April 14, 2011 • 24 mins
Mickey Mouse gets along just fine with four digits on each hand, so why do humans have five of these digits? In this episode of Stuff to Blow Your Mind, Robert and Julie ask why so many creatures evolved with a five-fingered discount.
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Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind from how Stuff
Works dot com. Hey, welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Julie Douglas and Julie.
I've I've always noticed when I'm watching these these cartoons,
especially things like Futurama and in the simpstance, um, and
(00:25):
even I think like Mickey Mouse, you'll you'll you'll look
at their hands and instead of five fingers, they'll have four. Yes, yeah,
it's odd, it's odd. I mean sometimes you'll see someone
add in that fifth finger, and you know it'll look
a little cramped. And I think that's the reason. Is
that is that if you're if you're drawing a cartoon character,
if you add all five appendages to the hand or
(00:48):
philanges right, um, then then it looks a little cramped.
So it's better just to knock one of those fingers
off and the viewer will get over it pretty fast. Yeah,
I've heard that, and I've heard that especially in the
days of hand drawing, like with Mickey Mouse, if you
had to do an extra digit, then you had to
do that fifty thou times more. So you might as well,
like save some energy and I've also heard that um
(01:10):
that that the four finger or the three fingers and
a thumb are modeled more off of paw prints, which
is another interesting thing. Interesting, but it got us thinking
about why why do we have these five digits hanging
out on our hands? Anyway, Indeed, it's an interesting question.
And and initially I was just kind of taken by
the question of, hey, what is how did this develop? Why?
(01:31):
Five one up, six one four and uh? And it
turns out there's a lot there's a lot of interesting
uh meat to this one once you really start digging
into bones and bones and and I mean that's why
it basically comes down to the meat and the bones.
And and it turns out the five fingers, for the
most part, is deeply ingrained invertebrate and not an enemy
(01:52):
and in also in our embryonic development. And there's no
like easily identified adaptive or functional explanation, like you can't say,
I mean you just think of all the things you
use your your hands for. It's hard to make an
argument for for like something in the wild where you'd
be like, oh, well, you totally need five fingers to
pick up a rock, and and the bash in the
(02:14):
head of some sort of a you know, primeval grasslands
dwelling her before right, Yeah, I know, I mean they
don't necessarily need that, right. So it's the question again
is why why do we have this? Why why is
it the perfect design for us? Because because you also
see uh, you know, differences. You also see things like
hitting ways polydactyl cats where they have six toes. Yehody
(02:37):
goodbye is fine, they're thriving on that little island. Yeah,
And of course Honey would have a bunch of six
fingered cats. Totally makes sense. An ambulan, it was rumored,
had a six digit This is still a rumor, though
it is not terifiable. Well. Um, reggae artist Jimmy Cliff
had an extra finger in each hand. Hat have him removed? Um,
and he turned up great Liam Gallagher, lead vocalists of
(02:59):
O A. Uh, he has six toes on his left foot.
And of course the fictional Hannibal Elector had six fingers
on one of his hands. Yes, of course, yeah, so
we know it happens, and you know it's it's sort
of like a mutation. I guess you would say, yeah, yeah, yeah, yeah,
but um, but it also begs the question of like,
what can you imagine a world where we didn't have
(03:20):
five fingers on a regular basis, you know, on each
hand and um on each foot. I mean we have
really a like a five fingered economy if you think
about it. Yeah, Like right now, whatever you're doing, listener,
unless you're driving a vehicle, you know, by all means uh,
fold in one of your one finger on each hand
and just try to continue doing it. Notice how how
(03:41):
strange it may feel. It's awkward, right right, And think
about this too, Like our base number systems are in five, ten,
and twenty or one hand to hands and two hands
and two feet right right, that's how that that equates,
right in Our entire economic system is predicated on our
fingers on counting. Yeah, so I think it's often referred
(04:01):
to as a vertebrate vertebrate economy, Yes, a vertebrate economy.
And just in case you think we're mad in Greenland,
the word for seven translates a second hand too, so
it's assumed the first hand is already up right, so
second hand to two digits, I will seven. I was
really fascinated, you know what you're talking about, how it's
like all of our number systems are based on five
(04:22):
tens or twenties, but it's greenland right where it's based
on a twenty system, like one place where I can
never imagine someone taking off their boots to do a
little mathematics, like so what if someone knows I'd love
to hear an explanation on on that. I guess you
you can still count. It's hard. I'm trying to count
with my toes through my shoes, and I really don't
(04:43):
have a lot of control over like piggish three through four.
You know, maybe it's a way to stave off frost bite,
you know, like you keep your toes warm by moving
them and counting them. Do you do your outer tables.
I'm not a math person. I'm sorry. Yeah, I'm not either.
I am not an athlete. But this was something when
we were Another thing that speaking of math and fingers,
(05:04):
the other thing that comes to mind instantly, which you
said you had you had not heard of, this was
the on your multiplication tables, your nines, where you can
say you want to do what's three times nine? You
hold your fingers up and you put down your third
finger for three, and then you have two on one
side of the folded finger and then seven fingers on
the other to take it seven and you can go
(05:24):
across the board with it like you want to see
eight by eight times nine. You put down your eight
finger and you have seven on one side and two
on the other, which I think is brilliant. I wish
I hadn't known about this growing up, right, Yeah, I mean,
because it almost feels like cheating. Well it does. And
the curious thing is, over the weekend, I was talking
with one of my sisters about it, and and she
reminded me that it was the janitor at our school
(05:45):
that taught everybody that he would come up to you,
like while you're in the cafeteria line. He'd be like, hey, kids,
come here, I'm gonna I'm gonna clue you in. You're
gonna get ahead in life. Um, which is the you know,
the kind of stuff you get from the janitor and uh.
