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Welcome to this episode of SciShow Talk Show! This week Hank talks with Jeff Good & Jessi Knudsen Castañeda with a Netherland Dwarf Rabbit named Cheeks.

Hosted by: Hank Green

Jeff Good: http://good-lab.dbs.umt.edu/Good_Lab/Home.html

Animal Wonders: https://www.youtube.com/user/Anmlwndrs
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[Intro plays]

HANK: Hello and welcome to the SciShow Talk Show, that day on SciShow where we talk to cool people about the cool things that they're doing. Right now, we have with us Jeff Good, who works at the University of Montana, and is an evolutionary biologist studying domestication of rabbits. So, you spend a lot of time with bunnies, that can't be too bad.

JEFF: Nah, nah they're ... agreeable.

HANK: Yeah are you... are you just sorta over it?

JEFF: Am I over bunnies?

HANK: Or do you not like, did you not like them to begin with.

JEFF: Yeah, it's a complicated relationship, but I generally find them pretty interesting.

HANK: You find them interesting but not so adorable? 'Cause when I think bunnies I think of putting it on my face and *blbulbulbulbuubrum* like that. Not so much?

JEFF: That's odd that I haven't done that.

HANK: You have the opportunity, you could be doing it all day!

JEFF: I know! Yeah, I have that opportunity.

HANK: Um, I'm sure there are many fascinating things about what you're studying right now, but what struck us here at SciShow is rabbits giving us insight into how the domestication of animals happens. Why are rabbits good at this?

JEFF: Well, so rabbits are really useful for this because they're a relatively recent domestication event, so rabbits were domesticated about 1400 years ago.

HANK: That seems like a pretty long time ago.

JEFF: A pretty long time ago, but much more recent than a lot of other domestication events, like cattle, and dogs, and chickens, and things like that. And so rabbits were fairly recent, they were domesticated on the Iberian Peninsula.

HANK: Where is that? I know science, not geography.

JEFF: That's fine, so Portugal, Spain, and into southern France, and
so that sticking out is the Iberian Peninsula. That is where wild rabbits live, and...

HANK: Well, wild rabbits live all over the place... am I right, or am I wrong about that?

JEFF: Well, so there are many different species of rabbits, but the rabbits that, gave, basically were domesticated are European-

HANK: Gave rise to all of the domesticated rabbits we have now, which are tremendously diverse.

JEFF: Tremendously diverse, yeah, in terms of what they, size, shape, and everything else. So they were, so wild rabbits are from that region of the world, they were domesticated by monks in southern France, because they were used as a food source, they were used as a food source there anyway and they still are, and they're hunted frequently, still they're managed as a game species, but monks domesticated them.
The lore is that they domesticated them because young rabbits are not considered meat, they were considered fish, so baby rabbits were considered fish. And the rumor was that, you know, that you could eat them during Lent. So Lent, a lot of hungry monks.

HANK: Yeah, sounds like somebody just really wanted a sandwich during Lent, that had some meat on it, and was tired of fish, or that there just weren't a lot of fish around. I guess I could, I could see making that compromise, if it wasn't strictly prohibited. It was like, "Well, all these things we definitely can't have, but no one said anything about baby rabbits".

JEFF: It's all about the exceptions. So, that was, you have to, anything that's domesticated for the most part we think its you know it's a very tough process, to domesticate something.

HANK: So this takes... a long time?

JEFF: Well, some things are not, amenable to domestication, some things are, and it takes a lot of strong selection, and so actually a lot of what we know about the evolutionary process, and one of the reasons that that I'm interested, probably the primary reason I'm interested in domestication is 'cause I'm an evolutionary biologist, and domestication tells us a lot about the evolutionary process. On the Origin of Species started with, the first chapter is all about domestication. Artificial selection is a way to understand the mechanism of genetics and natural selection.

HANK: Right, and we can watch it happen much more quickly, 'cause we have a hand in it.
So, when I think of rabbits, I don't think of something that might be particularly hard to domesticate. To me, like, I would much rather try to domesticate a rabbit, than, say, a bull, cow. 'Cause that seems to me like "that might kill me," whereas with a rabbit, I feel like, if things go sour I can just kill this thing, with my hands.

