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In this episode of the SciShow talk show, Michael and Hank discuss human posture and evolution and Hank shares some personal information, and then Jessi from Animal Wonders shares Leonard, the legless lizard.

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[intro music]

Hank Green: Hello and welcome to a special episode of the SciShow talk show, and it's special for like no other reason than Michael Aranda is here. Woo! Can we just put in some fake applause there? [applause]

So, here on the SciShow talk show, we talk and it's SciShow. That's how it works, and, uh, today Michael has... are you going to try to stump me?

Michael Aranda: I have a stumpy question for you.

Hank: Do you have anything besides a stumpy question?

Michael: No.

Hank: So we're just going... I'm going to attempt to be not stumped, and then we're gonna see an animal.

Michael: Mm-hm.

Hank: So, you're ready now. You know what's coming. Do your thing.

 Stump Hank

[Stump Hank card]

Michael: So, this should be, um, relevant to everybody who sits in front of their computer for hours on end. [Hank raises his hand] Why is it that if sitting up straight is the good, natural, healthy way to sit, why does slouching feel so good?

Hank: I am definitely a sloucher. Emily, who Michael works with on the Brain Scoop, she has amazing posture, and I'll look at her and I'll be like "something's weird about you," and then I'll be like "oh, it's that you're sitting up straight".

Michael: Alex Day also has, like, perfect posture.

Hank: Yeah, always. Yeah, and I'm like, is that.... I'm like, it feels like in this ultra-slouchy culture almost like an affectation, because that's not what we do. We're like.... This is how I watch movies. [slouches really low] Like, as time goes on, just lower...

Michael [slouched]: This is weird because we're like thrusting our crotches at each other.


Hank: I'm stuck...

Michael: Good! Glad that's on video.

Hank: Um, I mean, to me sitting up straight is active, and slouching, I'm resting on, like, my ligaments and bones and the connections between all of it, and that's... there's no... I'm not exerting any energy to be in that position. I also, like, I have a problem where I get closer and closer to the screen that I'm watching, and so I have this, like, terrible forward neck, and I try to fight it, and whenever I put my neck back it's like *creak* I can hear it in my ears.

So that's my answer. I think it's because it's a less active... your position to sit in.

Michael: You're pretty close there. Naturally, your spine is held up by the ligaments that go down your spine.

Hank: It's an amazing interwoven web of connections. I will be amazed sometime. I will be experiencing a pain somewhere, and then I will realize that the pain has nothing to do with the place that I'm experiencing the pain, and it actually... I have a limp, because I have arthritis in my foot, and so I will get neck pain because of my foot.

Michael: That's strange.

Hank: And I'm like, "God dang it, I should not have broken that toe in seventh grade." [photo of seventh-grade Hank] My whole life, just ruined by one pool party! Tom! There was a guy named Tom; I pushed him in the pool and I broke my toe on his foot. It's all his fault.

And that's why my neck hurts.

Now continue!

Michael: So, um, naturally, our ligaments are meant to hold us up in the upright position. When you slouch, you stretch out the ligaments over time, so someone who is a chronic sloucher... you're stretching those ligaments out, which means to sit up you have to rely more on the muscles in your back than is natural, so it feels more active, like you said. You have to be engaging those muscles to stay upright, and it just feels like you're more relaxed when you don't use those muscles and you're just resting on wherever your ligaments are holding your back up.

Hank: So does that, like, in the history of humankind, was there a period when slouching was less common or less, or we were less able to slouch, or we... you know.

Michael: As far as I understand it, the human spine is not all that wonderfully designed for the way that we walk, 'cause we're bipedal, but we weren't always bipedal.

Hank: It's a recent evolution.

Michael: We've rotated upwards, and so the human spine is not as robust as theoretically it could be, given another few million years of evolution.

Hank: So you're saying that I'm slouching because, in a sense, my ancestors were more hunched because they were quadrupedal.

Michael: I don't know. I'm saying you're slouching because you're slouching. It's a vicious cycle.

Hank: I think the -- I think that the argument could be made. It's also that I'm slouching 'cause I'm slouching. But our spines aren't particularly well designed because we are such a recent evolutionary innovation, and so we slouch because we are only recently bipedal.

Michael: There is good news, though. Your ligaments will...

Hank: No they won't.

Michael: They will. It takes longer...

Hank: But I won't.

Michael: Right, but if you at home would like to improve your posture, your ligaments will shorten over time. It takes much longer for that to happen than for them to lengthen, so you have to be really pro-active about sitting up straight, and over time your posture will improve.

Hank [sitting straight]: It hurts already.


Hank: Well, thank you for that fascinating bit of insight into my body. I am now.... Now I know not to be disappointed in the body but just in myself.

Michael: Yeah.

 Special Guest

Michael: I'm ready for an animal.

Hank: You're ready for an animal? You know what you're gonna see?

Michael: I don't know.

Hank: You don't know.

Michael: Is there still time to pick?

Hank: I don't know. I don't think so, I think it's just gonna show up. Maybe there'll be time to pick.

Michael: Whatever; I'm ready.

Hank: It's just gonna show up.

Michael: I'm ready. Let's see it.

[Special Guest card]

Hank: This is Jessi from Animal Wonders, and she has brought for us a very unique treat.

