Click on NOTE CATEGORIES to browse by topic, read through the entire archives, or type a topic in the search box.In this episode, Katy is talking about technology. Specifically where technology meets your head. No, not how technology affects mental health or how you think, but how it could be affecting the actual structure of your skull. Katy and her guests get into headphone dents, tech neck, and bone horns.
OVERVIEW
(time codes are approximate)
00:01:30 - Act 1: Headphone Dents with Brock (Jump to section)
00:13:25 - A Gamer (Curtoss) replies (Jump to section)
00:17:30 - "Continental Drift" and the skull (Jump to section)
00:23:10 - Act 2: Are Young People Growing Horns?
(Jump to section)
00:52:10 - Habits Have Consequences and other takeaways (Jump to section)
01:00:00 - Bony Development - 5 years Later (Jump to section)
LINKS AND RESOURCES MENTIONED IN THE SHOW
Author correction on Nature Article
Episode 119: Taking Bone Mechanics by the Horns
PODCAST TRANSCRIPT
(Theme music)
This is the Move Your DNA podcast, a show where movement science meets your everyday life. I’m Katy Bowman, biomechanist, author, and skeleton-shaper. All bodies are welcome here. Let’s get moving.
(music fades)
Friends, today we are talking technology, specifically where tech meets your head. And no, not how technology affects mental health or how you think, but straight up how it could be affecting the structure of your head. Today’s show is in two acts. Act one is some of my thoughts on this video that went on social media platforms like Twitch and TicTok, where a gamer realizes his headphones have left a headphone-shaped dent in his head. Act two is a look back on some research that made the headlines in 2018; That a lot of forward-head position, so think “smartphone” looking position, might be changing the shape of a small bone in the skull. So we covered this on the podcast years ago, and we’re revisiting that coverage plus checking in with how that research is holding up five years later. Here we go.
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The last couple of months I’ve been working on some longer writing about the physical effects of so much tech use. There’s a lot of focus on the mental effects (as there should be), but not as much on the physical. Or rather, I think some of the physical effects - like the impact of increased spinal curvature, near-looking, and extra sitting - they're just being normalized pretty quickly and I’m trying to keep these effects in the conversation. Not only because they are their own set of issues, but also because I think they relate. They're entwined with, really, some of the mental health outcomes that we are seeing. Because things like “brain function” and “arm and leg function” aren’t as easily separated as we would like to think that they are.
So, I was discussing some of the writing I'm doing and related tech imagery that I was imagining to go with this article with my team, and one of them threw out this video, where a gamer found dents in his head when shaving his head live on his social media platform for a charity fundraiser. His reaction was so authentic, here’s a beeped version: "Dude the shaver's working like a champ. I've got an indent right here. This is where my headphones go! My *** headphone indented in my head. What the ***. I thought that was just my hair! I thought just my hair did that."
So, I immediately wanted to do an episode about this and reached out to our podcast audio engineer, Brock Armstrong, to see if we could schedule it in and also why I thought it was cool and he comes back with something like, "Oh yeah, I have a dent in my head from my headphones too." Which made me want to bring him on the show to discuss.
KATY: Hey Brock.
BROCK: Well hello!
KATY: Thank you for coming on to the show that you edit and listen to.
BROCK: I get to listen to it every time there is an episode, but I don't often get to talk so this is pretty fun.
KATY: So I wanted to do this podcast and I ran it by you and you said that you have - you had a head dent. But you're not a gamer, right?
BROCK: I do game. I definitely do game. And I do wear a headset when I game which probably exacerbates the fact that my job requires me to wear headphones as well so I've got - currently wearing those great big headphones that cover your ears and have the great big strap that goes across the top of your head. Which are very similar to the ones I wear when I'm gaming as well. And years ago, I noticed that it really - the strap that goes across the top of my head fits very nicely, coincidentally, into a crevice in my skull or in my head. And so when you brought this up I thought, "Yeah, that's totally me!"
KATY: I got that. I have that. Ok the reason that this jumped out to me is I had just gotten back from the Museum of Osteology in Oklahoma City.
BROCK: As one does.
KATY: If there's a museum of bones, I'm gonna go. I've also been to the Museum of Penises in Iceland. You just can't keep me away.
BROCK: Would you call that the Museum of Boners?
KATY: That... we need that intersection. The museum of boners does not exist as far as I know. Because most of them are flaccid...
BROCK: I set you up for that one and you brought it home.
KATY: Thank you. In this museum was a lot of different skeletons of what humans have done to their skeleton for a variety of cultural reasons. So there are remnants in our skeleton that are about the things going on. They can see the tool used that someone was using by the remnants in their skeleton. Like if they were bow and arrow users versus spear users. As I put in Move Your DNA you can see the bones of professional pitchers have taken this thing that they do repetitively and it has changed the shape of the bone because of these mechanical forces. One exhibit, though, that they had was head wrapping. So this was - they also had foot binding so everyone's probably most familiar with foot binding: this idea of folding the foot around and tightening it that way so it grows within this confined area. But I hadn't really seen that they had done the same thing - this particular group - that they had done the same with their heads. I think a lot of this stuff starts when our bodies are younger. More flexible. More like a green twig. Less like an old dusty stick where things fracture and break. And there's also for people who have seen Grow Wild, I put in a picture talking about thigmamorphogenesis, the idea of mechanical forces affecting how shape forms. I found a tree in a forest that had a cable wrapped around it and the cable was very narrow - much more narrow than the girth of the tree above and below it, but it couldn't widen in this particular area. So you could see this constriction had been there as the tree was getting bigger. And it had done the best it could given this mechanical restraint. So I had that in my head, plus seeing the skeletons that had been wrapped. You know they're not hit and fractured, they're just slowly squeezed. There's a mechanical...
BROCK: Gently squeezed too.
KATY: Gently squeezed. It's very low force but it's almost ubiquitous. We talk about casts. It's like a cast that sits there and the skull grows taller and longer given this constraint. And even they had said they had done surgery in many cases to put wood into where there's a number of bones in the skull that maybe the sutures wouldn't then completely cover the brain because of the elongation that had happened. And they had done surgery and inserted wood plates - it was blowing my mind. And then I saw the headset thing. You had mentioned that your partner is skeptical if whether or not this dent in your head is a thing.
