April 22, 2014 • 42 mins
Rise of the Vampire Bat: It's a hard-knock life for an exclusive blood drinker, yet somehow three species of vampire bat take full honors as the only obligate sanguivores. How did they evolve? How does vampire physiology work? Tune into this bloodthirsty episode of Stuff to Blow your Mind to find out.
Learn more about your ad-choices at https://www.iheartpodcastnetwork.com
See omnystudio.com/listener for privacy information.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind from how Stuff
Works dot com. Hey you welcome to Stuff to Blow
your Mind. My name is Robert Lamb and I'm Julie Douglas,
and this week we're talking about vampires. Specifically, we're talking
about vampire bats. But I feel like I have to
to urge everyone, like, don't don't run away, because because
(00:24):
on one hand, vampires, of course, as just is a
is a whole. It's like bringing in all of the
various fantasy elements. They're like, that's completely overblown, to the
point that most people I think are getting, if not
completely already forward with vampires, you know, we kind of
know what to expand with it. And then with vampire bats,
I don't want to, you know, discredit them either, but
(00:45):
on a at a surface level, it's easy to say, oh, well,
their bats and they drink blood from cows, no big deal.
I've seen them on I've seen Attenborough talk about them
on documentaries, and yes, they're they're neat, but I don't
necessarily need to hear about them for an hour. But
the thing is, we really start asking questions about the
blood diet and about the vampiric lifestyle style and how
(01:07):
that evolved really get into some crazy imaginative areas that
that that that really blew my mind. Yeah, these guys
are so interesting for for many many reasons. And we've
talked about bats. I think we had a couple of
bad episodes last year. Maybe we've talked about how um,
we'll just we'll discuss a little bit about this, but
(01:28):
we've talked about how they have rich social bonds and
they are amazing creatures, and they have these these four limbs.
If you look at their bodies, it's very easy to
see the human hand and the human armbones replicated in
that wingspan. That alone gives us this idea that there's
so much to this mammal that's only flying mammal um
(01:51):
that relates to us. And then there's the weirdness of
the blood diet too. So let's let's launch into these
guys because they're so amazing. Yeah, vampire bats. Now, bats
exist in various places throughout the world. We have both
both the Old World and the New World bats, the
New World of course being the America's. But out of
all these species and uh, and we're talking over a thousand,
(02:14):
like five more or less different species of bats in
the world, they make up a quarter of all mammal species,
and yet vampire bats limited to three species currently, all
three live in the New World in the America's ranging
from Mexico to Brazil, Chile and argat Argentina. And there's
a reason for that. Yes, we'll get into that in
(02:36):
a little bit. But when we're talking about these three species,
we were talking about does modest rotundus, diphilia eco data
and Diningma's jungi and respectively, were talking about the common vampire,
the hairy legged vampire, and the white winged vampire. Yes,
and these are all three again their vampires their single bars.
They live which in their obligates obligates samla single bars,
(02:59):
meaning they live exclusively on blood. There are obligated to
drink it. It's not just a situation of like, yeah,
I eat blood, eat bugs and then I get a
little blood here and there. No, they exist solely on blood.
And as will discuss, like that's that's a hard road,
like blood is not a great nutrient. Like if you
had to choose one thing in the world to live upon,
(03:21):
that's not a good choice. Like that's why you have
that's really one of the reasons you have only three
species out of these thousands of species of bats that
do this. The rest are living on fruits or insects.
And then here these these guys and gals, and they're
depending upon blood. Yeah, in a pretty limited region if
you look at it from a world perspective. Um, but
let's look at the way these guys appear to us,
(03:44):
because they're they're quite striking. Um. They have these pig
like noses that if you ever look at angry birds
and you see the pigs, they've got big gizmo ears, right,
and um, they have a kind of a it's been
described as a cleft on its chin which helps to
channel the blood. And then of course these just razor
(04:05):
sharp teeth. Yeah. And the and the nose you mentioned
is all. They also have this this kind of nose
leafing it's called, which almost kind of makes their nose
looks like some sort of a fungus. Uh. And and
you find these all in other bats as well, not
just the vampire bats. But they give the the vampire
about a very distinct appearance. And in fact, early naturalist thought,
(04:26):
you know, I guess, based mostly on illustrations at this
point that those leaves might be sharp, so their noses
are kind of these these razor blades that they might
be using to slice open their prey in order to
drink the blood, which isn't so then the nose leaves
have have to do with echolocation and also thermal location,
not only seeing things with sight, but also detecting changes
(04:46):
in temperature so they can see where that blood is
to see where see where where to strike, and where
to drink exactly. They actually it's sort of like an
infrared system that can actually sense that heat. But um.
But what I love about the way they look and
these depictions of them is they almost look like these
fictional like medieval etchings or something or something that would
(05:07):
come out of the mind of man, because they look
so bizarre they do. They have this goblin the UH
look to them, and it's right because you you look
at the illustrations of fantastic goblins and whatnot and monsters
and demons, and then you look at the bat, and
then you have to know what comes first. You know,
to what extent has the bat influenced our iconography of
(05:29):
the monstrous? To what extent has the monstrous UH interpreted
our interpretation of the bat, because for instance, the vampire thing,
it really our understanding of the vampire bat is fairly recent. Uh.
