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- [00:01]
A
Welcome to the rest is science. I'm Hannah Fry.
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B
And I'm Michael Stevens.
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A
Here's a question for you, Michael. What is going on with feet?
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B
With my feet? Yeah.
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A
Not just yours, but also yours. Okay.
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B
No one knows what's going on with my feet because I never show them off.
- [00:16]
A
Do you not?
- [00:17]
B
Okay, I guess I did once when I stepped on Legos, like for a bit to get views. But when I was a small child, like a child, I had hairy feet. Yes. And I was walking around barefoot one day and my dad's friend, whose name was Al, like, I'm not afraid to name and shame, he looked at me and he goes to my dad, he goes, whoa, your son's feet have a lot of hair on them.
- [00:39]
A
Wait, how old were you at this point?
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B
Okay, in my mind I'm like four, but I'm sure, I'm sure I was like a teenager.
- [00:45]
A
Are we talking about like sort of soft, downy, children hair or are we talking about like.
- [00:50]
B
No, we're talking about look at my beard and then imagine toes coming out of it. It's almost like that even at home. I've been married to my wife for 10 years now. I still just wear socks all the time so she won't go whenever she sees me.
- [01:05]
A
Are they still hairy?
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B
Well, yeah, I haven't shaved them.
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A
Wow.
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B
But this episode is not about me, okay? This episode is about our entire species.
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A
It is about our entire species.
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B
I hadn't really thought about it until you mentioned it, but they are a bit weird.
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A
They are very weird. They're very different to other anim feet. And that is what we're going to get into it. But listeners, don't worry. We're going to come back to Michael's feet as well because I've got more questions. I've got more questions.
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I have no more answers. Or do I? This episode is brought to you by Cancer Research uk.
- [01:44]
A
Scientists have found that cancer risks usually increase with age and size. But some species defy the odds.
- [01:51]
B
For example, deep sea Greenland sharks, they can grow over 6 meters long, weigh more than a small car, and yet live for up to 400 years.
- [02:02]
A
Now, understanding how Greenland sharks, cellular repair and immune systems seem to have managed to keep them cancer free for centuries. That could open up exciting research pathways.
- [02:13]
B
Essentially, over millions of years, evolution has been running the world's most successful cancer prevention trial. And sometimes breakthroughs can can be found in unusual places.
- [02:23]
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So by exploring the unexpected, Cancer Research UK scientists are uncovering new ways to tackle over 200 types of cancer Their work has helped to double survival in the UK over the last 50 years and continues to save and improve lives around the world.
- [02:39]
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For more information about Cancer Research uk, their research and breakthroughs and how you can support them, visit cancerresearchuk.org TheReestiscience for
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- [04:10]
A
your favorite rack store for free. Great brands, great prices. That's why you rack. So I was in Cambridge the other day having lunch and I ended up chatting to a colleague of mine called Shreyas Mandre. He raised this question with me. I'm like, why are human feet so weird compared to every other creature that exists? Okay, if you think about it, the same solution has evolved over and over again in the form of hooves and trotters.
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What's a trotter? A trotter like a paw.
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A
It's like a. It's on a pig, you know?
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B
Oh, okay.
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A
It's got a split, it's got kind
- [04:53]
B
of like toes, but it's different than a hoof. Pigs don't have hooves, do they?
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A
It's sort of halfway between. It's slightly softer than a hoof.
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B
See, I'm not afraid to admit what I don't know.
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A
Do you know? I'm also now worried about the limits of my own knowledge of trotter Versus hoof.
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Is anyone Jewish here? Because they would know. They've got that whole rule about you can't eat a hooved animal unless it chews cuddle.
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A
Really?
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B
Yeah.
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A
Do you know what? I think trotter might be a kitchen word.
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B
Yeah. Because if you look up pig's trotter on Wikipedia, it's a culinary dish, and the picture is pretty grim. Grim. Like, it's good. It illustrates the trotter.
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A
That's what you needed.
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B
It does not look appetizing.
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A
It does not.
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B
It looks quite undignified.
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A
I would not want to be that pig. Put it that way. Okay, but here's.
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B
Hold on. If you're gonna be a pig who's going to be slaughtered, you could do worse than being the pig whose trotter gets pictured on Wikipedia for eternity. You're immortalized.
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A
I don't think I would care that much about legacy as a. Oh, I would.
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B
I'm like, I'm in it. I'm in it for the legacy, for the fame. Yeah, yeah.
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A
For the photos, the immortality of my trotter.
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B
My little trotter. My little trotters.
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A
Okay, here's the thing, right? Hooves make really good mechanical sense. You know, you've got. You want to be a fast, heavy runner. You. You. You evolve hooves, right? It's not. You're not damaging the ground. If you want to sprint and hunt, then you evolve paws. These are much softer. They're like squishy jelly bean pads. If you want to climb, then you evolve a kind of second pair of hands, which is what. What you get with monkeys, human feet. What is going on with them?
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B
Right. It's kind of halfway between climbing and not climbing.
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A
Right.
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You can't grasp, but monkeys have much more opposable toes.
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A
They do.
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B
In fact, my daughter has a book about human evolution, and it's got all these artist renderings of early hominids, and they all have, like, hand feet. So, yeah, not only is that different, but also Homo sapiens are the only animals on this planet that wear shoes. Right now we put them on horses, sure. When they're doing labor for us, we'll put them on dogs, but only when the dog is gonna be walking on something we made like asphalt or concrete, by the way. Do you say asphalt or asphelt?
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A
Asphelt.
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B
Oh, you say felt.
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A
I don't know. It doesn't come up that often. It doesn't in my world, I'll be honest.
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B
Well, anyway. And so why. What's going on there? Our feet are weird.
