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Short Stuff: Why do kangaroos hop? · Stuff You Should Know

• 0:04
  Speaker 1: Hey, and welcome to the Short Stuff. I'm Josh, and
• 0:06
  Speaker 1: there's Chuck and Jerry's here for Dave, where we're just
• 0:08
  Speaker 1: hopping along talking about kangaroos and how they hop.
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  Speaker 2: That's right. I want to thank our old colleague Kristin
• 0:16
  Speaker 2: Conger for writing this article from How Stuff Works back in.
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  Speaker 1: The day and creator of Unlady Like the podcast too.
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  Speaker 2: As well as Jennifer Horton wrote another article that I used.
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  Speaker 1: Great to hear Jennifer and then take.
• 0:30
  Speaker 2: The San Diego Zoo website and nat Geo all pitched
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  Speaker 2: in for this one.
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  Speaker 1: I thought this was a particularly well researched short stuff,
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  Speaker 1: so I should have known that Jennifer Horton and Kristin
• 0:41
  Speaker 1: Conger had something to do with it.
• 0:43
  Speaker 2: Yeah. So we're talking about kangaroos a little bit, mainly
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  Speaker 2: going to get to how and why they hop, but
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  Speaker 2: we should start out by talking about the fact that
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  Speaker 2: rus are marsupials or pouched mammals, because they have a marsupium,
• 0:57
  Speaker 2: which is a little pouch where their little joey develop.
• 1:02
  Speaker 1: Yeah. We talked to think a lot about this in
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  Speaker 1: the Naked Mole Rat episode where essentially like the marsupial
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  Speaker 1: fetus does not develop as long inside the body of
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  Speaker 1: the mom as it does inside the pouch. Essentially, at
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  Speaker 1: some point it's what you would call born, but really
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  Speaker 1: it's just crawling out of the birth canal outside into
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  Speaker 1: the world for a second, and into the pouch. And
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  Speaker 1: then the little Joey latches onto a nipple in there,
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  Speaker 1: and the nipple grows three times in size, just like
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  Speaker 1: the grench's heart, and so the little Joey couldn't let
• 1:37
  Speaker 1: go of the nipple even if he or she wanted
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  Speaker 1: to until they develop a little further. It's quite ingenious.
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  Speaker 1: Hats off natural selection. That's a great one.
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  Speaker 2: Yeah, that's maybe the fact of the podcast for me.
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  Speaker 2: That's kind of nutty.
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  Speaker 1: Oh, I'm sorry I took that. I didn't realize that
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  Speaker 1: it was.
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  Speaker 2: What do I have to always take the fact of
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  Speaker 2: the show?
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  Speaker 1: I like to, you know, I.
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  Speaker 2: Mean, I know it's in my contract and not yours,
• 1:59
  Speaker 2: but I'm willing to give every now and then.
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  Speaker 1: That's very generous of you, think you.
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  Speaker 2: All right, So Australia is obviously what people you know,
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  Speaker 2: what comes to mind when you think of marsupials in general,
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  Speaker 2: because koalas and kangaroos. But we have done a great
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  Speaker 2: episode on the opossum, which live all over the place,
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  Speaker 2: especially North Central and South America. But we're talking about
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  Speaker 2: kangaroos and wallabies here because they don't have four legs
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  Speaker 2: like our opossum friends. They have two big old feet
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  Speaker 2: and two little littler arms.
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  Speaker 1: Yeah, that's a great way to think about it. They
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  Speaker 1: don't have four legs. They have two legs and two arms.
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  Speaker 1: And it makes sense like if you've ever seen a kangaroo,
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  Speaker 1: or you just bring one to mind, if you're capable
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  Speaker 1: of using your mind's eye. They're sitting on their feet
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  Speaker 1: and they're standing or sitting up right, and they're little
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  Speaker 1: almost Titanica arms are just kind of hanging out there,
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  Speaker 1: not doing much of.
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  Speaker 2: Anything, Yeah, except boxing, probably the kangaroo. The first sightings
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  Speaker 2: apparently traced back to a Dutch merchant named Francisco Pelsert
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  Speaker 2: who got shipwrecked off the coast of Australian sixteen twenty nine,
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  Speaker 2: and about one hundred and fifty years later they were
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  Speaker 2: pretty well known throughout Europe and by seventeen ninety one
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  Speaker 2: they had brought those things over to London.