And he showed us the trick with the fingers for
the for the the nine center multiplication table. And it
was I mean, granted, I learned this and went on
(06:05):
to learn very little else about mathematics, So I don't
know if it works. Maybe it was a handicap that
actually held me back, but or maybe you completely rocked
like grade school mathematics, you know, thanks to the janitor.
But it but it does underline just how integrated it
is in our inter mathematical systems, right, right. It's something
we take for granted, right, the fact that we've got
all these fingers. So the question is again why just
(06:27):
five um? And you talked about the limb development and
it's governed by the hots gene expressions, right, which divide
the embryonical limb but into five sectors of the anterior
posterior access and essentially mapping where the digits will land, right,
so automatically. I mean the reason why we we normally
(06:48):
have five and we don't have an commutation of six
or seven is because it's it's it's those coordinates have
already been plotted for us. Yeah, it is. It is
really hardwired into our system. It's a and it basically
comes down to evolutionary laziness or or evolutionary contingency at
some point the ancient past. And we're going to get
into some of the details on that in a second.
(07:09):
You uh, this stuff five digit system would rolled out
and natural selection has never changed the underlying floor plant. Yeah,
it's been like the gold standard. Yeah, it never tinkered
with that. It's kind of like the neighborhood that I
live in. You have all these bungalow houses, and it's
clear that when they first built these, uh you know,
several decades ago, they were all basically the same house. Now,
(07:30):
over time, individual owners have changed them. So you have
some some very nice editions that are made onto some
some very crappy editions that are made onto others. Um,
you know, and and all sorts of alter alterations have
have happened. But if you walk into any one of
those houses, you'd instantly be able to tell, oh, this
is the same house. I can see the same floor plant.
(07:51):
You drive down the street and you can see the
same house after the same house, even though evolved over
the decades. Yeah, you're right. It's like, hey, there's that
nineteen twenties blue print from Sears and Robots. To get
rid of the basic system there, you'd have to doze
the whole thing. Likewise, to get rid of the five
fingered um evolutionary discount, you would have to just go
(08:12):
you'd have to go back to a very ancient point
in our development and and just rewrite all vertebra history
from there on, right, and you'd have to have good
reason to do so. Yes, I'm you know, I mean
you use your time machine responsibly. That's hard to argue
that that's a good use of the technology. But but yeah,
let's let's go back in time then, um. Scientists think
(08:34):
that the five fingered system emerged sometime before modern amphibians
split from birds, mammals and reptiles. And this is approximately
three forty million years ago. Is this is the this
is the Devonian period, right, Devonian days, and based on
tetrapod fossils from roughly six three sixty million years ago,
(08:57):
Scientists that believe digits first evolved uh in principally aquatic animals,
and we merely took them with us when we made
the transition from finn to limb. In fact, there's a
there's a particular species we look at, uh. Yeah, that's
called the Acinstega canstega a can tostega. Let just see
if I coul say it three times, um, which is
like a fish like salamander um. Again from the Devonian period,
(09:21):
and it was actually a game changer, and how we've
come to understand the evolution of our own digits. Um.
But this little sucker is probably one of the most
primitive examples of a tetrapod that you could find, and uh,
it revealed that it had a believe eight fingers is
this correct? Yeah? And so it kind of first of
all that that startled everybody and thinking, what it's not five?
(09:43):
What's going on here? That eight fingers? Yeah, So that
that was sort of a world rocking thing um for
anthropologists at the time. And then the other realization that
they have when they looked closer, in close, for at
the fossils, is that it didn't exactly develop this these
uh eight digits to crawl out of the water and
(10:04):
onto land. Yeah, there's this there's this common mistake we make,
and I think a lot of it comes back to
the whole um. You know, you're you're in grade school
and you you're learning about evolution, and you have this chart.
Of course, you have the one where it's the eighth
the ascent of man, where the eighth is slowly becoming
the man in sequence, and then you also have the
one showing the fish crawling up on the ground under
(10:25):
the shore, sprouting legs and then turning into something like
a large prehistoric skunk. Uh, and and it it's very
useful in understanding how evolution works. But it also it
also has this this subtle um message to that that
this is the goal. That this fish was was was
old and busted and the skunk creature is the new hot. Yeah.
(10:49):
It's like this this manifest destiny idea of becoming bipedal. Right,
like we just assume that all creatures just you know,
they all they sprouted these limbs and then like you say,
they just they called out became skunks. Yeah, what are
you doing. Get out of the water, come on land
where it's happening with some legs, developed some hands, and
start building cities and beating yourself with stones. Yeah. But
they started that should started to look at the fossils
(11:11):
in the context of their environments, and they figured out
that they were monkeying around the bottom of lagoons with
their eight fingers. Um, and that these eight fingers came
off a poorly designed wrist and paleontologist Dr Jenny Clark
so the design was quote like using a table knife
as a pillar with the blade on the ground. Ut.
So this is one of the many clues that they
(11:31):
that touch pods weren't necessarily evolving solely to crawl out
of the water, right, they needed to use these these
appendages more effectively in the water. Yeah, yeah, exactly, And
they figured out, well, they actually have been on the
water for a really long time evolving like these finally
tuned legs what would become finally tuned legs for us,
and using them there. Um. You know, we thought at
(11:55):
first that you know, they would they'd be using their
elbows to prop themselves up and get out of the water,
but in fact, they would use their elbows to stick
their head out of the water, you know, for a
moment and breathe air. Um. And they would also use
their their limbs to grasp onto things that would help
them loyally propel out and like ambush a prey or something. Yeah,
(12:15):
we're basically talking about fish with hands, which which to
me instantly brings the mind of like a shark holding
a shotgun. But um, which would be which would be
kind of awesome, that would really watch this this year's
Shark Week for that. But but no, there are a
number of number of basically fish with hands species today.