JEFF: That's true, that's true, it's not so much the danger or the domestication process with rabbits, but they, they're very skittish, and in general, you know, you can think of a rabbit as the, you know, the Snickers bar of, in this case western Europe; everything eats them, mortality is all do to predation so they're generally freaked out, a lot and so... 

HANK: Whenever I get a Snickers bar it looks terrified, cause it's like oh god no it's finally gonna happen.

JEFF: You already said what you wanted to do to the rabbit and you know like they're scared, right? So that process of going from a wild animal to domestic is, requires, among other things, basically removing that fear response and so with rabbits, if you go out and get wild rabbits and put them in captivity, they usually die.

HANK: Just of stress..

JEFF: Yeah they just, they don't do well in captivity and they, they go pretty quick.

HANK: That makes, that makes sense, I imagine that that's not just one gene that codes for being stressed out around humans or, you know, potential prey or potential predators. That's probably a very deeply ingrained thing.

JEFF: Right, and so that was the question that we actually wanted to address with the study, was that..."what is it that allows an animal to... what is selected on, what are the key steps?" Most of what we know about domestication has to do with the diversity of domestics. So we know a lot about the genetic basis of domestication in dogs, for example, with respect to all the different sizes and shapes of different dogs.

HANK:  So like how we just sort of change things.

JEFF: Right, how we change their color and their shape and their
size and... 

HANK: But that's not...

JEFF: ...And that tends to be simple, simple genetic changes of large effect as we would say, so they have simple mutations that have a large effect on a phenotype.

HANK: So we have a little mutation and suddenly it's a chihuahua instead of a, you know, small dog.

JEFF: Right, so a single mutation usually does something very severe to create the change. So the question is what is the genetic basis of that very key early step where you, where you're not talking about selecting particular traits in domestics, but you're talking about selecting on the ability to be in a domestic situation.

And so what we found in the study was it was quite striking, so what we did was we compared populations of wild rabbits with, that are still alive and running around the Iberian peninsula, and we compared that with a diversity of different breeds, and we just simply asked "What's different between the two?" And the answer was, not much. And so it turns out that the genetic basis of that step of domestication in rabbits probably had a lot to do with many, small genetic changes and for the most part those aren't fixed things that are different between all wilds look like this and all domestics look like this, but probably more changes in frequencies of different variants of genes and collectively you get the domestic phenotype. So it's quite complicated. And we saw that it was a lot of-- seems to be a lot of genes involved, in, that are expressed in the brain and probably involved in behavioral responses and neural responses.

HANK: Are there other traits that are good for a domestic animal to have? 'Cause it doesn't have to be just like alive in captivity, it has to be useful to us.

JEFF: Right. So the other thing that you might expect to see, so the key of being a domestic, is shifting from strongly seasonal breeding scenarios to breeding year-round. And there's definitely, it's the case that domestics will, you know, there's a reason that we have the term 'breed like rabbits'. They will breed constantly, year-round for the most part and have really high production, whereas in the wild they have this fixed breeding season as do most things and they...it's much more restricted and so, probably a really strong selective pressure was to basically relax that. And we didn't find direct evidence for that in our study.

HANK: Interesting.

JEFF: We know it must be there, but the signal wasn't at least clear from the first pass that we did.

HANK: So it's almost like, when we domesticate an animal, we're selecting for traits that make them easier to domesticate over time. Because obviously if you can have them breeding more, then you can select for more traits more quickly.

JEFF: Right. Right. So, it does have a bit of a runaway process; as soon as you can breed them more often, you can have more generations, you can select stronger... and so you definitely see that, but this question of pretty much all domestics become, you know, non-seasonal breeders, it is an interesting pattern, and so there is some follow up work that a collaborator of mine is doing to try and get at that and actually doing genetic crosses between, so cross-breeding domestics with wilds - which is difficult for all the reasons that I said; it's very hard to keep wild rabbits in captivity. So they're actually doing that, and then looking at the offspring of that, and then also taking those offspring and then breeding them again with domestics and looking at the variation. And what you expect to see is some are seasonal breeders, some will breed year- round and things like that.

HANK: So it's definitely not just a behavioral thing, it's... they are incapable of breeding year round.