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A
They are Weird. They are weird. But I think the shape of them in particular when people first started trying to make robots, okay, the first time that you sort of needed to like construct a foot to see how it could work. And they tried to make these, these like flat feet just like kind of moving like this. Right. Which is maybe that's how our feet have evolved. Maybe it was that we were previously climbing trees and then they just became slightly flatter, slightly less able to grip around the trunk of a tree and slightly more attuned to going on the ground, to walking. So when people first start building robots, they made these perfectly flat feet and it was a total disaster. Because what that means is if your feet are completely flat, you can't roll forward. Right. So instead, like the early robots, like Asimo, which is, you know, a particularly famous one, they have to, if you look at them, they have to stand essentially with their knees permanently bent in order to be able to, to move forward. Right. It's really, really energy intensive to like kind of lift your feet up this way. And if you look at an ape walking, that's essentially what they're having to do.
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B
Oh really?
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A
Because their, their feet are so flexible, Right. That when they are down on the ground. Boof. They have them very flat. And so their knees and their hips are continually having to be bent in order for them to propel themselves forward. It's like really energy intensive. They don't like doing it at all. Would much rather be in the trees.
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B
And so a firmer foot that's less flexible like a human foot, is better for walking.
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A
Right. You sort of want the rigidity in order to be able to kind of press off. But you also don't want it to be flat.
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B
Right.
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A
Because the flat obviously takes a lot of energy.
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It needs to be somewhere in between.
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A
Yeah. But then here's a question. Okay. You don't want it to be flat, you want it to be rigid. Why isn't it shaped like a rocking chair? That would help you propel forwards.
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B
Oh yeah.
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A
I mean that would make way more sense.
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B
I mean, it needs to be. I need to be able to move it like I need my toes to be able to sometimes give more or less resistance to the rocking motion.
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A
Agreed. But like this kind of, this effect of like rolling forwards and yet our feet are arched exactly the opposite way.
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B
They are, aren't they? Yeah.
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A
So this was a genuine puzzle. Why is it that are arched that way around rather than the other way around?
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B
Can I make a guess or. I would guess that it's like architectural for support that that arch, just like an arch in architecture holds weight better than a saggy rocking chair type foot.
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A
I don't think that's the primary reason.
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B
So what other reason is there?
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A
It's probably because standing still would be really difficult if our feet were bent like a rocking chair. And people have tried this with robots as well. Right. So the sort of next generation of robots had rocking chair type feet. But then standing still would require you to continually tense yourself. You'd have to like permanently be locked in place.
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B
Yeah.
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A
And so it just doesn't work either. So instead, with the arch the other way, it means that you can kind of create a triangle between the big toe, sort of pinky side of the foot and your heel. And you're kind of sitting on a little tripods.
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B
Yeah.
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A
Kind of be in a. In a relaxed state. But in the 1950s, people were like, this does still really not make a lot of sense. Like, why have we got this? Maybe the foot arch is there for structure, but, you know, makes sense why we don't have these flat feet. But what is going on? Like, why are our feet in this particular shape? So in the 1950s, this English orthopaedic surgeon, he was like, guys, I've cracked this, I've worked out. He was kind of looking at the human foot and he knew it couldn't be a rocking chair. But he also knew that if it was just this fluffy, fluffy bag of joints, you know, this insane number of bones.
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B
Like a monkey foot.
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A
Like a monkey foot, then we wouldn't be able to push off and it would be really, really difficult. So he was like, right, there must be this kind of structure that's going on in here. This is the explanation that he managed to come up with. Okay.
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B
Oh, you've got a cardboard model. I did. Looks like you built it yourself.
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A
I did in the car on the way here.
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B
It's got like an arch. It's like a cardboard shaped boomerang.
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A
Yeah. It's got three different parts to it. Okay. So those of you who are watching, you can see this is sort of like learn with Hannah.
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B
Yeah.
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This is my model of the foot and how a foot works or how they thought the foot worked in the 1950s. Okay, so.
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So let me say what I'm seeing.
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A
Cool.
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Three parts. One looks like a boomerang shape and then attached to one end is a little ellipse that is hinged like with a brad, so it can swirl around 360.
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A
I mean, that's not what you Want
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in your old foam, that's not what you want. And I can tell that because you've connected the far end of the boomerang to the far end of the ellipse with a rubber band. So it's almost like a bow and arrow type shape.
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A
Exactly. It's like a bow and arrow type shape. Exactly. So what you can't quite see here, I've essentially split the foot into three sections. And then we have like a tendon running between. So here is the heel.
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B
Right.
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A
It's kind of the back of the foot. And then you have essentially the foot arch that goes up and over. And then this here is the toes. Okay, Right.
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So now the ellipse is the toes.
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The ellipse that can move around is the toes.
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B
Yeah, the hinges there.
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A
So here was his idea. He was like the foot being this shape, like a bow from a bow and arrow. This makes perfect sense because when you put your foot down, you've got lots of nice kind of elasticity so your foot doesn't get damaged. The kind of the string from the bow hits the ground first and absorbs lots of the energy as. As you hit the ground. But if you move forward by lifting your heel up, then what you're doing is you're tightening this bow, you're tightening the. The tension between your heel and your toe. And that's the thing that's giving your foot this structure. That's the thing that's giving your foot this strength, this stiffness in order for you to be able to push off and move forwards. Right. It's something that just made abso. Perfect sense.
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B
Yeah.
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A
As a result of. Of this explanation. This explanation, by the way, stood for, like 70 years. Everyone was, like, super happy with it. And it led to something called Jack's test, which you can do it on yourself. There was a bit of me, Michael, that was going to suggest that you get your feet up for this, but. But maybe not. May.