BROCK: Yeah. Well, she knows it's a thing.
KATY: It's a thing.
BROCK: Because she can feel my head and feel it but I think the interesting thing to do - and if I ever retire from being an audio engineer and don't have to wear headphones on a daily basis, it would be interesting to see if it does return to (quote unquote) "normal". If that dent sort of fills itself in. But it really has been since the early 90s, maybe late 80s, that I've worn headphones pretty much daily.
KATY: It's daily. So you have never had a week off of headphone use
BROCK: I'm sure I have. But I haven't sat and felt my head.
KATY: Not dent checking.
BROCK: Now I will.
KATY: That's right. OK. I just... I really wanted to know more about it. And certainly, there are things that can change shape. The first thing was like ok well, I wore glasses when I was younger and I could take my glasses off. And even overnight I feel like my glasses dent didn't fill in totally.
BROCK: Not totally.
KATY: Even if you squeeze your nose - it's thin. Some of the dent shapes I saw ... I was following up and reading online and so many of the things that I read were ... I couldn't get to the bottom of it. I couldn't get to the bottom. Because if I tried to read about head dents, you want to find something out you read on the internet, they were all quoting this one story about - this one study about this is how much force it takes to fracture a skull.
BROCK: Mm-hmm.
KATY: And so, therefore, with this one study then there couldn't be head dents. And I was thinking well I know that there's positional plagiocephaly - which is like when you lay a baby down for a very long time, their heads can change. It's not a high-impact type of thing. I know that there are many other bony changes that can come from not high-impact things. And we weren't necessarily talking about a fracture, right? We were talking about this slow low-load application. So that did not feel like a helpful piece of data for me. Certainly ok we know that your head's not fractured because of your headphones.
BROCK: Yeah.
KATY: But is it misshapen?
BROCK: It's very easy to tell it hasn't been fractured. But yeah, I feel like people who wear, for instance, cowboy hats. My uncle wore a cowboy hat almost every single day. He was a farmer in Saskatchewan and wore his cowboy hat every day and he definitely had a line across his forehead. That's not a fracture. That's not a blunt force trauma. It's not an uncomfortable squeeze, but it is a constant squeeze. So that's the way I feel about my headphones are probably contributing - not in a fracture risk but just in a gentle resting squeezing. But as you always say, your body adapts to the thing it does most. And if you're spending a significant amount of time having a tissue squeezed, it does sort of follow that that would fall into it. And then I have the added thing of being, I have osteoporosis. So whether that factors into the equation here or not, I'm not sure.
KATY: There are some things that soften bones but these are sort of rare other things and in general, I think the reason this clip went viral is there's a lot of people with headphones on. "Am I doing something to my head?" And I think more people took them off and said, "Yep, there's a dent." Now it seems like there's a dent. The next question is, is the dent permanent or is it just something that's about the immediate change in fluid and other softer tissues that sit above the skull? And then the third question is, is there something more permanent, possibly, happening underneath what we see in the soft tissue changes? To me, those are three separate things that you could possibly look at. I'm not sure really about any of them at this point. But my first data point was, I really wish when I was looking at this video to be like, "Well, where's the follow-up video?"
BROCK: Yeah. C'mon, gamer. Do proper science.
KATY: Yeah, if you took the headphones off did it fill back in? Put it out there man. The people want to know. So I can just ask this person. I imagine that - I don't really know how things go viral outside of just they get reshared - that doesn't necessarily mean the person's off limits. So I just sent this guy a message. Because I wanted to know, at least for my own data point. Was your dent permanent? And he wrote back...
BROCK: Very quickly. Surprisingly quickly.
KATY: He wrote back so quickly. So thank you so much. So, Curtoss is his Twitch username.
KATY: Right. Curtoss. So props to his parents if that's the name that they gave him. It might just be a play on Curtis, but anyway. I asked him a couple things. I wanted to know 1) If the dent had filled up. And then 2) I was just interested. Like I was asking you - how long are you wearing headphones in order to have something like that happen to your head? So this is what he wrote:
I believe the viral nature of the clip has led to a ton of misconceptions about the head dent, and I'm glad you're interested in the truth of the situation! I've read a ton of articles already calling it permanent, disfiguration, and all sorts of things.
The reality is that it's just soft tissue and it's bounced back to normal after a few days! I've heard that it's similar to the dents some people get on their nose/behind their ears from wearing glasses all day every day. I know it's much less interesting this way, but the dent was only temporary. I wear a specific headset for my job (I don't even wear it while I stream or play videogames, as insinuated by every news source) and after several hours of it sitting in the same spot, the temporary indent forms. I've been wearing it for several hours for the past few years while I work, but now I just sit it further back on my head and have no issues with it. I'm glad it went away so quickly, but also don't want anyone to get scared out of using headphones because of it! I imagine many more people have this temporary indent that just don't know about it because their hair covers it.
BROCK: Mmm.
KATY: So there you go. It came back.
BROCK: It came back.
KATY: At minimum if this was a concern, in the same way we vary our carry, just think about your headset as, again, a cast, and go for maybe use different headgear. Swap out like a chair. The same way we don't say use the same chair all the time.
BROCK: I could use my headset back on my head, I suppose. I just never thought about it. Because honestly as long as it's not actually impairing my brain in some way or my cognition ...
KATY: Right.
BROCK: I'm not too worried about a slight wobble in my skull. But it is still interesting. And I will start shifting my headset just a little bit.
KATY: Or you could wear it upside down. Like sometimes I like to put my backpack on my front - make it a front pack. Maybe instead of it going on the top of your head, you make it like a smile underneath you.
BROCK: Like a big beard.
KATY: Like a big beard. Exactly. Just do that and send me one picture and then you never have to do it again. And then people are concerned about headsets. Probably they should be more wary of hearing and headsets. Not the skeletal lump or the dent that's in there. It does seem like, and again it's one of those things that's pretty nuanced, but having sound, especially if it's a louder sound coming in your ears constantly, could be a thing probably more than. And I don't know if that relates to cognition the way we think about it. But I come from a family of headset wearers, pilots, and air traffic controllers, who were in headsets 8 hours to 12 hours a day depending on if they were flying and air traffic controlling. And I can tell you that hearing was a big thing for that particular group, just from my own experience.
