November 27, 2021 • 40 mins
For at least the last 200,000 years, between 10-15% of the human population are left-handed and this fact has utterly left science baffled. In searching to explain handedness, all sorts of contradictory evidence has emerged, creating a fascinating mystery. Learn all about it in this classic episode.
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Episode Transcript
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Speaker 1 (00:00):
Hi, everybody, it's February. No, it's not. It's not that
at all. But we're gonna go back in time today
because that's what we do every Saturday with our Saturday
Selects Picks, and we're going back to February because I
want to talk about lefties. Are you a lefty? Get
kick with your left hand? You have punch people with
(00:20):
your left hand? You're right with your left hand. Do
you eat with your left hand? Do you? Well? I'm
not going to talk about other things that you might
can do with left hands or right hands, but you
get the picture. Here's the episode, everybody, Why do Lefties Exist?
Welcome to Stuff You Should Know? A production of I
(00:41):
Heart Radio. Hey, I'm welcome to the podcast. I'm Josh
Clark with Charles W. Chuck Bryant and Jerry's over there too,
and this is stuff you should not the podcast. Man,
oh man. I would love for people to just the
(01:03):
fly on the wall in the studio sometimes and get squashed.
There'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 a that's for us. We we
deserve a little something. Yeah, And that's called pre show
fun fun hammering out the details, hammer and other details.
(01:24):
I thoroughly enjoyed researching this one. Oh really, it burned
my brain a little bit. It burned my brain a
little bit too. But um, I just I didn't know
anything about handedness and uh no not really don't use
your hands much. Well, I mean as far as uh
why you are left or right handed or ambidextrous. It
was all kind of new information for me. I feel
(01:46):
like I had read that IO nine article, which we
should give a huge shout out, because I was in
forming partially the basis of this um episode. Yeah, why
are so few people left handed? From IO nine and
they sourced a lot of great stuff and Discover magazine
and their articles so and science and science. So it's legit.
It is legit, uh possibly even to legit to quit yeah, yeah,
(02:11):
which I could not do with my left hand. I
guess I can't. I just did it. You just did
to your sign sign signing to me. Yeah, I'm equally
bad at at doing too legit to quit finger motions
with either hand. I'm right handed, by the way, what
about you, I'm right handed, but that is weird since
you have your MC hammer pants on. I thought you
(02:32):
would be good at that. That's all. Just it's not
hard to put on pants. It's hard to do too
legit to quit finger motions. Yeah, I'm right handed. Um
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, um, oh, yeah, yeah, I think. I think
(02:52):
some people are way dominant with their one hand, and
some people skew more towards you. I can do some
things with this hand. Uh, and some people are ambidexterous,
which we'll talk about very few though fewer than you think. Yeah,
but um, I am heavily heavily right handed. I cannot
do many uh what's the word I'm looking for, um,
(03:14):
trying to find my not like my fine motor skill tasks.
I cannot do very well with my left hand. I
can just like club things and smack things and knock
stuff over and knock stuff over like Frankenstein clearing at
table pretty much. What about you? And can you do
anything with your left hand? I used to think I was,
you know, pretty much just strictly right handed, but then
(03:36):
I I especially researching this. I paid attention, and I'm like, no,
I used my 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 this article points out, or actually it was
a science Um article that said, there's there's this idea
that there isn't a dominant hand that you have uses
(03:58):
for both hands in one kind of specializes in one
thing and one specializes in another. And the the example
they used to illustrate that was um cutting like meat
with a fork and knife. Yeah. I was gonna ask
you about that, you know, like I was thinking about it.
I was like, oh, yeah, I guess I do use
the knife pretty well with my left hand. I thought, crazy, No,
my fork is in my left hand. My knife is
(04:19):
in my right hand too, and then I switched the
fork over to my right hand. That's what I did too.
I was gonna ask you that. 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. Yeah, well, I come to
think of it, though, I play guitar in drums, So
I mean I have some left hand skill, I guess, um.
(04:40):
And I know if you break your dominant hand, you're
gonna learn pretty quickly how to adapt, So it's possible
to learn, uh force do. Yes, it's all very interesting
to me. It is, and we should say if you
happen happen just randomly to be listening to this episode
on August Happy National Left Handed Day, Yeah, I looked
(05:02):
out when I looked that up, I was like, I
wouldn't it be one of those another stuff you should
know coincidence if this was happened to be released that No,
not even close. Yeah. Um. And it's good that left
handed people have their own day because they've been fairly
maligned throughout the millennia. Yeah, let's talk about that. Actually, okay, Um,
throughout history. In fact, even if you look at the
(05:25):
words throughout history, there is a you know, uh the
poopoo left handers basically, Yeah, Like the word l y
f T left yeah, from Anglo Saxon means weak and
that's where the word left comes from. Yeah, And the
word sinister from Latin is the word for left. Yeah.
Anybody who saw that episode of the Simpsons where Ned
(05:46):
Flanders opens the left Toorium knows that because he says,
I have a a sinister reason to invite you all here,
sinister meaning left handed man. And that was when he
announced the Leftorium. That show was so smart, you know,
very smart. So many of those jokes like just flew
over my head back in the day. Well they're coming
back to roost. Uh. There's a long list of um.
(06:10):
Countries who have languages that link the word right with
being good, uh, in the left with being bad or wrong. Uh.
And in some countries even making hand gestures with your
left hand is a no no well and a lot
of countries are a lot of cultures that eat food
with their hands rather than utensils. Um. Using the left
(06:33):
hand to eat or do a lot of things with
is considered taboo because it's exactly right. You use the
right hand to eat with, use your left hand to
wipe with right and um, I think if you pay
attention and notice, I'll bet you have a hand that's
dominant and that that um activity wipe in your butt.
Yeah yeah, I'm already are you Oh yeah, okay, But
(06:56):
if you if you try the other hand, I'll feel
very weird. Whatever whatever hand you use normally, it's gonna
feel weird if you use the opia, and you'll just
end up very messy. Sure, I wonder if you had
a subconscious thing like you know, I was just eating
these candy pecons with my right hand, and I know
I'm going to go back and eat them with my
right hand. Oh, I don't even use my hands to eat.
(07:17):
I'm I'm a little too germ conscious. I scoop food
up in the croak of my elbow, which is very
clean because it doesn't come in contact of other stuff,
and then I eat out of the croak of my elbow.
That's pretty funny. Um. 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, ten
(07:40):
of people are left handed, and throughout history minorities have
been picked on. That's right, this one thing. Um, there's
there's at least a couple of cultures that equate left
handedness with clumsiness. Yeah, that makes sense to me. Some
hypotheses theorized that UM tools tool making. For a very
long time time, UM has been done following right handed techniques.
(08:03):
Still is in many cases. Um, and 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. Yeah, like, uh,
colonial day, dad is teaching his two sons. Let's go
(08:26):
with the son and a daughter even, let's mix it up,
how to use a saw. And you know, the son's
left handed and he keeps he can't saw. Well, so
the dad's just like he favors the daughter because she's
you know, she's better with the saw. It's just it's
easy to see how that could happen. Like he's mad
at Roger but pleased with Prudence because Prudence she's always
sawing things. Well that's a colonial name. Yeah, sure, well
(08:49):
I feel like it is. Okay, Well what else is there? Who? Goody?