And again they're in there in the New World, they're
in the Americas. But the idea of the vampire, of
some sort of creature that sustains itself on blood, on
human blood, especially, like, that's a very old idea that
(05:51):
you find, uh, you know, back in even in the
Hellenistic ages, and perhaps you know even earlier indeed. But
let's let's get into some of their feeding habits, because
this is really interesting stuff. In a study published in
the journal BMC Biology, it was found that vampire bats
of this species does modus rotundus by the way, if
they were named rotundus at the time, because their stomachs
(06:13):
looked appear to the people it is very very large
to the researchers, um. But little did they know that
the stomach was actually filled with blood at that moment,
so that's why the stomach looked so rotund. But they
found that these bats could recognize recorded human breathing sounds
much better than human participants could. And vampire bats feed
(06:34):
on the same prey, by the way, over several nights
and the authors of the study proposed that the bats
us breathing sounds to identify prey in the same way
um humans use voice to recognize each other. So it's
kind of it's interesting not only that they have the
certain live stock in mind, but they can differentiate between
(06:55):
that live stock based on their breathing patterns. And we've
talked about this ability with bats before, this sort of
zen like ability just to to take everything else in
the background and have it sort of receeed and really
hone in on the prey. Yeah, they're amazing creatures and
and it's easy to focus on on all of this, uh,
(07:16):
the alien aspects of the bat, because as we discussed
in the previous podcast, it's it's it's almost impossible to
put ourselves in that perspective and to imagine seeing the
world as the bat sees the world. But they're also
really social creatures. They typically gather in collegues about a
hundred animals, but sometimes they meant living may live in
a group of a thousand or more. And uh, incidentally,
(07:36):
over that time, a hundred bat colony can drink the
blood of twenty five cows. But but again, they're they're
very social. You see actual um reciprocal altruism in vampire bats.
You see, because this will discuss, it's essential with with
a blood diet to to get that blood every night
if possible. And if you go forty eight hours without
(07:57):
blood as a vampire bat, you're starving yet your toast. Yeah,
and so we we we see examples of the vampi
of vampire bats bringing blood back and feeding the famished bats,
the bats that haven't had enough to eat, and and
looking after each other in this in this fashion. And
that one of the theories here with this is that
bats picked up this behavior, this kind of altruism, is
(08:19):
looking after one another because in their habitats, as you
see the horse die aways, you see the camel and
the giant slop disappear from the continent, leaving them only uh,
you know, much more limited food supplies. They had to
do this in order to survive. Yeah, there's a kind
of cooperation, just like among humans. Right. If you kind
of help me out this time, I'll help you out
next time. You know, you can't find a source of blood,
(08:42):
right there, there's what I said yesterday, right exactly. Yeah,
And there's they're they're even you know, there's some degree
of of argument uh in this on this particular topic
among bat researchers. But they may be able to weed
out cheats. So if you're taking blood but not giving,
then they're going to cut you off. Ah, that's interesting.
(09:02):
And they have seen that in captivity all of the
bats will share a meal if if someone needs it,
but in their natural habitat the adult males will not
engage in this behavior the female as well. Of course,
they also like to sniff each other as a greeting
and they perform social grooming of one another, which is key.
(09:26):
We'll be getting back to that in a minute. Yeah,
And for their body size, vampire bats have one of
the largest brains among bats. The neo cortex is about
twice the average size of other bats. And as we
know about the neo cortex and humans, it's really important
in terms of social intelligence and social complexity. So it
(09:48):
would make sense that um it is so very large.
And if they have these very rich bonds with one another.
And we have talked about this before and the other
podcast about bad but a lot of the test to
do with their communication, which is super nuanced. We know
of course they can recognize each other's voices. We also
(10:09):
know that bats share a common gene for communication called
fox P two with us. And we also known, according
to researcher Mere Jean Quinn Child and her colleagues at
the University of Erlingen Nuremberg in Germany, that the younger
great greater sack bats that the baby ones were observed
(10:30):
stringing together screeches, barks, and hisses with no soccial context,
essentially practicing language much like a toddler does when it babbles. Yeah,
so again, you see a lot of parallels with humans.
All right, So let's talk about evolution. Now, mostly we're
interested in the evolution of of vampiresm of depending upon
that blood diet. But but let's let's step it out
(10:53):
a little, uh, a little more and think about the
evolution of the bat itself. Bats and birds. Obviously they
have a great deal in common. Both both are flying organisms,
yet they're very different. In birds, we have the aviens
emerging about a hundred and fifty million years ago during
the Jurassic period, uh, and they go on from there
to fly, swim, trott and borrow all over the world. Meanwhile, uh,
(11:18):
the mammalion bat dates back between seventy hundred million years ago.
But it's hard to say because even though they're one
of the most diverse groups of mammals today, they're one
of the least common groups in the fossil records. Uh.
Part of this is that they have small light skeletons,
they don't preserve all that well. And also, if you're
residing in a tropical environment, as a lot of these
(11:39):
these bats due today and and did historically, these are
not environments where where dead things last long decomposition is yeah,
things that it's breaking down, it's hot, it's moist, things
are eating. Uh, so it's chance the chances of fossilization
are reduced. Again. They're over a thousand different species of
bats in the world. They make up a quarter of
(12:00):
all mammal species. Uh. And among these we have the
mega bats as opposed to the microbats. These are large
bats found in the Old World tropical rainforests Australia, Asia,
and Africa. The biggest bat in the world is the
is the Malayan flying fox found in Asia. Waighs about
two pounds and has a wingspan a fan of about
six feet, and that's one of the fruit eaters. The
(12:20):
smallest bat in the world is Kitty's hog nose bat,
also called the bumblebee bat, and that's stuff found in
Thai land in ways about two grams uh. It's about
as much as a dime, by the way, and it
has a six inch wingspan. So both the bat and
the bird learned to fly in their own way. And
there are other fascinating examples of their covergent evolution. Several
(12:41):
dozen bat species and more than three hundred species of
hummingbird evolved to resemble each other, both anatomically and behaviorally, uh,
solely because they existed in similar environments and exploited a
similar resource name lamely nectar. All right, this is the
sugary liquid bribe of pollen producing plants. But those are
the nectivores. And we're here to talk about bats with
(13:03):
another highly specialized lifestyle for a liquid diet. And we're
talking here, of course about the songlevores, the blood drinkers.
