Why Do Lefties Exist?


Chuck: Charles W. "Chuck" Bryant

Vo: Voiceover Speaker

Vo: Welcome to Stuff You Should Know from HowStuffWorks.com.

[MUSIC]

Josh: Hey, and welcome to the podcast. I'm Josh Clark with Charles W. "Chuck" Bryant, and Jeri is over there, too. And this is Stuff You Should Know, the podcast.

Chuck: Oh man, oh man. I would love for people to just be a fly on the wall in this studio sometimes.

Josh: Get squashed.

Chuck: It's a lot of fun prerecord today, people; I hate that you miss out on that kind of stuff. But you know what? That's for us. We deserve a little something. And that's called preshow fun.

Josh: Fun, hammering out the details.

Chuck: Hammering out the details. I thoroughly enjoyed researching this one.

Josh: Oh really? It burned my brain a little bit.

Chuck: It burned my brain a little bit, too, but I didn't know anything about handedness.

Josh: You didn't?

Chuck: No, not really.

Josh: You don't use your hands much?

Chuck: Well, I mean, as far as why you are left- or right-handed or ambidextrous. It was all kind of new information for me.

Josh: Yeah. I feel like I have read that io9 article, which we should give a huge shout-out to because that was forming partially the basis of this episode.

Chuck: Yeah, "Why Are So Few People Left-handed?" from io9, and they sourced a lot of great stuff from Discover Magazine and their article, so-

Josh: And Science.

Chuck: And Science, so-

Josh: So it's legit.

Chuck: It is legit.

Josh: Possibly even "too legit to quit." Yeah?

Chuck: Yeah. Which I could not do with my left hand. Oh, I guess I can, I just did it. You just did, too, your signing to me.

Josh: Yeah, I'm equally bad at doing "too legit to quit" finger motions with either hand. I'm right-handed, by the way, what about you?

Chuck: I'm right-handed, but that is weird, since you have your M.C. Hammer pants on, I thought you would be good at that.

Josh: That's all just-It's not hard to put on pants, it's hard to do "too legit to quit" finger motions.

Chuck: Yeah, I'm right-handed to-well, I was about to say "to a fault," but heavily, heavily right-handed, because after reading this, I do believe that there is a bit of a spectrum, I think.

Josh: Oh yeah?

Chuck: Yeah, I think some people are way dominant with their one hand and some people skew more towards, yeah, I can do some things with this hand, and some people are ambidextrous, which we will talk about.

Josh: Very few, though, fewer than you think.

Chuck: Yeah, but I am heavily, heavily right-handed. I cannot do many-what's the word I'm looking for?

Josh: Tricks?

Chuck: Yeah. Like my fine motor skill tasks, I cannot do very well with my left hand. I can just like club things and smack things.

Josh: And knock stuff over.

Chuck: Yeah, knock stuff over. [LAUGHTER]

Josh: You're like Frankenstein clearing a table.

Chuck: Pretty much. What about you? Can you do anything with your left hand?

Josh: Ah, I used to think that I was, you know, pretty much just strictly right-handed, but then I, especially researching this, I paid attention and I'm like no, I use my left hand a little more than I thought. I'm definitely not ambidextrous and if there is such a thing as a dominant hand, it's clearly my right. But this article points out, or actually it's was a Science article that said, there's this idea that there isn't a dominant hand; that you have uses for both hands and one kind of specializes in one thing and one specializes in another. And the example they used to illustrate that was cutting, like, meat with a fork and knife.

Chuck: Yeah, I was going to ask you about that.

Josh: You know, like, I was thinking about it and I was like, oh yeah, I guess I do use my knife pretty well with my left hand, and I thought, crazy, no, my fork is in my left hand, my knife is in my right hand, and then I switched the fork over to my right hand.

Chuck: That's what I do, too, I was going to ask you that.

Josh: So I'm definitely right-handed but, you know, my left hand does a great job holding the steak in place with my fork, while I cut it with the knife.

Chuck: Yeah, well, come to think of it, though, I play guitar and drums, so, I mean, I have some left hand skill, I guess. And I know if you break your dominant hand, you're going to learn pretty quickly how to adapt. So it's possible to learn, if forced to.

Josh: Yes.

Chuck: It's all very interesting to me.

Josh: It is and we should say, if you happen, happen just randomly to be listening to this episode on August 13th, happy National Left-handed Day.

Chuck: Yeah, I looked, when I looked that up, I was like, ah, wouldn't it be one of those, another Stuff You Should Know coincidence if this happened to be released that week or something.

Josh: Nope.

Chuck: Not even close.

Josh: No such luck.

Chuck: Yeah.