Uh goody Alice. Okay, it's timeless, um, but there's still that.
If you're 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. Yeah, you're sitting
(09:11):
next to a right handed person at dinner. The elbow thing.
It's the worst. It's because there's 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 put them appropriately right. To
put the left handed person at the end of the
table so that their left hand is their left elbow
(09:32):
is off the table, and they don't have to worry
about bumping into other people. Yeah, my mom is left handed,
my father is right handed, and you came out right
handed crazy, I sure did so. Um, despite everybody knowing
that there's a right handedness and a left handedness, it
turns out, after investigating this kind of thing, science is
(09:56):
really baffled as to what exactly is going on. Why
we would have handedness, yeah at all, where it comes from.
Why the proportions seem to be steady. There's a lot
of questions that you know, come up when you look
into handedness. Whereas you know the average person who just
kind of taken for granted, but no, not the average scientists. No, No.
(10:19):
There are a lot of interesting theories though. Um. One
is is that, uh, as we all know, we have
a left hemisphere in the right hemisphere of our brain,
and we are one of the only mammals that are
very much um, 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.
(10:41):
And that is primarily controlling the opposite side of the
body as the hemisphere. UM. But language and um controlling
your you know, fine motor skills like things you do
with your hands and your fingers have often been linked
because uh, they are generally on link together and on
(11:02):
one hemisphere of the brain right for for the most part,
people who are right hand and they make up the
vast majority of human beings. By the way, Yeah, I
saw as low as seventy, but nothing lower than that,
you know, eighty didn't Yeah, you're right, sorry, exactly, UM.
Those people have their language center in the left hemisphere,
(11:23):
and I guess also their motor cortex in the left hemisphere,
and the know, the left and the Uh. There's a
lot of questions about why this would be when the
brain supposedly is a 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
(11:48):
to do stuff right right, So, um, 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
um not have to cross over the corpus colossum. Yeah,
it's it's just like cluster together. It makes sense. It
does make sense, but it's also a pretty thin explanation.
(12:10):
If you 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 in opposite sides of
the brain to give each other a break, rather than
just weighting it down on the same side. The point is, though,
is if you crack open a human brain and you
look for the motor cortex and the language region, the
(12:31):
language center, you're going to find them most likely, statistically speaking,
on the left hemisphere. Hence more right handedness right because
of what you said that, um, that brain lateralization where
stuff that's carried out in the left hemisphere is going
to manifest itself in the right. So if you're shaking
somebody's hand using your right hand, the left hemisphere is
(12:53):
blowing up. That's right. If you're taking in um visual
information with just your left eye because you got right
eye closed or it was poked out by a seagull
or whatever, then your right hemisphere is going to be
active rights right. Interestingly, though, if the opposite isn't true,
If you have your language center in your right hemisphere,
(13:16):
it doesn't always mean that you're going to be left handed.
It means you're more likely to. But um, I like
the way this article looked at it. It's it's an
evolutionary rule of thumb. It's not. I think they said
between sixty one and seventy of lefties have the language
centers on the left um over of right handed people right,
(13:37):
which raises a really great question. Are is there such
a thing as right eas and lefties or is there
such a thing as right ees and non right ees?
Because if there, if if a righty and a lefty
are equally exactly the same thing, if handedness is completely
u binary like that, Yeah, then if you're a lefty,
(13:58):
your language center should be on the right hand side,
and that, like you said, that's just not the case
in most lefties even Yeah, that's true, And the I
nine 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'd have
more lefties. Right, Yeah, well that's the idea. But I think, um,
(14:21):
there are a couple of the explanations, possibly of genetic
mutations along the way too, In particular, uh one about
two hundred thousand years ago that basically mutated us to
the fact that we are going to be more right
handed in the in the language center is going to
be on the left hand side. Uh. And then more recently, um,
(14:43):
there's a theory that there was a second mutation uh
two between twenty thousand and a hundred thousand years ago
where that basically balanced things out or it canceled that out,
which means the possibility of left handedness became a thing,
or else we would have all been right handed. Right.
That makes sense too. It does make sense and that
(15:03):
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,
and then that second gene came along and canceled that
(15:26):
out in some parts of the population. Yeah. I think
it's the D gene and the C gene. Um. 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 uh, promotes the
right handed preference. The C gene is less likely within
(15:48):
the gene pool. Uh. And so there you have like
a fifty fifty chance of being left handed if you
have that C gene. Okay, I got you. Yeah, But
you don't have a fifty chance of being a left
handed person in general. You have about it only if
you had chance. Yeah, because the D gene is more prominent,
(16:08):
and that means almost certainly you're going to be right handed. Okay.
So the caveat we should add to all of this
is that, um, this is all just strictly conjecture. Um.
And we'll get to a little more of this conjecture
right after this. So, Chuck, we were saying that it's
(16:38):
possible that genetic mutations far back in human history account
for this, and um, there is a lot of evidence
that there have humans have been mostly right handed for
about the last two d thousand years. Fossil evidence suggests this.
Looking at um neanderthal skeletons early human skeletons, UM, you
(16:59):
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 that arm connected to that hand, and it would
stay in the fossil record through the skeletons right They
(17:23):
also have looked at other fossils as far back as
one point six 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. Sure
uh and he is a one point six million year
old Homo air gaster and um they he he was
(17:47):
clearly right handed as well. Other fossils have turned up
evidence of right handedness the the teeth. Striations on the
teeth suggest eating with their right hand. So what we
what we can say with a pretty decent amount of confidences,
at least for the last two hundred thousand years, humanity
has been a majority right handers, and there's been maybe
(18:08):
about this constant ten proportion of left handed people, which
makes the mystery even more crazy to me. Yeah, but
it also makes sense that um an early tool building
and teaching how to use tools. UM, I mean it
holds true today. They've done studies that you know, you
teach your son or daughter to tie a tie, and
(18:31):
it's it's going to be more difficult if they're left
handed and you're right handed for them to try and
do it with their left hand. So there they'll pick
it up easier if they go against their instinct and
learn it how you've talked with. The studies have shown that, Yeah,
so you learned faster from watching somebody and then using
the same hand. The Yeah, and that makes sense. Back
(18:51):
in the you know, with Took took In showing his
pal how to use the bone to smash skull. You know,
it's if he picks of his buddy picks up with
this left hand, Took Took's gonna shake his head, no, no, yeah,
use right hand or they're just gonna you know, they
want everyone wants to fit in, even back at in
the old days. Well that's actually a suggestion of why
(19:14):
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. Um, and
parents and teachers would force children to learn how to
write with their right hand, effectively wiping out a lot
(19:36):
of the left handed population. Yeah, and um, just jumping
back a minute, I wanted to mention something important that
the whole correlation versus causation thing um with the whole
language center link. Uh, it's not necessarily that that's a correlation.
They appear to be strongly linked, but no one is
(19:56):
saying that because the language hemisphere is on the left
side of your brain, that's causing you to be right handed. Right.