How did the blood drinkers evolve? Well, the first vampire
bats emerged less than twenty six million years ago, according
to genetic evidence, and they are closely related to insect
eating bats that may have gorged on the parasites of
(13:26):
prehistoric beasts. So if you've just feasted on a fat,
juicy tick, let's say, then it's not too far of
a walk in logic to see how some bats may
have begun to have the taste for blood or to
seek it out as as a mean source. Right, And
we we see this to a certain degree in birds. Uh,
(13:49):
there are birds that occasionally or even frequently feed on blood.
Vampire finches of the Glagos Islands occasionally feed by drinking
the blood of other birds. Meanwhile, there are plenty of
birds that feed on picks and other parasites and large animals,
you know, ox peckers and the like. They're eating the ticks,
they're eating the fleas, whatever. And then if there's a
little blood there from the host organism, they'll they'll go
(14:09):
ahead and cross that line and have some of it
as well. But there's little or no convergence between birds
and bats when it comes to blood. When we're talking
about obligate blood drinking, you don't see uh, any obligate
blood drinking birds. Well, I think imagine the pigeons out there,
so so central are these blood meals to the vampire
(14:31):
bats that they actually have been missing around or modifying
a plasma gen activator gene, which we haven't. Humans have it,
and it protects against heart attack by producing proteins that
bust up blood clots and they clear vessels. Um. But
they actually have this, uh, this gene that they can
activate in their saliva. And David Liberles, a geneticist at
(14:54):
the University of Wyoming and Laramie, studied three species of
vampire bouts and found this modification. And he found that
two species that prey on lifestock acquired additional mutations that
prevent these p A proteins from being silenced by natural inhibitor.
So he says that's a process that humans and other
mammals used to put a harness on blood clotting, but
(15:15):
feeding on mammals, he says, is a key adaptation for that.
So it's just further evidence that this is so important
to them that they've been tinkering over time their genes
say hey, we need to make this process more solid. Yeah,
like thet a genetic level, they are completely committed to
(15:35):
this blood diet and we're going to get into into
some more aspects of this little more. But it's such
a specialized diet that it demands a very specialized physiology.
It's not. And that's something to keep in mind again
when you think of of humanoid vampires, like, what would
it take for a human? Could a human live on
blood exclusively? No, a human couldn't. It would require a
different species of humanoid exactly entirely. Yeah, you'd have to
(15:57):
be a very tiny humanoid first of all. Um. But
I did want a little side note here mentioned that
the anticoagulating enzyme that they produce has been synthathesized by
researchers and it is called draculin. Nice. It isn't that nice,
And it's used in medication for strict victims to keep
tissue damage and a minimum by keeping that blood flow
to the tissues. Yeah, like we discussed when we were
(16:18):
talking about leeches, I believe any animal that that depends
on blood has to be kind of a hacker. And
the and the the bat though it's hard to call
about a parasite. You see people shying away from them
as bat and calling them a carnivore, but still they
have to be able to hack the blood. And so
from a medical standpoint, as we try to figure out
ways to hack the blood, we end up turning to
(16:40):
the to the leeches, to the bats, the parasites of
the world, to the blood drinkers of the world, and
see how they do it. Um. You mentioned the evolution
of the bat and the idea that they evolved from
insect eating bats in prehistory, and I just wanted to
run through UM that that that idea because it gave
me some visual old, didn't it It did? And uh
(17:01):
And specifically I was reading a fantastic book and you
were reading this as well, by Bill Shoot called Dark Banquet,
Blood and the Curious Lives of Blood Feeding Creatures. It's
available on paperback, hardcover, and kindle, and it's it's really excellent,
excellently written, great for just about any any reading level,
in any science level. UM. But he really goes into
(17:23):
this topic and I was. I really enjoyed it so
much I wanted to hit the three uh or so
hypotheses that he mentions. Now, the first hypothesis is, again,
we have these proto vampire bats and they're feeding on
blood in gorge ectoparasites found on large prehistoric animals. So
think of all those crazy prehistoric animals that we covered
in the past. Or you send pictures of um and there,
(17:45):
and there of course loaded with parasites, big old ticks,
big old fleas, other things that are gorging on the blood. Yeah,
it's a feast. And you're a bat, you're you're you
eat insects, and it's a world in which the insects
are are the available prey. And here is a large
animal and it's crawling with these things. So you're you're
gonna you're gonna eat those, right, You're gonna eat those
(18:06):
big blood gorge ticks and whatnot. And so that the
idea here is that they're dining on those and over
time they crossed the line, you know, they start drinking
some blood from the host, and then they reached the
point where they're living exclusively on the blood of the
host animal and ignoring all of those ticks and fleets. Now,
this is supported by the fact as a theory, as
(18:28):
a hypothesis, rather that bats are insectivore. So we know
that that prehistoric bats would have been eating insects, and
there are anecdotal reports of vampire bats praying on vampire moths. Now,
just that's gonna come as a surprise for a lot
of you, because yes, there is a vampire moth um
blood on blood here, yeah, and you'll find him in Malaysia,
(18:50):
you'll find him in Thailand. You're all southern Europe and
and so there. Again, there's anecdotal evidence that vampire bats
have preyed on blood engorged insects, So take that point.