There's a batfish, there's a hand fish, and there's a
frog fish, and again they use these these limb like
(12:38):
fins to sneak up on prey, to move around in
tight spaces and the ga and navigate rocks and an
anchor against strong currents. So hands can become very, very
useful in the water without even any dream of ever
getting out of out of the water and crawling around.
And so it's it's this kind of stuff that suggests
something called pre adaptation, which it's conditions in which there's
(13:02):
no predictable outcome of an evolutionary development. In other words,
Anna Cathstega, our little fish frint became a terrestrial creature
out of chance. That's that's the idea behind this discovery.
UH Discovery magazine's article Coming onto Land explains this by
using the example of bone, which they say could have
developed as a place where animals could store extra phosphorus,
(13:25):
and only later did it come to support bodies. So
it's not like that bone in the scenario developed simply
so that we we become vertebrates and we'd be able
to stand upright and support all of our muscles and
flesh and so on and so forth. It's that's that
it could have been an accident of our evolution, which
is really fascinating to think about. Yeah, there's a biologist
(13:46):
by the name of Michael Coates, um whose article was
my first introduction to this topic. And and he argues
that the reduction to five digits from you know eight
or so. Um it, it moves along the same lines
with the development of complex risks and ankle joints, because
in using these uh is it begin is an animal
(14:07):
against you use these digits in these stins to do
more more things underwater, it's putting weight on them, um
and and putting and that means increased weight on the
wrist and ankles. So it goes back to the whole
idea of the knife being used as a pillar with
a blade down and the limb has to adapt to
to be able to stabilize vetteran and to have pressure
(14:28):
on the wrist and ankle areas. Yeah, and so there's
there's this idea of preadaptation, of all this tinkering going on,
so to speak. And it just happened that that it
all developed in a way of course, over you know,
hundreds of millions of years hunting, you know, in this case,
what we're talking about through hundred fifty million years ago
um to eventually support what would become us, right, which
(14:51):
is really simplistic way of talking about evolution, but it's
it's an interesting again paradigm shift away from saying, here's
this fish and it had to become man, and so
it develops some fingers. No, it's more like the serious
is fish and it develops some fingers for an entirely
different project and then at some point realized, hey, actually
I can crawl up on land with these. Yeah, we're
(15:13):
simplifying things a good bit, but that's basically yeah, that's
that's just spare you like a ninety minute talk on
on that one point. This presentation is brought to you
by Intel Sponsors of Tomorrow. Now, we have some species
(15:36):
that have have also developed a false thumb, which is
pretty interesting. Moles and panda's amazingly because a panda isn't
an animal that I generally don't respect all that much,
because there it is at the zoo, taken up valuable space,
costing all this money, and it's just setting there on it. Oh,
you think it's coddled. Yes, I know it's coddled. The
worst was and I love the zoo here in Atlanta.
(15:58):
But they had a you know, your forced to market
with it, like the panda becomes this huge marketing instrument.
And they actually had this campaign where they showed various
very interesting animals of the zoo, various zoo animals, and
they were wearing panda mask remember that it was it
was kind of like like, these animals are okay, but
it would be even better if they look like pandas
put a panda mask on them and maybe we'll get
(16:19):
people excited. And there was this guy, oh, come on, yeah, yeah,
it was really demeaning. I have to say it was
effective in getting your attention there, right, yes, it was.
So it's an effective at campaign. And and but then
the thing about Pandas, and we could probably do a
whole podcast on this, they're actually far more interesting than
they give them credit. And one of those that those
things is that they have this false thumb pseudo digit, right, yes,
(16:40):
and it's basically a remodeled wrist bone and uh and
moles have it as well, so it's not a true digit,
and that it's sprouting out from the wrist bone is
part of the wrist bone. But this is a case
though that that it actually helps us an adaptive mutation
because if they're they're grasping a bamboo, So it's not
just some sort of random mutation that came a long right,
(17:00):
And it's not like the hemming wats cats where they
really have no reason to extra maybe not back of whiskey,
yeah yeah, or you shoot a lion on safari, that
kind of thing. Yeah, um so yeah, touch apolo. They
rarely maintain a polydactus six digit because it would have
limited evolutionary use unless it was formed for a distinct
purpose like the pandas and their pseudo digit. Right. So again,
(17:23):
that's why we're seeing this, this culling back of digits
to five, because it really does seem to be the perfect,
at least for us right now, in this day and age,
way to get about, which begs the question, you know,
what are we what are we going to look like?
Because we are you know, in the future, because we
already know that tool use has shaped the way that
our hands are modern hands work today. Right. Yeah, you're
(17:46):
throwing things, you're you know, like the basic the movement
that you make when you when you throw it dart,
like that's utilizing a lot of the what's going on.
It's really important in your wrist and a lot of
the evolution that's taking place to get us, uh, you know,
to where we have hands like luck we do today. Yeah.
