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MLA Full: "SciShow Talk Show: More about Animal Weapons with Doug Emlen & Professor Claw the Emperor Scorpion." YouTube, uploaded by SciShow, 13 August 2015,
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Chicago Full: SciShow, "SciShow Talk Show: More about Animal Weapons with Doug Emlen & Professor Claw the Emperor Scorpion.", August 13, 2015, YouTube, 21:37,
Doug Emlen returns to SciShow to talk about the parallels between arms races in animals and arms races in humans. Then Jessi joins the show to show off an animal with it's own set of weapons.
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 Doug Emlen (00:00)


Hank: Hello and welcome to SciShow Talk Show, the day on SciShow where we talk to interesting people about interesting things.  Today, we have again Doug Emlen of the University of Montana and also the author of Animal Weapons, a book about how animals hurt each other, and also about how people hurt each other.  Tell us a little bit about how you made the transition from being a studier of animal parts to interested in the-- our human abilities.

Doug: It was a surprise.  So I spent a lot of time traveling around the world studying animal weapons, and for me that usually means beetles with horns, and so I had this chance to step back and start looking at animal weapons everywhere to look at when and why some weapons get really big. And we talked last time a bunch, when I had those elk antlers that we brought out about how expensive these things are.  That's one of the universal themes in the weapons that I study is that they're all exorbitantly expensive.

And so the question I started asking as an evolutionary biologist is what are the conditions that cause populations to evolve to these bigger and bigger and more and more expensive weapons?  What are the conditions where bigger weapons are better?  Because most of the time, bigger weapons aren't better, for the--the lion's a perfect example, it slows you down too much.

So what are the conditions where all of a sudden, it doesn't matter if it slows you down, it doesn't matter if it costs a third of your body weight, you need to have the biggest weapons, because the ones with the biggest weapons win, and that's that sort of special circumstance, and in animals and in people, it's duels, and this was a surprise.

I mean, I teach animal behavior, I've known for years that there are certain conditions that lead to intense competition, so males will fight viciously with other males over access to females, but most of those species don't have big weapons either.  The type of fight matters.  You have to have rival animals confronting each other one on one in a duel.

So dung beetles face this incredible competition.  You've got all these different rival males. You've also got other species of beetles and flies and everbody's trying to eat the dung and sort of pull it away--I know this is hard for us to get, we don't think of dung as like, the nectar of the gods.  But if you're an insect, it really is.  It's one of the best food sources out there, and these insects are clamoring to stash it away so that they can use it to raise their young.

Well, dung beetles do a couple different things.  Some of them carve these big balls and then then push them away.  That's a strategy, to grab a bunch of food, push it away from everybody fast.  Works great.  And those males carve these balls and they roll 'em away, females will follow a male and then they find a place, they bury it, that male might have to fight 50 rival males before he gets there, and these battles are scrambles, all these different males come and they pile on top, they're pulling and tugging in different directions.

A male might have to fight 5, 6, 7, 8, 10 different rivals at the same time.  The fights are unpredictable, 'cause you got 10 rivals all piling in at once, so weapons never turn up in species that fight above ground and roll things like balls, but then there's other dung beetles, and what they do, the female digs a tunnel.  The males plant themselves at the edges to the tunnel and they fight all intruders that try to enter.

One change in behavior.  You roll a ball or you dig a tunnel, and that made all the difference, because if you're fighting in a tunnel--and I have a--I brought my tunnel example.  If you're fighting in a tunnel, where are you gonna go?  You can't have ten rival males fight you at one time.  They won't fit in the--only one can fit in the tunnel at a time, and when they go in the tunnel, they gotta fight each other face to face, so a change in behavior caused the beetles in these--some subset of species, to fight in duels.