It's another scenario that lends support to this idea. Is
the whole grimming thing, right, you had pointed that out.
That's that's important socially that you sit there and groom
(19:11):
each other. So that would be an opportunity to pick
out some nice, juicy morsels, right, That's so that could
lend some support to it. And I said that it
was a sort of short walk in logic to say
you would cross over. But that's also a little simplistic, right,
because that's like saying that if you had to be
a cannibal in this very dire situation as a human being,
(19:34):
that once you had that, you might go cannibal for
the rest of your life, right right. Yeah. We find
it increasingly when you try and apply some sort of
mathematical model for evolution, if you fall into this trap here,
because it's not a situation able X plus y equals
z here so it must be the same here, and
it gets gets complex anyway, Um that expert brock Fenton
(19:55):
disagrees with this, uh, this theory that we've been discussing,
and he argues on some three points. Number one, ectoparasites
are small, Like even if we're talking about a prehistoric animal,
it's it's still gonna have small parasites. It's not like
the giant elephant head giant ticks. So let's take like
thousands of these things. Yeah, you still a lot of them,
(20:15):
and it's gonna be difficult to act. The ectoparasites are
difficult to find on other animals, and vampire bats are
restricted to a very slim portion of the Americans. And
so part of his argument is, if this was really
how things were gonna go down, why didn't it go
down like this in other places? So he presents hypothesis
number two, the idea that proto vampire bats fed on
(20:36):
insects and larva crawling around the gaping wounds of large
prehistoric mammals. So, which is another wondrously grotesque image to
imagine a giant prehistoric creature. It's, you know, it's shambling
through the forest. Maybe it's something that attacked it, had
got into a fight, or it just ripped itself on
some thorns, just got this bleeding hole. So what happens
to a bleeding hole on an animal? Insects come for it, right,
(20:59):
things start laying their squirming larvae in there, and uh.
And so a bat might come and say, well, hey,
I want to hang out where all these delicious insects
are hanging out. And then they end up inevitably drinking
from that font as well, which again is kind of
too easy to walk here. Yeah. Shoot. In his book Counters,
he says that the scenario requires large wound sits on
(21:21):
a regular basis um and uh. And also, as we're
gonna get into a little later, vampire invertebrate blood is
water and protein. There's no fat, so vampire bats can't
store it as fat like non blood drinking bats store
away their their their food. Uh. They need to feed
and consume fifty of their body weight and blood each night.
So you need to be able to find if you're
(21:43):
depending upon wounds, uh, surrounded by insects, you've gotta be
able to find those wounds surrounded by insects on a
regular basis basis, and also echolocation is gonna be useless
in finding these animals. Um It's it's just that there
are a number of holes in this argument as well. Now,
a third hypothesis here is something called the arboreal feeding hypothesis,
(22:05):
and it really focuses on carnivorous members of the neotropical
bat family Philisto muda i found in South America where
formerly there had been vast forests which were then replaced
by grasslands. So what does that mean. That means that
all of a sudden you have very small little islands
of forest area, and you have a lot of big
(22:29):
mammals taking refuge in these trees, sleeping in them at night,
and so all of a sudden you've got a population
of one tree that might be hosting many different hosts
um as opposed to being spread out through the forest.
And this is an opportunity for vampire bats. So what
you're talking about here is a bunch of animals like
sloth taking refuge in these trees, falling asleep, and then
(22:52):
these vampire bats, who are so stealthy by the way,
sneaking up and just saying well you don't mind if
I do, and taking their blood samples there, and then
of course this would encourage that behavior over and again
as an adaptation in this scenario. Because if you've got
that loss of habitat, and all of a sudden you've
got these mammals congregated in the trees, well that makes
easy pickings. So which hypothesis is true? Well, the answer
(23:18):
still open to debate. Uh. That you know, it's possible.
As with a lot of things, it's more of a
combination of these ideas as opposed to one distinct idea.
And uh, and we have to remember that it's it's
it's it's difficult to avoid falling into the trap of
thinking of evolution as this clockwork predictable scenario. Again, if
it's X here, then it's X there. Uh. If we
(23:40):
turn back the clock and did it again, everything would
come back to the same place that we get the
same results. And that's that's likely not how it goes.
Um For whatever reason, a single group of New World
leaf nose bats evolved as the only vertebrate obligate sangle bores.
And it's pretty amazing. All Right, we're gonna take a
quick break. When we get back, we're gonna talk more
(24:01):
about the hard knock life and uh blood letting. All right,
we're back. Let's talk about these vampire bouts because if
you made it this far in the Vampire About Territory,
you're about to get this serious blood payoff. Because this
(24:22):
is fascinating stuff. And uh, maybe we should start this
section as like, you imagine you are the vampire bout,
dear listener. Yeah, I imagine that you have sort of
gone down this uh almost evolution. I wouldn't almost say
an evolutionary dead end, but you've you've gone down far
enough that you're you're in this very niche area and
(24:44):
there's no there's no turning back. It's like that line
in Macbeth where Shakespeare says, you know, if I've waited
that the main character says, I've waded through blood so
far that if I were to turn back, it would
be just as much work to keep going. And that's
where the vampire bad is. It's a hard knock life
that the vampire back has evolved into, but there's no
turning and turning back at least not anytime soon, that's right.
(25:04):
So you are stuck with this blood diet and the
bad news here is again and We've talked about it before.
Blood just doesn't have much to it in terms of nutrients.
In fact, a percent of it is water. So what
do you have to do Every night? You must go
out and hunt and lap up of your body weight.