Josh: And it's good that left-handed people have their own day, because they have been fairly maligned throughout the millennia.

Chuck: Yeah, let's talk about that actually.

Josh: Oh, okay.

Chuck: Throughout history, in fact even if you look at the words, throughout history, you know they've pooh-poohed left-handers basically. Like the word "L-Y-F-T."

Josh: Lyft?

Chuck: Yeah, from Anglo Saxon, means weak.

Josh: That's where the word left comes from?

Chuck: Yeah. And the word "sinister" from Latin is the word for left.

Josh: Yeah, anybody saw that episode of the Simpsons where Ned Flanders opens the Leftorium knows that.

Chuck: [LAUGHS] That's right, I forgot about that.

Josh: Because he says, "I have a sinister reason to invite you all here." Sinister meaning left-handed, and that was when he announced the Lefttorium.

Chuck: That show was so smart, you know.

Josh: Very smart.

Chuck: So many of those jokes, like, just flew over my head back in the day, before I got smarter.

Josh: Well now, they are coming back to roost.

Chuck: There is a long list of countries who have languages that link the word "right" with good and the left with being bad or wrong. And in some countries even making hand gestures with your left hand is a no-no.

Josh: A lot of countries, or a lot of cultures, that eat food with their hands, rather than utensils, using the left hand to eat or do a lot of things with is considered taboo.

Chuck: Because you wipe.

Josh: That's exactly right, you use the right hand to eat with, you use your left hand to wipe with, right? And, I think if you pay attention and notice, I'll bet you have a hand that is dominant in that activity.

Chuck: Wiping your butt?

Josh: Yeah.

Chuck: Yeah, I'm a righty.

Josh: Are you?

Chuck: Oh yeah.

Josh: Oh okay. But if you try the other hand, it'll feel very weird. Whatever hand you

use normally, it's going to feel weird if you use the opposite.

Chuck: Yeah, you will just end up very messy [LAUGHS]. I wonder if you had a subconscious thing like, you know, I was just eating these candied pecans with my right hand and I know I'm going to go back and eat them with my right hand.

Josh: Oh I don't even use my hands to eat them. I'm a little too germ-conscious. I scoop food up in the crook of my elbow, which is very clean, because it doesn't come in contact with other stuff, and then I eat out of the crook of my elbow.

Chuck: That's pretty funny. So, why have people been, I mean, why have they picked on left-handed people? There are some theories that it's just a minority. You know, 10 to 15% of people are left-handed and throughout history minorities have been picked on.

Josh: That's right, that's one thing. There's at least a couple of cultures that equate left-handedness with clumsiness.

Chuck: Yeah, that makes sense to me.

Josh: Some hypotheses theorize that tools, tool making, for a very long time, has been done following right-handed techniques.

Chuck: Still is, in many cases.

Josh: Sure. So when a lefty was trying to make tools or do whatever, using right-handed tools, they would have been clumsy with them, and therefore, the idea that left-handed people were clumsy or weak, or whatever, could have developed and carried on.

Chuck: Yeah, like colonial day dad is teaching his two sons-well, let's go with a son and a daughter, even, let's mix it up-how to use a saw, and you know the son is left-handed and he can't saw well, so the dad is just like, he favors the daughter because, you know, she's better with the saw. It's easy to see how that could happen.

Josh: Like he's mad at Roger but pleased with Prudence.

Chuck: Yeah, because Prudence, she is always sawing things well.

Josh: That's a colonial name, right?

Chuck: Oh sure. Well, I feel like it is.

Josh: Okay, well, what else is there? Who?

Chuck: Goody Alice [LAUGHTER].

Josh: It's timeless.

Chuck: But, there's still that if you're a lefty today you might be frustrated with things like scissors and can openers and spiral notebooks and things that, sort of, favor the right-handed.

Josh: Yeah, or sitting next to a right-handed person at dinner. The elbow thing.

Chuck: It's the worst.

Josh: It's, because there are so few left-handed people, if you're planning a dinner party, first of all, it's just common courtesy to know the handedness of all of your guests and then to-

Chuck: Sit them appropriately.

Josh: Right, to put the left-handed person at the end of the table so that their left elbow is off the table and they don't have to worry about bumping into other people.

Chuck: Yeah, my mom is left-handed, my father is right-handed.

Josh: Huh. And you came out right-handed?

Chuck: Yeah.

Josh: Crazy.

Chuck: I sure did.

Josh: So, despite everybody knowing that there is a right-handedness and a left-handedness, it turns out, after investigating this kind of thing. Science is really baffled as to what exactly is going on, why we would have handedness.

Chuck: Yeah, at all.

