[Intro]
Hank: Hello!
Welcome to SciShow talk show, that day on
SciShow where we talk to interesting people
about interesting things.
Today, we have joining us Douglas Emlen, also
known as Doug, author of "Animal Weapons",
a book about the various arm races that have
gone on between all sorts of animals including,
turns out, us.
Doug, hi!
Doug: Hello.
Thanks for having me here.
Hank: How's it going?
Yeah, absolutely.
Doug: It's going great.
Hank: So, I love science books and I was excited
to find out that there was someone right here
in my very small town of Missoula, Montana
who had written one.
Uh, tell us a little bit first about your
research.
Who do you research?
Doug: I work on beetles is what it comes down
to.
And I want to qualify that the book is on
animal weapons and I work on animal weapons,
but I work on a special subset of weapons
which are the really, really big weapons and
I just have to confess at the outset, I have
been crazy about animals that are so bizarre
looking and extreme that when you look at
them, they look like they shouldn't be possible.
These are animals that look like they should
tip over [Hank laughs] or they should trip
or they should get tangled in the trees or
the branches when they move, because the things
sticking off of their bodies are that extreme
and so, in the case of the beetles, there
are thousands of species that have horns sticking
off the front of their bodies.
It can be coming off the thorax or the shoulder
blades or coming off the heads.
There are species with one horn, two horns,
five horns, all sorts of weapons coming off
these things and most of my research concerns
[Hank takes beetle, mumbles "I want one" and
something else (?)] sort of the genetics and
the development and the evolution of these
weapons.
Hank: So like why it happens, how it happens?
Doug: You got it, all of it.
I started out years ago looking at beetles
that were even smaller than these guys, little
tiny dung beetles that had crazy horns coming
off their bodies and we really didn't know
much about what they did so a lot of the research
was watching them in the wild and figuring
out how they used the horns and they're basically
analogous to what you'd see as antlers in
elk or deer.
The males have the weapons.
Females don't.
And they use them in these battles over access
to females and these things are extreme.
Th-they're expensive to produce, they're awkward
and expensive for these guys to carry, they
make it more difficult for them to maneuver,
to do basically anything.
I mean, imagine having an extra leg on your
head for everything that you do.
It would get in the way all the time, but
the ultimate currency that matters in life
is reproduction.
And they help a lot when it comes to getting
access to reproduction.
These things tend to crop up in species where
there's intense competition among males over
access to a limited number of reproductively
available females and in those battles, that
is literally do or die.
If you fail to breed, you're done.
I mean, that's it.
That's the end of the game in the evolutionary
sense.
So, so these guys, these weapons matter a
lot in competition for reproduction.
Hank: So, this is a big set of, is a big weapon,
but it doesn't feel huge to me.
I was wondering if you could show me an actual,
like, like-
Doug: Put it into context for you?
Hank: Put into context.
Doug: I can do that.
Can I get up and go get it?
Hank: Yeah, go get it.
[SciShow Transition]
Doug: We are back on, alright.
So, to scale that up to a more appropriate
size for us to appreciate, I happen to have
a pair of elk antlers.
And again, the key point is these antlers,
relative to the size of that bull elk, are
actually smaller than some of the horns that
these beetles produce and carry around on
their bodies.
And I can promise, and I can give it to you
if you want, these things are heavy.
I mean, it's - it's incredible to imagine
a bull carrying this around, you know, on
top of their heads for everything they did!
Hank: That's - that's like as big as they
get, right?
Doug: This is a pretty decent sized male.
They get a little bit bigger.
Hank: Yeah, because I see - I see elk but
I don't see them this far away and so I have
a hard time imagining that they really are
that big.
Doug: And, they're that expensive.
When these weapons get big, they get expensive.
They get very, very expensive for these animals
to produce and the antlers are a really good
example to illustrate that point.
Hank: Well, they do all that work to produce
them and they're so energetically expensive
to even have, to carry,
D:
(?) You can just sit here and do your exercises
with these things, they weigh a ton.
