's related to lots of other environmental factors. I suspect you're just born right or left footed.
- [18:16]
Dr. Samantha Meem
I'm right handed, but ambidextrous when I play soccer.
- [18:20]
Dr. David Carey
Sam, I'll tell you what, you're going to get the production team to come out and video you on a Saturday kickboat. Because we looked at this question in professional footballers a long time ago and we just took advantage of televised matches of elite games and we counted, we developed some software to input the data and we just counted how often these elite football players use their right or left foot. And there are surprisingly few players who are really two footed. So if you are, there's always a career for you in the women's national team when you're ready to hang up your science journalist. Because two footed players are rare, there will be lots of sports specific effects. The sport that really stands out in that regard apparently is fencing. So in fencing there are a whole bunch of over practiced, really important skilled movements that if you are left handed really gives you some sort of an advantage. And there's some claims out there in literature, I don't know how good they are. That some fencers have chosen to learn to use their left hand to give them a competitive advantage. The more exciting possibility is that again, if you have left hemisphere dominance for speech and language, you might have right hemisphere dominance for some aspects of processing visual spatial information or something. And so you might. It might be the case that there are some left handers who have super duper right hemispheres and that gives them advantage in sports. The story in fencing is really quite convincing.
- [19:39]
Dr. Samantha Meem
Yeah. And to what extent is it learned versus genetic? Like do we just socialize people to typically be more right handed or there's some like innateness?
- [19:49]
Dr. David Carey
You're asking all the right questions. I mean I would argue that if handedness was, let's just say, you know, it's good to specialize. So I pick up that crayon as a little boy and I start to use it or I throw that first ball in the garden or I do whatever that in some sense for many motor skills it might be useful if they require some learning to do, do it with one hand or the other. If that was all that was going on, half of us would be left handed and half of us would be right handed, which has clearly never been the case. So again, as I talked about before, in many cultures, writing languages go for left from right. It's kind of advantageous to be right handed in such cultures, but then what you would expect is in cultures like, well, in languages like Hebrew or Arabic where you write right to left, you should see a predominance of left handers and you just don't. The real mystery about handedness is that the genetics of it suggest that only about 25% of the variability is accounted by genetics. But talk to any parent. I don't know if you have children, but when you have children, their handiness emerges. You really have very little to do with it. And yet nine out of ten of those kids turn up to be right handed. Roughly speaking, if both parents are left handed, the children, about a quarter of the children would be left handed. So you'd have to have four kids to produce a lefty. On average, if both parents are right handed, it's about 5 or 6%. You'd have to have 20 kids to produce a lefty. But of course you get all kinds of. I'll get a bunch of email from your listeners saying I have three left handed children. What's going on? Those things do happen occasionally, but those are the odds. So this, the genetics are complicated, but it sure feels innate. It sure feels like handedness and footedness just emerged developmentally at different times and that really the children and the parents had little to do with it. You can suppress it, of course, an anti sinistral bias. And some of your listeners, hopefully, you know, not many I hope, but have still experienced that, right, that in some schools, in some cultures, in Africa and Asia, for example, it's much more common that, you know, this is the hand of Satan. You don't write with that hand or you don't eat with that hand, for example, for cultural reasons. This is the, this left hand is the hand you clean yourself with after you go to the toilet. So those, those effects are still around. So there's, there's no doubt that environment can affect your handedness. But I don't think, for example, kids are modeling. I don't think, you know, your daughter, your son would look at you and go, oh, mommy's writing with her right hand. I think I do that mainly because kids are lousy at left and right. And actually the visual bits of your brain are lousy at left and right too. You had to think about this being my left eye, didn't you? It's just an I. Oh, I did. According to your research, I almost made
- [22:22]
Dr. Samantha Meem
the L with my hand just to confirm.
- [22:25]
Dr. David Carey
That's a good solution. So any of these claims that kids model on their parents I find highly suspicious. Except maybe for really overskilled tasks like you're teaching your daughter how to tie her shoes in a particular order or something. That might be the case, but by the time you're doing that, her handedness
- [22:39]
Dr. Samantha Meem
has probably appeared psychologically. The fact that left handers have to learn how to adapt to a right handed world, do we think that that has had any impact on the way that they think or solve problems or approach tasks? Some kind of psychological flexibility that they may have? It's probably a hard thing to study.