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  Speaker 1: England, here's the fact of the podcast for me, Chuck, Okay,
• 3:21
  Speaker 1: can I take this one too? Or should I tee
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  Speaker 1: you up?
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  Speaker 2: No? Double up? Baby.
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  Speaker 1: So the name kangaroo the word, as far as anyone
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  Speaker 1: is able to say, we don't know for sure. It's
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  Speaker 1: apparently an Aboriginal word for I don't know. Isn't that awesome?
• 3:38
  Speaker 1: I don't know.
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  Speaker 2: That's pretty funny, it is. Here's the deal, though, is
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  Speaker 2: kangaroos are the only large mammals to hop. And that's
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  Speaker 2: basically as like they're you know, bunnies will hop a
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  Speaker 2: little bit, but the kangaroo moves around primarily by hopping,
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  Speaker 2: and I guess you wouldn't consider a bunny a large
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  Speaker 2: mammal anyway. Here's the deal. If you go back to
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  Speaker 2: twenty five million years ago and look at the fossil record,
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  Speaker 2: they didn't hop because Australia was a rainforest at the time.
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  Speaker 2: So those kangaroos were climbing around for a long long time.
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  Speaker 1: Yeah, So they actually developed what ends up helping them
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  Speaker 1: hop long before they actually started to hop. We called
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  Speaker 1: it the fourth toe. If you look at a kangaroo's foot,
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  Speaker 1: you can see how it's how it's hopping, and Chuck,
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  Speaker 1: I think I've kind of set us up for an
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  Speaker 1: ad break and we're gonna come back and finally talk
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  Speaker 1: about how kangaroos hop. What do you think?
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  Speaker 3: All right, let's do it shop shop stop.
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  Speaker 1: Okay, where I left off, Chuck, I was talking about
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  Speaker 1: the fourth toe, and this is the this is the
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  Speaker 1: design element that allows the kangaroo to hop. Because if
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  Speaker 1: you look at a kangaroo's foot, the first toe, looking
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  Speaker 1: at the kangaroos foot from the inside of the foot outward,
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  Speaker 1: the first toes pretty puny, might not even be there.
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  Speaker 1: The second and third toes they're okay, they're like smallish
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  Speaker 1: and they each have a nail, but they seem to
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  Speaker 1: be fused together to like web toes. Almost Then when
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  Speaker 1: you get oh, yeah, I didn't know she had web toes.
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  Speaker 1: Is she a fast swimmer?
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  Speaker 2: That's what everyone always asked. It's just the second third
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  Speaker 2: toe on one foot or had always been stuck together.
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  Speaker 1: But surely it would have to give you an advantage
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  Speaker 1: to some degree. I don't know.
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  Speaker 2: I can't remember the last time I swam with her.
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  Speaker 1: Well, next time you get a chance to race her
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  Speaker 1: and let me know how it turns. Out all right.
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  Speaker 1: Finally we get to the fourth toe, and the fourth
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  Speaker 1: toe is like this, this massive beast of a toe,
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  Speaker 1: and it's in line with the the leg bones of
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  Speaker 1: the kangaroo's legs, and this is where the actual hopping begins.
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  Speaker 2: Yeah, that's an actual adaptation, and like you said, that
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  Speaker 2: preceded their ability to hop. So I'm not even sure
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  Speaker 2: what the deal is with why they adapted that to
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  Speaker 2: begin with. But I mean, maybe it's just because they
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  Speaker 2: went from rainforest to sort of dry, grassy planes and
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  Speaker 2: they needed to get around more, and they don't know
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  Speaker 2: learned it eventually. They do have a fit though, we
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  Speaker 2: should mention that provides a little bit of support. But
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  Speaker 2: if you look up like the foot of the hind leg,
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  Speaker 2: like you know, from behind, they have these really I
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  Speaker 2: mean you can't see because it's on the inside, but
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  Speaker 2: they have these really strong elastic tendons that store energy
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  Speaker 2: up for those massive, massive jumps.
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  Speaker 1: Yeah, like a spring. When they go downward, all of
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  Speaker 1: that tendon gets a bunch of energy, kinetic energy stored
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  Speaker 1: in it, and then when they bounce upward, it gets
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  Speaker 1: it's released, and it can send them flying. Chuck. I
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  Speaker 1: had no idea how far they can hop and how
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  Speaker 1: fast did you?
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  Speaker 2: Yeah, but it's always fun to relearn that, you know,
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  Speaker 2: because it's pretty astounding.