Josh: Where it comes from? Why the proportions seem to be steady? There's a lot of questions that come up when you look into handedness, whereas the average person would just kind of take it for granted. But no, not the average scientist.

Chuck: No, no.

Josh: No

Chuck: There are a lot of interesting theories, though. One is, is that as we all know we have a left hemisphere and a right hemisphere of our brain, and we are one of the only mammals that are very much, have a-it's called brain lateralization, when primarily, and this isn't across the board, but primarily one hemisphere controls certain things and the other controls other things, and that is primarily controlling the opposite side of the body, as the hemisphere. But language and controlling your, you know, fine motor skills, like things you do with your hands and fingers, have often been linked because they are generally linked together on one hemisphere of the brain.

Josh: Right. For the most part, people who are right-handed, they make up the vast majority of human beings, by the way.

Chuck: Yeah, 85 to 90%.

Josh: Yeah, I saw as low as 70, but nothing lower than that. No, 80 to-yeah, your right. Sorry. Exactly.

Chuck: Yes [LAUGHS].

Josh: Those people have their language center in the left hemisphere, and I guess also their motor cortex in the left hemisphere.

Chuck: Right.

Josh: And the-no, the left.

Chuck: [LAUGHS] Gotcha.

Josh: There's a lot of questions about why this would be. The brain supposedly is always looking for efficiencies, as much as possible. So they're saying, okay, well, these are two very human activities-speech, language and using your fingers to do stuff. So, they're also some of the more complex activities that humans engage in. So it makes sense that you just leave it up to one side of the brain, so that these things can-not have to cross over the corpus callosum.

Chuck: Yeah, it's just like clustered together, it makes sense.

Josh: It does make sense but it is also a pretty thin explanation, if you-

Chuck: Yeah.

Josh: You could also say the other, the exact opposite, that it would make more sense that our motor skills and our language skills would be on the opposite sides of the brain, to give each other a break. Rather than just waving it down on the same side. The point is, though, if you crack open a human brain and you look for the motor cortex and the language region, the language center, you're going to find them most likely, statistically speaking, on the left hemisphere.

Chuck: Hence, more right-handedness.

Josh: Right, because of what you said, that brain lateralization, where stuff that's carried out in the left hemisphere is going to manifest itself in the right. So if you are shaking somebody's hand using your right hand, the left hemisphere is blowing up.

Chuck: That's right.

Josh: If you're taking in visual information with just your left eye, because you've got your right eye closed or it was poked out by a seagull, or whatever, then your right hemisphere is going to be active, right?

Chuck: That's right. Interestingly, though, the opposite isn't true if you have your language center in your right hemisphere; it doesn't always mean that you're going to be left-handed. It means you're more likely to, but, I like the way this article looked at it, it's an evolutionary rule of thumb. It's not, I think they said between 61 and 73% of lefties have the language centers on left; 90%, over 90% of right-handed people.

Josh: Right, which raises a really great question. Is there such a thing as righties and lefties? Or is there such a thing as righties and non-righties? Because if a righty and a lefty are equally, exactly the same thing, if handedness is completely binary like that, then if you're a lefty your language center should be on the right-hand side, and like you said, that's just not the case in most lefties, even.

Chuck: Yeah. That's true. And the io9 article also points out that it's, they don't know why necessarily, but this is just how we evolved. It could have just been the opposite, and then we would have more lefties.

Josh: Right, well, that's the idea.

Chuck: But, I think there are a couple of explanations possibly of genetic mutations along the way. Two in particular, one about 200,000 years ago, that basically mutated us to the fact that we are going to be more right-handed and the language center is going to be on the left-hand side. And then, more recently, there was a theory that there was a second mutation, 20,000, between 20,000 and 100,000 years ago, where that basically balanced things out or it cancelled that out, which means the possibility of left-handedness became the thing, or else we would have all been right-handed.

Josh: Right.

Chuck: That makes sense, too.

Josh: It does make sense in that the humans possibly evolved to use their hands more, and by using their hands more, our brains were forced to become specialized and basically forced to choose. So then some sort of gene was set up that made the developing human brain most likely to be a right-handed person, right?

Chuck: Yes.

Josh: And then that second gene came along and cancelled that out in some parts of the population.

Chuck: Yeah, I think it's the D gene and the C gene. There are two alleles, which is the manifestations of a gene at the same location, and the D gene is more frequent in the population, so it's more, it promotes the right-handed preference. The C gene is less likely within the gene pool, and so there you have like a 50/50 chance of being left-handed if you have that C gene.

Josh: Okay, I got you. But you don't have a 50/50 chance of being a left-handed person, in general; you have about a 10% chance.