And actually this is from the Journal of Anatomy. It's
an article by Professor Richard W. Young who called Evolution
(18:09):
of the Human Hand. Excuse me. The article is called
Evolution of the Human Hand, the role of throwing and clubbing,
and he posits that had our male and female hominid
ancestors would have been more apt to survive if they
were successfully wielding a club against their adversaries. Uh, if
they and that would allow them to dominate other hominids
and essentially ensure that their club happy DNA were passed
(18:32):
on club happy DNA. Yeah, and hence this this more
perfected wrist motion right or grasping two of clubs. He says, quote,
the fossil record indicates the adaptation for throwing and clubbing
to influence hands structure at or very near the origin
of the hominid lineage continued for millions of the years thereafter.
(18:53):
And then just to go give a little bit ahead
of this quote, he says, two unique hand grips were
thereby produced called the power in Prison grips. So we know,
you know that obviously we were not done evolving. It
continues to tinker. We've we've got our handy little um
risks and fingers so adept partly because we could use
(19:13):
tools and we could club other people and things. It
makes it instantly I think of baseball where you go.
I mean, we're the main centerpiece. There is the throwing
and the swinging, throwing of a ball and the swinging
of basically a large club. Yeah yeah, yeah there. I
mean that's how the club evolved, right, Which is nice
to quit clubbing people and start make it into a
(19:34):
sport involving balls instead of heads um. But it did
make me think, like, what are we gonna look like? Oh,
I don't know a thousand years from now. I mean
obviously that the iPad has a great influence server us
right now, and the iPhone does, and if it were
to continue with us for a thousand years, you know,
would our current hand structures changed so that we were
have like stylist pen like little pendages at the at
(19:55):
the I guess our fingers because when you first mentioned
to me, I instantly I was thinking keep board because
I guess, you know, I've just been using a keyboard,
so I'm like, oh, I guess we'll have more fingers
so we can we can type more. But but yeah,
with the with things like the iPad, we're already getting
into situations where where you don't need all those fingers
to operate an iPad. And and uh, and we've talked
before about the more that we the more we develop
(20:17):
a human machine in our actions, we're getting into a
situation where we're fingers and limb limbs won't even be necessary.
Um so right, and and and specifically we're talking about
like brain computer interfaces, right, so you know, eventually one
day we'll be able to Google in our brain without
even having to enter anything with our fingers. And then
we'll have our handy dandy Exo skeleton arms that are
(20:38):
super strong lifting things just for fun. Well, why would
we lift things? We have the robots bring us, right,
we don't even like thinking like maybe we'd have fingers
just enough to open our sun drop cans while we
use our brain computers. But now we probably have a
cute robot that's going to come over and open our
sun drop for us. There you go. For now we
could admire our fingers, look at them, because you're not
(21:00):
always going to be with us in the in the
same way they are. Now. Yeah, sorry, I know you
you were literally looking at your finger. Well there you go. Yeah.
Well hey, you know, it looks like we have a
little listener mail here. I almost say if you were
mailed that that means I don't think anybody's actually watching.
I don't see anybody under the table today. All right,
(21:21):
we'll check again, just make sure, okay, all right, Well
we have a mail here from Ah you can have
from under there. Um, we have mail here from Adam,
and Adam actually writes them about robots distinction robots, so um,
he says. Enjoyed the podcast Online Robots and especially the
mention of my favorite sci fi author, Isaac asimop. I
(21:43):
was surprised that you mentioned Little Lost Robot from I
Robot but didn't bring up the highly um applicable liar
also in I Robot by way a quick summer, It
is about a robot that is accidentally able to read
minds programmed to not be able to harm humans. The
robot's brain gets fired after he can see in the
minds of humans, the harm that would be created by
(22:03):
telling either the truth or by telling a lie in
a certain situation. It's probably my favorite story in an
already fantastic book. Enjoy. I have to say, it's been
a while since I read Um, I Robot, and I
really don't remember that's sort of at all, so maybe
I skipped it. I don't know, but it sounds cool.
I'm gonna have to pick up my copy. And we
(22:23):
also heard from Beth. And Beth writes to us on
her iPhone and says, yeah, and her maybe maybe or
her stylus evolved finger if she's writing this from the future,
which is not indicated by the sent date on this email,
but at any rate, Um. She writes it and says, hey,
Julian Robert, I wanted to write because I just listened
(22:44):
to your Defeat Your doppel Ganger's podcast. I have actually
seen my doppelganger. A manager at work when I was
in college brought in a photo of her niece and
showed it to me, explaining that it was taken at
a Renaissance festival. I told her that I had never
been to one, and that I had no clue where
this was or when she had gotten gotten it. I
thought the girl in the photo was me, even down
(23:04):
to the freckled face, her hair in a bun with
a clock flip and a man shirt T shirt on.
She looked just like me. It was really weird experience
to be told that was not me in the photo.
Keep up the great show. I love it. So that's
that's really Yeah, that's very creepy and cool. Now, you
didn't get to tell the story in the actual Doppelgangers episode.
But didn't you have a doppelganger in college? Oh? Yeah
(23:27):
I did, but um, and my hair at the time
was pretty pretty blonde, like bleach blonde, So who knows.
I think. I think it's more like an archetype that
I was fitting. But for a year solid people would
just come up to me and said, I love your band, good,
buy a drink. Okay, you had like a rock star doppelganger. Yeah,
that's cool, it was cool thanks toppelganger. Well, hey, if
(23:51):
you have anything you want to share with us, um,
be it related to your fingers or to your doppelganger,
your toast or your toes, or various sci fi references
that I've made or failed to make uh. Feel free
to let us know. You can find us on Twitter
and Facebook as blow the Mind, and you can also
drop us a line at blow the Mind at how
(24:14):
stuff works dot com. For more on this and thousands
of other topics, visit how stuff works dot com. To
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on iTunes.