They there, 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 like a
(20:19):
red flag or a signal that they're both usually in
the same hemisphere, and they do seem to be connected.
And one hypothesis for why they're connected, I thought was
pretty smart. Um. The idea that language spoken language emerged
out of gestures hand movements, which would require fine motor skills,
(20:39):
right that I don't have trying to do the two
legit to quit things. 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.
(20:59):
And I mean, so it stuck around. It didn't become
obsolete just because we started speaking. Yeah, I like that theory. Um.
We we did mention that this is a largely uniquely
human trait um, But they have followed. Uh, they've basically
been looking at our closest ancestors to try and figure
a lot of this stuff out. Although it did see
some studies that said that, like cats are left handed
(21:22):
because they'll go to swat things with their left hand,
but um, I'm not so sure about that. Yeah, there's
not only is it difficult apparently to um test or
do you attribute 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. Um,
(21:44):
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? Yeah, is
the one you're comfortable with, the one you that you're
actually better with. Yeah, that's a good point. Um. But
they have been looking at our our primate ancestors since
(22:04):
about the nineteen twenties, and they have found patterns. Um.
Apparently lemurs and are more left handed, and other prosim uh,
prosimians um. Macaques and old World monkeys for the most
part are evenly split, and guerrillas and chimpanzees are about
thirty five lefty. Um. But this is interesting. The more,
(22:26):
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. It's the exact opposite.
It implies that we were originally left handed right as primates,
and then as we evolved we became right handed. So
(22:47):
therefore right handed people are more involved than left handed
people in some weird way. Yeah. So again it's another
inconsistency where and of course this is in primates too. Um.
That doesn't necessarily mean it's the same thing with you. No,
definitely not. But I mean, if you're looking at our
ancestry and trying to figure out where handedness came from,
you have to go pretty far back right, And I
(23:11):
that's a pretty good example of how this body of
work or knowledge is very contradictory. Still, yeah, it's baffling,
it's pretty awesome. Hey, Chuck, Hey, you sent me something
about um ambidextrous nous. Yeah. I thought this was kind
of interesting from mental flaws, like, like, it was just
kind of my understanding that anybody who said, oh, I'm
(23:32):
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 um condition. I guess you'd call
it yeah, um, because I don't know if there is
a is a strict definition for what constitutes being ambidextrous.
Like a you know, a switch hitter in baseball doesn't
(23:55):
necessarily mean they're ambidextrous. It means they've taught themselves to
hit from the other side of the plate. Um. If
you notice, as a baseball fan, you're never gonna see
a player that hits uh 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
(24:16):
a switch hitter, he was a much better hitter. I
think it was as a lefty and not as a righty.
So that's not image extrous now, someone who's taught themselves,
because it's a valuable skill in sports to be somewhat
embed extrous or in a lot of sports. UM. But
as far, I think writing is one of the things
that they can look at UM as a clear indicator
(24:36):
of which hand, uh you're you're best at And they
say about only about one percent can write equally as
well with either hand, So that's like super low UM
apparently too. So this handedness in this UM 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. Yeah.
(24:58):
So like for example, UM, people who are ambidextrous UM
are more likely to suffer from schizophrenia, to have schizophrenia.
And there it's not just UM ambidextrous people. Apparently lefties
UM show a greater propensity towards schizophrenia. Something like people
with schizophrenia are left handed, which is a very high
(25:21):
proportion considering the general populations about ten and um. More
than that, dyslexia and stuttering as well, right, which suggests
that left handedness has an effect on how your brain
is wired. It's not just as simple, Oh my my
hand is I use my left hand. My my brain
(25:42):
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. Yeah. The um
we we talked about synesthesia before, one of our favorite
Uh what do you call it? A condition? Is it? Yeah?
Is it? Sure? I always just think of condition is
(26:03):
something that's uh, you know, derogatory. Yeah, like a malady
or something. I mean I think that falls under that
one is one, but the other one isn't necessarily that one.
So like a malady is a condition, but excipition isn't
necessarily a malady anyway. That's my long windway of saying.
Synist eats are awesome. Uh. And the rate of and
(26:26):
u ambidextrian synist eats is much higher, uh and left
handedness than in the general population. Right, So we have
some clues here, like UM, it's 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, and a lot of
(26:48):
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've got some advantages in life. We'll talk
about those right after this. So, Chuck, one of the
(27:18):
things that UM left handedness possibly bestows confers upon you
as a benefit is the idea of thinking quicker, to
be able to process information more quickly. Yeah. Uh, they
have done some studies on this. UM did did a
couple of studies, one of which UM they sat down
a hundred people, eighty right handers, twenty left handers and
(27:40):
basically to show them a computer screen with a single
dot either on the left or the 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? Right?
So something shows up on the left side. I'm sure
you have a clicker in your left hand and clicker
in your right hand. You click the left hand clicker,
but this is all happening very fast. That's right. Um,
and left handed subjects were overall faster. Uh. And the
(28:03):
other tests 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 handed, Uh, we're faster, but just at matching letters
that were on both sides of the line, right, which
I thought was interesting well, and that supports this idea
that um, the the brain. The fact that um, some
(28:26):
left handed people's motor skills and language centers are on
different sides in their brains, uh, could make them talk more.
The side of their hemispheres of their brains are more connected,
there's more white tissue where their corpus colossum is more efficient.
It makes sense in a way, but at the same
(28:46):
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, because it doesn't really do do a lot
at this point. We don't know enough to make it fit.
And it's actually kind of contradictory to some other stuff
too as far as handedness goes. Yeah, but they do
(29:07):
say that if you're left handed, you may be like
a better gamer or or a pilot, because you're able
to just process this quick information super fast, like rapid
fire stuff coming at you. It also suggested to that
language can be processed in both hemispheres among left handed people,
which again would require a lot more connections between the
(29:29):
two hemispheres, faster communication between the two and hence quicker thinking. Yeah,
and that you in the long run, as you age
in 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, you're just you know, screwed,
(29:51):
You're in You're in trouble. And of course this has approven.
This is just there postulating here, right, But I mean,
as to this mystery, Yeah, you definitely haven't an advantage
in sports in a lot of cases. Though, Yes, but
not in the way that you would think. It's not
necessarily because your brain is communicating. The hemispheres are of
your brain are communicating. It's more because your opponent is
(30:15):
statistically likelier to be expecting you to be a right
handed person to have trained against the right handed person
exactly to be used to playing a right handed person.
Whereas if you're a left handed person, they're playing you. Now,
you're going to throw them off guard. You're gonna catch
them off guard. You're gonna be able to get the
drop on them because they're not used to you. Whereas you,
(30:35):
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 your Rocky. Yeah, Rocky was left handed. Apparently. Um,
and there's a bunch of sports figures in real life
that we're left handed, and apparently it's one of those
(30:57):
things where they're disproportionately represented. Yeah, as far as successful
athletes go compared to the to the population at large. Yeah,
and I think, um, a lot of times you'll hear
about like m M A or boxing. Tennis is another
big one because if you're used to playing right e's
most of your life, that left handed server comes up
there and it's it's different, it's weird, right, And the
(31:19):
difference is so pronounced that, like if you are a
pro tennis player or something like that or pro boxer.