H: I want to.
Let me see.
D:
But, um, not only is it expensive for these
animals
H: Oh my god.
D: to carry that everywhere they go
H: Hello, buddy.
D:
but producing
H: Uuuoohh...
I'm not a strong man.
D:
I'll let him hold it.
[laughing]
D:
It costs a lot for the animals to produce
it.
There's been some really neat studies looking
at how much it costs the males to actually
produce that and the most recent estimates
suggest it costs a whole elk as much to produce
a rack of antlers as much as it costs a cow
to raise two calves all the way to weaning.
That's a huge investment.
H: Oh yeah.
You could be
D:
And one of the ways to appreciate that
H: making so many more babies.
If you were, if you were sharing that wealth.
D:
Exactly.
Well, no that's the point.
They wouldn't be making any babies if they
didn't allocate the wealth.
And that's a really good place to point out
the cost.
They're building bone.
And they need phosphorus and calcium in order
to make the bone and they can't get enough
of that from the, the forest (they feed on?)
So some of these studies suggest that these
guys
H: Cannibalize from their own bones?
D:
They do.
They shunt it.
They leach these things out of the rest of
their skeleton and pour it into these weapons.
And then they throw their weapons away at
the end of the season.
So these males actually go through a brittle
bone osteoporosis period exactly during the
(?) when they need these things and they're
smashing into rival males in these knockdown,
drag out, do-or-die battles.
And again, elk are sort of an example that
we can see and relate to, and because they're
heavy it's easy to appreciate how expensive
they are, but it's, it's important to recognize
that there are all kind of animals that do
that, right?
So there's rhinoceros beetles, there's dung
beetles, there's flies, there's crabs, there's
shrimp with huge claws.
There're thousand of species out there where
the males are doing exactly the same thing.
They're shunting huge amounts of resources
into these weapons for one purpose.
Just to duke it out, fight over access to
females.
H: But there are, there are other reasons
to have weapons.
Cause traditionally, we think weapons are
for... killing.
Uh, and these don't do that much killing,
I imagine.
D:
Nope.
Well... no.
H: Occasionally.
D:
Occasionally.
No, that's actually one of the fun twists
that come out of reading about these arms
races, is one of the things that happens in
this kind of a weapon.
You've got the very small number of males
with the huge weapons, you have lots of the
population somewhere in between with sort
of intermediate weapons, and you've got the
smallest males with the fewest resources and
the tiny tiny little weapons.
The weapons end up becoming hugely disparate
in size from animal to animal within a species
within a population.
And it makes them a good signal.
It's not an accident that the really big,
best-conditioned male has the huge weapons.
It's because he is in the best condition and
the healthiest and the most resistant to parasites
and had access to the best food and that's
why that male had the really big weapons.
That's the male that's gonna win the fight.
So if you're a male and you're going up to
another male and you gotta decide do I wanna
launch into this thing, it makes really good
sense to look at the weapons first.
But what it means is these males don't actually
fight as often as you'd think they would.
H: Right.
They're just signalling.
D:
They can fight.
H: Right, of course.
D:
And they will fight.
H: I can (?)
D:
But what happens is most of the encounters
end up getting resolved without a fight.
H: So we have weapons used as a deterrent,
as a signal, but then there are also weapons
that are developed that are actually used
for death and killing.
D:
There are.
H: And you know, you look at, you look at
lions, they got big teeth,
D:
Yeah.
H: But it's not like this, you know, they
don't have like teeth sticking out of their
face.
And they're just not like hitting- cause they
gotta be sleek, they gotta be fast...
D:
Right.
H: But there are some animals that have crazy,
crazy teeth.
And that...
D:
And I got one of those two.
H: Okay, sh- let's talk about that.
H: Alright, so this is a crazy... set of teeth.
I just don't (?), like...
Why would a predator that has to chase and
be, and like, cause we think of tigers, and
you know, cats now, it's mostly
D:
Yep.