BROCK: I get yearly hearing tests because I just want to keep on top of it. Whether I suspect there's a problem or not, I go and get my hearing testing because not only do I rely on it for making my living but also for being alive. I want to keep an eye on it... keep an ear on my hearing.
KATY: Both. Both. You're an audiophile. I know it's important to you. But yeah, definitely monitor hearing. And then all this is about age and that we start. And one thing that I do like to bring to the work is there's a difference maybe between going into multiple hours of headset use at ... how old were you when you started wearing a headset.
BROCK: I was a teenager for sure. Highschool. So 17? 16/17.
KATY: Yeah this might look differently if we start kids on it at 4. If they're in headsets and pads starting at 3 and 4 where, again, our bones are a lot more malleable - again something to watch.
KATY: Mm-hmm.
BROCK: So we have a little bit of continental drift going on in our skull. Can you explain that a little bit?
KATY: Well your head is made up of plates that come together at sutures. And there's an entire body work profession around trying to just detect - I don't even know how you would detect such subtle movement in these particular plates. But I know that there is a tremendous amount of muscular coverage of these plates. And we tend to think about things halfway. Where we think of that musculature as moving the eyebrows in the skull but the other parts of that muscle still attaching the plates themselves and can be maybe not allowing so much... there's not a lot of continental drift. Is that the term? Not a lot of continental drift where they would necessarily overlap each other as they do and make earthquakes. If you look closely at the sutures between these plates, it's a pretty - they've grown together. But there is still some play. It would be interesting to see how much play there is. There might need to be some nanotechnology involved. But I have not looked to see how much movement there is. That would be an interesting follow-up for this episode.
BROCK: But possibly those could be more susceptible to these kinds of dents? If my headphones are running right across one of those tectonic plates...
KATY: Yeah.
BROCK: ... I'm just gonna keep using geological terms that I'm not familiar with…
KATY: I'm gonna continue misusing geological... no I think you're right.
BROCK: …and keep bastardizing it.
KATY: That's a good question. And I think that that was also part of why, when I saw, "Oh right, you're squeezing" ... I'm gonna step back. I'm going to use the pelvis as an example. We think of the pelvis as a single bone but it's not. Right?
BROCK: Yeah.
KATY: It is where three different bones come together. And where we tend to have issues is at the places where these bones come together: your sacroiliac joint, your pubic symphysis. Because your pelvis has a right half and a left half and a bone to the back which is also your sacrum. So your skull is sort of like that. You're never just pressing on the skull as one complete piece of anatomy. Yes, it's so complex. It's so sort of grown together that you can pick up a skull, oftentimes, and have the whole thing come with you. But there are still places where there would be a change - it's not homogenous. It's not homogenous. The bones aren't homogeneous all the way through. There's a place where there is a suture. And so all the bones that we see are dead and dry and old. It's the difference between looking at wood and looking at a tree.
BROCK: Yeah.
KATY: So it's going to be very difficult to detect some of the flex - FLEX - flexibility of what's happening in the spine. So I would - that's gonna be - now I'm already curious to be going down another path of how much of the movement of our skull is happening in that area. And for children - so when children come, they don't even have all their plates - their bony plates aren't all fully formed yet. What becomes eventually bony plates will be partially cartilage. And so that's why when we're younger we're much more susceptible to being shaped by the mechanical environment because we're not full even that bony tissue yet.
BROCK: That's why you have to roll your baby. Roll that baby.
KATY: You gotta get the baby - change the position of your baby a lot. Let them be physical and more active and avoid just repetitive positioning for sure. Definitely don't start your two-month-old on gaming yet. Too soon. Too soon.
BROCK: Not quite. Too soon. Especially not for true reality.
KATY: And also interesting is the correction for positional, that misshapen skull due to lots of constant pressure, is wrapping it with a helmet. Is putting a something over your head that puts the pressure on. So sort of what the headphones are doing to perhaps a lesser extent. Ok, well we could talk forever about the skull and...
BROCK: My misshapen head.
KATY: And geology.
BROCK: Ruined geology for everyone else.
KATY: Exactly, sorry. All my geologist listeners out there. Please feel free to write in to make all the corrections but just so you know, we know that we don't know what we're talking about.
BROCK: Thanks for having me. Allowing me to speak on the podcast.
KATY: Always. Always. Feel free. Feel free to edit yourself down however you see fit. In addition to thanking you, Brock for coming on, I’d also like to thank Curtoss (Curtis) for getting back to me about your experience. I hope “going viral” shall we say, didn’t come with any added stress. And remember, everyone, people you see online are actual people, like you. Please behave accordingly.
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So, technology moves us, and sometimes that means over and over and over again in a single position. In 2018 The Washington Post put out this article that had the headline - Get ready for it: “Horns are growing on young people’s skulls. Phone use to blame, research suggests". Click-baity, right? Well, it worked. The article was based on a study published in the journal Nature, that same year with this title: Prominent exostosis projecting from the occipital squama more substantial and prevalent in young adult than older age groups.
So, this study found that 40% of the people between the ages of 18 and 30 who were X-rayed for other reasons had, let's just say for simplicity, a bone spur growing from the base of their skull. What was actually going on? I’ve brought on my friend Dr. Jeannette Loram, a biologist, and also a Nutritious Movement teacher to discuss.
KATY: So let me just lay down a few definitions. And I want to start with the term exostosis. Exostosis which was in the paper. So I wonder if there's an article. So article could mean for most people research article or media article. The term article is, I guess, just about the write-up. So I'll use research versus - what's a good word to use for the story about the research? I'm not sure. Maybe it'll just flesh itself out.
JEANNETTE: Yeah.
KATY: But anyway. Researchers use exostosis. Exostosis is the formation of additional bone from the surface of an existing bone. Exostoses are benign, meaning they’re not like a tumor - but benign, because if you look up that word it’ll say something like “benign bone growth”. But Exostoses are not benign in the fact that they’re not problematic. They’re just not malignant. They can still be symptomatic. And you are probably, listeners, already familiar with the phenomenon of exostosis. Because another word often used for exostoses are bone spurs. And one example of common exostoses would be bunions. So if that helps get a framework around what maybe some of the research is saying or what that paper was saying.