You're gonna train against the lefty before a match against
the lefty. Yeah, you know, you're gonna do what you
can to prepare yourself. Yeah. And I think Robert Lamb
wrote this on how staff forks are left handers quicker,
I'm sorry, better at sports and um. He also points
(31:40):
out that through history, uh, this probably comes from like
soldier training, mainly training and fighting and jousting and sword
fighting and everything against other right e's as well, So
a lefty would have a left handed warrior might be
more prone to be, you know, the great leader, like
perhaps Alexander the Great right who was a left handed
(32:01):
What's weird though, is if that has been the case,
if humans have been left handed and right handed, the
proportions have been roughly the same for the last two
hundred thousand years. If you're left handed combatant, wouldn't then
the proportion of left handed people have grown over time
because of natural selection because you you have an advantage
(32:23):
in battle or something like that. So therefore the population
of right handed people would drop in relation to the
population of left exactly. That makes sense. And I remember this,
but that hasn't happened. Yeah, I remember our podcasts on
castles like eighty years ago. Remember they built the staircases
going on the right hand side. I can't even do
(32:45):
you remember how mine fending lee difficult? That was for
me to understand. Did you have our time with Oh? Yeah,
we had to re record it I think twice because
I kept getting it wrong. Yeah. We also got in
trouble for for a cussword in that one too. Those
that was a dark day many years ago. Um. Yeah,
but the Yeah, the the castle steps would wind up
(33:06):
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 advantage taken
away even though you have the higher ground, because all
(33:28):
of a sudden you're cutting the guy's knees off. They
were cutting them off at the knees. Yeah, you know
that hurts. It does. But also included with natural selection
two 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
(33:48):
over that long of a period too. I see what
you mean, you know, unless the advantage isn't so great
as to you know, cause uh, that natural selection to occur,
you know. Maybe. Um, there are more US presidents that
have been left handed, more MENSA members for whatever that's worth.
Half half of the twelve US presidents, so it's World
(34:10):
War two have been left handed. So whereas the normal populations,
ten or fifteen percent lefties US presidents of World War
two has been And apparently in the campaign all three
candidates H. W. Bush, Clinton, and Pero were left handed. Yeah,
that's a percent of the population. Peroh man, he was
(34:32):
fun to watch. He was Dana Carvey was fun to
watch doing Pero too. Oh yeah. Uh. And they say
more musicians more or musicians are more likely to be
left handed. Maybe, um. And it does run in families,
even though identical twins can have opposite hand preferences. Oh weird,
And um there is In the nineteen eighties, it was
(34:54):
a Harvard neurologist that said that, ah, lefties are right
eas whose brain centers in the womb change because of
high testosterone. Yeah, so there's there's theories that we become
handed in the womb because of something like that, or
birth trauma or some sort of trauma while we're in
(35:14):
the womb and that, Yeah, it just adjusts the the
the construction of our brains. Um. Supposedly, a mother's age
has an impact on her kids. That's crazy. Statistically speaking,
a mother UM over forty who gives birth is has
a higher likelihood of having a lefty kid, way higher,
(35:36):
like h or something. Yeah, like that's pretty high. Yeah,
it's more than I don't even know what that means. Yeah,
and then I guess your hand preference emerges about by
seven months, but then it's like set by age three,
So before seven months you're just flinging poop with both
hands equally as well. Pretty much. Yeah. I wrote a
(35:56):
story about a guy who found out as an adult
that has 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. He didn't seem to take it like that,
but he did see it came across like he felt
like something had been kind of taken from him. He
(36:17):
said it also explained a lot that he was like
so so with stuff that involves its right hand seemed
to be better with his left and um that he
looked into it, and that by doing that, which is
very popular, like kids were forced to become right handed
through the twentieth century. Um that you are basically making
(36:38):
a a less pronounced copy of the person. You're taking
the original and making like a slightly dimmer effect simile
of it, like forcing their being to reorganize like that
interesting whereas they thought they were trying to give them
an advantage, to actually give them a disadvantage exactly. But
I would imagine that if you did that till say
(37:02):
age eighteen, and then all of a sudden started using
your dominant hand that you were naturally born with. It's
all like Spinley in week right, but then once you
once you train it to to to bulk back up. Yeah,
I would imagine your brain would would be better off
like that, be fuller. So to continue the abuse right
until eighteen, discontinued the abuse, and then bam, you got
(37:25):
a super kid on your take your little old man
Spinley hands and fingers like, um, build them back up
and Mr Show character remember Titanico and they were crossed
in the hospital. You know they're getting back together. Yeah, yeah,
that's exciting. So p FT tweeted something some picture is
very exciting, the whole gang. If you want to know
(37:47):
more about Paul if Tompkins or Handedness or Mr Show
or any of that jazz, you can type that stuff
into the search bar at how stuff works dot com.
Since I said search parts, time for listener mail, I'm
gonna call this Christian shout out. Hey, guys started listening
of a few months ago and I've already listened to
about a hundred and sixty episodes. Um. And by the way,
(38:12):
we mentioned this a lot, but if you're just on iTunes,
say and you think, boy, these guys have got three
hundred episodes one yeah, we've got like how many now
seven change? Yeah, seven hundred plus that you can find
on our website. UM, stuff you should know dot com. Yeah,
And as a little pro tip, if you go onto
stuff you should know dot Com a k the website
(38:34):
with one of the worst searches in the world, just
do control F and open up your web browsers search
and then type it in and on our podcast archive page.
If you're looking for something, yes, okay, it'll bring it up.
Don't search for it don't bother searching for it using
our search tool on the site. Are we working on that?
I hope so, because this is really bad, like it
(38:54):
doesn't bring up anything really Yeah, wow, that's pretty bad.
Otherwise it even there, I don't know. I guess for
looks lame. Um. So getting back to this, we do
have a lot of podcasts out there, for those of
you who don't know, we have seven hundred plus talking
about He's uh. He listened to a hundred and sixty episodes.
(39:15):
His favorite thing about them is how you don't poo
poo anybody's beliefs. I'm a Christian, So when I was
very much so begrudgingly, ah, listen to your evolution suite,
I was expecting to be mad, but to my surprise,
I heard a very non biased view of evolution. Um.
I do believe in evolution, but it's a long story.
By the way, after many years of hearing creation a
(39:35):
slam uh, people talk about evolution is a very pleasant surprise.
So I just want to say thanks for putting your
hearts but not your opinions into that episode. That is
from Matt very sincerely, and we've been taking a task
here and there We try to do our best matt
um to keep things on the level like that, but
we are human and we do uh flounder here and
(39:57):
there with that, but we we try, and we appreciate
your kudos for that. Yeah, thanks man. Yeah, 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 if you
had your arm tied to your waist till you're eight
as a baby. Uh. You can tweet to us at
s y s K podcast. You can join us on
(40:19):
Facebook dot com slash Stuff you Should Know. You can
send us an email to stuff podcast at how stuff
Works dot com and has always joined us at our
home on the web, Stuff you Should Know dot com.