H: chase-y... uh,
D:
Yeah.
Like a cheetah.
H: run-em, run-em-down.
D:
Run-em-down.
(?)
H: And that's gonna slow
D:
Which is
H: you down.
D:
exactly why there aren't very many things
out there like this.
H: Yeah.
D:
So this is a really screwed up animal.
H: Ha!
D:
You look at it... everything about these guys
is a mess.
But, um
H: So, they, they actually, they do close.
Then you have this happening.
[holds up head] Which is, I mean, it's terrifying,
but it's also a little silly.
D:
So this was a problem for me, right?
So here I was, trying to read about all these
animal's crazy weapons and most of the weapons
that I study, and most of the weapons I was
reading about, are these weapons that are
used by males.
H: But it looks like a walrus tusk, which
would be used by
D:
Well, so walrus tusks are used by males.
They're sexually dimorphic.
They play by the same rules as the beetle
horns and the elk antlers.
These guys didn't.
So there was this problem.
It was clear that there were also other examples
of really extreme weapons that weren't specific
to the males, that weren't used in these battles
over access to females, they had- they were
used by predators.
And you raised the key point there.
Why would you ever get an extreme weapon in
a predator?
Because most predators have to, they have
to fly fast, or swim fast, or run fast, they
gotta be agile.
You picture something like a lynx chasing
a snowshoe hare [snaps fingers] they burst
out of the prey (?), I mean they just explode
H: So you have, you have weapons.
D:
out of their hiding place
H: but you have appropriate, efficient weapons.
D:
Because if they get too big they slow you
down.
They make you awkward and gangly and you're
not gonna catch they prey in the first place.
So the bottom line is bigger weapons are better
for killing.
You can kill bigger prey if you have bigger
teeth.
But when they get to the point where they
make your head all screwed up or the head
has to tip back in order to arrange for the
teeth you can't catch the prey in the first
place.
H: Yeah, you've got your eye socket literally
is closing cause you have to have the muscles
flying through there like that.
That's weird.
D:
Exactly.
H: This is a weird shape for an animal.
D:
So... so the point is most predators can't
play by those rules.
They'd never make it.
They would starve because they wouldn't be
able to catch their prey.
And so the trick with these guys is that they're
not your normal predator.
They were not fast.
These are not cheetahs with big teeth.
These were big, stocky, robust animals that...
they could not have run down anything.
But we don't think that that's what they did,
so the- the latest palaeontological studies
suggest looking at joint- you know, articulation
and what these guys have, their muscle size
and what they did.
The latest ideas on sabertooths is that they
actually hung out on branches of trees.
And they dropped onto unsuspecting prey, like
the bubbling juvenile mastodon.
Ans they literally dropped from above and
plunged the suckers into the back of the neck
of their prey.
And so they were ambush predators.
And that's the ticket.
That's the key to understanding weapons like
this because an ambush predator doesn't have
to run fast.
They don't have to stalk and chase down their
prey.
And they wait and grab it when the prey comes
close to them.
Or they drop like a cat.
But if you think about it, there actually
are a lot of predators that are ambush predators
and many of them have crazy weapons like that.
H: I also want to point out that this is how
this thing's jaw actually hinges.
To get it open enough to get these...
D:
So the way I like to explain that is it's
like opening up a stapler.
If you wanna use a stapler where you punch
it down into paper you have to flip open the
bottom hinge.
H: (?) ...extra hinge.
D:
To flip the bottom all the way out of the
way because it's the only way you can bring
it into contact.
And that's why these guys have a special hinging
mechanism that lets their jaw fold all the
way back so that they can use those things.
And if you look at it when they close their
jaw- I mean these were really screwed-up animals.
Their heads were tilted back in order to project
the jaws forward so they couldn't see where
they were running.
And they- these things got in the way- imagine
eating with teeth like that.
H: Yeah.
D:
I mean think about it.