And this is this is a hard thing to do
(25:26):
because you can't store any fat that it might have
because it doesn't have any fats. So you every night
are obligated to go out. You can't sleep it off,
you know. You Also you can't hybrid it. You can't
build up stores for later. You're there's no uh, there's
no preparing for the winter. If winter comes, you're you're
gone if you can't get blood. So and that's why
(25:46):
we see these three species of vampire bats living in
tropical areas. They cannot knack it in areas that have
cold climates. So that's right, you cannot hack the cold weather.
You have to take advantage of these areas that have
warmer web other and you must be really wildly. So
it's not just like, hey, I gotta go out and
get some blood. No, you're gonna be the best at
(26:08):
getting blood. Is any blood getting mammal is gonna get. Yeah,
you've got to use your stealth to the highest degree
because you need to prey on sweeping animals. You need
to not wake them up while you're drinking their blood.
And you can't exert a tremendous amount of effort and
energy finding your prey because again you're you're you're on
a very tight budget here. You have to eat every night,
(26:32):
and you can't spend too much energy because you can't
store that much energy. So you can't go on long
drawn old hunts covering you know, vast miles of of area.
You have to you have to really hone in. You
gotta make it work, and you've got to You've gotta
get defeating, that's right. And so as a result, you
have this exquisitely sensitive heat detecting molecule covering nerve ending
on your nose, and this allows you to detect infrared
(26:55):
heat that is just beaming from areas on a livestock's
body and and that that's sort of like the the
area that you know you're going to hone in on,
because as you said, you don't have tons of energy here.
You gotta be fast. Yeah, you gotta go right for
the vein. There's no just crawling around on it's romp
until you find an area that's that's that's right. You
can't feel it out, you gotta see it. You gotta
(27:16):
focus in on it, and luckily the vampire back can
douce that. Yeah, and these guys that mostly attack from ground,
though sometimes it's from the trees, but they can actually run.
It's only like two point five miles per hour or something,
but still that's pretty fast, and that they think. The
reason for that, researchers think, uh, is because if they're
around something like a horse or a cow, it's easy
(27:36):
to get trampled upon, So you gotta get out of
their fashion. Good people to hop away. But it's pretty
amazing to see them running, all right. See you land
next to the cow. You hit the ground running more
or less than you you you scamper up there right
to the place that that hot spot that you've you've
seen with your your your fantastic heat vision. And this
is where you're gonna feed. What do you do? Well,
(27:58):
first thing you do is you lick that area where
where you're gonna apply the incision the saliva anticoagulants. Yes,
because the saliva here is key and is really amazing
to quote Bill Shoot from his book Dark Banquet, the
process actually consists of a maddening cascade of chemical reactions
(28:18):
that must occur before clot forms. Because again, you're making
when you make your incision now with your your sharp teeth,
you're making a very small wound. You're not just you know,
you're not making this enormous font from which to drink.
You're making something that giving its own devices, given the
body's own defenses, this would normally close up in a
couple of minutes. This is not You're not just you know,
(28:39):
opening a jugular here and dancing around the fountain. You're
creating a small wound, but anticoagulants in the blood prevented
from clotting, allowing you to feed there for the amount
of time necessary to get that full meal. Yeah, in
this case about minutes. And if you think about their incisors,
they are knife sharp um. In fact, Bruce Patterson, a
(29:00):
zoologists at Field Museum in Chicago, says, you can actually
cut yourself handling a bat skull in a museum. They're
that sharp. Because again we're talking about efficiency here, getting
in and getting in quick, and their tongues also get
into the game here because they contain a specialized groove
that allows a blood meal to flow via capillary action.
(29:21):
So they do not suck, they slurp, They lap up,
which is another thing to keep in mind because again
it's it's a small wound. It's not going to be
held open by suction. And uh and to your point
about the teeth, that's another aspect of this too, is
that it's such a small cut in with such a
sharp knife you barely feel it while you're sleeping. UM.
In his book, Bill Shoot talks about an encounter with
(29:44):
a bat and a hen that had him reeling. And
I love this, you know what I'm talking about. So
I was thinking about this. Not only does the bat
have data from UM from the infrared molecule and data
from the breathing pattern of the livestock, but also has
been observing it and perhaps taking those observations and passing
(30:06):
them down among its young and so on and so forth.
And what I mean is that Bill Shoot saw this
bat sidle up to a hen. Thought the hen was
going to be like, no way getaway, but it did not,
because the bat then went and cuddled up to the
hen right at this area it's called UM I think
it's called a brood patch. It's where chicks will go
(30:28):
because there's more heat and more capillaries that are congregated there,
so there's more heat available. So essentially, this bat is
mimicking a chick and cozing up with the hen. And
what he said is that he saw the hen like
visibly looked to be relaxed and then settled down, and
then the bat kind of burrowed down a little bit more,
(30:50):
and a couple of minutes later he saw evidence of
that blood from underneath the hen where that bat had
been suckling a the vein. I mean, I think it's
amazing that essentially said hello, hen, I know I look
like a bat, but really I'm a sweet little chick
who just needs a little warmth. That is amazing. Now
(31:12):
you mentioned the tongue earlier, and the tongue is also
really key here. Again, the bat is not sucking the blood.