Chuck: Yeah, because the D gene is more prominent and that means almost certainly you are going to be right-handed.

Josh: Okay, so the caveat we should add to all of this is that this is all just strictly conjecture.

Chuck: Sure.

Josh: And we will get to a little more of this conjecture right after this.

[MUSIC]

Josh: Chuck?

Chuck: Yes.

Josh With over 150,000 titles to choose from, from fiction, nonfiction, best sellers-every category imaginable-Audible.com has you covered.

Chuck: That's right, buddy. They also have free apps for iPhones, Android, and Windows Phone. You can download and listen on your iPhone, Android, iPod, Kindle Fire, Windows Phone, and over 400 other MP3 players.

Josh: And unlike a streaming or rental service, with Audible, you own your books.

Chuck: That's right. You have a "my library" feature that lets you access your books any time, even from your phone.

Josh: Audible, right now, is offering our listeners a free audio book of your choice and a free 30-day trial membership. Just go to Audiblepodcast.com/SYSK and choose from over 150,000 titles. Download a title free and start listening. It's that easy. Go to Audibleposcast.com/stuff and get started today.

Chuck: That's right. And I am going to personally recommend the book The Psychopath Test by Mr. Jon Ronson, a friend of Stuff You Should Know, and he actually reads it himself, the author, which is pretty great and it's an awesome book. Go check it out on Audible.com

Josh: Yep, that's Audiblepodcast.com/stuff.

[MUSIC]

Josh: So Chuck, we were saying that it's possible that genetic mutations, far back in human history, account for this.

Chuck: Sure.

Josh: And there is a lot of evidence that humans have been mostly right-handed for about the last 200,000 years. Fossil evidence suggests this. Looking at Neanderthal skeletons, early human skeletons, you can see evidence on the skeletons of right-handedness, and they think that it's so obvious and obviously prominent because these people were using things like spears. So if they did have a hand preference, then a spear would definitely develop the arm connected to that hand and they would stay in the fossil record through these skeletons, right?

Chuck: Yeah.

Josh: They also have looked at other fossils as far back as 1.6 million years. There's a skeleton called, I want to say the Kokomo Boy, even though it's not, but I love that song. It's the Nariokotome Boy.

Chuck: You like "Kokomo"? [LAUGHTER]

Josh: Sure. And he is a 1.6-million-year-old Homo ergaster. And he was clearly right-handed, as well. Other fossils have turned up evidence of right-handedness. The teeth, striations on the teeth, suggest eating with their right hand. So what we can say with a pretty decent amount of confidence is that, at least for the last 200,000 years, humanity has been a majority right handers. And there has been maybe about this constant 10-15% proportion of left-handed people. Which makes the mystery even more crazy, to me.

Chuck: Yeah, but it also makes sense that in early tool building and teaching how to use tools. I mean it holds true today; they've done studies that, you know, you teach your son or daughter to tie a tie and it's going to be more difficult if they are left-handed and your right-handed, for them to try and do it with their left hand. So they will pick it up easier if they go against their instinct and learn it how you have taught, with the right hand.

Josh: Right. Studies have shown that. You learn faster from watching somebody and then using the same hand movements that they do.

Chuck: Yeah, and that makes sense back in the, you know, with Tuk Tuk and showing his pal how to use the bone to smash a skull; you know, it's if his buddy picks up with his left hand, Tuk is going to shake his head, no.

Josh: No, don't be stupid.

Chuck: Yeah, use right hand. Or they are just going to-everyone wants to fit in, even back in the old days.

Josh: Well, that's actually a suggestion of why left-handedness is possibly not a little more prevalent among a certain age group today. Because it was equated with being weird, or off, or crazy, or whatever, and parents and teachers would force children to learn how to write with their right hand, effectively wiping out a lot of the left-handed population.

Chuck: Yeah, and just jumping back a minute, I wanted to mention something important, the whole correlation versus causation thing. With the whole language center link, it's not necessarily-that's a correlation. They appear to be strongly linked, but no one is saying that because the language hemisphere is on the left side of the brain, that's causing you to be right-handed.

Josh: Right, and again, the reason that they are linked, in a lot of scientists' minds, is that speech and fine motor skills are basically uniquely human, almost uniquely human, and it's just a little, it's kind of light a red flag or a signal that they are both usually in the same hemisphere, and they do seem to be connected. And one hypothesis for why they are connected, I thought was pretty smart-the idea that language, spoken language emerged out of gestures, hand movements, which would require fine motor skills, that I don't have trying to do the "too legit to quit" thing. But the idea that language emerged out of that would suggest some sort of connection between the two. Like maybe the fine motor skill section is the more ancient of the two and then language evolved out of that. But we also still need our fine motor skills to, like, eat with a fork and knife and everything, so it stuck around. It didn't become obsolete just because we started speaking.