One on one fights, matched encounters, inside the confined space of the tunnel, and in that kind of a setting, the male that was bigger, stronger, and the male with the bigger weapons won every time, and so it always paid to have the bigger weapon, just like that, those species launched into an arms race, and sometimes the horn is back here, sometimes it's there, sometimes it's here, all these different lineages of beetles launched into arms races and got bigger and bigger and bigger weapons, and all it took was a change in behavior that took a fight that had been a scramble and turned it into a duel, and that's the piece that transfers.

Hank: And it's interesting, because this is interspecies combat that creates this. 

Doug: Intro.

Hank: Not--That's what I meant.  Yes.

Doug: It's--most of the--it's within the species combat.

Hank: Yes, so it's--it doesn't happen if it's, you know, it has to be just like us, just like humans competing with humans, it has to be--wow.

Doug: Exactly.  Now, just to be clear, there are other kinds of arms races, so you get into arms races between immune systems and animals and the pathogens that infect them or there are predator-prey arms races.

Hank: Yes, speed arms races.

Doug: But the kinds of arms races that lead to these ridiculous, I mean, arguably absurd weapons are one-on-one showdowns within a species: rival males battling for the prize. And-

Hank: So, yeah, are we in one of those ridiculous arms races?

Doug: I think we are. I mean, people are-

Hank: Cuz how much of those are-

Doug: I think we're in the after-effects of one of those really-

Hank: So how much of the money- How much of the, you know, you talk about the resources that an animal has access to versus the resource that a culture has access to.

Doug: Yes.

Hank: We spend a lot of our resources on our arms race.

Doug: We do. And I guess I would argue that there are predictable reasons for why we do that. So the first really good example of this happened- and I don't have a good prop of a ship with oars coming out the sides of it, but it was the ancient oar galleys that people see pictures of from the ancient Mediterranean.

Hank: Mhm.

Doug: They had tons of these ships, and they would shuttle troops from place to place, and they were all rowed by these- these rows of long oars that would come out the sides. For literally a thousand years, the ships didn't change at all. They looked almost exactly the same. They had the same number of rowers, they were about the same length, made out of the same kinds of woods. Nothing happened "evolutionarily", because all they did is shuttle troops from place to place. Somebody invents a battering ram - this is classic with a new technology: it happened so fast that nobody can figure out who invented it, because instantly, everybody had it.

Hank: Right.

Doug: Soon as somebody had it, you had to have- A battering ram changed everything, because now, a ship could smash into another ship. And that was by, of necessity, a one-on-one interaction, a very close-range interaction; you had to move up, and turn into and strike the side of another ship, and you could splinter the hull and sink the ship. [snaps.] Duels.

All of a sudden, a ship was a unit. That vehicle was a weapon, they fought one on one, and you had to have a faster, bigger ship. And so these things got bigger and bigger and bigger. They got longer until they started to buckle, they started adding one row of oars to two, to two became three. They started adding more and more people to each oar.

Within a hundred years, after a thousand years of not changing at all, within the blink of an eye, like a hundred to two hundred years, these ships went from pentaconters that had like 50 rowers, to this massive, double-hulled sort of Catamaran-style monstrosity that had four thousand oarsmen. And two thousand Marines on the deck. And so a change in technology caused the ships to interact like that, and that sparked an arms race. 

Hank: To me, this seems, it seems extremely inefficient. Like, in that particular...

Doug: There's nothing about big weapons that's efficient. 

Hank: No yeah but like, but how, like to me, in some ways, how do animals continue to pay for that, those things. And how do cultures continue to pay for them? Like, wouldn't it be so much easier to just find a way to just avoid that and be the dung beetle that pushes his ball off somewhere else? 

Doug: Yes, yes.

Hank: And not have to pay that 30% of your body weight for an antler.

Doug: So what happens, you reach a point where you have these elaborate, very expensive weapons, that we talked about last time, function beautifully as deterrents, because they're so expensive. But you reach a point where it's not cost-effective anymore and what usually happens in these systems, these things get really big and really pricey and not everybody can afford to pay the price. And we touched on this last time, that you end up getting a lot of variation among individuals and how big their weapons are. Because only a few can really afford to produce the really big weapons. They cost a fortune. So what are you going to do if you're the little guy? 