Welcome to Stuff to Blow Your Mind from how Stuff
Works dot com. Hey, welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Julie Douglas and Julie.
I've I've always noticed when I'm watching these these cartoons,
especially things like Futurama and in the simpstance, um, and
(00:25):
even I think like Mickey Mouse, you'll you'll you'll look
at their hands and instead of five fingers, they'll have four. Yes, yeah,
it's odd, it's odd. I mean sometimes you'll see someone
add in that fifth finger, and you know it'll look
a little cramped. And I think that's the reason. Is
that is that if you're if you're drawing a cartoon character,
if you add all five appendages to the hand or
(00:48):
philanges right, um, then then it looks a little cramped.
So it's better just to knock one of those fingers
off and the viewer will get over it pretty fast. Yeah,
I've heard that, and I've heard that especially in the
days of hand drawing, like with Mickey Mouse, if you
had to do an extra digit, then you had to
do that fifty thou times more. So you might as well,
like save some energy and I've also heard that um
(01:10):
that that the four finger or the three fingers and
a thumb are modeled more off of paw prints, which
is another interesting thing. Interesting, but it got us thinking
about why why do we have these five digits hanging
out on our hands? Anyway, Indeed, it's an interesting question.
And and initially I was just kind of taken by
the question of, hey, what is how did this develop? Why?
(01:31):
Five one up, six one four and uh? And it
turns out there's a lot there's a lot of interesting
uh meat to this one once you really start digging
into bones and bones and and I mean that's why
it basically comes down to the meat and the bones.
And and it turns out the five fingers, for the
most part, is deeply ingrained invertebrate and not an enemy
(01:52):
and in also in our embryonic development. And there's no
like easily identified adaptive or functional explanation, like you can't say,
I mean you just think of all the things you
use your your hands for. It's hard to make an
argument for for like something in the wild where you'd
be like, oh, well, you totally need five fingers to
pick up a rock, and and the bash in the
(02:14):
head of some sort of a you know, primeval grasslands
dwelling her before right, Yeah, I know, I mean they
don't necessarily need that, right. So it's the question again
is why why do we have this? Why why is
it the perfect design for us? Because because you also
see uh, you know, differences. You also see things like
hitting ways polydactyl cats where they have six toes. Yehody
(02:37):
goodbye is fine, they're thriving on that little island. Yeah,
And of course Honey would have a bunch of six
fingered cats. Totally makes sense. An ambulan, it was rumored,
had a six digit This is still a rumor, though
it is not terifiable. Well. Um, reggae artist Jimmy Cliff
had an extra finger in each hand. Hat have him removed? Um,
and he turned up great Liam Gallagher, lead vocalists of
(02:59):
O A. Uh, he has six toes on his left foot.
And of course the fictional Hannibal Elector had six fingers
on one of his hands. Yes, of course, yeah, so
we know it happens, and you know it's it's sort
of like a mutation. I guess you would say, yeah, yeah, yeah, yeah,
but um, but it also begs the question of like,
what can you imagine a world where we didn't have
(03:20):
five fingers on a regular basis, you know, on each
hand and um on each foot. I mean we have
really a like a five fingered economy if you think
about it. Yeah, Like right now, whatever you're doing, listener,
unless you're driving a vehicle, you know, by all means uh,
fold in one of your one finger on each hand
and just try to continue doing it. Notice how how
(03:41):
strange it may feel. It's awkward, right right, And think
about this too, Like our base number systems are in five, ten,
and twenty or one hand to hands and two hands
and two feet right right, that's how that that equates,
right in Our entire economic system is predicated on our
fingers on counting. Yeah, so I think it's often referred
(04:01):
to as a vertebrate vertebrate economy, Yes, a vertebrate economy.
And just in case you think we're mad in Greenland,
the word for seven translates a second hand too, so
it's assumed the first hand is already up right, so
second hand to two digits, I will seven. I was
really fascinated, you know what you're talking about, how it's
like all of our number systems are based on five
(04:22):
tens or twenties, but it's greenland right where it's based
on a twenty system, like one place where I can
never imagine someone taking off their boots to do a
little mathematics, like so what if someone knows I'd love
to hear an explanation on on that. I guess you
you can still count. It's hard. I'm trying to count
with my toes through my shoes, and I really don't
(04:43):
have a lot of control over like piggish three through four.
You know, maybe it's a way to stave off frost bite,
you know, like you keep your toes warm by moving
them and counting them. Do you do your outer tables.
I'm not a math person. I'm sorry. Yeah, I'm not either.
I am not an athlete. But this was something when
we were Another thing that speaking of math and fingers,
(05:04):
the other thing that comes to mind instantly, which you
said you had you had not heard of, this was
the on your multiplication tables, your nines, where you can
say you want to do what's three times nine? You
hold your fingers up and you put down your third
finger for three, and then you have two on one
side of the folded finger and then seven fingers on
the other to take it seven and you can go
(05:24):
across the board with it like you want to see
eight by eight times nine. You put down your eight
finger and you have seven on one side and two
on the other, which I think is brilliant. I wish
I hadn't known about this growing up, right, Yeah, I mean,
because it almost feels like cheating. Well it does. And
the curious thing is, over the weekend, I was talking
with one of my sisters about it, and and she
reminded me that it was the janitor at our school
(05:45):
that taught everybody that he would come up to you,
like while you're in the cafeteria line. He'd be like, hey, kids,
come here, I'm gonna I'm gonna clue you in. You're
gonna get ahead in life. Um, which is the you know,
the kind of stuff you get from the janitor and uh.