- [23:02]
Dr. David Carey
The common claim that's made is that if you look at people who are left handed for writing, what's really common and has been common as long as we've measured it, is that only some of them are really left handed. So in other words, they'd use their left hand to write, but they'd use their left hand to comb their hair, they'd use their left hand to brush their teeth and to do all kinds of thread, a needle and so on. There are some, but they're not very many right handers like you and me, Sam. We are mostly like that. We're mostly pretty right handed. The most common explanation for this effect is, well, those Poor lefties have grown up in that right handed world. They've been compelled to use their right hand for all kinds of different things. And right handed discs and scissors you talked about, I mean, I'm skeptical partially because we make thousands of hand actions every day that are not constrained by tools like scissors. Right. You know how many people are using a can opener frequently in their life in this day and age of pull tops and so on? So I will be getting a bunch of hate mail from left handers who listen to your show saying, Dr. Carey, you're totally wrong. This right handed world is really annoying. I absolutely get that. But you make a lot of movements that are not constrained. So for example, I'm not doing it so much and we're probably audio only now, but when we speak, we move our hands around. We gesture when we speak. That's even asymmetrical. If you're a right hander, you'll make lots of gestures like this. So for the listeners, I'm swinging my hands like I'm conducting an orchestra. So these are called beater baton gestures. And right handers make lots of bimanual ones where we use both hands. What that shows you is I can do that with my left hand. But the weird thing is, Sam, is I don't. I mostly gesture maybe 75, 80% of the time with my right hand when I only use one hand. That effect is much weaker in left handers, much weaker. So that can't be, you know, culture. Nobody was telling you which hand to use when you talk or anything like that. And it's not skilled either, it's not learned. But we make a lot of those kinds of gestures. We're unconstrained, we're perfectly capable of doing them with our non preferred hand. And yet we don't. And that's different in right handers and left handers. And that's odd. So that doesn't fit in this world that says left handers are two handed because they've had to do a few skilled tasks with their non preferred hand. What we don't know, you can't do the experiment, right? Nobody in the world wants to take a bunch of kids and force them to do things with their non preferred hand to see what effects that has over the subsequent 20 years. You can't do the experiments anymore. And that's why scissors in a hand preference inventory. Asking people which hand they use scissors with is silly because most scissors are right handed. You need to ask them about other things.
- [25:44]
Dr. Samantha Meem
I confirmed with our producer Teresa, who's left hand dominant, she uses left to right, but her right hand for many other things.
- [25:52]
Dr. David Carey
So I thought, for the longest time, I thought, this is crazy. This is baseball gloves. Teresa grew up in a house where, you know, she got her big sister's glove or her brother's glove and it's a glove for the left hand. So she had to catch with her left hand and throw with her right. Yeah. So it's baseball related. Get out of North America. In Britain we're so hard, we play rounders without a glove. Same thing. So it's not baseball gloves, it's not environmental. A substantial proportion of left handers throw with the right hand. It's weird, nobody understands it. And even these other asymmetries like footness, yes, left handers are more likely to be right, left footed than right footed, but not by that much compared to right handers where we are overwhelmingly right footed. So even asymmetries like that, that's hard to understand in a right handed world kind of way. And in fact, for sports, like what you guys call soccer, what I'd call football, you would argue if you're a football savvy, mom or dad, you're rolling the ball at your child's left foot because you want to produce people who can use their left foot proficiently because they're rare.
- [26:56]
Dr. Samantha Meem
Yeah.
- [26:57]
Dr. David Carey
So there you have it.
- [27:00]
Dr. Samantha Meem
On this International Left Handers Day, what is one thing you'd want listeners left handed or not to take away from this conversation and your research?
- [27:08]
Dr. David Carey
I think at least in North America and Britain and parts of Western Europe, there's less pressure on people to switch handedness. So rejoice in being unusual, rejoice in being a minority. People like you, over centuries have suffered a lot of stigma, a lot of pressure to switch hands. So I guess that would be my message on, you know, I love left handers. We even have a coffee cup somewhere that says we love lefties in our lab. We think they're fantastic. We over recruit them for our studies as opposed to those earlier imaging experiments. Imaging experiments that you talked about where lefties were. No, that's just too much noise for our data. We'll leave them alone. So I guess that would be one thing about my research. What would I say? I can tell you about one finding before we finish and that is we are lucky. Here in Bangor we have a research magnetic resonance imaging facility. So if you were visiting me here, Sam, and you're not claustrophobic, we could put you into the magnet and a few hours later we could tell you your language dominance. A lot of people can't do that. Well, we're developing techniques at Bangor now which let us predict which side of your brain is dominant for language. So I don't have to scale. If you're a left hander, for example, there are about three or four little tests I could give you that cost nothing, that don't require you to go into a scanner. That would take me 15 minutes. And then I can tell you pretty much if you're left or right dominant for speech and language. So that's been pretty exciting. We're just publishing that work now, but that's kind of exciting. But if anybody wants to get in touch and ask me any questions about adolescent brain asymmetry, I'd be delighted.
