Five-fingered Evolutionary Discount

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 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 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?

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

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 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 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 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 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 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 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 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 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, 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 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 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 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 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 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. 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, 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. 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 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 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, 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, 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? 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

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 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. 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 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 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 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, 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 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 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, 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 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 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 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 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 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 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.

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 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, 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, 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, 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 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 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 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. 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 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

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 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 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 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 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, 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 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 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

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 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 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 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 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 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 on iTunes.