Chuck: Yeah, I like that theory. We did mention that this is largely, uniquely human trait, but they have followed, they've basically been looking at our closest ancestors to try and figure a lot of this stuff out. Although I did see some studies that said that like 30% of cats are left-handed because they will go to swat at things with their left hand. But, I'm not so sure about that.

Josh: Not only is it difficult, apparently to-

Chuck: Test.

Josh: Or to attribute a handedness to an animal. It's also difficult to attribute handedness to a person. Because the idea of whether or not you're left-handed or right-handed, it's still questionable, like, if you write with your right hand but you actually can write better with your left hand, or something like that. Which? What are you? Is it the one you're comfortable with or is it the one that you're actually better with?

Chuck: Yeah, that's a good point. But they have been looking at our primate ancestors since about the 1920s and they have found patterns. Apparently lemurs are more left-handed and other prosimians. Macaques and Old World monkeys, for the most part, are evenly split, and gorillas and chimpanzees are about 35% lefty. But this is interesting: as they say here, the more primitive the primate, the more likely it is to be a lefty, which goes in the opposite of the gene mutation.

Josh: Right. It's the exact opposite; it implies that we were originally left-handed as primates, and then as we evolved, we became right-handed, so, therefore, right-handed people are more evolved than left-handed people in some weird way.

Chuck: Yeah, so again, it's another inconsistency where-and of course, this is in primates, too; it doesn't necessarily mean it's the same thing with humans.

Josh: No, definitely not, but if you're looking at our ancestry and trying to figure out where our handedness came from, you have to go pretty far back.

Chuck: Right.

Josh: That's a pretty good example of how this body of work or knowledge is very contradictory, still. It's baffling, it's pretty awesome. Hey, Chuck.

Chuck: Hey.

Josh: You sent me something about ambidextrousness.

Chuck: Yeah, I thought this was kind of interesting, from Mental Floss.

Josh: Like, it was just kind of my understanding that anybody who said "I'm ambidextrous" knew what they were talking about. But it turns out, that's really just not the case. For the most part, it's a very rare condition, I guess you'd call it.

Chuck: Yeah, because I don't know if there is a strict definition for what constitutes being ambidextrous. Like, you know, a switch hitter in baseball doesn't necessarily mean they are ambidextrous, it means that they have taught themselves to hit from the other side of the plate.

Josh: Right.

Chuck: If you notice, as a baseball fan, you're never going to see a player that hits equally as well on both sides. Like you know, the great Chipper Jones, here from Atlanta, he favored one side of the plate. Although he was a switch hitter, he was a much better hitter, I think it was as a lefty and not as a righty.

Josh: So that's not ambidextrous.

Chuck: No, it's someone who's taught themselves, because it's a valuable skill in sports, to be somewhat ambidextrous-or in a lot of sports. But as far, I think writing is one of the things they can look at as a clear indicator of which hand you're best at, and they say only about 1% can write equally as well with either hand. So that's like super low.

Josh: Apparently, too-so this handedness and this lateralization of the brain and division of labor, and all that, has a lot to do with how your brain is connected and apparently handedness is a part of that, too. So, for example, people who are ambidextrous are more likely to suffer from schizophrenia, to have schizophrenia. And it's not just ambidextrous people, apparently lefties show a greater propensity towards schizophrenia. Something like 40% of people with schizophrenia are left-handed, which is a very high proportion, considering the general population is about 10%.

Chuck: More than that, dyslexia and stuttering as well, for lefties.

Josh: Right, which suggests that left-handedness has an effect on how your brain is wired. It's not just a simple, oh my hand, I use my left hand, my brain is otherwise the exact same as a right-handed person. The brain does appear to be different, in some ways, especially in the ways that it's connected.

Chuck: We talked about synesthesia before, one of our favorite-what do you call it? It's not a condition, is it?

Josh: Yeah, sure.

Chuck: Is it? I always just think of condition as something that's, you know, derogatory, bad.

Josh: Yeah, no.

Chuck: Like a malady or something.

Josh: I mean, I think it falls under that. One is one, but the other one isn't necessary that one. So like a malady is a condition but a condition isn't necessarily a malady.

Chuck: Anyway, that's my longwinded way of saying synesthetes are awesome.

Josh: Yeah.

Chuck: And the rate of ambidexterity in synesthetes is much higher, and left-handedness, than in the general population.

Josh: Right. So we have some clues here, like it's, handedness has to do with how your brain is wired and if your brain is wired in such a way that you are left-handed, your brain is wired differently from a person with a right-handed brain, right?