- [28:36]
Dr. Samantha Meem
Very, very cool. Thank you so much, Dr. Carey, for talking to us about all this really cool research.
- [28:40]
Dr. David Carey
Well, thank you, Sam. It's a pleasure.
- [28:42]
Dr. Samantha Meem
Dr. David Carey is a quote, vanilla brained, right handed clinical neuropsychologist at Bangor. My dad was nice at Vanger University. You can find his research taking place at Bangor University.
- [29:03]
Capital One Bank Spokesperson
With no fees or minimums on checking accounts. It's no wonder the Capital One bank guy is so passionate about banking. With Capital One, if he were here, he wouldn't just tell you about no fees or minimums. He'd also talk about how most Capital One cafes are open seven days a week to assist with your banking needs. Yep, even on weekends it's pretty much all he talks about. In a good way. What's in your wallet? Terms apply. See capitalone.com bank capital1na member FDIC
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CFA Institute Representative
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- [30:08]
Paige from Giggly Squad
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- [30:33]
Dr. Samantha Meem
Prices and participation may vary. At Edward Jones, we believe Rich means opening yourself to new possibilities. That's why your dedicated financial advisor meets you where you are, helping you move forward with confidence. Let's find your rich Edward Jones member. SIPC. Ever wonder if your dog is a lefty or a righty? Turns out science has been wondering the same thing, and now there's a rubric for that. It's called the dogenbra Inventory. The name is a nod to the Edinburgh Handedness Inventory, which has been a common and standard test used to measure whether humans are right or left handed. This is essentially the same idea, but for dogs. As we mentioned throughout the episode, about 90% of humans are right handed. But dogs, you know, there's no clear pattern. While individual dogs do tend to favor one paw over the other, there's no overall right pawed majority among dogs. So why does this even matter? Well, paw preference turns out to be a window into a dog's brain. Just like in humans, the right side of a dog's brain controls its left body and vice versa. And one hemisphere often takes the lead on a given task. That dominance is called lateralization. It turns out lateralization is connected to behavior, emotions, even immune responses. Dogs with a strong paw preference tend to be more confident and less anxious than dogs with a weak preference. And interestingly, left paw dogs may have a slightly more pessimistic outlook on life, at least according to some studies. And then there are ambilateral dogs which have no clear paw preference. Some earlier research suggests that these dogs may be more reactive to loud noises and thunderstorms. So if you have a dog and you want to know if they're a lefty or a righty. Thankfully, these researchers created a standardized scoring system out of four simple tests. The first is the Kong test. A Kong is an odd shaped bouncy toy with a hole in the center. To do the test, you stuff treats inside a Kong and watch which paw your dog uses to hold it steady. The second test is the food reaching test. You place a treat under the couch and then see which paw they use to reach with. Third, the stairs test. Sit your dog at the top of a staircase and see which paw they use first to come down the stairs. And then the fourth one is the walking test. It's similar to the stair test, so you note which paw steps off a curb or ledge first. When you're taking your dog for a walk on a leash, make sure you try these tests a couple of times just to make sure you can replicate your response. Then tally up your right and left paw scores for each test and plug them into a formula. The results would place your dog into one of five categories, strong left pod, weak left pod, ambilateral, weak right pod, or strong right pod. The researchers who made this scoring system tested 43 dogs with this method, though with a little more stats than you'd probably do at home, they found something really interesting. Dogs don't always use the same paw for every task. So your dog might be a righty at the Kong, but a lefty on the stairs. That's why there are four tests and a more sophisticated scoring system combining them. So a dog that shows a preference in every task scores higher than one that only favors a paw. Sometimes there's a sex difference too. Male dogs leaned left pawed in their study, at least on the conch test, echoing a pattern seen in humans where left handedness is a lot more common in men. The researchers, who are from the University of Bari Aldomoro in Italy, hope someday to build a huge dog handedness, I mean podness database that would match the datasets that we have for humans. For Warner Bros. Discovery, Curiosity Weekly is produced by the team at Wheelhouse DNA. The senior producer and editorial correspondent is Teresa Carey. Our producer is Chiara Noni, our audio engineer is Nick Kharisimi, our fact checker is Lauren Colella and head of production for Wheelhouse DNA is Cassie berman. And I'm Dr. Samantha Yuin. Thanks for listening. Ever wonder if your dog is a lefty or a righty? It's called the dog and bra in Dog and Bra Inventory. Okay, you try saying it. It's hard. And interestingly, left Pod dogs may have a slightly more pessimistic outlook on life, at least according to some studies. It's really funny. Like, how did they test that? You seem pessimistic and they're like furrowing
- [35:15]
Dr. David Carey
their little dog brow. Cute.
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Dr. Samantha Meem
I love it.
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