JEFF: It is, it's a mixture of behavior as well as a lot of the seasonal changes are tied into pretty deep-rooted physiological changes that happen in the body. So a lot of seasonal breeders, when they're not in their breeding season, they actually have their reproductive tissues regress totally. So their testes are basically-

HANK: Don't have to take care of them.

JEFF: Yeah, well why invest a lot energy into producing sperm, for
example, when you are not going to use it for a while? So, you see that with a lot of strong seasonal breeders; they have a reproductive season, that's when they are doing things like investing energy in reproductive structures, and then when they're not doing that they're worrying about other things.

HANK: Interesting. I have no idea - that makes perfect sense - and I'm glad that that's not how humans operate. It would be very weird to have our reproductive organs degenerate for several months of the year.

JEFF: Right. And there would be a busy couple months too, right? It would be... Nothing would get done.

HANK: We'd just get nothing done. The world economy would collapse.

JEFF: Absolutely.

HANK: Every eight months.

JEFF: Yeah.

HANK: This is maybe gonna be the first time where you're gonna know more about the animal than our friend from Animal Wonders, Jessi. Cause she's going to bring us-

JEFF: Maybe, I don't know... she's good-

HANK: She's gonna bring us a rabbit and you seem to know a lot about rabbits.

--- (10:46)

HANK: Go-oh god!

(laughter)

JESSI: This is Cheeks! He's a Netherland Dwarf rabbit.

HANK: Cheeks...

JESSI: Aw, show off, bud.

HANK: Okay, well... Jeff, what do you think?

JEFF: ... Cheeks?

HANK: Tell us about Cheeks.

JEFF:  So this is an example, the dwarfs are that they, I mean we think that, at least a lot of the dwarf breeds of rabbits are a single mutation. So this is exactly the opposite of what we talked about, this really complicated process of making a domestic rabbit from a wild rabbit. Where you have selection on many little things.
This is probably one major mutation that has caused it to be, you know, very, very, very small relative to a wild rabbit. And since that trait has been passed along to other dwarf breeds and, you know, diversified further.

But this is the kind of thing that we know a quite a bit about in domestication in general is what gives us the genetic basis of these, of these very, you know, kind of striking phenotypes 
like this is, traits like this, that you know, size or color, which is much much later after the fact from, you know, the original domestication event.  

HANK: So, how... how big are wild rabbits, and how big do domesticated rabbits get?

JEFF: So, wild rabbits get, they're quite a bit bigger than this, but the largest domesticated rabbit is, you know, more than twice the size of a wild rabbit. I don't actually know the exact, you know, the exact weight range, but some of the domestic breeds are gigantic. 

JESSI: The Flemish Giant...

JEFF: The Flemish Giant is huge.

JESSI: ...is over 50 pounds.

HANK: 50 pounds...

JESSI: And this is one of the smallest, they get about 500 grams, so it's like two pounds, two and a half pounds. Now I thought that the Netherland Dwarf was the first dwarf that had the mutation. 

JEFF: I thi-- I believe-- OK so this was the..?

JESSI: The original I thought that they, they bred them..

JEFF: And then they bred that, they basically passed that, cause it's a single gene, it's easy to pass around. 

JESSI: And then they did mixed breeds.

JEFF: Right.

JESSI: But didn't they take wild, i mean they got small domestic rabbits and then they bred them with wild rabbits to make them even smaller.

JEFF: Oh, I don't actually know... See I didn't know that. With this particular...

HANK: See, yup yup, Jessi wins. I feel like Jessi's winning. 

JESSI: Combined... No, no no no. Points; put points by us, though...

HANK: This is a competition.

JEFF: So.. um.. that, the process of breeding back out to wilds is always very difficult, so it's possible sometimes to kinda restock. My understanding is that this particular mutation was, you know, this very s... I think it's been isolated to a single gene...

JESSI: It is, yeah.

JEFF: ... on chromosome four.

JESSI: Yeah.

JEFF: That um, is... basically... causes this dwarf phenotype.

JESSI: Yeah.

JEFF: ... and then you can move that around. And there's also similar parallels in, for example, in dogs, a lot of the dwarf phenotypes. And sometimes it's the overall size that's small, sometimes it's..