Chuck: Yeah.

Josh: And a lot of studies have backed that up and have come up with things like it's entirely possible that if you're a left-handed person, you got some advantages in life. We'll talk about those right after this.

[MUSIC]

Josh: Hey, Chuck.

Chuck: Yeah.

Josh: You spend, you specifically, spend 90% of your life in your underwear.

Chuck: Hmm. Might be a little higher for me.

Josh: Okay, so let's say more than 90%; that's significant.

Chuck: Exactly, that means it's even more important to have comfortable underwear that doesn't get all saggy and the waistband is not ill-fitting and, you know, underwear can get kind of gross, too, let's be honest.

Josh: It is, so, you need to replenish your supply frequently, and luckily there's such a thing as MeUndies.com to help you do just that.

Chuck: Oh yeah man, MeUndies, I'm actually wearing mine right now.

Josh: I see.

Chuck: It's the most comfortable underwear you will ever wear, seriously; it is insane how good they make you feel. They fit perfect, they don't ride up on you, and they pull moisture away, literally, away from your skin, to keep everything cool.

Josh: Yep, and speaking of cool, they have cool styles for men and woman, all of them look great and you can check out the photo's yourself at MeUndies.com.

Chuck: Yeah, they have more than undies, too; I'm actually partial to those pajama pants.

Josh: Yeah.

Chuck: Super comfortable.

Josh: Beautiful stuff.

Chuck: So here, we'll make it easy on you folks. Just go to MeUndies.com/stuff, and you're going to get 20% off your first order and free shipping. And you can save even more when you buy a pack of them.

Josh: And they guarantee you're going to be happy with them, or your first pair is free. Once you feel MeUndies on your body, you're never going back. Isn't that the old saying?

Chuck: It is. Remember, to get that 20% off just go to MeUndies.com/stuff.

[MUSIC]

Josh: So Chuck, one of the things that left-handedness possibly bestows, confers upon you as a benefit, is the idea of thinking quicker. To be able to process information more quickly.

Chuck: Yeah, they have done some studies on this. Did a couple of studies, one of which they sat down 100 people-80 right-handers, 20 left-handers-and basically just showed them a computer screen with a single dot, either on the left or right side, and you had to press a button. It's just a speed test basically. Like which side is it on, left or right?

Josh: Right, so if something shows up on the left side, I'm sure you have a clicker in your left hand and a clicker in your right hand, you'd click the left hand clicker. But this is all happening very fast.

Chuck: That's right, and left-handed subjects were overall faster. In the other test they had to match up multiple letters that appeared, in some cases on either side of the line and in other cases on just one side. And again, left-handeds were faster, but just at matching letters that were on both sides of the line.

Josh: Right.

Chuck: Which I thought was interesting.

Josh: Well, and that supports this idea that the brain, the fact that some left-handed people's motor skills and language centers are on different sides in their brains could make them talk more. The sides of their hemispheres of their brains are more connected. There's more white tissue or their corpus callosum is more efficient. It make sense in a way, but at the same time you're like, "Wait, that doesn't make any sense." So it's kind of, this data should be taken and just locked away in a box until we understand the whole thing more.

Chuck: Right.

Josh: Because it doesn't really do a lot at this point; we don't know enough to make it fit.

Chuck: No.

Josh: And it's actually kind of contradictory to some other stuff, too, as far as handedness goes.

Chuck: Yeah, but they do say that if you're left-handed you may be like a better gamer, or a pilot, because you're able to process this quick information superfast. Like rapid-fire stuff coming at you.

Josh: It also suggested, too, that language can be processed in both hemispheres among left-handed people, which again would require a lot more connections between the two hemispheres, faster communication between the two, and hence, quicker thinking.

Chuck: Yeah, and in the long run, as you age and your brain deteriorates, you may be in better shape as a lefty because your other hemisphere may be able to pick up that slack more easily, whereas if you're just a dumb right hander, your screwed. [LAUGHTER]

Josh: You're in trouble.

Chuck: But of course this isn't proven, this is just postulating here.

Josh: Right. But I mean, it adds to this mystery.

Chuck: Yeah, you definitely have an advantage in sports in a lot of cases, though.

Josh: Yes, but, not in the way that you would think. It's not necessarily because your brain is communicating, the hemispheres of your brain are communicating. It's more because your opponent is statistically likelier to be expecting you to be a right-handed person. To have trained against a right-handed person.

Chuck: More practice, basically.