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  Speaker 1: Okay, so they can go up to fifteen to twenty
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  Speaker 1: miles per hour. Yeah, and for those of you in
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  Speaker 1: Australia who don't know, that's about twenty four to thirty
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  Speaker 1: two kilometers per hour. That's fast. That's like golf cart
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  Speaker 1: speeds at top speeds.
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  Speaker 2: Even that's faster than a golf cart.
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  Speaker 1: Yeah, and then it can propel itself about twenty five
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  Speaker 1: feet forward, almost seven or more than seven and a
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  Speaker 1: half meters and six feet high. Yeah, nearly two meters high.
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  Speaker 1: So we could jump right over either of us chuck.
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  Speaker 2: Yeah, absolutely. I mean you're taller than I am, so
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  Speaker 2: you might get your forehead grazed.
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  Speaker 1: It could just barely clear me. I'm five foot eleven
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  Speaker 1: and a half if I'm fully honest.
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  Speaker 2: Yeah, they would look at me and just be like,
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  Speaker 2: no problem, shorty.
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  Speaker 1: They just free willy right over you.
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  Speaker 2: I used to be five to ten, now I'm more
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  Speaker 2: like five to nine. I'm shrinking, as we all argue, yeah,
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  Speaker 2: what is up with that? You shrink?
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  Speaker 1: You know are? But I mean does that mean our
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  Speaker 1: vertebra are fusing together, or like our knees are getting shorter.
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  Speaker 1: Have we compacted the shin bones and our legs and
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  Speaker 1: that's what's doing it? That doesn't make any sense.
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  Speaker 2: To well, we should do an episode like a shorty
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  Speaker 2: maybe on the shrinking as you age, because that's it's
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  Speaker 2: definitely a thing. That's why, like you see an old
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  Speaker 2: man that has these giant ears, they didn't always look
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  Speaker 2: that way.
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  Speaker 1: Oh I didn't know that. Yeah, wow, what a development.
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  Speaker 2: All right, So back to the kangaroo, we need to
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  Speaker 2: talk about their tails a little bit because they have
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  Speaker 2: those huge tails that act as a counterbalance to the
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  Speaker 2: hind feet. So if you look at a kangaroo hop,
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  Speaker 2: that tail moves down like in mid air, that tail
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  Speaker 2: is moving down to meet kind of where the feet are,
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  Speaker 2: and when they land, the tail raises, so it kind
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  Speaker 2: of just does this little opposite motion to balance everything out.
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  Speaker 1: And it makes a really satisfying, boring sound.
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  Speaker 2: Of course.
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  Speaker 1: So what's great about this? You said that the kangaroo
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  Speaker 1: is the only land animal that or an only large
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  Speaker 1: mammal that hops, and the reason why it hops is
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  Speaker 1: because it's actually a tremendous adaptation for moving quickly across
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  Speaker 1: land in a really efficient manner because the way that
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  Speaker 1: the kangaroo is built, the bast they hop, the less
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  Speaker 1: energy they have to expend. It's a pretty beautiful system.
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  Speaker 2: Yeah, it's pretty crazy and one of the most efficient
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  Speaker 2: travelers in the animal kingdom overall. You know that, Like
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  Speaker 2: you said, they had that great range. And part of
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  Speaker 2: what's going on with their efficiency is is they have
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  Speaker 2: a like when they're bending down to jump and then
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  Speaker 2: leaping up, that's contracting and suppressing their respiratory system, which
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  Speaker 2: actually is like makes it more efficient. It makes those
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  Speaker 2: stomach muscles contract and expand and just forces air in
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  Speaker 2: and out without like having to do so, you know,
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  Speaker 2: by using your own energy.
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  Speaker 1: Yeah, and they also have to use less muscle energy
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  Speaker 1: in their legs because when they jump really far high
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  Speaker 1: and fast, when they land, those super elastic tendons that
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  Speaker 1: help them hop just contract even further, and that means
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  Speaker 1: that they expand or spraying i think is the technical term,
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  Speaker 1: even further. So when they get going, they really can
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  Speaker 1: just they can just keep going a while. They're also
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  Speaker 1: their heart is really attuned to this kind of endurance
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  Speaker 1: workout right. Yeah, it's when they're not going fast. When
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  Speaker 1: they're just kind of hopping from place to place in grazing,
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  Speaker 1: that's when it's harder and they have to end up
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  Speaker 1: using their tail to kind of balance themselves as basically
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  Speaker 1: like a well a third foot.