Now you have muscles all over your body and these muscles need to attach to something so they can generate leverage. If you’ve ever seen a skeleton - live or even a model or even a picture, I think - you can see that the skeleton itself isn’t really smooth. There are bumps on your bones. They're tiny areas that stick out a bit. And these tiny mountains of bone are usually what a muscle’s tendon will attach to. And they are called in anatomy protuberances or eminences. There might be another term too. And I'm not actually certain on the difference between a protuberance or an eminence. It might be the size of it where it gets classified differently.
But anyway, this is important in the HORNS discussion because the paper wasn’t explaining a new bone. I mean it certainly wasn't explaining a horn. But it wasn't explaining a new bone. Rather, the authors were discussing about an increase in length of a protuberance. Something that all skulls already have because it's where you have ligaments and muscles attaching to. And the protuberance they were discussing was the external occipital protuberance. So, external means that it’s on the outside, of the skull, in this case. Occipital is one of the bones of the skull. Your skull is not actually one bone. It's got 22 bones including the bones of the face, and there's some variation. But let's say 22 bones. And the occipital bone is the bone in the lower back of the skull, just above your neck. And protuberance just simply means a part that sticks out. So external occipital protuberance. It's this tiny little lump on the back of your skull where it provides a connection point so the parts that are attached to it can generate leverage to support your head or move your head as needed.
The paper is describing exostosis of a bony protuberance, and (anatomy is so great!) excessive growth of a protuberance actually has its own name. (Of course, it does.) And it is, I don't even know if I'm going to say it right. Jeannette, you can weigh in. It's an enthesophyte. I think. Enthesophyte.
JEANNETTE: That's how I would pronounce it.
KATY: Yeah.
JEANNETTE: I actually found this a difficult read because of that word that they used way more than they did actually exostosis. Without defining it.
KATY: That's right. And that's another issue with reading papers that are outside of your field.
JEANNETTE: Right.
KATY: Because if I'm gonna read a paper, even in biology, I feel like I'm having to - I use - every field, you say, they co-op terms from each other. There's only so many language terms. And when you're trying to describe a phenomenon you're reaching into the same pot of language. Sometimes you create new words. Sometimes you put a bunch of other Latin words together to describe a phenomenon. So they don't always mean the same thing. But they want to clarify because some bone spurs happen on smooth bone. And that has its own name. (I feel like I could be googling a lot of language.) They have their own name. And I feel like it's like an enso... and ensophyte? Do you know what it is?
JEANNETTE: So, I was actually very confused by what, by this fact that they were talking about enthesophytes but the abstract in the title had exostosis.
KATY: Right.
JEANNETTE: And what I discovered, again by googling, these are definitions that I found. That the enthesophyte was an abnormal bony projection at the site of the attachment of a tendon or a ligament. And then osteophyte was an abnormal bony projection in the joint space.
KATY: Yeah.
JEANNETTE: So my interpretation was that exostosis was the general term.
KATY: Right.
JEANNETTE: But the specific terms were enthesophyte and osteophyte. Does that make sense?
KATY: That's right. Yes. So osteophyte is the other term I'm looking for. So exostosis is, to me is the growth of it.
JEANNETTE: Right.
KATY: And the sub-classification of an enthesophyte or an osteophyte is more the location of that growth.
JEANNETTE: Yeah. That was exactly my interpretation.
KATY: And I think that the reason they have a different language is ... Levers aren't - they're not equal in length. I mean nothing is equal when you consider ... equal is not the right word. They're not exactly the same shape because your bones are being created by you as you move around. And so people who move in different ways would need different lever lengths. Our lever lengths are all different. And I think of bony protuberances as levers. They are shorter than the long levers of, let's say, the humorous or the femur. But mechanically speaking their function is the same. They're there for leverage to generate torque. And so I think it's helpful to have when you're measuring something that is bearing greater torque than say the surface of two bones that there would be a variance of it. So the fact that there are two terms makes sense to me. I think that bone spurs are probably more osteophytes. The way people are used to thinking about it - your problematic bone spur would be an osteophyte. But I would not say that a ... I mean what is a bunion? Is a bunion then an osteophyte? Probably.
JEANNETTE: That's a good question.
KATY: Yeah. But I don't know. And the thing about exostosis is, there's a mechanical process to exostosis. It doesn't mean that it's the only way that it can come about.
JEANNETTE: Right.
KATY: But the easy way that I explain it is when you have things pull on your body quite a lot the excessive pull - and excessive is relative - but let's say that more than the load that you create regularly through repetitive movements, it needs to - the tissues involved in those motions need to beef themselves up so to speak. They have to diffuse the load better. So, they can do that by changing shape a little bit. And then there's also maybe some protective features. There's maybe not only one feature - not only one problem that exostosis solves but in general the understanding of it is you're mechanically loading it so much that it has to change its shape to deal with the burden. And the paper was measuring 1200 skulls and saying this lever is longer. But it wasn't only that it's longer. So the lever length seems to change in people with age.
JEANNETTE: Right.
KATY: So, let's switch to what do you think ... Horns. I feel like horns was very clickbaity. I feel like horns tend to go - they tend to just pull up visions of demons.
JEANNETTE: Yeah.
KATY: You know what I mean? The demonizing of handheld devices or technology or "Look, now we have horns." I'm not even sure it was not on purpose that it was done that way. But there was a huge reaction. A big reaction to this idea that this idea that technology would be harmful to us. And a lot of pieces that I read were moral pieces. This is just another paper trying to make the fact that we use technology so much - a moral issue. Look we're ruining our kids. They have horns now. Instead of just trying to take the emotion out of it just to say, "Hey are there changes to our skeleton in some particular way." So I liked the criticisms where they were more here's the problems but the phenomenon is definitely worthy to look at even further.
JEANNETTE: Yeah.
KATY: My big thing is, I didn't want this for people who only read the headlines to go, "Well that was debunked, right?" I hear people say that all the time. "They debunked that." And it's like, No, that's like a battle of the media clickbaity things, and then it just falls away. The interest in the phenomenon because it's just this emotional roller coaster. I felt like this was really important to those who are interested in the impacts of movement, posture, positioning, alignment, culture. I thought it was worth a discussion because I think it's very interesting and totally relevant. What I saw though was this idea that now our future generations are gonna have horns. You know what I mean? That we are evolving. Or I think I saw a picture, you know the typical picture of someone coming out and growing out and back down to a computer and a horn, now the horns are on the end.