Michael: Treat, is it?

Hank: It's a treat.

Michael: A treat?

Hank: Yes.

Michael: I think of "treat" as, like, [mimes eating] "these are tasty treats, mm".

Hank: I feel like I'm being treated right now.

Jessi Knudsen Castañeda: I hope you don't wanna eat him.


Michael: I don't; that's why I'm saying.... Let's continue with the, uh, the SciShow talk show.

Jessi: Sounds good.

This is Leonard. Leonard. I want you to guess what Leonard is. What kind of animal does he look like?

Hank: I've been told that Leonard is not a snake.

Jessi: He's not a snake. He sure looks like one.

Hank: I have been pre-informed. Yes.

Jessi: He looks like a snake, and that's kind of a misnomer. A lot of people think any animal without legs, you know, that's a reptile, is a snake, and that's not true. This is actually a lizard. It's a legless lizard.

Hank: I mean, I can tell that it looks different from a snake -- it's a little shorter, it has different, sort of, quality of skin, the facial structure is very different...

Jessi: Yeah.

Hank: And it also has this very interesting muscle contraction going on along the side of its body, and I wanna know what that is.

Michael: I also felt like.... The few times I saw him stick his tongue out, it looked different than I've seen snake tongues.

Hank: Thicker.

Jessi: Yeah. Yeah, let's talk about all those things. Let's talk about that face first, you know. Only a face a mother could love.

Hank: I don't know; I think he's handsome.

Jessi: He's pretty neat.

Michael: He's got a kind of a dragon face.

Hank: Yeah, dragon face, totally.

Jessi: Little scowl. Yeah. Well, that's gonna be the biggest indicator of why he's not a snake. There's two things that he has on him that snakes do not have.

Hank: Ears.

Jessi: Ears, yes -- an external hole for the ear. Now, snakes do have ears, it's just covered by skin. It's a different kind of ear. But he does have those tiny little holes, very back of his mouth there. And the other thing.... Do you know the difference, the other one?

Hank: Well, I was seeing, and I felt like the cloaca was much further up the body.

Jessi: Well, that is true. Let's stick with the head, and then we'll move back to the rest of the body.

Hank: Okay.

Jessi: The head. On its head, its eyes are different. So, a snake does not have eyelids. They can never close their eyes. They have an actual spectacle over their eye, a scale over it. These guys have actual eyelids. So lizards have eyelids and external ears.

Hank: And that, yeah, the eyelid I feel like gives them a little more personality -- makes them a little.... There's something a little more inhuman about a snake because it doesn't have those eyelids.

Jessi: Yeah. It's that stare, and they don't, kind of... as much expression.

Yeah. He's got eyelids and he's got those ears. So then, let's travel on back his body, this neat muscle contraction you were talking about there. Not the movement -- that line he's got going down there.

So, snakes are really neat. They can expand their body to eat. Y'know, this guy can't do the same type of expanding to eat something huge; he can only fit the size of his mouth. He can only open his mouth and fit something to eat, and he's gonna eat insects and other really tiny things like, uh, baby mice and stuff like that.

But when it gets back to his belly, he wants to be able to eat as much as he can in the eating, so that line down his belly here is gonna help him expand.

And then, you're right, his cloaca. Can you see where it starts?

Hank: Yeah. It's, like, not even half way down.

Jessi: Right there [points] is his cloaca, and on a snake it would probably be closer to over here [points much further down]. But yeah, more than half his body -- about two thirds of his body -- is made up of tail, and that is.... He's called a legless lizard. He's also known as a glass lizard.

Hank: Right.

Jessi: And so he has this neat moving ability. He will roll -- oh yeah, he'll do it, he's gonna do it on his own there. If he's grabbed by a predator, say, most likely by his tail because that's the main part of his whole make up, yeah. We grab by his tail here, he'll do that rolling movement (we call it an alligator role) and it will break off his tail into actually several different pieces. People say it looks like shattering glass. Then all of those pieces will move around, y'know, the predator is completely confused -- one animal turned into five.

Michael: Moving around as in, like, still doing muscle contractions?

Jessi: Yeah, yeah! Flipping around on the ground, mm-hm. There he goes. See that neat movement?

Hank: Yeah. That's something that I've never seen a snake do.

Jessi: No, they don't really do that. He does that. That's kind of his, his...

Hank: And I feel like he's harder. I don't know if that's just...

Jessi: He's not as flexible, yup.

Hank: Right.

Jessi: He can't move like a snake does; he has a harder body, a not as flexible body.

And you were talking about his tongue? He had that tongue there. It's not.... It is forked, just a tiny bit, like little nubbins instead of, say, fingers like this [stretches two fingers], it's like this [curls two fingers].

Hank: It's also making a noise.

Jessi: He's hissing a little bit, yeah! [laughs] He's saying, "Hey, you know, I wanna get down into my little burrow, not in these bright lights on a table here." That's his thing.


Hank: This is a very cool animal. Thank you a lot for sharing him with us.

Jessi: Yes, thank you for having us. Say thanks, Leonard!

[Hank and Michael wave at him]

Hank: Thank you for joining us for this episode of the SciShow talk show. Thanks to Animal Wonders for bringing in the animals, and for Michael Aranda for being himself. Goodbye!

[outro music]