Josh: Exactly. To be used to playing a right-handed person, whereas if you're a left-handed person they are playing you now, you're going to through them off guard. You're going to catch them off guard, you're going to be able to get the drop on them because they're not used to you. Whereas, you, being a lefty, you're still statistically likelier to have played right-handed people, so you know how to handle them. They don't know how to handle you. You're the wild card, baby. You win.

Chuck: You're Rocky.

Josh: Yeah, Rocky was left-handed apparently.

Chuck: Southpaw, yeah.

Josh: And there is a bunch of sports figures, in real life, that were left-handed, and apparently it's one of those things where they are disproportionately represented, as far as successful athletes go, compared to the population at large.

Chuck: Yeah, and I think like a lot of times you'll hear about MMA or boxing. Tennis is another big one, because if you're used to playing righties most of your life, that left-handed server comes up there and it's different, it's weird.

Josh: Right and the difference is so pronounced that like if you are a pro tennis player, or something like that, or a pro boxer, you're going to train against a lefty, before a match against a lefty. You're going to do what you can to prepare yourself.

Chuck: Yeah, and I think Robert Lamb wrote this on How Stuff Works, "Are Left Handers Better at Sports?" And he also points out that through history, this probably comes from like soldier training. Mainly training and fighting and jousting and sword-fighting and everything against other righties, as well. So a lefty would have, a left-handed warrior might be more prone to be the great leader like perhaps Alexander the Great, who was supposedly left-handed.

Josh: What's weird, though, is if that had been the case-if humans have been left-handed and right-handed, the proportions have been roughly the same for the last 200,000 years. If you're a left-handed combatant, wouldn't then the proportion of left-handed people have grown over time, because of natural selection? Because you have an advantage in battle or something like that. So therefore the population of right-handed people would drop in relation to the population of left-handed people.

Chuck: Because you've killed them.

Josh: Exactly.

Chuck: That make sense.

Josh: It does but it hasn't happened.

Chuck: I remember our podcast on castles like 80 years ago, remember they built the staircases going on the right-hand side?

Josh: I can't even. Do you remember how mind-bendingly difficult that was for me to understand?

Chuck: Oh no, did you have a hard time with it?

Josh: Oh yeah, we had to rerecord, I think, like twice, because I kept getting it wrong.

Chuck: Yeah we also got in trouble for a cuss word in that one, too. That was a dark day, many years ago.

Josh: Oh yeah.

Chuck: Yeah, but the castle steps would wind up on the right side of the wall to give the advantage to the person higher on the stairs, swinging a right-handed sword. Because obviously you couldn't swing a right-handed sword going up the stairs because the wall is on your right. But, a left-handed combatant. Ah ha! Advantage taken away.

Josh: Exactly.

Chuck: Even though you have the higher ground. Because all of a sudden you're cutting the guy's knees off. They were cutting them off at the knees. You know?

Josh: That hurts.

Chuck: It does.

Josh: But also included with natural selection, too, is if there were any real disadvantages to being a left-handed person, or there were advantages to being a right-handed person, this population shouldn't have remained steady over that long of a period, too.

Chuck: I see what you mean.

Josh: You know?

Chuck: Unless the advantage isn't so great as to cause that natural selection to occur.

Josh: Maybe.

Chuck: There are more U.S. presidents that have been left-handed. More Mensa members, for whatever that's worth.

Josh: Yeah. Half. Half of the twelve U.S presidents since World War II have been left-handed. So whereas the normal population is 10 to 15% lefties, U.S. presidents since World War II has been 50%. And apparently-

Chuck: Crazy.

Josh: -in the 1992 campaign, all three candidates, H.W. Bush, Clinton and Perot, were left-handed. That's 100% of the population.

Chuck: Perot, man. He was fun to watch.

Josh: He was. Dana Carvey was fun to watch doing Perot, too.

Chuck: Oh yeah. And they say more musicians are more likely to be left-handed maybe, and it does run in families, even though identical twins can have opposite hand preferences.

Josh: Oh weird.

Chuck: In the 1980s, there was a Harvard neurologist that said that lefties are righties whose brain centers in the womb changed because of high testosterone.

Josh: Yeah, so there's theories that we become handed in the womb because of something like that, or birth trauma, or some sort of trauma-

Chuck: Yeah, I saw that too.

Josh: -while we are in the womb. And that, yeah, it just adjusts the construction of our brains. Supposedly a mother's age has an impact on her kids.

Chuck: Oh yeah, that was crazy.

Josh: Statistically speaking, a mother over 40 who gives birth has a higher likelihood of having a lefty kid.

Chuck: Way higher, like 125%.

Josh: Yeah, yeah, like that's pretty high. It's more than 100%.

Chuck: I don't even know what that means.

Josh: Yeah, and I guess your hand preference emerges about by seven months.