JEANNETTE: Yeah.
KATY: As I was talking about it with other folks - this idea of morphology. Morphology - the study of shape and what shapes us. I love morphology. I've always said that your skeleton is - it's an autobiography of sorts. Because you're writing it. But it doesn't necessarily mean that things are handed down. So I just thought it would be a really cool place to talk about why this is not that case.
JEANNETTE: Right.
KATY: How do we talk about morphology and culture? What are genetic changes? Adaptations? Evolution? Let's talk about some of the selection process so, what do you want to start with?
JEANNETTE: Ok. So these are really complex and big topics. I'm gonna try and I think we should go step by step.
KATY: Always.
JEANNETTE: And define things so that people can try and easily separate them out. And it can be challenging. Evolutionary biology is probably one of the hardest literatures to get into. So I think we should start with defining evolution. Natural selection. What different people mean by adaptation. And then bring in some culture. Talk about the role of culture and gene interaction.
KATY: Right. Ok.
JEANNETTE: Does that sound like a sensible path?
KATY: That's great. And plasticity. I'd like people to understand plasticity.
JEANNETTE: Plasticity would be good. So we'll define all those...
KATY: Ok.
JEANNETTE: ... so that hopefully if you do ever want to look at papers you will have a clear idea of what biologists mean when they say certain things and also just to see how different the mechanisms are within an organism's lifetime versus when we're talking about evolution and passing things on.
KATY: Yeah.
JEANNETTE: So I have a lot of words at this stage. So I think, Katy, if you want to interrupt me at any point with a question or something that doesn't make sense, please feel free before I go on a horrible monologue.
KATY: Right. And I think I will interrupt with this idea of what would a listener - what would their question potentially be.
JEANNETTE: Yes, I think that would be great. So evolution, I'm going to use as a very general definition is descent with modification. So what that means is really there are genetic changes within a species and since those changes are genetic they can be passed to the next generation and so forth. And that definition encompasses both large-scale evolution - so when we're talking about the descent of different species from a common ancestor. So for example, human beings, chimpanzees, and gorillas had a common ancestor at one point. So that includes that large-scale aspect of evolution and then also small-scale evolution which would be, this might sound a bit complicated but changes in gene frequency from one generation to the next. And I'll give an example because I think it's always easier to understand when you have an example. So, in the human beings, there are various hemoglobin variations. Hemoglobin is the molecule in your red blood cells that carry oxygen. And there are various mutations that change the structure of those hemoglobin molecules. And they usually have some deleterious effects like anemia. But they can also give protection against often the most lethal forms of malaria. So in certain areas of the world, you'll see a much higher frequency of those genes that code for different types of hemoglobin in areas of the world where there is lots of malaria. And you don't have that in people with European descent for instance who have for many generations been living in areas without malaria. So that's a sort of more small-scale evolution within human beings. Does that make sense?
KATY: It does for me. Everyone out there?
JEANNETTE: Hopefully!
KATY: It would be so nice if we could do Romper Room style.
JEANNETTE: I know. Hands up!
KATY: Is that good?
JEANNETTE: So that's evolution. And when we talk about selection - so this gets a little bit more complicated. So I should say one thing first; evolutionary changes can occur both by what we term selection but also by something, by chance. And that's something that people don't often realize. So the term that evolutionary biologists use is genetic drift. So evolutionary changes can occur just by chance through this process of genetic drift. And I say that not to confuse matters further, but just so that you might see that term, and we often don't realize that some changes just come about through no selective forces at all. It's just random chance. So it would be - I'll give you an example. Again, if you have 10 red ants and 10 black ants, very tiny population. And one day a deer runs through a forest and it stands on them and it stands on 7 red and 3 black. The population would be then skewed toward black ants. Not through any difference in their biological function but just because it was dumb luck. So a lot of changes that we see are not necessarily selective. So that's just to put that aside.
KATY: And then, let me just pop in here. So dumb luck, I'm trying to think of examples of dumb luck. I love your deer example. So just like natural catastrophes. Are those dumb luck?
JEANNETTE: Yeah. And those effects are much greater obviously the smaller the population. So human beings would have, back in the day, when we lived in small tribes, had pretty small populations.
KATY: Right.
JEANNETTE: So there could be a natural disaster and it's just chance.
KATY: It just left everyone who had one thing.
JEANNETTE: And I think people forget that that's sometimes there's no rhyme or reason. It's just a sampling error if you're a mathematician.
KATY: Right. It's hard not to attribute purpose to everything. It's really challenging.
JEANNETTE: It is. Which actually is interesting because often people think natural selection is purposeful. But it's not. It's really mathematical. It's not purposeful.
KATY: Right.
JEANNETTE: I'll try to explain that next. So natural selection, this is of Charles Darwin fame. So individuals with heritable traits - so that means characteristics that can be passed on. So individuals with heritable traits that favor survival and reproduction will tend to leave more offspring than others without those traits, causing those heritable traits to increase in frequency over generations. Again, that sounds like a bit of a mouthful. But if you go back to my example with the hemoglobin, there's something which everybody has probably heard of which is sickle cell anemia. Now sickle cell anemia can have some quite serious consequences. Your red blood cells, there's a very simple genetic change which results in a change in the structure of the hemoglobin molecule. And what it means is your red blood cells become sickle-shaped. They are actually more likely to burst. They're very fragile. So anemia can result along with other things. But, like I said, they also confer resistance to malaria. So in populations with high malaria, those traits would have resulted in increased survival and reproduction. So they tended to leave people with that mutation or that genetic change had more offspring and over a period of many generations, those characteristics increased in the population.
KATY: I'm just going to restate it a little bit more simply. A sickle shape to a cell is an asset in areas with malaria.
JEANNETTE: Yeah.
KATY: So because it's an asset, if you had the non-sickle shape, you would have more people not surviving malaria.
JEANNETTE: Yes.
KATY: And so those with the non-sickle shape would die off or not make more people.
JEANNETTE: Yes.