So, so the wear patterns on the teeth suggest
that these guys had to know their food through
the sides of their mouths, because there was
no way to get around the giant teeth!
So they could kill something, but once they
had it what're you gonna do?
Basically they had to eat sideways through
their mouths to get past these things.
And so the idea there is that normally predators
face sort of a tug-of-war balance.
Killing bigger prey means you want bigger
jaws, bigger mouths, bigger teeth- but it
slows you down.
So if you have to catch the prey there's this
balance.
Selection for maneuverability
H: There's also
D:
keeps the weapon small, selection for killing
keeps it big.
Once you're an ambush predator, that constraints
gone.
H: All you need is
D:
Off to the races.
H: big, big weapon.
D:
Yeah, really big jaws.
H: I am fascinated.
This, this is Douglas, Douglas Emlen's book
Animal Weapons.
You can get it, um, wherever books are sold
D:
Hopefully.
H: Um, so: If I was an animal that had to
worry about ambush predators, which thankfully
I no longer am, what kind of strategies would
I be hoping for?
D:
I know what I'd want.
H: Yeah.
D:
That'd be a really good suit of armor.
H: Alright.
Uh, Jessie's going to join us with an animal
that has a really good suit of armor.
D:
Exactly.
Hank: Alright everybody, this is Jessie Knudsen
from Animal Wonders, and she has a present
for us.
It's wrapped up.
Jessie: It is like a present, yeah.
Well she's sleeping and she can get cold easily-
and it's wintertime now.
So I wanted to make sure that she stayed nice
and warm.
But.. here she is.
H: There's a soft ball.
There's a soft ball in here.
J: This is a southern three-banded armadillo.
And she's got a heck of a set of armor there.
D:
Yeah.
That's amazing.
J: Yeah.
D:
This is a dream come true.
Can I hold it?
J: Uh-huh ha ha.
D:
Please?
J: In a second.
D:
Please?
J: In a second.
Yeah, well, you touch her and then I'll let
you hold her in a second.
D:
I've always wanted to see an alarm
J: Cause she'll roll up into a ball
D:
That's okay.
J: if she smells someone unfamiliar.
D:
So most of the animals would (?) do that,
right?
J: Exactly.
Exactly.
So that's her
D:
Armadillos(?) do that.
Pillbugs do that.
J: Yeah, they have the same, same type of
mechanism that's allowing them to survive
over and over, is that they will, if they
are threatened, they will roll right up into
a ball.
H: Aw, that's cute.
J: She can roll...
D:
Aw, man, that's (?), that is so cool
J: completely up... into a ball.
H: And the tails makes like the other piece
that the head...
J: Yeah!
She's like a little puzzle.
H: Perfect.
J: Yeah!
D:
Little jigsaw puzzle.
J: Yeah.
H: Oh man.
Aww.
J: Little hat piece there.
H: Aww.
Yeah.
I'm sorry.
J: Are you coming (?) back out there?
H: Where did this little girl come from?
J: She was, um, purchased to be a mascot for
the World Cup.
H: Well that's weird.
J: And, um to bring in, you know, people,
to come, you know, "Woo!
We have our own armadillo!"
Cause the mascot for the World Cup was the
Brazilian three-banded armadillo, and they
raised funds to, to help out with the endangered
species and conservation.
Um, but these guys look very similar to the
three-banded- the Brazilian three-banded.
And so she was purchased for that, and then
when the world cup was over- no use for her
any more, and so she was sent to a rescue
and we rescued her from there.
H: Was it- was it like a bar, or something
wanted to have it?
Or what, like, who...
J: I don't, I don't know exactly who the people
were.
H: Cause like, "Come on in to get, uh, to
get
J: "See the armadillo!
H: "Armadillo.
And buy beer."
J: Yeah.
H: More (?)
J: Yeah.
And drink.
Yeah.
H: Yeah.
J: I'm not sure, but... but then she lost
her home, and
H: Now I have a new one.
J: Now she has a new one.