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B
Maybe. Maybe later.
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A
Maybe later. But if you stand barefoot, that's it's
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B
for the rest is Science After Dark. Yeah.
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A
That's the subscription.
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B
Yes, yes.
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A
You know, I think Lily Allen once said she's got onlyfans, but she only shows pictures of her feet.
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B
Okay.
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A
And she said that she makes more money from that than she does from her actual music.
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B
I believe her.
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A
That's incredible, isn't it?
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B
Yeah, well, she probably doesn't have, like, Ticketmaster fees and a recording label to pay.
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A
Very true.
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B
She just snaps them with her phone and ka ching, ka ching.
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A
Hello. I'm gonna come on to that a bit more later. The foot fetish stuff. It wouldn't be a, a proper episode about feet if I didn't mention. No, we have to, we have to, we have to. Okay, so, so there's this thing called Jack's test. If you stand barefoot with your, your weight on the floor and you have somebody else pull your big toe backwards so you're kind of standing like this, and then you get someone else to effectively tighten so they like, they pull your big toe up, then you will see your arch tighten, basically. You see your arch kind of getting tighter, more stiff essentially. And everyone was like, well, this is the proof that his explanation is correct. It's, it's very clear that moving the big toe moves this tendon, the plantar fascia that runs between the front and back of your foot. And everyone was like, well, there you go, this is it. We, we worked out, this is absolutely fine. And then what would happen is this kind of like really fed into the, the medical understanding of what it meant for feet to, to, to be working correctly. So you, you might have heard this idea of people saying you're very flat footed.
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B
Yep.
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A
And that being considered a real problem.
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B
Right.
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A
And it comes from this exact same explanation that if your foot is too flat, if your arch is too narrow, then you can't get the tension properly and it affects the way that you end up walking. There was some confirmation bias going on in this too, because people would go to doctors and they would say, we've got loads of pain in our feet. And the doctors would look at their feet and say, well, it's cause your feet are flat. I can see that there's a flatness to your foot and that must end up being the problem. Okay, the slight issue, right, with this explanation. Well, there's two. The first is if this really is the way that feet work, well, then how come people who do have completely flat feet can walk?
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B
Yeah, they can, they can.
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A
It is possible. You don't need, you don't actually need the art.
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B
Well, I remember being told as a kid that I had flat feet by my doctor, but I didn't know what to do. The symptoms were supposed to be right. I could walk fine, I could run fine. It's never been a problem.
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A
What did they say about it?
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B
I don't remember anything outside of he made me walk around barefoot in the doctor's office. Maybe he just wanted a free sweeping of his floor. Not that hairy.
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A
Maybe he thought your feet were so flat because he couldn't See through all the hair.
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B
He couldn't see through all the hair. It was like this forest. No, but I remember him telling my mom, yeah, he's kind of got flat feet. But then nothing ever came of it, so.
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A
Right. And it doesn't matter at all because. Because while some people who have pain in their feet have flatter feet than others, there are also, like, loads of people who've got incredibly flat feet and, like, run marathons and do all the stuff, and they're absolutely fine. Like, they're completely fine.
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B
That's what I was thinking. Yeah.
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A
And then the other are plenty of
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people with really nice arches who have absolutely, completely.
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A
The other big clue that this. This explanation was completely wrong is that for this explanation to work, the way that they constructed it is you sort of have to fuse the heel and the arch. You kind of. This particular joint is, like, quite rigid in the explanation. But then it turns out that there have been some surgeries where people who've got really bad arthritis have had that joint physically fused. And it makes it really, really difficult to walk. Right. So how can it be.
- [17:14]
B
And this is the joint between the heel and the rest of the foot.
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A
Let me get the example.
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B
I didn't know there was even a joint there.
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A
There's. There's. I mean, there's lots of joints. I think there's 30 joints in the foot in total. Oh. I mean, this is sort of pretending that there's two.
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B
There's. Yeah, right. But yeah, there's.
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A
It's called the navicular medial cuneiform joint.
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B
Okay.
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A
Okay. And if you fuse it in, the existing idea of how feet work, not a problem at all, but in reality makes somebody's ability to walk significantly worse. So it's like, well, this. This is like there's something wrong going on here.
- [17:50]
B
Something missing.
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A
Something is wrong going on here. Very recently in 2020, this paper that my colleague at Cambridge was. Was involved in, a group of scientists, mechanical engineers and biologists essentially were like, something's going on here. Something. Something not right. So they decided to look at the foot from. From a completely different angle. Because this entire time when we've been thinking about the mechanics of a foot, we'd been looking at the arch that runs from the toes to the heel.
- [18:18]
B
Yeah.
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A
But this group were like, well, hang on a second. There is another arch going on in your foot. Your foot doesn't just bend front to back. It also bends left to right. Like, if you think about the way that you're Pringle. Like a Pringle Exactly. You feet now.
- [18:38]
B
Yeah, I know, but I've got shoes on. So I'm like, no, it's pretty darn flat.
- [18:42]
A
But yeah, I know you're talking your commerce soul underneath. Yeah, exactly. And actually they were like, well, hang on a second. Maybe it's the, maybe the stiffness because you need, your, your foot needs to have this stiffness in order for you to be able to push off and propel yourself forward. So they were like, maybe the stiffness is coming from the arch that runs in the other direction instead, rather than front to back. Maybe that one's not as important. Maybe it's. Maybe it's side to side from the big toe to the pinky toe. So what they did got hold of some cadaver feet. Huh. Gets gruesome.
- [19:15]
B
Keep going.
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A
They mounted these feet into this like quite heavy duty materials testing machine where they would like press weights down on the foot to see how much force it would take to bend the mid foot.