Hank: Sneak? 

Doug: Sneak. You switch to Plan B. Right? If you can't play by the rules, you break the rules. So you see sneaking in system after system. And what I think happens is that when the sneakers start doing too well, it no longer pays to have the big weapons. You can do better by not spending 30% of your body investment into a weapon, and instead putting those resources into other things. And so, so you get this cycle where the weapons start to get bigger and bigger and bigger and bigger, and then cheaters invade and completely erode and the bottom drops off. 

Doug: And suddenly the technology is not cost effective anymore and the arms race collapses. 

Hank: So where are we at now? I think this is fascinating and, like, you know the thing about the cold war was that now the weapons are so huge and not that expensive. I mean we made them expensive by making lots of them but nuclear weapons are so powerful that you almost can't use them.

Doug: Yes-

Hank: That was a very weird arms race because we ended up not ever using the weapons - so far. Fingers crossed.

Doug: So, there are so many parallels. And I'll just add the caveat again: I'm not a military historian, I come from somebody studying beetles and the rainforest. But what happened is you ended up getting the powers coalescing around the Warsaw pack and NATO one on one.

You had the USSR versus the United States, the two super powers, the two countries that were relatively evenly matched economically. They could afford to play this game, sized up toe to toe line in the sand. And you had politically a duel. And that's exactly the situation that sparks an arms race in animals so the prediction is that's the situation that should spark a race in technology.

If you look at animals like crabs, crabs don't just run into battle and beat each other up. They size each other up. They go through a very special sort of sequence of stages. They start by looking at each other and if one of them has a much bigger claw the little guy walks away 'cause those weapons are expensive, they make deterrents, and deterrence is huge for the Cold War, so big weapons are deterrents, and the little guy won't attack a big crab in all out war, he'd lose.  Walks away.

But if the crabs are pretty even, then it sort of ratchets up to the next level.   So, you know, one sort of whacks the other one and they push a little bit and they shove if they're asymmetrical, the little guy leaves again.  Over before it starts.  There's no point in fighting a really dangerous battle if you know you're going to lose.  But if they're still pretty even, then it ratchets up to the next level.  Well, you look at what the historians have put together for the way the Cold War played out, and we had the proxy wars.

Hank: Right.

Doug: I mean, essentially what happened is you had superpowers with awesomely deadly nuclear weapons, they didn't use the nuclear weapons.  They did the little whack, you know, the pushing and the shoving, they used conventional weapons and that played out in Korea, Afghanistan, Vietnam, these were showdowns between the superpowers that didn't go nuclear, they were just like si--you know, you push, oh, yeah, he's still there, I'm not going any further, back down.  And so, in these kinds of conflicts, deterrence really works, and I think that's what happened during the Cold War, but if I can run with it one--there's one more parallel.

Hank: Uh-oh.

Doug: I really wanna bring up.

Hank: We're gonna get really close, to like, where we're at right now.

Doug: Yes.

Hank: That makes me nervous, but tell me anyway.

Doug: I would love to be wrong, and I kinda hope that I am, 'cause again, I mean, this started out as a thought experiment, by comparing animals to people and seeing what can we learn, are there things we can learn about ourselves by studying the way that arms races work in animals.

And at the end of the day, I guess I feel as a scholar, as an academic, if you're gonna play that game and you're gonna start down that path, then you need to follow it all the way through to where it takes you, even if it's a little scary where it takes you, and again, I'll be delighted to be shown wrong, but where it took me is that you end up with--we all know the Cold War was spectacular on every front, I mean, it led to catastrophic levels of spending on both sides, investing in the militaries, tanks got into arms races, submarines, missiles, planes, aircr-- every single technology that existed was swept up into a race and they all got more and more and more expensive at the same time, so this race truly exploded.