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  Speaker 2: Yeah yeah, why does it say fifth in here?
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  Speaker 1: That's so weird? I know, because they specifically said that
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  Speaker 1: their two front arms.
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  Speaker 2: You know, hey, well maybe i'll get in touch with
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  Speaker 2: the color. It gives me a good reason get in
• 11:00
  Speaker 2: touch with her. Say what the hell did you mean
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  Speaker 2: this fifth leg thing all those years ago?
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  Speaker 1: You're going to ruin her week?
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  Speaker 2: She's like, who is this?
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  Speaker 1: Right?
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  Speaker 2: I guess we'll close quickly, just on a little you know,
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  Speaker 2: I mentioned the wallaby the slight differences between the wallaby
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  Speaker 2: and the rue. Mainly it's the kangaroo is just a
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  Speaker 2: lot bigger. They have a lot more link between their
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  Speaker 2: ankles and their knees, and they're just taller. They can
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  Speaker 2: be like eight feet tall, whereas a wallaby is maybe
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  Speaker 2: like three feet a little over.
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  Speaker 1: Can you really say it any other way than that?
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  Speaker 2: I don't think so.
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  Speaker 1: I mean, why would you anyway? Yeah, this is probably
• 11:36
  Speaker 1: long after your wheelhouse, But did you ever watch Rocco's
• 11:39
  Speaker 1: Modern Life.
• 11:40
  Speaker 2: Never heard of it.
• 11:42
  Speaker 1: It's a great cartoon. Yeah, it's a cute little cartoon.
• 11:46
  Speaker 1: It was on Nickelodeon and Rocco was a wallaby.
• 11:49
  Speaker 2: Oh nice.
• 11:51
  Speaker 1: Did you ever watch Dark Winged Duck?
• 11:53
  Speaker 2: Never heard of it?
• 11:54
  Speaker 1: No, that's not it. What was the Duck with Jason
• 11:57
  Speaker 1: Alexander as the duck?
• 12:00
  Speaker 2: Oh, I don't think. I don't think I know of
• 12:01
  Speaker 2: such a show.
• 12:02
  Speaker 1: It was like a raunchy com like superhero duck show that.
• 12:08
  Speaker 1: It's pretty good. Whatever the name of it was. Look
• 12:10
  Speaker 1: it up. Jason Alexander, George f and Seinfeld played the
• 12:14
  Speaker 1: main duck.
• 12:14
  Speaker 2: Oh wow, and that was a good one too.
• 12:17
  Speaker 1: Yeah. I think Dark Wing Duck is like a Duck
• 12:19
  Speaker 1: Tails spin off. That's not what I'm talking about.
• 12:22
  Speaker 2: All right, Well, I mean if we're recommending animated shows,
• 12:24
  Speaker 2: I might as well. And we're in Australia, I gotta
• 12:26
  Speaker 2: recommend Bluie again. Still watch that?
• 12:28
  Speaker 1: Okay? I never watched that one. Yeah, So, stepping out
• 12:32
  Speaker 1: of the animated shows, but continuing with the recommendation, I
• 12:36
  Speaker 1: watched the Jake Gillenhall movie Enemy last night. Oh yeah,
• 12:41
  Speaker 1: it was Denis. Have you seen it?
• 12:46
  Speaker 2: Yeah, I saw back back then.
• 12:48
  Speaker 1: Man, it is a good movie.
• 12:50
  Speaker 2: Yeah, crazy ending, yes, but.
• 12:53
  Speaker 1: So like it was one of those movies that I
• 12:55
  Speaker 1: was like just sitting there thinking about it afterward, and
• 12:58
  Speaker 1: so I love those If you go look them up online,
• 13:02
  Speaker 1: there are people who have given great thought to explaining
• 13:05
  Speaker 1: these things, and I found, I think, on slash Film
• 13:09
  Speaker 1: a really great explanation of what was going on. But
• 13:12
  Speaker 1: before warned if you watch Enemy, you may regret reading
• 13:18
  Speaker 1: the explanation of it. It's almost to me it was
• 13:21
  Speaker 1: better before I knew, and I just had to accept
• 13:24
  Speaker 1: it on its own terms.
• 13:26
  Speaker 2: Yeah, love that movie.
• 13:28
  Speaker 1: All right, Well that's it for Enemy, and that's it
• 13:30
  Speaker 1: for obviously kangaroo hopping. Right, that's right. Short, Stuff is that.
• 13:37
  Speaker 2: You?
• 13:38
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