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B
And these were cadaver feet that were not compensating for the extra weight. They were just looking at the structural properties, structural properties of foot, nothing else.
- [19:38]
A
And then once they'd done that, they then got out some scissors and they started snipping the joins between the toes.
- [19:47]
B
Right.
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A
Not just between the toes, but in that direction. Right. Trying to break the arch that runs through left foot.
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B
And watch when it fails.
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A
And it turns out that this like, you know, really decades and decades and decades old understanding of the foot just crumpled as the snips took place. Wow. Because almost all of the rigid structure of the foot comes from the left to right arch, not the front to back arch. Wow. Like, completely shattered this biomechanical dogma that existed. Yeah. When they ran the numbers, the, the, the front to back arch only accounts for about 25% of the foot's rigidity.
- [20:27]
B
Okay.
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A
Now the reason why this works, the reason why you get this stiffness, something called Gaussian curvature. The reason why you get stiffness from. From there being a bend. It's a bit like, you know when you have a slice of pizza.
- [20:38]
B
Yep.
- [20:39]
A
So a slice of pizza, if you try and get it in your mouth. I'm doing this with a piece of paper. We'd be much more fun if it was actual pizza.
- [20:45]
B
But I'm imagining.
- [20:47]
A
You're imagining. Okay. If you have a slice of pizza and you try and get it into your face, right.
- [20:52]
B
You're holding it from like the crust end, so the tip is gonna flop down.
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A
It flops down really easily.
- [20:58]
B
Yeah.
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A
But what people automatically do is they've realized that if you fold it along the length of the pizza, then when you try and get it in your mouth, it remains straight in the other direction.
- [21:10]
B
Now, I've seen the famous, like, Ted Ed animation about this pizza. Why pizza folding makes things rigid.
- [21:16]
A
But.
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B
But you're saying that this is also what makes our feet rigid and great for walking.
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A
Yes. So it all comes down. All comes down to this idea of Gaussian curvature. So Gaussian curvature is something that measures the curviness of a surface, and it's made up of two numbers. So one number is how curvy it is in one direction. The other number is how curvy it is in a perpendicular direction.
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B
Perpendicular direction.
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A
Exactly. So if you imagine that you're on the surface of a globe, right, Say you're at the equator, one number would be north to south, how curvy is in that direction, and the other would be east to west. Now, the key thing, it's positive if it curves away from you. Okay. Okay. Now, the key thing about gassing curvature is that you cannot change the Gaussian curvature of a surface unless you cut it or warp it.
- [22:04]
B
Right.
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A
So if you start off with something that is completely flat, you know, like a piece of paper or a piece of pizza, if you start off with something that is completely flat, it has zero Gaussian curvature, which means that even when you bend it, it has to end up with zero Gaussian curvature.
- [22:20]
B
Right. So when you bend a sheet of paper, you produce, say, positive curvature in one direction. One axis.
- [22:26]
A
Yeah. Now, the only way those two numbers multiplied together can still make zero is if the other direction is zero. Right. You forced it to have a positive number in one direction, and a positive number times zero is still zero. So you have forced it to have zero curvature in the other direction.
- [22:44]
B
The curvature of a flat sheet of paper is 0.
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A
0 times 0.
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B
In all, 0 times 0. Oh, so it's the product that matters.
- [22:52]
A
Yes.
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B
So if you create a curvature of, say, one, I don't know what the units are, but positive one, that means you're like turning your page into a taco. The curvature in the perpendicular direction needs to be. Be zero because one times zero is still zero.
- [23:07]
A
Exactly, exactly. So this is why the folding pizza thing works.
- [23:11]
B
Yeah.
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A
You force it to have a positive curvature in one direction, which means it, by the law of light, curvature has to not have curvature. Yeah.
- [23:20]
B
The only way it could have a different curvature in the perpendicular direction now is if it warped or broke.
- [23:25]
A
Exactly.
- [23:26]
B
Which it's strong enough not to.
- [23:27]
A
Exactly. It's the same reason why corrugated cardboard works, because you take the paper. I mean, it's actually quite thin, corrugated cardboard. Right. But you take it and you curve it. You deliberately give it a curvature in one direction.
- [23:40]
B
Yeah.
- [23:40]
A
Which means that it then can't bend in the other direction.
- [23:43]
B
Right.
- [23:43]
A
So it's the same with your foot. You deliberately curve it in one direction between your little toe and your. Your, your big toe. And it means that then it cannot curve in the other direction, which means that it has this stiffness as you propel yourself forward.
- [23:57]
B
I want to take a quick tangent and talk about globes.
- [24:00]
A
Yeah.
- [24:01]
B
Because the Earth is going to have positive curvature to the same degree in both east, west and north, south directions on those axes. So its curvature, if we call it one in each direction, is one one times one. What can I do to a globe such that the product of those two curvatures is still one?
- [24:22]
A
So actually, with the globe, this is the reason why maps don't work. Yeah.
- [24:27]
B
Because if I try to flatten, I'm changing gaussian curvature from 1 to 0.
- [24:31]
A
And so it doesn't work.
- [24:32]
B
It'll get ripped. Right.
- [24:34]
A
Without you ripping it, cutting it, or warping it.
- [24:37]
B
Are there other shapes I can bend it into that still have a Gaussian curvature of one?
- [24:44]
A
Yes. Not a cylinder, because that's got a Gaussian curvature of zero because it's bent in one direction, but not in the other. Not a Pringle, because that has got positive in one direction and negative in the other. It's still gotta be positive. Positive, because that's the only way that you get a positive number overall. So you're looking at, like oblate spheroids, you know, sort of like deformed balloons. That's essentially all you got.
- [25:09]
B
Okay. All right.