Stuff you Should Know is a production of I Heart Radio.
For more podcasts my Heart Radio, visit the i heart
Radio app, Apple Podcasts, or wherever you listen to your
(40:39):
favorite shows.
Hi, everybody, it's February. No, it's not. It's not that
at all. But we're gonna go back in time today
because that's what we do every Saturday with our Saturday
Selects Picks, and we're going back to February because I
want to talk about lefties. Are you a lefty? Get
kick with your left hand? You have punch people with
(00:20):
your left hand? You're right with your left hand. Do
you eat with your left hand? Do you? Well? I'm
not going to talk about other things that you might
can do with left hands or right hands, but you
get the picture. Here's the episode, everybody, Why do Lefties Exist?
Welcome to Stuff You Should Know? A production of I
(00:41):
Heart Radio. Hey, I'm welcome to the podcast. I'm Josh
Clark with Charles W. Chuck Bryant and Jerry's over there too,
and this is stuff you should not the podcast. Man,
oh man. I would love for people to just the
(01:03):
fly on the wall in the studio sometimes and get squashed.
There'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 a that's for us. We we
deserve a little something. Yeah, And that's called pre show
fun fun hammering out the details, hammer and other details.
(01:24):
I thoroughly enjoyed researching this one. Oh really, it burned
my brain a little bit. It burned my brain a
little bit too. But um, I just I didn't know
anything about handedness and uh no not really don't use
your hands much. Well, I mean as far as uh
why you are left or right handed or ambidextrous. It
was all kind of new information for me. I feel
(01:46):
like I had read that IO nine article, which we
should give a huge shout out, because I was in
forming partially the basis of this um episode. Yeah, why
are so few people left handed? From IO nine and
they sourced a lot of great stuff and Discover magazine
and their articles so and science and science. So it's legit.
It is legit, uh possibly even to legit to quit yeah, yeah,
(02:11):
which I could not do with my left hand. I
guess I can't. I just did it. You just did
to your sign sign signing to me. Yeah, I'm equally
bad at at doing too legit to quit finger motions
with either hand. I'm right handed, by the way, what
about you, I'm right handed, but that is weird since
you have your MC hammer pants on. I thought you
(02:32):
would be good at that. That's all. Just it's not
hard to put on pants. It's hard to do too
legit to quit finger motions. Yeah, I'm right handed. Um
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, um, oh, yeah, yeah, I think. I think
(02:52):
some people are way dominant with their one hand, and
some people skew more towards you. I can do some
things with this hand. Uh, and some people are ambidexterous,
which we'll talk about very few though fewer than you think. Yeah,
but um, I am heavily heavily right handed. I cannot
do many uh what's the word I'm looking for, um,
(03:14):
trying to find my not like my fine motor skill tasks.
I cannot do very well with my left hand. I
can just like club things and smack things and knock
stuff over and knock stuff over like Frankenstein clearing at
table pretty much. What about you? And can you do
anything with your left hand? I used to think I was,
you know, pretty much just strictly right handed, but then
(03:36):
I I especially researching this. I paid attention, and I'm like, no,
I used my 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 this article points out, or actually it was
a science Um article that said, there's there's this idea
that there isn't a dominant hand that you have uses
(03:58):
for both hands in one kind of specializes in one
thing and one specializes in another. And the the example
they used to illustrate that was um cutting like meat
with a fork and knife. Yeah. I was gonna ask
you about that, you know, like I was thinking about it.
I was like, oh, yeah, I guess I do use
the knife pretty well with my left hand. I thought, crazy, No,
my fork is in my left hand. My knife is
(04:19):
in my right hand too, and then I switched the
fork over to my right hand. That's what I did too.
I was gonna ask you that. 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. Yeah, well, I come to
think of it, though, I play guitar in drums, So
I mean I have some left hand skill, I guess, um.
(04:40):
And I know if you break your dominant hand, you're
gonna learn pretty quickly how to adapt, So it's possible
to learn, uh force do. Yes, it's all very interesting
to me. It is, and we should say if you
happen happen just randomly to be listening to this episode
on August Happy National Left Handed Day, Yeah, I looked
(05:02):
out when I looked that up, I was like, I
wouldn't it be one of those another stuff you should
know coincidence if this was happened to be released that No,
not even close. Yeah. Um. And it's good that left
handed people have their own day because they've been fairly
maligned throughout the millennia. Yeah, let's talk about that. Actually, okay, Um,
throughout history. In fact, even if you look at the
(05:25):
words throughout history, there is a you know, uh the
poopoo left handers basically, Yeah, Like the word l y
f T left yeah, from Anglo Saxon means weak and
that's where the word left comes from. Yeah, And the
word sinister from Latin is the word for left. Yeah.
Anybody who saw that episode of the Simpsons where Ned
(05:46):
Flanders opens the left Toorium knows that because he says,
I have a a sinister reason to invite you all here,
sinister meaning left handed man. And that was when he
announced the Leftorium. That show was so smart, you know,
very smart. So many of those jokes like just flew
over my head back in the day. Well they're coming
back to roost. Uh. There's a long list of um.
(06:10):
Countries who have languages that link the word right with
being good, uh, in the left with being bad or wrong. Uh.
And in some countries even making hand gestures with your
left hand is a no no well and a lot
of countries are a lot of cultures that eat food
with their hands rather than utensils. Um. Using the left
(06:33):
hand to eat or do a lot of things with
is considered taboo because it's exactly right. You use the
right hand to eat with, use your left hand to
wipe with right and um, I think if you pay
attention and notice, I'll bet you have a hand that's
dominant and that that um activity wipe in your butt.
Yeah yeah, I'm already are you Oh yeah, okay, But
(06:56):
if you if you try the other hand, I'll feel
very weird. Whatever whatever hand you use normally, it's gonna
feel weird if you use the opia, and you'll just
end up very messy. Sure, I wonder if you had
a subconscious thing like you know, I was just eating
these candy pecons with my right hand, and I know
I'm going to go back and eat them with my
right hand. Oh, I don't even use my hands to eat.
(07:17):
I'm I'm a little too germ conscious. I scoop food
up in the croak of my elbow, which is very
clean because it doesn't come in contact of other stuff,
and then I eat out of the croak of my elbow.
That's pretty funny. Um. 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, ten
(07:40):
of people are left handed, and throughout history minorities have
been picked on. That's right, this one thing. Um, there's
there's at least a couple of cultures that equate left
handedness with clumsiness. Yeah, that makes sense to me. Some
hypotheses theorized that UM tools tool making. For a very
long time time, UM has been done following right handed techniques.
(08:03):
Still is in many cases. Um, and 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. Yeah, like, uh,
colonial day, dad is teaching his two sons. Let's go
(08:26):
with the son and a daughter even, let's mix it up,
how to use a saw. And you know, the son's
left handed and he keeps he can't saw. Well, so
the dad's just like he favors the daughter because she's
you know, she's better with the saw. It's just it's
easy to see how that could happen. Like he's mad
at Roger but pleased with Prudence because Prudence she's always
sawing things. Well that's a colonial name. Yeah, sure, well
(08:49):
I feel like it is. Okay, Well what else is there? Who? Goody?