KATY: And then so what you do, is you end up over time having people with the sickle shape being successful in that environment, having more babies who have the sickle shape, they're more successful. And then over time what happens is you have entire populations that share a particular trait because that trait works well in that environment. It's not an optimal trait. It's always relative for an environment.
JEANNETTE: That's right.
KATY: I just wanted to restate it simply.
JEANNETTE: Thank you. That was way clearer than my definition.
KATY: I like both. I like both. I think there's just different types of - there's people listening with different backgrounds and...
JEANNETTE: Yeah, and I'm sorry I always talk as a biologist.
KATY: You should. You're a biologist.
JEANNETTE: It's something that I cannot get away from. That was great. That's exactly what I was trying to say in much harder words. But also, as a good example, when we look at that trait in an area without malaria, there's no benefit to it. It's actually costly. So that trait probably occurred in other populations around the world but essentially there was a negative selection when that happened. Because natural selection would favor its removal from the population when malaria is not present.
KATY: Right. So that would be a drift?
JEANNETTE: No. That's still selection.
KATY: I mean the fact that there's a randomness to sickle cell's coming on.
JEANNETTE: Ok, so no it's not drift. I'll explain what it is.
KATY: So let me just sum up the part that is... I'm just kind of checking my own. So someone else for a reason you're about to explain, had sickle-shaped cells in an area without malaria. They wouldn't necessarily survive better. In fact, it would be more of a liability.
JEANNETTE: It would be the opposite, yes.
KATY: It would be the opposite. In which case you would find people with a non-sickle cell reproducing more and you would see fewer and fewer sickle-shaped cells in folks and then you just end up in a population that has very little of that occurring.
JEANNETTE: Exactly. Your question relates to the mechanism of change. So for natural selection to work, it has to select something. So there has to be a variation in a trait. So in this case, some people have sickle cell red blood cells and some don't. And that occurred because there was a mutation.
KATY: Right.
JEANNETTE: At some point. In somebody or in several people there was a mutation. And mutation is a change in the genetic code. And it can be for a number of reasons that not everything is perfect in biology and mistakes happen. It's essentially mistakes that happen in the copying of DNA. And that change occurred presumably in one or more individuals. And then over many of hundreds or thousands of generations, the selection in the malaria areas happened. And conversely, if one of those mutations happened in a population without malaria, it would stay very low or be removed entirely because it has a negative effect.
KATY: Oh my gosh. Where to now. We could just keep going.
JEANNETTE: Yeah. I know. We could keep going.
KATY: So horns are not... I keep calling them horns...
JEANNETTE: Yeah, so there was no way that the horns or whatever else you want to call them are a genetic change. You need hundreds, thousands, of generations to really see...
KATY: And it would have to be a benefit. The person with ...
JEANNETTE: Yes.
KATY: ... the person with the change would have to be more successful in a particular environment. But then I was thinking, well, I guess if the future is all tech-based with the person with the longer lever, you know, would the neck be able to withstand larger bouts of time? And that's to me that's the loop. We are really well suited for the chair. We are really really well suited for ...
JEANNETTE: Right.
KATY: ... well, we don't know what it is. And also, one of my other points is, handheld devices is such a random thing. I mean you are looking at - this is my other critique of the paper - which is, this is the first generation, they measured 20 to 30-year-olds, which was the group. Or 18 to 30-year-olds. It's not just handheld devices. This is the first generation that's grown up completely on a computer.
JEANNETTE: Yes. Absolutely.
KATY: You know what I mean? I got my first home computer when I was probably 12. But it was such a small percentage of my life. I had two crap games. And most of them were just typing. And I never played them for more than an hour every couple of days because it was much more fun to go do other things. Everyone else was doing other things. So everyone else was drawing you into a bunch of other things. So it's really recently that children have spent so much time on the computer and also not doing anything else. Not walking, not riding their bikes, so it's not only this idea of things in our hands. I think there's a lot of interesting ways that this research can be continued upon. Because these are new skeletal environments. But will it persist? I don't think so.
JEANNETTE: Yeah. No. And the other thing is, and this is, again, maybe getting a little too complex. But when we go back to where this is what we would call phenotypic plasticity. Your skull is responding. This feature is a response to the environment. Now there's a lot of debate that goes both ways but if phenotypic plasticity could constrain evolution and it could potentially accelerate it. So by that, I mean if you already have the flexibility to deal with a situation it may constrain evolution because there won't be significant advantage to the person who mutates a, something that's constitutive. By constitutive I mean they always express this external protuberance. Because your body already has the capacity to do it if it needs to.
KATY: No.
JEANNETTE: So does that make sense?
KATY: I said no. So in my mind, I was building the example of, this is not something you're born with. Right? This is something that is increasing in length over time - over load applied over time.
JEANNETTE: Yes.
KATY: But your plasticity, your ability - sorry I'm just trying to talk myself through so you can see where I don't understand.
JEANNETTE: Yeah.
KATY: So my ability, though, for it to grow longer, my plasticity, my phenotype plasticity, that's just what it is.
JEANNETTE: Exactly. I think I haven't explained myself well. So we have that, assume, we have that plasticity. I know nothing about the genetic control of these exostoses and it seems to be from just the few bits that I've looked at through these papers that it seems to be early on in development everything - the bones and the joints and - are set.
KATY: Right.
JEANNETTE: But what I'm saying is if you say just theoretically, that a mutation occurred in development - in a developmental process that meant that you had a larger protuberance at that point - at the eop.
KATY: That you came with the gene for that, at adult you're going to have the ten millimeter...
JEANNETTE: Yep. Exactly. Which is unlikely because often development is quite constrained. But in theory, if you had that you would really have no, say there was a selected advantage again. In theory, something made you - made this impact your reproductive fitness or your survival - which again is a longshot - but let's just say that was possible or it occurred. You still have nothing over the person that has the flexibility to generate it by phenotypic plasticity. So there's no differential between you for selection to act on. So that's why there's a theory that actually our flexibility or our ability to be phenotypically plastic can actually constrain genetic change for that reason.
KATY: Um-hmm. That's why we haven't changed that much. Because our plasticity range is quite large.
JEANNETTE: It's quite large. And yeah and lots of things like this are set by regulatory path gene pathways that are very unlikely to change because they're all interlinked and it gets very complex. But it's just - it seems the situation on so many levels that it would be unlikely that we would see any evolutionary change in that feature.