- [25:10]
A
But, you know, let's save this for the globe episode. Let's see what kind of crazy deformed balloons we can make.
- [25:17]
B
And crazy deformed maps.
- [25:18]
A
And crazy deformed maps. Yeah, yeah. But back to the foot, though. This is like. Okay, so maybe this is what was going on all this time. And it has since been confirmed they've done high speed X rays of what is going on with the foot. So where you can take an X ray as somebody is walking or moving their foot, sort of move away from the cadaver feet. At this point, watch a runner, essentially move around while having X rays done
- [25:45]
B
with a slow motion X ray. I would love to watch those.
- [25:48]
A
No, actually, in fact, I think I
- [25:49]
B
have some how did they get volunteers for that? Because X ray videos are amazing. Like, I've seen X ray video of people swallowing and chewing. But of course it's a carcinogen, all these X rays being shot at you. So it's not a good idea. They used to, of course, have actual X ray boxes at shoe stores.
- [26:12]
A
Yeah.
- [26:13]
B
You could put your. Put a shoe on your foot and then stick your foot in the box and look through this window and see the bones of your foot and how they were being squished or not by the shoe. Yeah. Not a good idea.
- [26:24]
A
That was a bad idea.
- [26:26]
B
But they were helpful. If you didn't want to live a
- [26:28]
A
long time and have comfy feet, if
- [26:31]
B
you wanted comfy feet, if you wanted the next few years to be really comfortable, they were great.
- [26:37]
A
I think you can think of everything on a spectrum, right? Between how much do you care about comfy feet versus how much do you care about wanting to live.
- [26:44]
B
Right.
- [26:44]
A
And in the limit, if my feet were excruciating all the time, I'd be fine with a shorter life, you know? So this is just. Yeah, there you go. Exactly.
- [26:51]
B
It all balances out.
- [26:52]
A
It all balances out. All balances out. Yeah. When you, when you do these X rays, it's like the foot is this spring loaded trampoline, essentially. You're just the second before your toes leave the ground, the arch just visibly recoils. It kind of springs back into its curved shape and that elastic bounce releases all of that storage energy, throwing the
- [27:12]
B
body forward, moving you forward.
- [27:14]
A
Moving you forward. Yeah.
- [27:15]
B
Wow.
- [27:16]
A
Isn't that cool? Yeah, I really like that a lot. They ended up going further because they were sort of. Okay, well, if it is about this way around rather than that way around. When you go back in the fossil record, it was before this paper came out about the direction that we know that it matters in. There was a bit of a question about this because some of our ancestors, Lucy, for example, the one that was found 3.2 million years ago. Right. Has like these very flat feet.
- [27:42]
B
Flat in the direction of toe to
- [27:44]
A
heel, flat in the direction of toe to heel, but not flat in the direction of big toe to little toe.
- [27:51]
B
Okay, so is that evidence that she was a walker?
- [27:54]
A
It's evidence, yeah.
- [27:55]
B
Bipedal walker, yes.
- [27:56]
A
That it was like this. She was essentially transitional. She was somewhere between climbing trees and walking upright.
- [28:03]
B
So then what's the point of the curvature from toe to heel?
- [28:07]
A
So that still helps with the.
- [28:09]
B
It's a quarter of the support. Yeah.
- [28:12]
A
It's just not providing the Stiffness.
- [28:14]
B
Right.
- [28:14]
A
It's helping you propel forward. It's part of the kind of traction trampoline, like spring loading. It's just not the thing that's giving you structure in order to be able to, like, lever yourself forward. Okay. But it looks as though this evolution of the. The big toe to little toe arch came about one and a half million years before our genius.
- [28:38]
B
Really before. Before Homo. Before Homo.
- [28:40]
A
Yeah. This is a key evolutionary step as to how we learn to stand.
- [28:46]
B
Oh, interesting.
- [28:47]
A
Mm. It's good, isn't it?
- [28:49]
B
Yeah.
- [28:49]
A
Isn't that good? Here's the thing I really like about this, is that this paper was published in 2020.
- [28:54]
B
Yeah.
- [28:55]
A
You know, like, that's like no time ago. Six years ago.
- [28:59]
B
Yeah. So has this been studied further? When are we going to see it folded into what podiatrists recommend and the way shoes are designed?
- [29:09]
A
Great question. Cause I think it's gonna probably take quite a long time.
- [29:12]
B
Yeah.
- [29:13]
A
Because you're right that actually a lot of the time, the way that shoes are designed, thinking of the arch, thinking of the front to back arch and trying to support it and so on. But, yeah, it's. It. I think it probably will end up taking a lot of time, but I think it really does demonstrate just how good science is at never sitting still and continually questioning its own. This is, like, completely common knowledge. Right. You pick up any textbook from the last 70 years or so, and this is like, yeah, yeah, yeah. This is absolutely how it works.
- [29:40]
B
And it's not.
- [29:41]
A
And it's not.
- [29:42]
B
So not only were they were these researchers willing to keep questioning, they also found such a fun but gruesome way to test it. Taking cadaver feet, putting weight on it, and then snipping muscles, like mutilating this foot to watch how it withstands the weight and the destruction.
- [30:04]
A
You know, the other thing you can see from the fossil record, you can see the exact moment that we invented shoes.
- [30:10]
B
Oh, go on.
- [30:11]
A
Basically somewhere between 26,000 and 30,000 years ago.
- [30:16]
B
So not that long ago.
- [30:17]
A
Not that long ago. After clothes, actually, we were wearing clothes.
- [30:21]
B
Okay. We were wearing clothes before shoes.
- [30:23]
A
Clothes before shoes.
- [30:24]
B
Now that's almost surprising to me because I think, all right, certainly you need clothing when you start migrating into colder climates, but no matter where you live, your little footsies are gonna get hurt by rocks.