A lot of people think that we survived that race because of deterrence, and in particular, because of the weapons of mass destruction, the nuclear weapons were so deadly that neither side was prepared to actually use them, and because of that, just like crabs on a beach, they size each other up and then they back down and walk away without actually trying to kill each other.  The Cold War ended without entering into, you know, a full-scale knock down drag out nuclear war, thank goodness, or we wouldn't be here.

But, you have to look at where we are today.  So essentially what happened is the Soviets overspent and couldn't sustain the race any longer, and so the United States sort of emerged as the biggest crab on the beach, the superpower left standing. We still spend a ton on military and I think we owe it to ourselves to start to think about, is that a good idea?  Are we safer because of that?  And that's where things get murky.  On the one hand, yeah, we have the biggest weapons on the block, there's no question.

Hank: If there's only one big crab on the beach, there's never any fights.

Doug: And it's happened, it's happened, exactly.

Hank: And the crab's are like, ooh, never mind, I'm gonna--

Doug: Or, the only alternative, the only recourse available, there is nothing else on the political landscape at the moment, there's a few things that we might want to watch down the road, that could stand toe-to-toe with a full scale, full cost conventional or other type of battle.

The only thing the opponents of the United States can do is cheat.  And so if you look at what we deal with, you know, anywhere that our troops are on the ground, we're dealing with sneak tactics, we're dealing with guerrilla warriors that, you know, that dress like civilians, that's just like a beetle mimicking a female to sneak in and get close, they're cheating.

They're using, you know, sticking a pipe bomb or an IED by the side of the road, these things, they're very destructive to a small number of our soldiers, I'm not gonna belittle that for a second, but they're not a direct threat to the sovereignty of the United States, they're not actually a direct threat to most of the population of the United States, these are small scale cheating tactics that are brought about by foes that can't afford the weapons systems that we have and they can't afford to fight us in a one-to-one duel.

But the reason these things work is because the weapons systems that we have should function like a deterrent, and if you look at what happened in the Cold War, the reason that the weapons systems worked as deterrents is because the deadliest weapons of all, the nuclear weapons, were also the most sophisticated and the most expensive, and really only the superpowers could afford, and there's a few other countries that were part of the alliances that had a few, but really, you had to be one of the wealthiest states out there to even play that game, and you had this one-on-one showdown with the two superpowers with these really expensive state of the art thermonuclear warheads that were very, very expensive. They worked as deterrents, but as you mentioned a minute ago, these things aren't so expensive anymore, we got tons of them lying around left over from the Cold War, and the technologies aren't, you know, some of our aircraft carrier designs and our fighter planes might be really, really expensive but the nuclear warheads per se aren't.

So, suddenly, it's no longer a good signal.  If anybody can afford 'em, then it's not necessa--it's not a proxy for fighting ability, you can't look at the weapon of an opponent and instantly get a read on what their military capacity is anymore, because just about anybody can afford these things, and so what happens is the weapons of mass destruction end up not being effective as deterrents, and they end up being something that's in the arsenal of the cheats and the sneaks, and now you've got a situation where the really biggest, most heavily armed country on the block is facing rivals who might pretty soon have their hands on weapons of mass destruction, and as far as I'm concerned, all bets are off in that situation.

We're not safer now because of weapons of mass destruction, 'cause we're not playing by the same rules.  When you look at beetles or you look at knights or you look at the ships of the line, they were very consis--they were predictable ways that these things played out, it was always the wealthiest or the best fed animals that had the biggest weapons, it was the wealthiest states that had the most expensive, most state of the art, most effective weapons, they always fought against each other in very predictable repeatable ways, so that you could ratchet up and you could ratchet down again, I mean, there were rules in a sense, to the way these things unfolded.