KATY: Right. So I have lots of different hats that I wear. So without saying it has to be a biological takeaway or a technical takeaway, what's your takeaway?
JEANNETTE: My takeaway, I think, would be I had some issues with how the paper was written but I don't believe these guys - I think they just made some mistakes in how they present things. Or maybe not presented it in the best way. But I would definitely look at this and think habits have consequences. And these guys are chiropractors that presumably seeing something quite interesting in their population. They might have something in it. So it would definitely be if it's true that we're seeing these things in younger and younger people, its something we should be aware of in terms of our habits. And I definitely - not just from this study, but from everything else that I have read - think that extended periods of sedentary time, looking at a device has negative consequences. So, I think it's valid. I would be really interested to see what comes out of it. But as a parent it's definitely - I do not want my children to spend hours in any position for any length of time really. But I also, as a parent, have that whole guilt concept of what do I do about it. And I think that's where your work comes in so well. But we have all the issues with skulls and screens and how to navigate that. Which is super challenging, I think for our generation and our kids.
KATY: Yeah.
JEANNETTE: So. Yeah. And that's the point when I put my head in my hands and I just want to sell my house and go buy a plot of land in the middle of nowhere and but yeah. I think that's my takeaway. It's worth taking these people seriously, I think.
KATY: Yeah.
JEANNETTE: And seeing what comes out. I think now there will be lots of follow-up of this kind of thing and it will be interesting to see what comes out of it.
KATY: Yeah. I think my takeaway is probably fairly similar. I can see some of the tendency to dismiss as "these have always ranged in shape and don't worry about it." And that is true. There's always - there are many documented ranges of shape. Of course, no one has correlated them to the weights of the heads. You know what I mean?
JEANNETTE: Right. Yeah.
KATY: It was very Move Your DNA as far as the orca fin goes. Male orcas have taller dorsal fins.
JEANNETTE: Yes.
KATY: They have bigger bodies overall. So my hypothesis would be that you see longer protuberances in heavier heads. And probably males tend to have heavier heads. But you would see that there was a natural relationship between length and weight. Because that's what it's for. And also I think it's really important that none of the papers discuss your trapezius muscles. It's not just the weight of your head, it's also the tension. So that's another piece and why ...their measures of posture were poor. And I also don't think that posture is the best thing here. I think load is the bigger thing to understand. Also, two-dimensional posture measures scientifically are very poor because of the way that it's done. But anyway, if we were to do something more about measuring trapezius EMG for example, that would give us greater understanding of just the amount, just the tensions that are on this bone. It's not only the weight of the head it's all these other things. But you could do little things like bend your knees to make the weight of your head less. So there's a lot of compensation things. But anyway, that's mechanical aside. The other thing that would be concerning is that these are normal. Variance is normal. But it's kind of like a folded fin. There's a difference between seeing a few orcas with a little bend to their fin from a known accident or some known outlier and then seeing every single one who lives in a particular way with a folded fin. So you can put them under the sentence of going folded fin syndrome. We see it in the wild. We see it here. Ok, that's true. But what is the frequency and the distribution and the actual geometry? So that's what they're doing here so I pay attention to that.
JEANNETTE: Yeah. I think it would be really nice if they started to compare this data and other data sets for X-rays to fossil remains. And there's lots of collections of skulls which are presumably much easier actually to measure.
KATY: Actually measure.
JEANNETTE: And also they have populations which had very high load to the area. Like what's the term? Tumpline? Tumpline. Where they have the men and women that carried things with a band around the forehead and then they carry them and there's a baby on the back. And I think those populations are very high load to that part of the head and the neck where they're really using the neck and the back to help support the weight. I think that's where you see this as well. So it would be very interesting to see well we know that these populations have this very high load and then we compare to maybe other populations who are weavers or I'm thinking of Victorian Britain where they had people working at looms and for very long periods of time, whether those people also had these kinds of features. To try and build up a bigger picture.
KATY: A bigger mechanical ...
JEANNETTE: A bigger mechanical picture. And I hope that this paper might actually bring those two fields together. People actually do some really big big studies.
KATY: There's so much out there. Some graduate student sees this and hopefully... "that's my thesis right there."
JEANNETTE: Exactly.
KATY: But I also think that seeing something in children that you've only seen in adults is also an issue because you're setting bone - bone robusticity and bone density are interesting. I don't know if this would fall under plasticity. You kind of set limits when you're a child for your skeletal experience as an adult.
JEANNETTE: Right. Yeah.
KATY: And so and the people who do have larger protuberances, there's surgery for it. It is not symptom-free. So that was another thing that was expressed. It's like we're seeing this thing that has known - whatever a shape - so what. Well, there's symptoms and surgeries associated with this shape, and the fact that it's becoming more ubiquitous perhaps, and at a younger age this would be predicting the experience for a group of people and then trying to figure out why. And I also think that with technology, whether this is technology or whatever it is. I mean weaving was technology at some point. And people figured it out and we've been trying to get away from it.
JEANNETTE: Yeah.
KATY: I'm very hopeful. When I think of smoking - if I look at TV movies from the 50s and the 40s and photos, everyone was smoking. They were smoking on TV. Doctors were smoking.
JEANNETTE: Oh yeah.
KATY: There were no good use practices around it. And technology has come on so quickly there are no good use practices around it. And I think that we're pretty good at recognizing an issue and then trying to put safety practices around it. Right? We've done it with... I've had this dream of doing this video, you know, just about the addictive nature of let's just say handheld. If you think of every time you picked up your phone. It's on the toilet. It's in your car. It's all these sites. Imagine if you just had a flask and were taking a nip out of your flask.
JEANNETTE: Oh yeah, that's true!
KATY: And taking a video of just like drinking it. This would be a problem if it was alcohol. If you were taking little sips of it while you're sitting at a stoplight because you couldn't go for a full 11 minutes without checking...
JEANNETTE: I can't tell you how much I love that picture on so many levels.
KATY: Can you imagine a little video of "this would be a problem" and then just do it with the phone to get some context for what it looks like? And that's another thing. I don't think that technology requires a head position. That's the other assumption here.
JEANNETTE: Yeah.