- [30:37]
A
Well, not really, because you just build up calluses on them.
- [30:40]
B
Sure.
- [30:40]
A
I mean, that's what dogs.
- [30:41]
B
I've got little dainty princess feet, and I can't even walk on sand without being like, ow. But that's because I never expose them. They have no chance to build up calluses.
- [30:52]
A
Oh, right. Okay. This is probably, you know, this is the combination of two together.
- [30:56]
B
So how do we know that shoes came about around then?
- [31:00]
A
Because of toes. Oh, yeah. So what happened is our toe bones, our small toe bones especially, suddenly became really pathetic. Oh, yeah. Before they were like really strong. And you. Amazing.
- [31:14]
B
So you're saying that our little tiny pinky toes, like such that sometimes the nail on it is so small you can barely paint it. It's because of shoes.
- [31:23]
A
Yeah.
- [31:24]
B
Wow.
- [31:24]
A
Yeah, because they don't need to be as strong anymore when you've got the additional support underneath. I'm quite a big fan of walking around in bare feet. I've got to be honest, you know, like on holiday, if I could get away with it, I would just.
- [31:36]
B
Just be barefoot the whole time.
- [31:37]
A
Yeah.
- [31:38]
B
Yeah. Not me. I don't sleep in socks. That's like the only time we don't need.
- [31:43]
A
Until you've got the warmth. The warmth there already.
- [31:45]
B
They're already warm enough. They get too hot. Yeah. If I wear socks at night, but in the mornings I'll get up to make breakfast and I'll be walking around barefoot and I'll just be like, whoa, this is so inappropriate. I feel so naked. And so I don't know what my daughter thinks. Cause I'm always like, oh, I gotta go put on socks. And she's like, why? And I'm like, well, because I've lost my mind. A long time ago, I did.
- [32:10]
A
I'm still upset about something that someone said 40 years ago. Yeah, I think I've seen a picture of your feet, though. Can I tell you why?
- [32:17]
B
You better.
- [32:20]
A
Do you know about. I mean, we said we were going to get onto foot fetishes.
- [32:24]
B
Oh, sure. Yeah.
- [32:25]
A
Well, come back for that after the break.
- [32:33]
B
I live 7,000, 636km away from Hanna, so we rarely get to see each other in person. That's what makes this such genuinely thrilling news for us. And maybe for you too, because for the first time ever, you can see both of us live on stage at Gullhanger's inaugural festival. It's gonna be amazing to be able to reach through the screen and meet those of you who watch and listen to the show in the flesh. The rest is fest runs from the 4th to the 6th of September at London's South Bank Centre. So get some tickets and get ready for some fun, some serious fun. Go to southbankcenter.co.uk to find out more.
- [33:24]
A
This episode is brought to you by Cancer Research uk. In the uk, nearly one in two people will face cancer in their lifetime. The question is, could science stop cancer before it begins?
- [33:35]
B
And over the past 50 years, Cancer Research UK has helped double cancer survival in the UK. And that's proof of what research can achieve. Like take cervical cancer. Almost every case is caused by hpv, the human papillomavirus. And when scientists uncovered that link, prevention became possible.
- [33:52]
A
Indeed it did, by vaccine and it's protection that works way before the cancer itself can actually grow. After the vaccine was introduced, cervical cancer rates in England were nearly 90% lower than expected in women in their 20s. I mean, we're now genuinely at a point where this is a disease that is disappearing in younger women in the uk. This is something that I really hope my daughters will never have to deal with.
- [34:13]
B
For more information about Cancer Research uk, their research breakthroughs and how you can support them, visit cancerresearchuk.org REST ISScience hi,
- [34:24]
A
this is Gary Lineker from Goal Hangers. The rest is football. This episode is brought to you by Wise. It's only when you start moving money between currencies that you really think about the exchange rate, the fee and what might be hidden away in the small print. Whether you're living abroad, paying someone overseas, or just trying to manage your money across borders, you want a fair exchange rate, an easy transfer and no surprises along the way. Wise keeps things simple. Wise is a smart way to move the currencies you need around the globe. It works in more than 160 countries and with over 40 currencies, most transfers arrive instantly. Wise uses the mid market exchange rate like the one you see on Google, with no markups or hidden fees. So when money needs to move, you can see the rate, know the fee and get on with it. Join millions saving billions on hidden fees by downloading the Wise app today. Be smart, Get Wise T's and C's Apply. Welcome back, Michael. Do you know about WikiFeet?
- [35:31]
B
I do.
- [35:32]
A
Do you know that you're on there?
- [35:33]
B
Am I? Really?
- [35:34]
A
You are.
- [35:35]
B
Well, like I said, I did show my feet off in my Lego video, but otherwise let's. Do you have my Wikifeet page bookmarked?
- [35:44]
A
I did look at it the other day. So essentially there are a lot of people who really care a lot about feet, who find feet extremely titillating, should we say? And there is a website called Wikifeet which collects. Is it called WikiFeet? I was Fetipedia or something. Wikifeet. There we go.
- [36:10]
B
How does that portmanteau work? Which one do they put?
- [36:12]
A
Which one did they do which? Collects feet pictures from celebrities. And then other people can go on and rate them and enjoy. Enjoy looking at them.
- [36:24]
B
Yeah, okay.
- [36:25]
A
I'm looking at a picture of your
- [36:26]
B
feet right now, so gotta show me what photos people have.
- [36:29]
A
I don't think these are that hairy.
- [36:32]
B
Ah, okay. Yeah, that's from the Lego video.
- [36:35]
A
Okay, so here's what. Here's what they have. I mean, I think that's a normal.