JESSI: The legs.

JEFF: ...Shortening of the limbs and so you can get... And those are different genetic bases. 

JESSI: Yeah.

JEFF: Which is, you know, quite a bit more dramatic, but much more simple, in a sense, than what we think of was the method for domestication, yeah.

JESSI: Actual domestication. Yeah, yeah these guys they're still known... You wanna hold? Alright. So hold him. I know it's, it seems like it would be easy to hold a rabbit, but you have to really make sure you support their back. If he struggles and kicks he can actually dislocate his vertebrae. 

JEFF: You don't want that.

JESSI: So put your hands under him, and just support his hips. There you go.

HANK: Hey, ohh. Oh my gosh. That is soft.

JEFF: So, this wouldn't be a mutation that you would, select on if you were breeding them for food, for example.

JESSI: No, just cuteness.

HANK: Unless it's extra delicious. We don't know.

JEFF: It's true maybe it's...

JESSI: Some people might know.

HANK: Somebody probably knows.

JESSI: I don't know.

JEFF: Maybe these are an exception even as adults to the Lent requirement.

HANK: Yeah yeah, cause they're tiny...

JEFF: They're tiny...

HANK: ...So they're basically fish.

JEFF: They're basically fish. Could be, I dunno.

HANK: I mean, you look like a fish to me, with the big ears and the fuzzy, and the giant... Yeah.

JESSI: Sure, huge teeth.

HANK: Yeah...

JEFF: So most of the selection that you see in domestic breeds of rabbits is quite recent and it's just on all these traits that we find, you know, curious or bizarre or... 

HANK: Adorable

JESSI: Cute, or extra soft, or that--

JEFF: Extra soft...

JESSI: -- shortened nose so it makes.. But then their eyes stay the same and so they look like they're little babies...

HANK: Babies

JESSI: ...Infants, which humans, really, find desirable.

HANK: Cheeks seems to be very, very domesticated.

JESSI: Yeah, well these guys, they kind of have a...

HANK: 'Cause he's licking me.

JESSI: He is! He's like "thank you".  (to Jeff) Do you want some rabbit kisses?

JEFF: Sure.

HANK: Mm-mph.. Oh, no, don't jump.

JEFF: It's okay.

JESSI:  There you go. You look so natural with a rabbit in your hands. Are you gonna do the...? Do the face!

HANK: Yeah. do the. Just put it on your face.

JEFF: Oh... This is the.. I dunno like this?
That is nice!
You were on to something earlier.
Yeah they're quite amazing.
I mean you think, so you know, even, as an evolutionary biologist we always come back to Darwin. So Darwin wrote, you know, that you couldn't find anything that was more wild than a wild rabbit, and more tame than a tame... He said it in, you know, much more eloquent than I just did. But essentially to that nature, that it's one of the most striking examples of differences in behavior between a wild and a domestic. And you can see that here. If this, yeah. Well, it wouldn't be pretty if this was wild.

JESSI: No! No, it wouldn't.  And Hank, you were talking about, how you could just, if it went sour, went south or whatever, you could just kill it? These guys are pretty powerful. They, their back legs are pretty darn powerful, and they have the big claws back there. They could do some damage to you.

HANK: I believe it.

JESSI: You wouldn't go away unscathed.

HANK: Yes, but, if I had the choice between a bull and a rabbit, I would go for a wild rabbit over a wild bull.

JESSI: That's true. Just get a red curtain.

HANK: Yeah, uh huh, uh huh. Yeah, that seems like something I would not be successful at. Jeff, thanks for coming on and talking about your work.

JEFF: It's my pleasure. My pleasure.

HANK: It sounds really fascinating. Keep it up.
Jessi and Cheeks, thanks for visiting and sharing... your cuteness with us. 

HANK:  Jessi's youtube channel is youtube.com/Animalwonders Montana There's a link in the description. And maybe we can link to some of you papers or something down there.

JEFF: Absolutely, my website, we study all kinds of things, in addition to domestication, so I'd be happy to do that.

HANK: Awesome. Thanks for watching this episode of the SciShow Talk Show. If you want to keep getting smarter with us you can go to youtube.com/scishow and subscribe.

[outro plays]