There are in crabs, there are in beetles, there are in elk, there are in most of these other technologies.  Those rules don't apply now.  I mean, I think when you start getting lots of countries on the landscape and maybe even, you know, rogue organizations that aren't even nationalities with their hands on weapons of mass destruction, then all the rules break down, and you end up something much more like the scramble of the dung beetles, where everybody's piling on at once.  Those things are chaotic, they're unpredictable, and the last thing we want is an unpredictable outcome in something like a weapons of mass destruction technologies.

Hank: You're right, I didn't wanna know, I didn't wanna know.

Doug: We have to ask ourselves now whether the cheaters or the sneaks are on the verge of having technologies that will allow them to do so well that conventional systems and the conventional security that we derive from those systems might collapse.  Kinda scary thought.

Hank: Scary thoughts. 

Doug: Let's hope I'm wrong.

Hank: Super fascinating that, you know, you started off studying beetles--

Doug: A long way from dung beetles.

Hank: Yeah.

Doug: Well, it is fun to think that studying beetles in a rainforest could actually tell you something that changes the way you look at the world around you.

Hank: Yeah.  Yeah.

Doug: Thanks.  Awesome.

 Professor Claw (16:20)

Hank: Well, let's study another animal weapon coming up right here with our friend Jessi from Animal Wonders.

Okay, what do we got?  What did you bring?

Jessi: What do you think it is?

Hank: Well, it's a coconut and a log.

Jessi: You're right! 

Doug: Better have a weapon, right?

Jessi: It is, yeah.  They have weapons on them, are you--

Hank: Ohhh, ahhh!  Oh my God, it was big!

Jessi: Did you really just stick your hand in a little--

Hank: I didn't know what it was!  You said what is it, I wanted to look!

Jessi: I'm not even holding it.  I have a glove in my lap. 

Hank: That was really big!  I thought it might be under the coconut.

Jessi: Natural selection, Hank. 

Hank: I wanted to show everyone the log that I wasn't lying.

Jessi: You can show them the log.

Hank: Okay, there's--ohh, there's two of them, that's why. 

Jessi: Oh, there's nothing there.

Hank: Okay, that's why--that was why it looked so big.

Doug: It's just big.

Hank: Oh, there's three of them.

Jessi: There's three of them.  There's the coconut.

Hank: That is a big bug.

Doug: Can you guys see? 

Jessi: Not a bug.  Not a bug.

Hank: Not a b--wha--okay, sorry, that was a big animal organism.

Jessi: There you go.  Yeah, yeah.  Yeah, these are actually arachnids, they have eight legs, plus two pincers.  I'm gonna go ahead and pick her up. 

Hank: Oh, nooo.

Jessi: The movement...

Doug: Oh, you didn't bring a black-light, did you?

Jessi: No, did not bring that.

Hank: Oh gosh, oh gosh, oh gosh.

Jessi: Okay, here she comes. 

Hank: Ohh, really?  That's how you do it?

Jessi: That's how you do it.

Hank: Oh, and then you put it on your hand?

Doug: Wow without the glove, I'm impressed.

Jessi: There she goes.  Alright, this is Professor Claw.

Hank: Hi, Profe--that makes you less terrifying.

Jessi: She is an emperor scorpion.  These guys are the second largest scorpion in the world.

Hank: That's a big--it's a big scorpion.

Jessi: It's a big scorpion.  Exactly.

Hank: I would--so, they get--do they get bigger than that?

Jessi: They get a little bit bigger than this, yeah.  If you pulled out her telson here, it would go all the way almost 7-8 inches.

The biggest ones are eight inches. 

Hank: Don't touch the tail.

Doug: Have you been stung yet?

Jessi: Don't touch the telson, yeah.  There's actually only 25 species out of about a thousand species of scorpions that are deadly to humans, and these guys are not, and you can actually kind of, just by looking at them, tell if they're deadly to humans or not.

Hank: Okay.  How?

Jessi: Just by looking at their claws there.  Huge weapons up front there.

Hank: Yeah.