It's it's lapping the blood. But but lapping. It's easy
to just say, oh, lapping and just sort of have
this loose idea in your mind of a dog or
a cat lapping up the milk or water, which even that, incidentally,
if you slow it down and look at the video
is a far more complicated process than we than we
(31:34):
give the credit. With the bat, you have this piston
like motion of the tongue and it causes the blood
to flow along a pair of grooves on the bottom
of the tug and into the mouth through that cleft
in the lower lip that we mentioned earlier. So you
have to imagine that again. It's like this piston action
of the tongue just and you get this flow going
(31:55):
out of the wound into the bat's mouth. Yeah, we're
talking about a tablespoon when it's all um done. But again,
that's half of the bat's body weight. So after it
leaves the tongue, it goes into the esophagus and down
into the stomach, which is richly lined with blood vessels
that absorb that water and that shunts it straight to
(32:16):
the kidneys before it actually goes to the intestines. So
that something is really important here because it is absorbing
all of that water. But the reason is is because
they have to work fast, these bats in terms of
digesting and expelling this stuff from their systems. Yeah, again,
they're loading up on blood and they have to be
ready to escape at a moment's notice, you know that
(32:37):
cow might wake up, uh anything at any time, and
you're gonna have to get away. You're gonna have to
then fly away. And you cannot be weighted down with
all of this waterway because again we're talking about just
just consuming you know, half your body weight and food
and you're and you're gonna have that that stomach just
filled with water. So you've got to get rid of it.
And that's why you have this rapid uh removed oval
(33:00):
of the water, shut it through the kidneys. And then
the bat vampire bat is urinating as it's feeding, Like
shortly after it starts feeding, it starts urinating because it's
it has to prepare for takeoff. Yeah, to add insult
to injury here, and it avoids soiling itself by extending
one hind limb sideways and downward. So it's like, I'm
(33:21):
not gonna get on any on me, but hey, you
sorry about that. And it's also an interesting scenario when
you start thinking about about the urine itself and it
has to the urine that the bat is pumping out
is getting increasingly concentrated as it goes. Because part of
the whole deal with our urine. Of course, we're getting
rid of these toxic aspects of our meal and uh,
(33:42):
and that's what the bat is doing as well. But
it's doing in such a such a such a fast
process at play here that you just have the concentration
of the urine is just building up and building up
the more that it urinates. And you get into this
interesting area here too, where despite the fact that the
vampire bat has this this liquid diet, and despite the
(34:04):
fact that it lives in the tropics exclusively, it lives
in its own kind of personal physiological desert, there's always
this risk of dehydration because it has to get rid
of so much of the water that it consumes through
its meals. That that that that again factors into the
economy of the vampire bat. It can't it can't live
(34:25):
in a place where it's any kind of dryness, because
it does it it's living, it's living with such a
slim margin um between it's it's it's life and complete dehydration. Yeah,
that's a that's a really complex balancing game there, And
I think it speaks again to this idea, or at
least in my head, that they almants feel like they're
cursed in a sense like in and of course I'm
(34:46):
evoking uh, vampire lore here, but you know you can't.
You can't hibernate. You have to live in this very
specific area, um and kind after night you must go
out and kill, well not the kill perpect blood. One
thing that makes me think about you. You've done freelance work,
(35:06):
of course, freelance writing, uh and I have as well.
And at times you do you like like like myself,
You've probably ticket You've thought yourself, well, could I just
depend up solely on freelance writing? And I feel like it.
You end up getting into this sort of vampire bat
situation where you're like, yes, if I, if I pray,
if I get enough gigs on a regular basis in
the in the just the right environment, and I never sleep,
(35:29):
never hibernate, then I can make it work. I can
just barely make it work, and I can survive and
and and pay all my bills. And then you end
up just defecating and urinating on yourself all the time
to avoid having to deal with any loss of energy, right,
and you're always looking for that that next that next kill,
that next job. Yeah, it is. It's kind of I
(35:50):
like that analogy. Yeah, the vampire bat is living on
the margins here, you know, it's just it's it's it's
found this niche. But it is a hard niche to
exist in. Indeed, it is. I want to point out
that we do have a few fossil vampire bats, including
the biggest vampire bat that that ever existed as far
as we can tell from the fossil record, and that's
(36:10):
the thirty percent larger uh do Modus dracula, which is
of course a great great name for a vampire bat
or some sort of a you know, Gothic band uh
And they were they were total vampires. They were not
any kind of transitional form, and they existed farther up
into the America's But the idea is, this larger bat
is depending on the blood of larger species, and if
(36:33):
those species died out in these sorry times, so did
this And so the domain of the vampire bat was
once larger and contained more species than it shrinks. And
it's then it's confined to these these hot tropical zones
and the few animals that they can still prey on
for blood. Ah. But what of global warming, which is
actually warming up many parts of the world, and this
(36:57):
has led some people to say, hey, we think that
there is going to be an increase in the vampire
bat population, specifically in North America, in Texas and some
parts of Louisiana in the next couple of decades, so
they might be coming to a city near you. Yes,
all right, so, um, we've given you guys a description
(37:19):
of these bats, but if you would like to see
them specifically on a vamp cam, you can at this
very moment. In fact, there's a there's a camera in
there twenty four hours a day you can observe these
and this is at the Organization for Bat Conservation, So
that's bad Conservation dot Org. Yeah. I was looking at
the other day and they're they're really adorable where they're
(37:40):
scurrying around. That's the thing about the vampire bad It's
like part of this responds to them, and we with this,
uh this something kind of cute about them, But then
there's also something that in the very depth of our
genes we we can't help but find a repugnant. They
walk that line. Well, the distance though of the vamp
cam makes it all sorts of adorable. Sure, like my
(38:01):
hand's nut in that cage with them, So that's so
cute that they're cuddling right now. And it's not full
color either, so it's got that going for it. So
there you go, the vampire bat, the evolution of the
vampire bat, the physiology of the fampire bat. I I
hope it it allows everyone to have even more respect
for these amazing creatures and just rethink the vampire equation
(38:23):
in general. Like it really made me rethink our ideas
of a vampiric human and what that would be like.