And he showed us the trick with the fingers for
the for the the nine center multiplication table. And it
was I mean, granted, I learned this and went on
(06:05):
to learn very little else about mathematics, So I don't
know if it works. Maybe it was a handicap that
actually held me back, but or maybe you completely rocked
like grade school mathematics, you know, thanks to the janitor.
But it but it does underline just how integrated it
is in our inter mathematical systems, right, right. It's something
we take for granted, right, the fact that we've got
all these fingers. So the question is again why just
(06:27):
five um? And you talked about the limb development and
it's governed by the hots gene expressions, right, which divide
the embryonical limb but into five sectors of the anterior
posterior access and essentially mapping where the digits will land, right,
so automatically. I mean the reason why we we normally
(06:48):
have five and we don't have an commutation of six
or seven is because it's it's it's those coordinates have
already been plotted for us. Yeah, it is. It is
really hardwired into our system. It's a and it basically
comes down to evolutionary laziness or or evolutionary contingency at
some point the ancient past. And we're going to get
into some of the details on that in a second.
(07:09):
You uh, this stuff five digit system would rolled out
and natural selection has never changed the underlying floor plant. Yeah,
it's been like the gold standard. Yeah, it never tinkered
with that. It's kind of like the neighborhood that I
live in. You have all these bungalow houses, and it's
clear that when they first built these, uh you know,
several decades ago, they were all basically the same house. Now,
(07:30):
over time, individual owners have changed them. So you have
some some very nice editions that are made onto some
some very crappy editions that are made onto others. Um,
you know, and and all sorts of alter alterations have
have happened. But if you walk into any one of
those houses, you'd instantly be able to tell, oh, this
is the same house. I can see the same floor plant.
(07:51):
You drive down the street and you can see the
same house after the same house, even though evolved over
the decades. Yeah, you're right. It's like, hey, there's that
nineteen twenties blue print from Sears and Robots. To get
rid of the basic system there, you'd have to doze
the whole thing. Likewise, to get rid of the five
fingered um evolutionary discount, you would have to just go
(08:12):
you'd have to go back to a very ancient point
in our development and and just rewrite all vertebra history
from there on, right, and you'd have to have good
reason to do so. Yes, I'm you know, I mean
you use your time machine responsibly. That's hard to argue
that that's a good use of the technology. But but yeah,
let's let's go back in time then, um. Scientists think
(08:34):
that the five fingered system emerged sometime before modern amphibians
split from birds, mammals and reptiles. And this is approximately
three forty million years ago. Is this is the this
is the Devonian period, right, Devonian days, and based on
tetrapod fossils from roughly six three sixty million years ago,
(08:57):
Scientists that believe digits first evolved uh in principally aquatic animals,
and we merely took them with us when we made
the transition from finn to limb. In fact, there's a
there's a particular species we look at, uh. Yeah, that's
called the Acinstega canstega a can tostega. Let just see
if I coul say it three times, um, which is
like a fish like salamander um. Again from the Devonian period,
(09:21):
and it was actually a game changer, and how we've
come to understand the evolution of our own digits. Um.
But this little sucker is probably one of the most
primitive examples of a tetrapod that you could find, and uh,
it revealed that it had a believe eight fingers is
this correct? Yeah? And so it kind of first of
all that that startled everybody and thinking, what it's not five?
(09:43):
What's going on here? That eight fingers? Yeah, So that
that was sort of a world rocking thing um for
anthropologists at the time. And then the other realization that
they have when they looked closer, in close, for at
the fossils, is that it didn't exactly develop this these
uh eight digits to crawl out of the water and
(10:04):
onto land. Yeah, there's this there's this common mistake we make,
and I think a lot of it comes back to
the whole um. You know, you're you're in grade school
and you you're learning about evolution, and you have this chart.
Of course, you have the one where it's the eighth
the ascent of man, where the eighth is slowly becoming
the man in sequence, and then you also have the
one showing the fish crawling up on the ground under
(10:25):
the shore, sprouting legs and then turning into something like
a large prehistoric skunk. Uh, and and it it's very
useful in understanding how evolution works. But it also it
also has this this subtle um message to that that
this is the goal. That this fish was was was
old and busted and the skunk creature is the new hot. Yeah.
(10:49):
It's like this this manifest destiny idea of becoming bipedal. Right,
like we just assume that all creatures just you know,
they all they sprouted these limbs and then like you say,
they just they called out became skunks. Yeah, what are
you doing. Get out of the water, come on land
where it's happening with some legs, developed some hands, and
start building cities and beating yourself with stones. Yeah. But
they started that should started to look at the fossils
(11:11):
in the context of their environments, and they figured out
that they were monkeying around the bottom of lagoons with
their eight fingers. Um, and that these eight fingers came
off a poorly designed wrist and paleontologist Dr Jenny Clark
so the design was quote like using a table knife
as a pillar with the blade on the ground. Ut.
So this is one of the many clues that they
(11:31):
that touch pods weren't necessarily evolving solely to crawl out
of the water, right, they needed to use these these
appendages more effectively in the water. Yeah, yeah, exactly, And
they figured out, well, they actually have been on the
water for a really long time evolving like these finally
tuned legs what would become finally tuned legs for us,
and using them there. Um. You know, we thought at
(11:55):
first that you know, they would they'd be using their
elbows to prop themselves up and get out of the water,
but in fact, they would use their elbows to stick
their head out of the water, you know, for a
moment and breathe air. Um. And they would also use
their their limbs to grasp onto things that would help
them loyally propel out and like ambush a prey or something. Yeah,
(12:15):
we're basically talking about fish with hands, which which to
me instantly brings the mind of like a shark holding
a shotgun. But um, which would be which would be
kind of awesome, that would really watch this this year's
Shark Week for that. But but no, there are a
number of number of basically fish with hands species today.