KATY: That's the other takeaway for Move Your DNA. Part of what we're trying to do is how do you participate - how do you not miss the note from your office but don't have to get a horn about it? You know what I mean?
JEANNETTE: Yes.
KATE: The horn is a load. The cell phone is not triggering a bone growth. They're talking really about this idea that how you use your body affects its morphology or its phenotype.
JEANNETTE: Yep. Wonderful.
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This was a conversation between biologist Dr. Jeannette Loram and I, edited down from a much longer podcast episode. You can find the entire hour and 40-minute conversation in Episode 119: Taking Bone Mechanics by the Horns. Jeannette teaches movement classes and courses, including our Move Your DNA workshops in Scotland and England. Learn more from here at jeannetteloram.com (that’s Jeannette with two n’s and two t’s).
Further, as Jeannette suggested they would, the authors posted an ‘Author Correction’ that updated the original article to replace the language that implied any causal links between smartphone and the head’s bony shape that they were evaluating, while still maintaining a call for postural improvement education. Hey, that’s what I do!
So, I will link to that correction in the show notes.
Also, where do things stand on the bony development five years later? As you can imagine, it’s a mixed bag. There are actually lots of research articles on this topic. They were starting to roll out before this one got headlines and they've come out since then in different journals: journals of radiology (so those are journals that focus on bone imaging), biomechanics, and medical journals. And, I really think we're just at the beginning. Remember as ubiqudous as it feels this type of handbased tech, handheld tech is a decade old. So this is my general takeaway from the research that I’ve read (and I'll link to some of it in the show notes): Looking at adult populations pre and post the introduction of the i-phone or smartphone showed that a variance in this horn length (ha ha) isn’t significantly different in adults of a variety of ages. So it wasn't looking at younger people who are more malleable in tissue. This kind of most recent 2021 article was looking at adults of a variety of ages from 20, over 18 certainly, to 80. Others are talking about that growth like this could be mechanical, genetic, or inflammatory. Holding space for all of those pathways. But one paper in a journal called Clinical Biomechanics that was looking at teenage skulls concluded that the mechanical was important because in their sample, at least, there wasn’t any genetic or inflammatory factors. But what was most important to me, in that paper, is that the individuals that they were looking at were getting imaging because of poor posture (so, poor posture is measured clinically by a rating called a forward head protraction value. And it's a measure of how far forward the head is.)
So this really feels in line with my own personal hypothesis, which of course always stays flexible. But looking at general populations and phones use generally “in the culture” (how many decades have phones been available to this culture) is tricky this early on because people really use them at different frequencies and distributions. And I would say that phone use, even smartphone use, looks radically different in the last couple of years as it did to the preceding years, as it did to the early years. Right? Like we can't even really say phone use. That's already not very nuanced. So we have different frequencies and distributions of phone use. And also people have different relationships with posture and movement overall. You using the phone in a particular, in sort of an upright posture where you're maintaining your head position is going to be completely different that you curled all forward, fetal position, around your phone for a few hours a day. You doing it with a younger body is going to be different that doing it with an older body.
So I think, my educated guess is what we’ll end up seeing is more of a “posture problem” more than a “phone problem.” They are certainly related - at least for some people. But as the variety in the ... I keep wanting to say horn ... in the variety of the horn shape that we are seeing might already be showing not that forward head doesn’t have an effect, but there’s a range to “how far forward you wear your head and how often.” And some people are relatively more “taxed” mechanically by forward head position (If they have heavier heads, if they have taller bodies, or longer necks - their anthropometric dimensions we call them) and some people will just be much less mindful with their position when they're on the tech. They're not necessarily heavier in body parts or longer in segments, but they just hold themselves in a more curvy-spined way.
So I know it's nuance but keeping all this nuance is helpful because we are gonna want to keep tech and the way we use it separate in our minds. Why? Because if you try to show “a phone” or any technology as “the cause” and not something that relates to the physical posture, then when tech isn’t teased out to be the universal cause, it's very easy to just be like, “see, phones aren’t doing anything to our bodies.” This is where it's been debunked. Or this is where this is proven. Which isn’t necessarily true, even in the case of bony shape. But that will be the way it will be interpreted and shared for Google searches everywhere on “Is this a thing.” We've already seen in the earlier part of today's show how something like that can go.
We already know the relationship between position and mechanical loads and how these loads can change the state of our tissues. And, we can all learn about and mind our position to reduce mechanical loads to the neck which only serves us positively, and also make sure our general movement diet includes a variety of movements…not only screen-based ones.
Ok. This episode was brought to you by my NO-MORE TECH NECK STICKERS. What are those? These are repositionable decals that you put on your phone or computer screen (so they don't leave a sticky residue) that remind you there’s a different way to hold your head when you’re on tech. Tech, if I haven't said that already in this episode, does not require tech-neck. We just tend to take our posture habits into whatever we do. So you take these tech neck decals and you stick one of them into the corner of your device. And it's got this little tiny graphic that shows you “how to ramp your head” (which is a head adjustment that you make that changes the curve to your upper back and neck in an instant). It's an environmental modification that makes your tech-time friendlier on the old bod. So, get a strip of 7 decals for all the devices in your home for $7 at my website, nutritiousmovement.com/techneck (all one word - nutritiousmovement.com/techneck.) Decals also come with an instruction card that has a link to a video that demonstrates how to do the head ramp move. And it shows you when you're using your phone. These are some of the ways we stand up straight when we're on our phone but there's a way of standing - there's a way of adjusting your head and neck that really targets the cervical and the upper back curvature that we were discussing earlier. Those curves that really end up creating tension and pull on the bones of the skull when you're in this forward head position. Anyway, I'm getting off my soapbox now!
SWIPE RESPONSIBLY, FRIENDS. This is me, KB, SWIPING LEFT. (swipe sound)
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Hi! My name is Lynn Barron. I'm from Melbourne Australia. This has been Move Your DNA with Katy Bowman, a podcast about movement. We hope you find the general information in this podcast informative and helpful. It is not intended to replace medical advice and should not be used as such. Our theme music was performed by Dan MacCormack. This podcast is produced by Brock Armstrong. And is transcribed by Annette Yen. Make sure to subscribe to this podcast wherever you listen to audio and find out more about Katy, her books, and her movement programs at NutritiousMovement.com.
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