I feel like we focused, we focus far too much
on the supernatural aspects of of a humanoid vampire. We
focus on the viral aspects of like vamp vampirism as
a disease in these fantasy and scenarios, and of course
(38:44):
we end up fantasizing and focusing on like the sexy
and alluring aspect of some sort of a fictional vampire,
whereas if we look to the biological example, if we
look to the vampire bat, it paints an entirely most
entirely different idea about what evampiric human would look like.
(39:04):
I think the closest we've come is the nos Ferato
of the classic film and some of the rehashes we've seen,
which is kind of like this withered figure. Um, not
this robust character wearing shades and a leather jacket and
like ruling the night. No, because even the vampire bat
does not rule the night. It knows it. I mean,
(39:25):
I'm I'm anthromorphizing here. It knows it doesn't rule the night.
It has to stick to the shadows as a conservative energy,
and it has to get the easiest, uh most filling
meal it can. So the idea of this slim, ghastly
corpse like nos Ferato, you know, reeling in the shadows
like that's that's I feel like that's the corporate we've
(39:45):
we've managed to get. I agree. I wish that Jim
Jarmus is a new movie. Only Lovers Left Alive would
have explored that idea, would you explored in a blog
post by way Um, So check that out af if
you want to kind of do some reimagining of Dracula
and popular Lure. Yeah, I do want to see Only
(40:07):
Lover's Left Alive. I didn't think that I would want
to see another vampire film, but that one looks pretty good.
Till the Swinton The Magical unicorn of a human is
in it, so you kind of I mean, I have
to see it just for that alone. Yeah, I want
to see that. I also want to see Neil Jordan's Byzantium,
which sounds in like, on the surface, it sounds like
just another scenario of like to two vampires, like a
(40:28):
mother and a daughter vampire and they they're, you know,
trying to find their way in a world of vampires
living in the shadows. But it's it's misunderstanding each other. Yeah,
but it's her mother daughter, but it's it sounds more
interesting because it's like strong, supposedly strong female characters based
on a play by a female play right, So there's
there's something about that that I want to give that
(40:49):
one a shot as well. All right, So what about
you guys and gals out there, what do you think
about the science of a vampire bat the physiology and
evolution of vampire bat um. How does that make you
rethink these curious creatures? How does it make you rethink
the myth of the vampire as it exists in folklore
and in popular culture. Um, we'd love to hear from you,
(41:10):
and you can find us at all the normal places
there is, of course, Stuff to Blow your Mind dot com.
That's the mothership that should be your your first stop
when you think yourself, I wonder what those guys are
up to? Well, go to Stuff to Blow your Mind
dot com. That's where we will get the full dosage
of all of our activities, including our blog posts, are podcasts,
our videos, links out to our various social media accounts
(41:31):
such as Facebook, Twitter, Tumbler, Google plus, um, our YouTube
account which is mind Stuff Show. If you haven't followed
us there, if you're a regular YouTube user, go there
and give us a follow. Let's check out some of
our videos there. We have a number of cool new
projects that we're pushing out in the weeks ahead. Indeed,
and if you would like to get in touch with
us in the meantime, you may do so a blow
(41:53):
the mind at Discovery dot com. For more on MISS
and thousands of other topics, visit how staff works dot com.
H
Welcome to Stuff to Blow Your Mind from how Stuff
Works dot com. Hey you welcome to Stuff to Blow
your Mind. My name is Robert Lamb and I'm Julie Douglas,
and this week we're talking about vampires. Specifically, we're talking
about vampire bats. But I feel like I have to
to urge everyone, like, don't don't run away, because because
(00:24):
on one hand, vampires, of course, as just is a
is a whole. It's like bringing in all of the
various fantasy elements. They're like, that's completely overblown, to the
point that most people I think are getting, if not
completely already forward with vampires, you know, we kind of
know what to expand with it. And then with vampire bats,
I don't want to, you know, discredit them either, but
(00:45):
on a at a surface level, it's easy to say, oh, well,
their bats and they drink blood from cows, no big deal.
I've seen them on I've seen Attenborough talk about them
on documentaries, and yes, they're they're neat, but I don't
necessarily need to hear about them for an hour. But
the thing is, we really start asking questions about the
blood diet and about the vampiric lifestyle style and how
(01:07):
that evolved really get into some crazy imaginative areas that
that that that really blew my mind. Yeah, these guys
are so interesting for for many many reasons. And we've
talked about bats. I think we had a couple of
bad episodes last year. Maybe we've talked about how um,
we'll just we'll discuss a little bit about this, but
(01:28):
we've talked about how they have rich social bonds and
they are amazing creatures, and they have these these four limbs.
If you look at their bodies, it's very easy to
see the human hand and the human armbones replicated in
that wingspan. That alone gives us this idea that there's
so much to this mammal that's only flying mammal um
(01:51):
that relates to us. And then there's the weirdness of
the blood diet too. So let's let's launch into these
guys because they're so amazing. Yeah, vampire bats. Now, bats
exist in various places throughout the world. We have both
both the Old World and the New World bats, the
New World of course being the America's. But out of
all these species and uh, and we're talking over a thousand,
(02:14):
like five more or less different species of bats in
the world, they make up a quarter of all mammal species,
and yet vampire bats limited to three species currently, all
three live in the New World in the America's ranging
from Mexico to Brazil, Chile and argat Argentina. And there's
a reason for that. Yes, we'll get into that in
(02:36):
a little bit. But when we're talking about these three species,
we were talking about does modest rotundus, diphilia eco data
and Diningma's jungi and respectively, were talking about the common vampire,
the hairy legged vampire, and the white winged vampire. Yes,
and these are all three again their vampires their single bars.