H: (?) I'm glad.
J: You know, she does not have a name.
We've been calling her "her" and "armadillo".
She does not have a name.
She's a new ambassador and we're actually
looking for someone to name her...
H: Oh.
J: For a donation.
H: Oh, yes.
J: You know, they can, they can, they can
name this little lady right here.
H: Adopt an armadillo.
J: Exactly.
H: You're weird.
No offense.
J: She's really weird.
She's really weird.
And she, I think the weirdest part of her
is how she moves around.
H: Especially now that she's ice skating.
J: She is.
She is.
It's very hard for her to
H: Yeah, it's like she's got ice skates on
the front.
J: She just keeps her front feet like this
[points] and then she pushes around with her
back.
H: It's like you have just one fingernail...
I wanna see her belly, but I feel like it's
unlikely.
J: You can.
You might get a- if I open her up
H: I might get a glimpse.
J: and just get her calm and then... [holds
it up]
H: Oh, it's so fuzzy.
J: Yeah.
H: Oh, okay... oh, she's like, "I don't
J: She's like "I don't like this."
H: "I don't like this.
I don't like it."
J: Yeah.
And I was having a blanket on her.
I keep trying to put my hand on her like this
and keep her on my lap- make sure she stays
warm, because these guys, um, are very susceptible
to cold.
And they have a pretty low basal temperature
and metabolic rate.
They're low, just like humans, and so they
can actually get leprosy.
And everyone knows that.
Everyone knows that
H: Right.
J: At least most people do.
H: What leprosy thing?
D:
You didn't tell us.
H: Am I- am I- should I not lick my hands?
So they can get leprosy...
J: Can you get leprosy?
H: NO.
I- I'm.
Can I?
Sure.
J: Mm hm.
I can get leprosy.
Humans can get leprosy.
H: Everybody (?) can get leprosy.
J: Armadillos can get leprosy.
D:
Right, but you didn't tell me that before
this interview.
H: Fine, but most animals can't.
J: Most- most animals- most mammals, most
placental mammals can't because they have
a higher body temperature.
H: Oh.
J: And it'll kill it off.
But the ones that have lower, are able or
susceptible to it.
And she doesn't.
I mean, she's been tested and just like
H: She doesn't have it.
That's nice.
J: we would know.
We would know if we had leprosy.
H: Right.
J: Yeah.
H: Yeah.
Well
J: And it could be treated.
It's treatable now.
H: In armadillos as well as humans?
J: Yeah.
Yeah.
Yep.
H: Okay.
J: Yeah.
H: That's nice to know.
J: Yeah.
H: I don't know very much about leprosy.
I should do a SciShow on it.
J: You could do a SciShow on leprosy.
That'd be an upbeat one.
H: Yeah.
Not... yeah.
But there're always, yeah, are people always
like, "Don't touch armadillos, they'll give
you leprosy."
But really what it is is that they are capable
of getting leprosy and carrying it.
Alright.
Well.
This unnamed animal which you can name if
you go to Subbable.com and check out the Animal
Wonders campaign, uh, you can adopt an armadillo.
You can also get Douglas's, uh, Douglas Emlen's
book, Animal Weapons, on Amazon at Audible.com.
I could talk about this stuff with you for
hours, and I want to, um, but luckily, for
everyone else, you can just read the book,
and it'd be like talking to him for hours.
Um, so that's- got a link in the description
for that.
Uh, and you can check out Animal Wonder's
web- uh, YouTube channel at YouTube.com/AnimalWondersMontana.
So thanks so much for bringing in so thanks
so much for bringing in this unnamed, beautiful
beast.
D:
Soon to be named.
H: Uh, and it was just an absolute pleasure
to talk with you, Douglas.
D:
Pleasure.
H: This has been an episode of SciShow Talk
Show that I have really enjoyed.
Thank you for joining us, if you want to keep
getting smarter with us here at SciShow, you
can go YouTube.com/SciShow and subscribe.