There's a batfish, there's a hand fish, and there's a
frog fish, and again they use these these limb like
(12:38):
fins to sneak up on prey, to move around in
tight spaces and the ga and navigate rocks and an
anchor against strong currents. So hands can become very, very
useful in the water without even any dream of ever
getting out of out of the water and crawling around.
And so it's it's this kind of stuff that suggests
something called pre adaptation, which it's conditions in which there's
(13:02):
no predictable outcome of an evolutionary development. In other words,
Anna Cathstega, our little fish frint became a terrestrial creature
out of chance. That's that's the idea behind this discovery.
UH Discovery magazine's article Coming onto Land explains this by
using the example of bone, which they say could have
developed as a place where animals could store extra phosphorus,
(13:25):
and only later did it come to support bodies. So
it's not like that bone in the scenario developed simply
so that we we become vertebrates and we'd be able
to stand upright and support all of our muscles and
flesh and so on and so forth. It's that's that
it could have been an accident of our evolution, which
is really fascinating to think about. Yeah, there's a biologist
(13:46):
by the name of Michael Coates, um whose article was
my first introduction to this topic. And and he argues
that the reduction to five digits from you know eight
or so. Um it, it moves along the same lines
with the development of complex risks and ankle joints, because
in using these uh is it begin is an animal
(14:07):
against you use these digits in these stins to do
more more things underwater, it's putting weight on them, um
and and putting and that means increased weight on the
wrist and ankles. So it goes back to the whole
idea of the knife being used as a pillar with
a blade down and the limb has to adapt to
to be able to stabilize vetteran and to have pressure
(14:28):
on the wrist and ankle areas. Yeah, and so there's
there's this idea of preadaptation, of all this tinkering going on,
so to speak. And it just happened that that it
all developed in a way of course, over you know,
hundreds of millions of years hunting, you know, in this case,
what we're talking about through hundred fifty million years ago
um to eventually support what would become us, right, which
(14:51):
is really simplistic way of talking about evolution, but it's
it's an interesting again paradigm shift away from saying, here's
this fish and it had to become man, and so
it develops some fingers. No, it's more like the serious
is fish and it develops some fingers for an entirely
different project and then at some point realized, hey, actually
I can crawl up on land with these. Yeah, we're
(15:13):
simplifying things a good bit, but that's basically yeah, that's
that's just spare you like a ninety minute talk on
on that one point. This presentation is brought to you
by Intel Sponsors of Tomorrow. Now, we have some species
(15:36):
that have have also developed a false thumb, which is
pretty interesting. Moles and panda's amazingly because a panda isn't
an animal that I generally don't respect all that much,
because there it is at the zoo, taken up valuable space,
costing all this money, and it's just setting there on it. Oh,
you think it's coddled. Yes, I know it's coddled. The
worst was and I love the zoo here in Atlanta.
(15:58):
But they had a you know, your forced to market
with it, like the panda becomes this huge marketing instrument.
And they actually had this campaign where they showed various
very interesting animals of the zoo, various zoo animals, and
they were wearing panda mask remember that it was it
was kind of like like, these animals are okay, but
it would be even better if they look like pandas
put a panda mask on them and maybe we'll get
(16:19):
people excited. And there was this guy, oh, come on, yeah, yeah,
it was really demeaning. I have to say it was
effective in getting your attention there, right, yes, it was.
So it's an effective at campaign. And and but then
the thing about Pandas, and we could probably do a
whole podcast on this, they're actually far more interesting than
they give them credit. And one of those that those
things is that they have this false thumb pseudo digit, right, yes,
(16:40):
and it's basically a remodeled wrist bone and uh and
moles have it as well, so it's not a true digit,
and that it's sprouting out from the wrist bone is
part of the wrist bone. But this is a case
though that that it actually helps us an adaptive mutation
because if they're they're grasping a bamboo, So it's not
just some sort of random mutation that came a long right,
(17:00):
And it's not like the hemming wats cats where they
really have no reason to extra maybe not back of whiskey,
yeah yeah, or you shoot a lion on safari, that
kind of thing. Yeah, um so yeah, touch apolo. They
rarely maintain a polydactus six digit because it would have
limited evolutionary use unless it was formed for a distinct
purpose like the pandas and their pseudo digit. Right. So again,
(17:23):
that's why we're seeing this, this culling back of digits
to five, because it really does seem to be the perfect,
at least for us right now, in this day and age,
way to get about, which begs the question, you know,
what are we what are we going to look like?
Because we are you know, in the future, because we
already know that tool use has shaped the way that
our hands are modern hands work today. Right. Yeah, you're
(17:46):
throwing things, you're you know, like the basic the movement
that you make when you when you throw it dart,
like that's utilizing a lot of the what's going on.
It's really important in your wrist and a lot of
the evolution that's taking place to get us, uh, you know,
to where we have hands like luck we do today. Yeah.
And actually this is from the Journal of Anatomy. It's
an article by Professor Richard W. Young who called Evolution
(18:09):
of the Human Hand. Excuse me. The article is called
Evolution of the Human Hand, the role of throwing and clubbing,
and he posits that had our male and female hominid
ancestors would have been more apt to survive if they
were successfully wielding a club against their adversaries. Uh, if
they and that would allow them to dominate other hominids
and essentially ensure that their club happy DNA were passed
(18:32):
on club happy DNA. Yeah, and hence this this more
perfected wrist motion right or grasping two of clubs. He says, quote,
the fossil record indicates the adaptation for throwing and clubbing
to influence hands structure at or very near the origin
of the hominid lineage continued for millions of the years thereafter.