Uh goody Alice. Okay, it's timeless, um, but there's still that.
If you're 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. Yeah, you're sitting
(09:11):
next to a right handed person at dinner. The elbow thing.
It's the worst. It's because there's 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 put them appropriately right. To
put the left handed person at the end of the
table so that their left hand is their left elbow
(09:32):
is off the table, and they don't have to worry
about bumping into other people. Yeah, my mom is left handed,
my father is right handed, and you came out right
handed crazy, I sure did so. Um, despite everybody knowing
that there's a right handedness and a left handedness, it
turns out, after investigating this kind of thing, science is
(09:56):
really baffled as to what exactly is going on. Why
we would have handedness, yeah at all, where it comes from.
Why the proportions seem to be steady. There's a lot
of questions that you know, come up when you look
into handedness. Whereas you know the average person who just
kind of taken for granted, but no, not the average scientists. No, No.
(10:19):
There are a lot of interesting theories though. Um. One
is is that, uh, as we all know, we have
a left hemisphere in the right hemisphere of our brain,
and we are one of the only mammals that are
very much um, 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.
(10:41):
And that is primarily controlling the opposite side of the
body as the hemisphere. UM. But language and um controlling
your you know, fine motor skills like things you do
with your hands and your fingers have often been linked
because uh, they are generally on link together and on
(11:02):
one hemisphere of the brain right for for the most part,
people who are right hand and they make up the
vast majority of human beings. By the way, Yeah, I
saw as low as seventy, but nothing lower than that,
you know, eighty didn't Yeah, you're right, sorry, exactly, UM.
Those people have their language center in the left hemisphere,
(11:23):
and I guess also their motor cortex in the left hemisphere,
and the know, the left and the Uh. There's a
lot of questions about why this would be when the
brain supposedly is a 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
(11:48):
to do stuff right right, So, um, 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
um not have to cross over the corpus colossum. Yeah,
it's it's just like cluster together. It makes sense. It
does make sense, but it's also a pretty thin explanation.
(12:10):
If you 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 in opposite sides of
the brain to give each other a break, rather than
just weighting it down on the same side. The point is, though,
is if you crack open a human brain and you
look for the motor cortex and the language region, the
(12:31):
language center, you're going to find them most likely, statistically speaking,
on the left hemisphere. Hence more right handedness right because
of what you said that, um, that brain lateralization where
stuff that's carried out in the left hemisphere is going
to manifest itself in the right. So if you're shaking
somebody's hand using your right hand, the left hemisphere is
(12:53):
blowing up. That's right. If you're taking in um visual
information with just your left eye because you got right
eye closed or it was poked out by a seagull
or whatever, then your right hemisphere is going to be
active rights right. Interestingly, though, if the opposite isn't true,
If you have your language center in your right hemisphere,
(13:16):
it doesn't always mean that you're going to be left handed.
It means you're more likely to. But um, I like
the way this article looked at it. It's it's an
evolutionary rule of thumb. It's not. I think they said
between sixty one and seventy of lefties have the language
centers on the left um over of right handed people right,
(13:37):
which raises a really great question. Are is there such
a thing as right eas and lefties or is there
such a thing as right ees and non right ees?
Because if there, if if a righty and a lefty
are equally exactly the same thing, if handedness is completely
u binary like that, Yeah, then if you're a lefty,
(13:58):
your language center should be on the right hand side,
and that, like you said, that's just not the case
in most lefties even Yeah, that's true, And the I
nine 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'd have
more lefties. Right, Yeah, well that's the idea. But I think, um,
(14:21):
there are a couple of the explanations, possibly of genetic
mutations along the way too, In particular, uh one about
two hundred thousand years ago that basically mutated us to
the fact that we are going to be more right
handed in the in the language center is going to
be on the left hand side. Uh. And then more recently, um,
(14:43):
there's a theory that there was a second mutation uh
two between twenty thousand and a hundred thousand years ago
where that basically balanced things out or it canceled that out,
which means the possibility of left handedness became a thing,
or else we would have all been right handed. Right.
That makes sense too. It does make sense and that
(15:03):
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,
and then that second gene came along and canceled that
(15:26):
out in some parts of the population. Yeah. I think
it's the D gene and the C gene. Um. 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 uh, promotes the
right handed preference. The C gene is less likely within
(15:48):
the gene pool. Uh. And so there you have like
a fifty fifty chance of being left handed if you
have that C gene. Okay, I got you. Yeah, But
you don't have a fifty chance of being a left
handed person in general. You have about it only if
you had chance. Yeah, because the D gene is more prominent,
(16:08):
and that means almost certainly you're going to be right handed. Okay.
So the caveat we should add to all of this
is that, um, this is all just strictly conjecture. Um.
And we'll get to a little more of this conjecture
right after this. So, Chuck, we were saying that it's
(16:38):
possible that genetic mutations far back in human history account
for this, and um, there is a lot of evidence
that there have humans have been mostly right handed for
about the last two d thousand years. Fossil evidence suggests this.
Looking at um neanderthal skeletons early human skeletons, UM, you
(16:59):
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 that arm connected to that hand, and it would
stay in the fossil record through the skeletons right They
(17:23):
also have looked at other fossils as far back as
one point six 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. Sure
uh and he is a one point six million year
old Homo air gaster and um they he he was
(17:47):
clearly right handed as well. Other fossils have turned up
evidence of right handedness the the teeth. Striations on the
teeth suggest eating with their right hand. So what we
what we can say with a pretty decent amount of confidences,
at least for the last two hundred thousand years, humanity
has been a majority right handers, and there's been maybe
(18:08):
about this constant ten proportion of left handed people, which
makes the mystery even more crazy to me. Yeah, but
it also makes sense that um an early tool building
and teaching how to use tools. UM, I mean it
holds true today. They've done studies that you know, you
teach your son or daughter to tie a tie, and
(18:31):
it's it's going to be more difficult if they're left
handed and you're right handed for them to try and
do it with their left hand. So there they'll pick
it up easier if they go against their instinct and
learn it how you've talked with. The studies have shown that, Yeah,
so you learned faster from watching somebody and then using
the same hand. The Yeah, and that makes sense. Back
(18:51):
in the you know, with Took took In showing his
pal how to use the bone to smash skull. You know,
it's if he picks of his buddy picks up with
this left hand, Took Took's gonna shake his head, no, no, yeah,
use right hand or they're just gonna you know, they
want everyone wants to fit in, even back at in
the old days. Well that's actually a suggestion of why
(19:14):
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. Um, and
parents and teachers would force children to learn how to
write with their right hand, effectively wiping out a lot
(19:36):
of the left handed population. Yeah, and um, just jumping
back a minute, I wanted to mention something important that
the whole correlation versus causation thing um with the whole
language center link. Uh, it's not necessarily that that's a correlation.
They appear to be strongly linked, but no one is
(19:56):
saying that because the language hemisphere is on the left
side of your brain, that's causing you to be right handed. Right.
They there, 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 like a
(20:19):
red flag or a signal that they're both usually in
the same hemisphere, and they do seem to be connected.