Chuck: Oh really?

Josh: But then it's like set by age three.

Chuck: So before seven months you're just flinging poop with both hands equally, as well.

Josh: Pretty much. I wrote a story about a guy who found out as an adult that his mother had suspected he was left-handed when he was a baby, so she immobilized his left hand, so that he would be forced to learn with his right hand.

Chuck: That's abuse.

Josh: He didn't seem to take it like that, but he did-it came across like he felt like something had been kind of taken from him. He said it also explained a lot, that he was like so-so with stuff that involved his right hand, but he seemed to be better with his left and that he looked into it, by doing that, which is very popular-like kids were forced to become right-handed through the 20th century. That you are basically making a less-pronounced copy of the person. You're taking the original and making a slightly dimmer facsimile of it, by forcing their brain to reorganize like that.

Chuck: Yeah, it's a disadvantage. Interesting.

Josh: Yeah.

Chuck: Whereas, they thought they were trying to give them an advantage, they actually give them a disadvantage.

Josh: Exactly, but, I would imagine that if you did that to, say, age 18, and then all of a sudden started using your dominant hand that you were actually born with.

Chuck: It's all like spindly and weak.

Josh: Right, but then once you train it to bulk back up, I would imagine your brain would be better off like that; it'd be fuller.

Chuck: Right. So to continue the abuse.

Josh: Right, until 18, discontinue the abuse, and then bam, you got a super kid on your hands.

Chuck: Take your little old man, spindly hands and fingers, build 'em back up.

Josh: Like the Mr. Show character. Remember Titanica went and visited David Cross in the hospital?

Chuck: You know they're getting back together, supposedly?

Josh: Yeah, I saw.

Chuck: That's exciting.

Josh: I saw, PFT tweeted something, some picture. It is very exciting.

Chuck: The whole gang.

Josh: If you want to know more about Paul F. Tomkins, or handedness, or Mr. Show or any of that jazz, you can type that stuff into the search bar at HowStuffWorks.com. And since I said search bar, it's time for listener mail.

[CHIMES]

Chuck: I'm going to call this "Christian Shout-out." "Hey, guys. I started listening a few months ago and have already listened to about 160 episodes."

Josh: Not bad.

Chuck: And by the way, we mention this a lot, but if you're just on iTunes, say, and you think, "Boy, these guys have got 300 episodes."

Josh: 301.

Chuck: Yeah, we've got like, how many now?

Josh: 700 and change.

Chuck: Yeah, 700-plus, that you can find on our website, StuffYouShouldKnow.com.

Josh: Yeah, and as a little pro tip, if you go on StuffYouShouldKnow.com, a.k.a. the website with one of the worst searches in the world, just do Ctrl F and open up your web browser search and then type it in on our podcast archive page.

Chuck: Oh if you're looking for something?

Josh: Yes, it'll bring that up. Don't search for it. Don't bother searching for it using our search tool on our site. It's terrible.

Chuck: We're working on that. Are we working on that?

Josh: I hope so, because this is really bad, like it doesn't bring up anything.

Chuck: Really?

Josh: Yeah.

Chuck: Wow. That's pretty bad. Then why is it even there?

Josh: I don't know. I guess for looks.

Chuck: Lame. So getting back to this, we do have a lot of podcasts out there, for those of you who don't know. We have 700-plus.

Josh: I forget what we were talking about.

Chuck: He listened to 160 episodes. His favorite thing about them is how you don't pooh-pooh anybody's beliefs. "I'm a Christian, so when I was very much so begrudgingly listened to your evolution suite, I was expecting to be mad. But to my surprise, I heard a very non-biased view of evolution. I do believe in evolution, but it's a long story, by the way. After many years of hearing creationists slam people talk about evolution, it's a very pleasant surprise. So I just wanted to say thanks for putting your hearts, but not your opinions, into that episode." That is from Matt, very sincerely, and we've been taken to task here and there. We try to do our best, Matt, to keep things on the level like that. But we are human and we do flounder here and there with that, but we try and we appreciate your kudos for that.

Josh: Yeah, thanks, man. If you want to give us kudos, we would love to hear about that, or if you have any great stories that has to do with handedness, let us know.

Chuck: If you had your arm tied to your waist until you were 18.

Josh: As a baby. You can tweet to us @SYSKPodcast, you can join us on Facebook.com/StuffYouShouldKnow, you can send us an email to Stuffpodcast@HowStuffWorks.com, and as always, join us at our home on the web, StuffYouShouldKnow.com.

[MUSIC]

Vo: For more on this and thousands of other topics, visit HowStuffWorks.com.

[END RECORDING]