(18:53):
And then just to go give a little bit ahead
of this quote, he says, two unique hand grips were
thereby produced called the power in Prison grips. So we know,
you know that obviously we were not done evolving. It
continues to tinker. We've we've got our handy little um
risks and fingers so adept partly because we could use
(19:13):
tools and we could club other people and things. It
makes it instantly I think of baseball where you go.
I mean, we're the main centerpiece. There is the throwing
and the swinging, throwing of a ball and the swinging
of basically a large club. Yeah yeah, yeah there. I
mean that's how the club evolved, right, Which is nice
to quit clubbing people and start make it into a
(19:34):
sport involving balls instead of heads um. But it did
make me think, like, what are we gonna look like? Oh,
I don't know a thousand years from now. I mean
obviously that the iPad has a great influence server us
right now, and the iPhone does, and if it were
to continue with us for a thousand years, you know,
would our current hand structures changed so that we were
have like stylist pen like little pendages at the at
(19:55):
the I guess our fingers because when you first mentioned
to me, I instantly I was thinking keep board because
I guess, you know, I've just been using a keyboard,
so I'm like, oh, I guess we'll have more fingers
so we can we can type more. But but yeah,
with the with things like the iPad, we're already getting
into situations where where you don't need all those fingers
to operate an iPad. And and uh, and we've talked
before about the more that we the more we develop
(20:17):
a human machine in our actions, we're getting into a
situation where we're fingers and limb limbs won't even be necessary.
Um so right, and and and specifically we're talking about
like brain computer interfaces, right, so you know, eventually one
day we'll be able to Google in our brain without
even having to enter anything with our fingers. And then
we'll have our handy dandy Exo skeleton arms that are
(20:38):
super strong lifting things just for fun. Well, why would
we lift things? We have the robots bring us, right,
we don't even like thinking like maybe we'd have fingers
just enough to open our sun drop cans while we
use our brain computers. But now we probably have a
cute robot that's going to come over and open our
sun drop for us. There you go. For now we
could admire our fingers, look at them, because you're not
(21:00):
always going to be with us in the in the
same way they are. Now. Yeah, sorry, I know you
you were literally looking at your finger. Well there you go. Yeah.
Well hey, you know, it looks like we have a
little listener mail here. I almost say if you were
mailed that that means I don't think anybody's actually watching.
I don't see anybody under the table today. All right,
(21:21):
we'll check again, just make sure, okay, all right, Well
we have a mail here from Ah you can have
from under there. Um, we have mail here from Adam,
and Adam actually writes them about robots distinction robots, so um,
he says. Enjoyed the podcast Online Robots and especially the
mention of my favorite sci fi author, Isaac asimop. I
(21:43):
was surprised that you mentioned Little Lost Robot from I
Robot but didn't bring up the highly um applicable liar
also in I Robot by way a quick summer, It
is about a robot that is accidentally able to read
minds programmed to not be able to harm humans. The
robot's brain gets fired after he can see in the
minds of humans, the harm that would be created by
(22:03):
telling either the truth or by telling a lie in
a certain situation. It's probably my favorite story in an
already fantastic book. Enjoy. I have to say, it's been
a while since I read Um, I Robot, and I
really don't remember that's sort of at all, so maybe
I skipped it. I don't know, but it sounds cool.
I'm gonna have to pick up my copy. And we
(22:23):
also heard from Beth. And Beth writes to us on
her iPhone and says, yeah, and her maybe maybe or
her stylus evolved finger if she's writing this from the future,
which is not indicated by the sent date on this email,
but at any rate, Um. She writes it and says, hey,
Julian Robert, I wanted to write because I just listened
(22:44):
to your Defeat Your doppel Ganger's podcast. I have actually
seen my doppelganger. A manager at work when I was
in college brought in a photo of her niece and
showed it to me, explaining that it was taken at
a Renaissance festival. I told her that I had never
been to one, and that I had no clue where
this was or when she had gotten gotten it. I
thought the girl in the photo was me, even down
(23:04):
to the freckled face, her hair in a bun with
a clock flip and a man shirt T shirt on.
She looked just like me. It was really weird experience
to be told that was not me in the photo.
Keep up the great show. I love it. So that's
that's really Yeah, that's very creepy and cool. Now, you
didn't get to tell the story in the actual Doppelgangers episode.
But didn't you have a doppelganger in college? Oh? Yeah
(23:27):
I did, but um, and my hair at the time
was pretty pretty blonde, like bleach blonde, So who knows.
I think. I think it's more like an archetype that
I was fitting. But for a year solid people would
just come up to me and said, I love your band, good,
buy a drink. Okay, you had like a rock star doppelganger. Yeah,
that's cool, it was cool thanks toppelganger. Well, hey, if
(23:51):
you have anything you want to share with us, um,
be it related to your fingers or to your doppelganger,
your toast or your toes, or various sci fi references
that I've made or failed to make uh. Feel free
to let us know. You can find us on Twitter
and Facebook as blow the Mind, and you can also
drop us a line at blow the Mind at how
(24:14):
stuff works dot com. For more on this and thousands
of other topics, visit how stuff works dot com. To
learn more about the podcast, click on the podcast icon
in the upper right corner of our homepage. The how
stuff Works iPhone app has a ride. Download it today
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