And one hypothesis for why they're connected, I thought was
pretty smart. Um. The idea that language spoken language emerged
out of gestures hand movements, which would require fine motor skills,
(20:39):
right that I don't have trying to do the two
legit to quit things. 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.
(20:59):
And I mean, so it stuck around. It didn't become
obsolete just because we started speaking. Yeah, I like that theory. Um.
We we did mention that this is a largely uniquely
human trait um, But they have followed. Uh, they've basically
been looking at our closest ancestors to try and figure
a lot of this stuff out. Although it did see
some studies that said that, like cats are left handed
(21:22):
because they'll go to swat things with their left hand,
but um, I'm not so sure about that. Yeah, there's
not only is it difficult apparently to um test or
do you attribute 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. Um,
(21:44):
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? Yeah, is
the one you're comfortable with, the one you that you're
actually better with. Yeah, that's a good point. Um. But
they have been looking at our our primate ancestors since
(22:04):
about the nineteen twenties, and they have found patterns. Um.
Apparently lemurs and are more left handed, and other prosim uh,
prosimians um. Macaques and old World monkeys for the most
part are evenly split, and guerrillas and chimpanzees are about
thirty five lefty. Um. But this is interesting. The more,
(22:26):
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. It's the exact opposite.
It implies that we were originally left handed right as primates,
and then as we evolved we became right handed. So
(22:47):
therefore right handed people are more involved than left handed
people in some weird way. Yeah. So again it's another
inconsistency where and of course this is in primates too. Um.
That doesn't necessarily mean it's the same thing with you. No,
definitely not. But I mean, if you're looking at our
ancestry and trying to figure out where handedness came from,
you have to go pretty far back right, And I
(23:11):
that's a pretty good example of how this body of
work or knowledge is very contradictory. Still, yeah, it's baffling,
it's pretty awesome. Hey, Chuck, Hey, you sent me something
about um ambidextrous nous. Yeah. I thought this was kind
of interesting from mental flaws, like, like, it was just
kind of my understanding that anybody who said, oh, I'm
(23:32):
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 um condition. I guess you'd call
it yeah, um, because I don't know if there is
a is a strict definition for what constitutes being ambidextrous.
Like a you know, a switch hitter in baseball doesn't
(23:55):
necessarily mean they're ambidextrous. It means they've taught themselves to
hit from the other side of the plate. Um. If
you notice, as a baseball fan, you're never gonna see
a player that hits uh 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
(24:16):
a switch hitter, he was a much better hitter. I
think it was as a lefty and not as a righty.
So that's not image extrous now, someone who's taught themselves,
because it's a valuable skill in sports to be somewhat
embed extrous or in a lot of sports. UM. But
as far, I think writing is one of the things
that they can look at UM as a clear indicator
(24:36):
of which hand, uh you're you're best at And they
say about only about one percent can write equally as
well with either hand, So that's like super low UM
apparently too. So this handedness in this UM 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. Yeah.
(24:58):
So like for example, UM, people who are ambidextrous UM
are more likely to suffer from schizophrenia, to have schizophrenia.
And there it's not just UM ambidextrous people. Apparently lefties
UM show a greater propensity towards schizophrenia. Something like people
with schizophrenia are left handed, which is a very high
(25:21):
proportion considering the general populations about ten and um. More
than that, dyslexia and stuttering as well, right, which suggests
that left handedness has an effect on how your brain
is wired. It's not just as simple, Oh my my
hand is I use my left hand. My my brain
(25:42):
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. Yeah. The um
we we talked about synesthesia before, one of our favorite
Uh what do you call it? A condition? Is it? Yeah?
Is it? Sure? I always just think of condition is
(26:03):
something that's uh, you know, derogatory. Yeah, like a malady
or something. I mean I think that falls under that
one is one, but the other one isn't necessarily that one.
So like a malady is a condition, but excipition isn't
necessarily a malady anyway. That's my long windway of saying.
Synist eats are awesome. Uh. And the rate of and
(26:26):
u ambidextrian synist eats is much higher, uh and left
handedness than in the general population. Right, So we have
some clues here, like UM, it's 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, and a lot of
(26:48):
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've got some advantages in life. We'll talk
about those right after this. So, Chuck, one of the
(27:18):
things that UM left handedness possibly bestows confers upon you
as a benefit is the idea of thinking quicker, to
be able to process information more quickly. Yeah. Uh, they
have done some studies on this. UM did did a
couple of studies, one of which UM they sat down
a hundred people, eighty right handers, twenty left handers and
(27:40):
basically to show them a computer screen with a single
dot either on the left or the 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? Right?
So something shows up on the left side. I'm sure
you have a clicker in your left hand and clicker
in your right hand. You click the left hand clicker,
but this is all happening very fast. That's right. Um,
and left handed subjects were overall faster. Uh. And the
(28:03):
other tests 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 handed, Uh, we're faster, but just at matching letters
that were on both sides of the line, right, which
I thought was interesting well, and that supports this idea
that um, the the brain. The fact that um, some
(28:26):
left handed people's motor skills and language centers are on
different sides in their brains, uh, could make them talk more.
The side of their hemispheres of their brains are more connected,
there's more white tissue where their corpus colossum is more efficient.
It makes sense in a way, but at the same
(28:46):
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, because it doesn't really do do a lot
at this point. We don't know enough to make it fit.
And it's actually kind of contradictory to some other stuff
too as far as handedness goes. Yeah, but they do
(29:07):
say that if you're left handed, you may be like
a better gamer or or a pilot, because you're able
to just process this quick information super fast, like rapid
fire stuff coming at you. It also suggested to that
language can be processed in both hemispheres among left handed people,
which again would require a lot more connections between the
(29:29):
two hemispheres, faster communication between the two and hence quicker thinking. Yeah,
and that you in the long run, as you age
in 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, you're just you know, screwed,
(29:51):
You're in You're in trouble. And of course this has approven.
This is just there postulating here, right, But I mean,
as to this mystery, Yeah, you definitely haven't an advantage
in sports in a lot of cases. Though, Yes, but
not in the way that you would think. It's not
necessarily because your brain is communicating. The hemispheres are of
your brain are communicating. It's more because your opponent is
(30:15):
statistically likelier to be expecting you to be a right
handed person to have trained against the right handed person
exactly to be used to playing a right handed person.
Whereas if you're a left handed person, they're playing you. Now,
you're going to throw them off guard. You're gonna catch
them off guard. You're gonna be able to get the
drop on them because they're not used to you. Whereas you,
(30:35):
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 your Rocky. Yeah, Rocky was left handed. Apparently. Um,
and there's a bunch of sports figures in real life
that we're left handed, and apparently it's one of those
(30:57):
things where they're disproportionately represented. Yeah, as far as successful
athletes go compared to the to the population at large. Yeah,
and I think, um, a lot of times you'll hear
about like m M A or boxing. Tennis is another
big one because if you're used to playing right e's
most of your life, that left handed server comes up
there and it's it's different, it's weird, right, And the
(31:19):
difference is so pronounced that, like if you are a
pro tennis player or something like that or pro boxer.