- [36:39]
B
I may have been exaggerating for comedic effect.
- [36:43]
A
There's also this one.
- [36:43]
B
Hold on a second. I wanna.
- [36:45]
A
Oh, yeah.
- [36:45]
B
When I jumped in the water.
- [36:47]
A
Okay.
- [36:47]
B
I don't swim in socks. There you go. I'm not some kind of like, never nude foot guy. But wait a second, wait a second. What's my rating?
- [36:53]
A
I know I have your rating.
- [36:55]
B
What is it?
- [36:56]
A
You've done pretty well. You've done pretty well. No, hang on, let me get mine up. I want to see who wins.
- [37:00]
B
Oh, yeah.
- [37:01]
A
The thing that I find extraordinary about this, apart from everything, is that, oh, gosh, there's pictures of us together online. I mean, as I say, I will wander around without shoes on quite a lot of the time. My foot can't even sneak into shots somewhere without it ending up on this website.
- [37:19]
B
Exactly. Yeah. And you gotta control it because that's a gold mine.
- [37:23]
A
Right. This is clearly worth money.
- [37:25]
B
Gotta gatekeep it. Or dollars are the tickets.
- [37:28]
A
Look at this. This one's gone on there.
- [37:30]
B
Oh, no. Yeah, you got some arch poking up from the shoe. See, now, as a guy who reads a lot of Internet comments, I know what you shouldn't be doing.
- [37:38]
A
Yeah, I know. Well, I'm a.
- [37:39]
B
Or should be doing, depending on your goal.
- [37:42]
A
I do, actually. I mean, I do think about it now when being in front of a camera, like, okay, let's not.
- [37:47]
B
All right, but stop stalling. Who wins? What's our.
- [37:50]
A
One of us gets 4.82.
- [37:52]
B
Out of five.
- [37:53]
A
Out of five.
- [37:53]
B
Oh, let me guess who's who.
- [37:55]
A
And one of us gets 4.88.
- [37:57]
B
Okay, well, you're 4.88 correct. For sure. I think 4.82 is way too high for me.
- [38:05]
A
I think that's like.
- [38:06]
B
That's probably only based on, like, two ratings. One is from, like, my mom.
- [38:10]
A
No, 12. 12 ratings.
- [38:12]
B
12 ratings. But how many ratings do you have more? How many more more? Hundreds or thousands?
- [38:19]
A
No, not thousands.
- [38:20]
B
Not thousands. Not yet.
- [38:24]
A
Imagine if that's the conclusion that people draw from this episode.
- [38:27]
B
So this was all just year fishing for, like, more ratings on Wikifee. It's okay if that's what you're looking to do.
- [38:34]
A
You know, there is a bit of me that's like. I sort of don't really have a problem with it. Like, people having a fetish feet. Because they do. Right. And, like, it's not like you're. I'd be okay with setting up an OnlyFans as a feet thing. Am I saying that?
- [38:48]
B
Well, yeah, I mean, there's nothing. There's. I would just say that maybe you wouldn't like it because you'd rather them focus on other things about you.
- [38:55]
A
Yeah, true. But I did think about actually once setting up an OnlyFans, but all it is is me drawing equations on a blackboard fully clothed.
- [39:03]
B
Yeah, you should do that. I mean, it's only fans is for the fans, and I think that's what they want.
- [39:10]
A
I just think it'd be really funny.
- [39:12]
B
Let's talk about fetishes around feet.
- [39:14]
A
Yeah.
- [39:15]
B
Because, I mean, a fetish, what is it really? It's an interest in a part of the body that is not a primarily sexual part.
- [39:23]
A
Yeah, yeah. Or something that is not primarily associated with.
- [39:27]
B
Or something.
- [39:27]
A
Yeah.
- [39:27]
B
Right. So how come foot fetishes are seemingly so much more common than like, an elbow fetish or an armpit fetish?
- [39:38]
A
Yeah. So there is one explanation.
- [39:40]
B
Okay.
- [39:40]
A
But it's. There's not a lot of studies on this. Essentially, the one explanation is that in your brain there is effectively like a sensory map that relates to every part of your body. So there's a bit in there. You know, a certain part of your brain lights up when you touch somebody's hand while they're in a scanner and so on and so on and so on. And it's almost like a humunculus. Right. It's like a map of your body that is in your brain.
- [40:06]
B
Yeah.
- [40:06]
A
And in that map, it has been proposed that feet and genitals are extremely close together. So that you can imagine that in some people there may be some overlap in kind of cross wiring.
- [40:19]
B
Right, right.
- [40:19]
A
So you kind of. You play around with somebody's feet and they. They essentially get sexual stimulation.
- [40:26]
B
Right, right, right. So, I mean, that does make a lot of sense.
- [40:29]
A
Yeah.
- [40:30]
B
But you're saying we still have a lot more to learn.
- [40:33]
A
Still have a lot more to learn. Because I think that the original studies, or original study rather acted as though it was like a. And there you go. That's the answer.
- [40:42]
B
Right.
- [40:42]
A
But I think subsequent follow up has demonstrated that it's just not quite as simple as that. There's much more variation that you get within humans. I mean, you're right though that it is like this really prevalent thing throughout history. The Greeks and the Romans, I mean, they were really into feet. There was, there was one philosopher called Philostrasus who wrote he thought that the reason why he was so into feet was because he wanted to be a human doormat just so his lover would step on him.
- [41:10]
B
Okay. But then that to me becomes a second thing as well, which is dominance and submission.
- [41:16]
A
Yeah, yeah.
- [41:17]
B
I mean, it could be that that's where the whole origin of foot fetishes comes from.
- [41:22]
A
Maybe it does. I mean, there's also the Freudian suggestion. Do you want to hear this?