Jessi: If they have huge claws compared to their body size, they're gonna be less venomous. 

Doug: Huh, really?

Jessi: And if they have teeny tiny claws, compared to their body size, they're gonna be more venomous. 

Hank: Okay.

Doug: Now that's the kind of pattern I would love to look into.  I didn't know that.

Jessi: Yeah.  So, if you think about it, if they're going out there and they're hunting and you have these teeny tiny little claws, you know, you can't grab anything.

Hank: Right.  You're useless.

Doug: You're relying on the venom.

Jessi: But if you have these big claws, you just go and grab something and eat it. 

Hank: Right.

Jessi: Yeah, so she's gonna take down bigger prey or if something's attacking her, then she'll use her venom, but otherwise she uses her claws.

Doug: That also implies that there might be a trade-off in cost.

Jessi: Exactly.

Doug: I don't know how expensive, chemical weapons sometimes are expensive, sometimes they're not.

Jessi: Yeah.

Doug: But it implies that you otherwise, why not have big claws and really nasty venom?

Jessi: Exactly, have 'em both, exactly.

Doug: So, Jessi, if it were nighttime and we had a black-light, would she fluoresce?

Jessi: She would, she would, and I think that's really interesting, 'cause it's an evolutionary thing, and they've been trying to figure out why do they do that, why do they glow in the dark, essentially?

Hank: So they glow in UV light?

Jessi: Yeah, UV light.

Doug: They fluoresce in UV light.  Since they have book lungs on the undersides that also fluoresce if you flip them over, they fluoresce really brightly too.  I'm with you, I don't think, I'm not aware of any studies that have figured out why they do it. 

Hank: It's really helpful for people who are in the desert in the dark, because you can get a UV light, if you're going to the bathroom at night, and you can be like, where's the scorpion?

Jessi: That is really nice, yeah.

Doug: I practically guarantee you, you do that in the desert at night, you'll never camp in the desert again. 

Hank: Well, no, I mean, like--

Doug: Because they're everywhere, you realize, oh my god, there, there, there--

Hank: I have--I was talking to a friend of mine who was on a shoot, he was like, filming a movie, and like, they were shooting at night in the desert, and they had scorpion flashlights, and I was, like, is that like, a brand?

Doug: Yeah.

Hank: And they were like, no, no, no,  No, they're just--they're UV flashlights to identify scorpions on the ground.

Doug: That's cool.

Jessi: Yeah, and that's why a lot of scientists go out and biologists go out and study them, bringing out a herp light so that they can see all these guys.

Count their numbers and see what they're doin' out there. 

Hank: Oh man.

Jessi: Yeah, so the emperor scorpion.  Second largest scorpion in the world.  Not very venomous, big claws. 

Hank: Where is it from?

Jessi: Africa.  There you go.  Africa, Western Africa, um, they live in the rainforest and then some of the savannas, a little bit, but these guys--they're black because they blend in to the, you know, the--what do you call it?  The forest floor?

Hank: The leaf littler.

Jessi: Yeah, the leaf litter.  Yeah.  They blend right in.

Hank: Cool.  What a treat for us, Professor Claw. 

Jessi: Not to eat. 

Hank: Not to eat.  Sorry I brought up the eating. 

Jessi: Do you wanna go feel it out?

Hank: You look like a lobster.

Jessi: Oh, look, she's spinning out.  There you go. 

Hank: Tokyo Drift. Thanks, goodbye, Professor Claw.  Jessi, thank you for coming and sharing Professor Claw with us, and her babies.  If you wanna check out more of Jessi's stuff, that went to the wrong camera, you can go to  Doug Emlen, thank you for sharing all of your insights into both animal and human, I guess we are animals as well, as made very clear by the trajectories that we take with regards to our arms races.  The book is Animal Weapons, it's both about biology and military history, fascinating stuff, it's available wherever books are sold.  Thanks for watching and if you wanna keep getting smarter with us, you can go to and subscribe.