You're gonna train against the lefty before a match against
the lefty. Yeah, you know, you're gonna do what you
can to prepare yourself. Yeah. And I think Robert Lamb
wrote this on how staff forks are left handers quicker,
I'm sorry, better at sports and um. He also points
(31:40):
out that through history, uh, this probably comes from like
soldier training, mainly training and fighting and jousting and sword
fighting and everything against other right e's as well, So
a lefty would have a left handed warrior might be
more prone to be, you know, the great leader, like
perhaps Alexander the Great right who was a left handed
(32:01):
What's weird though, is if that has been the case,
if humans have been left handed and right handed, the
proportions have been roughly the same for the last two
hundred thousand years. If you're left handed combatant, wouldn't then
the proportion of left handed people have grown over time
because of natural selection because you you have an advantage
(32:23):
in battle or something like that. So therefore the population
of right handed people would drop in relation to the
population of left exactly. That makes sense. And I remember this,
but that hasn't happened. Yeah, I remember our podcasts on
castles like eighty years ago. Remember they built the staircases
going on the right hand side. I can't even do
(32:45):
you remember how mine fending lee difficult? That was for
me to understand. Did you have our time with Oh? Yeah,
we had to re record it I think twice because
I kept getting it wrong. Yeah. We also got in
trouble for for a cussword in that one too. Those
that was a dark day many years ago. Um. Yeah,
but the Yeah, the the castle steps would wind up
(33:06):
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 advantage taken
away even though you have the higher ground, because all
(33:28):
of a sudden you're cutting the guy's knees off. They
were cutting them off at the knees. Yeah, you know
that hurts. It does. But also included with natural selection
two 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
(33:48):
over that long of a period too. I see what
you mean, you know, unless the advantage isn't so great
as to you know, cause uh, that natural selection to occur,
you know. Maybe. Um, there are more US presidents that
have been left handed, more MENSA members for whatever that's worth.
Half half of the twelve US presidents, so it's World
(34:10):
War two have been left handed. So whereas the normal populations,
ten or fifteen percent lefties US presidents of World War
two has been And apparently in the campaign all three
candidates H. W. Bush, Clinton, and Pero were left handed. Yeah,
that's a percent of the population. Peroh man, he was
(34:32):
fun to watch. He was Dana Carvey was fun to
watch doing Pero too. Oh yeah. Uh. And they say
more musicians more or musicians are more likely to be
left handed. Maybe, um. And it does run in families,
even though identical twins can have opposite hand preferences. Oh weird,
And um there is In the nineteen eighties, it was
(34:54):
a Harvard neurologist that said that, ah, lefties are right
eas whose brain centers in the womb change because of
high testosterone. Yeah, so there's there's theories that we become
handed in the womb because of something like that, or
birth trauma or some sort of trauma while we're in
(35:14):
the womb and that, Yeah, it just adjusts the the
the construction of our brains. Um. Supposedly, a mother's age
has an impact on her kids. That's crazy. Statistically speaking,
a mother UM over forty who gives birth is has
a higher likelihood of having a lefty kid, way higher,
(35:36):
like h or something. Yeah, like that's pretty high. Yeah,
it's more than I don't even know what that means. Yeah,
and then I guess your hand preference emerges about by
seven months, but then it's like set by age three,
So before seven months you're just flinging poop with both
hands equally as well. Pretty much. Yeah. I wrote a
(35:56):
story about a guy who found out as an adult
that has 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. He didn't seem to take it like that,
but he did see it came across like he felt
like something had been kind of taken from him. He
(36:17):
said it also explained a lot that he was like
so so with stuff that involves its right hand seemed
to be better with his left and um that he
looked into it, and that by doing that, which is
very popular, like kids were forced to become right handed
through the twentieth century. Um that you are basically making
(36:38):
a a less pronounced copy of the person. You're taking
the original and making like a slightly dimmer effect simile
of it, like forcing their being to reorganize like that
interesting whereas they thought they were trying to give them
an advantage, to actually give them a disadvantage exactly. But
I would imagine that if you did that till say
(37:02):
age eighteen, and then all of a sudden started using
your dominant hand that you were naturally born with. It's
all like Spinley in week right, but then once you
once you train it to to to bulk back up. Yeah,
I would imagine your brain would would be better off
like that, be fuller. So to continue the abuse right
until eighteen, discontinued the abuse, and then bam, you got
(37:25):
a super kid on your take your little old man
Spinley hands and fingers like, um, build them back up
and Mr Show character remember Titanico and they were crossed
in the hospital. You know they're getting back together. Yeah, yeah,
that's exciting. So p FT tweeted something some picture is
very exciting, the whole gang. If you want to know
(37:47):
more about Paul if Tompkins or Handedness or Mr Show
or any of that jazz, you can type that stuff
into the search bar at how stuff works dot com.
Since I said search parts, time for listener mail, I'm
gonna call this Christian shout out. Hey, guys started listening
of a few months ago and I've already listened to
about a hundred and sixty episodes. Um. And by the way,
(38:12):
we mentioned this a lot, but if you're just on iTunes,
say and you think, boy, these guys have got three
hundred episodes one yeah, we've got like how many now
seven change? Yeah, seven hundred plus that you can find
on our website. UM, stuff you should know dot com. Yeah,
And as a little pro tip, if you go onto
stuff you should know dot Com a k the website
(38:34):
with one of the worst searches in the world, just
do control F and open up your web browsers search
and then type it in and on our podcast archive page.
If you're looking for something, yes, okay, it'll bring it up.
Don't search for it don't bother searching for it using
our search tool on the site. Are we working on that?
I hope so, because this is really bad, like it
(38:54):
doesn't bring up anything really Yeah, wow, that's pretty bad.
Otherwise it even there, I don't know. I guess for
looks lame. Um. So getting back to this, we do
have a lot of podcasts out there, for those of
you who don't know, we have seven hundred plus talking
about He's uh. He listened to a hundred and sixty episodes.
(39:15):
His favorite thing about them is how you don't poo
poo anybody's beliefs. I'm a Christian, So when I was
very much so begrudgingly, ah, listen to your evolution suite,
I was expecting to be mad, but to my surprise,
I heard a very non biased view of evolution. Um.
I do believe in evolution, but it's a long story.
By the way, after many years of hearing creation a
(39:35):
slam uh, people talk about evolution is a very pleasant surprise.
So I just want to say thanks for putting your
hearts but not your opinions into that episode. That is
from Matt very sincerely, and we've been taking a task
here and there We try to do our best matt
um to keep things on the level like that, but
we are human and we do uh flounder here and
(39:57):
there with that, but we we try, and we appreciate
your kudos for that. Yeah, thanks man. Yeah, 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 if you
had your arm tied to your waist till you're eight
as a baby. Uh. You can tweet to us at
s y s K podcast. You can join us on
(40:19):
Facebook dot com slash Stuff you Should Know. You can
send us an email to stuff podcast at how stuff
Works dot com and has always joined us at our
home on the web, Stuff you Should Know dot com.
Stuff you Should Know is a production of I Heart Radio.
For more podcasts my Heart Radio, visit the i heart
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(40:39):
favorite shows.
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