- [41:25]
B
No. What's that?
- [41:26]
A
Freud. See if you can, as Freud generally does. It's completely unhinged. Freud says that a foot fetish is because it's a trauma response to coming out of your mother's womb. The feet being the first thing that you see and then realizing that your mother doesn't have a penis and then thinking that her feet are penis shaped something and that you imprint on that.
- [41:52]
B
Look, maybe that explains my fetish for doctors because the first thing I saw when I came out of my mom was a doctor and I was like, hey. And it was a trauma response I had because my mother's wearing, you know, wearing scrubs, like. Anyway, I don't. Sometimes this Freudian stuff, it's like, it's like a fantasy. It's hilarious and I think useful in the same way that like fantasy novels are useful and they can be so, so inspiring. But I'm just like, I don't know how any of this is scientific.
- [42:23]
A
It's not.
- [42:23]
B
I mean, some of it I guess can be, but some of it I'm like, wow, this is really creative.
- [42:28]
A
Well, it's not false fireball, is it? It's just not false fireball.
- [42:31]
B
No.
- [42:31]
A
Unless you, I don't know, like do a controlled trial where you get half of all women to wear socks while giving birth.
- [42:39]
B
Yeah, exactly. And then you check the future fetishes of those babies and they're like, ah, I don't know. But see, they might just wind up being really into socked feet.
- [42:50]
A
The thing is, is that when it comes to fetishes, you can learn a fetish though. Ah. So there's an amazing study with rats.
- [42:59]
B
Okay, tell me about it.
- [43:00]
A
Can I tell you? Okay, so, so what they did, they wanted to see if they could give rats a fetish.
- [43:05]
B
So I love this. Yeah.
- [43:07]
A
They took virgin male rats and they gave a little. Put a little jacket on them. Cute little jacket.
- [43:13]
B
Okay.
- [43:13]
A
And some of the jacketed rats were put in with females. And then they all had a lovely time. They were like, this is brilliant. These jackets are great. And then the others, when they put on the jacket, they were. They were introduced to females, but they were not allowed to copulate. Okay. So they were like, right. So this is like a. The jacket is a cock block.
- [43:33]
B
Right.
- [43:33]
A
Essentially.
- [43:34]
B
Right.
- [43:34]
A
And so they sort of did that a few times. And then for the final test, they took the jackets off of everybody, of all of the rats. But the rats who had learned that the jacket meant good times. Okay. They then didn't know what to do when they weren't wearing the jacket. Ah. Because they had, like, so closely associated the jacket. They were just like, I can't. No, thank you.
- [43:55]
B
I can't get off without my jacket.
- [43:58]
A
I need my jacket to enjoy this. Vice versa. The ones who had learned that the jacket meant, like, disappointment.
- [44:05]
B
Yeah.
- [44:06]
A
When the jacket went on, they were like, no, thank you. I'm not interested. I can't. Can't do it. Can't do it while I'm wearing this.
- [44:13]
B
Yeah.
- [44:14]
A
So it's like there is something, some evidence that this is learned.
- [44:17]
B
There's some learning and some associations.
- [44:19]
A
Yeah.
- [44:19]
B
I mean, I don't find that surprising at all. I think, you know, as you get to know someone better and you have all these experiences together, the roots of your trees grow closer and you start to, like, just love things about them, physical things about them that you find so much more exciting than you used to, because. I don't know, it's them. It's theirs and you love them. So, like, I find myself, I don't know, get too personal. Like, basically, I just. Basically, as I get older, I find my wife more and more attractive.
- [44:57]
A
Oh, that's a lovely thing to say.
- [44:58]
B
And I'm not just saying that for, like, points or anything. I'm saying it because I've heard comedians, like old comedians make jokes about this too. And I'm like, yeah, that really is true.
- [45:10]
A
Right. That's lovely. That's lovely. But it's like the learned being with her and around her.
- [45:16]
B
And then what's the difference between just admiration, like, oh, your hair is so wonderful, and a fetish?
- [45:23]
A
I don't know. Is the jacket on or off?
- [45:26]
B
Right. And just how much do I want that jacket on? Do I think it's a nice jacket? Or do I think it's a nice jacket. Right. It's probably. There's a little spectral somewhere between.
- [45:39]
A
You got to decide every day where you are between those two endpoints.
- [45:42]
B
I do, I do.
- [45:43]
A
What I'm looking forward to is my Cambridge colleagues listening to this podcast and the first half being like, well, that's really very, very interesting. Sorry, what are you talking about? Rat fetishes.
- [45:54]
B
I'm glad someone studied that because it's good, isn't it? I would be embarrassed to be like, I need money to do this study.
- [46:03]
A
Do you want to see the jacket?
- [46:04]
B
Yeah. Oh, wow. That is so not sexy.
- [46:08]
A
It's not sexy, is it? But some of the rats thought it was.
- [46:11]
B
Some of the rats learned.
- [46:12]
A
Some of the rats thought it was. And some people think feet are.
- [46:16]
B
And some people like nostrils, you know? And I think the world needs all those kinds of appreciation.
- [46:23]
A
Absolutely.
- [46:24]
B
And we appreciate you.
- [46:25]
A
We certainly do.
- [46:26]
B
Thank you for listening and reach out to us. Ask us questions@therealiscienceolehanger.com and we will see you next time.
- [46:34]
A
Thank you. The right window treatments change everything.
- [46:41]
B
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A
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B
have 50,000 five star reviews to prove we deliver. Deliver. Whether you DIY it or want a pro to handle everything from measure to
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A
install, we have you covered.
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B
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- [47:07]
A
At blinds.com rules and restrictions apply.
- [47:12]
B
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