They live which in their obligates obligates samla single bars,
(02:59):
meaning they live exclusively on blood. There are obligated to
drink it. It's not just a situation of like, yeah,
I eat blood, eat bugs and then I get a
little blood here and there. No, they exist solely on blood.
And as will discuss, like that's that's a hard road,
like blood is not a great nutrient. Like if you
had to choose one thing in the world to live upon,
(03:21):
that's not a good choice. Like that's why you have
that's really one of the reasons you have only three
species out of these thousands of species of bats that
do this. The rest are living on fruits or insects.
And then here these these guys and gals, and they're
depending upon blood. Yeah, in a pretty limited region if
you look at it from a world perspective. Um, but
let's look at the way these guys appear to us,
(03:44):
because they're they're quite striking. Um. They have these pig
like noses that if you ever look at angry birds
and you see the pigs, they've got big gizmo ears, right,
and um, they have a kind of a it's been
described as a cleft on its chin which helps to
channel the blood. And then of course these just razor
(04:05):
sharp teeth. Yeah. And the and the nose you mentioned
is all. They also have this this kind of nose
leafing it's called, which almost kind of makes their nose
looks like some sort of a fungus. Uh. And and
you find these all in other bats as well, not
just the vampire bats. But they give the the vampire
about a very distinct appearance. And in fact, early naturalist thought,
(04:26):
you know, I guess, based mostly on illustrations at this
point that those leaves might be sharp, so their noses
are kind of these these razor blades that they might
be using to slice open their prey in order to
drink the blood, which isn't so then the nose leaves
have have to do with echolocation and also thermal location,
not only seeing things with sight, but also detecting changes
(04:46):
in temperature so they can see where that blood is
to see where see where where to strike, and where
to drink exactly. They actually it's sort of like an
infrared system that can actually sense that heat. But um.
But what I love about the way they look and
these depictions of them is they almost look like these
fictional like medieval etchings or something or something that would
(05:07):
come out of the mind of man, because they look
so bizarre they do. They have this goblin the UH
look to them, and it's right because you you look
at the illustrations of fantastic goblins and whatnot and monsters
and demons, and then you look at the bat, and
then you have to know what comes first. You know,
to what extent has the bat influenced our iconography of
(05:29):
the monstrous? To what extent has the monstrous UH interpreted
our interpretation of the bat, because for instance, the vampire thing,
it really our understanding of the vampire bat is fairly recent. Uh.
And again they're in there in the New World, they're
in the Americas. But the idea of the vampire, of
some sort of creature that sustains itself on blood, on
human blood, especially, like, that's a very old idea that
(05:51):
you find, uh, you know, back in even in the
Hellenistic ages, and perhaps you know even earlier indeed. But
let's let's get into some of their feeding habits, because
this is really interesting stuff. In a study published in
the journal BMC Biology, it was found that vampire bats
of this species does modus rotundus by the way, if
they were named rotundus at the time, because their stomachs
(06:13):
looked appear to the people it is very very large
to the researchers, um. But little did they know that
the stomach was actually filled with blood at that moment,
so that's why the stomach looked so rotund. But they
found that these bats could recognize recorded human breathing sounds
much better than human participants could. And vampire bats feed
(06:34):
on the same prey, by the way, over several nights
and the authors of the study proposed that the bats
us breathing sounds to identify prey in the same way
um humans use voice to recognize each other. So it's
kind of it's interesting not only that they have the
certain live stock in mind, but they can differentiate between
(06:55):
that live stock based on their breathing patterns. And we've
talked about this ability with bats before, this sort of
zen like ability just to to take everything else in
the background and have it sort of receeed and really
hone in on the prey. Yeah, they're amazing creatures and
and it's easy to focus on on all of this, uh,
(07:16):
the alien aspects of the bat, because as we discussed
in the previous podcast, it's it's it's almost impossible to
put ourselves in that perspective and to imagine seeing the
world as the bat sees the world. But they're also
really social creatures. They typically gather in collegues about a
hundred animals, but sometimes they meant living may live in
a group of a thousand or more. And uh, incidentally,
(07:36):
over that time, a hundred bat colony can drink the
blood of twenty five cows. But but again, they're they're
very social. You see actual um reciprocal altruism in vampire bats.
You see, because this will discuss, it's essential with with
a blood diet to to get that blood every night
if possible. And if you go forty eight hours without
(07:57):
blood as a vampire bat, you're starving yet your toast. Yeah,
and so we we we see examples of the vampi
of vampire bats bringing blood back and feeding the famished bats,
the bats that haven't had enough to eat, and and
looking after each other in this in this fashion. And
that one of the theories here with this is that
bats picked up this behavior, this kind of altruism, is
(08:19):
looking after one another because in their habitats, as you
see the horse die aways, you see the camel and
the giant slop disappear from the continent, leaving them only uh,
you know, much more limited food supplies. They had to
do this in order to survive. Yeah, there's a kind
of cooperation, just like among humans. Right. If you kind
of help me out this time, I'll help you out
next time. You know, you can't find a source of blood,
(08:42):
right there, there's what I said yesterday, right exactly. Yeah,
And there's they're they're even you know, there's some degree
of of argument uh in this on this particular topic
among bat researchers. But they may be able to weed
out cheats. So if you're taking blood but not giving,
then they're going to cut you off. Ah, that's interesting.
(09:02):
And they have seen that in captivity all of the
bats will share a meal if if someone needs it,
but in their natural habitat the adult males will not
engage in this behavior the female as well. Of course,
they also like to sniff each other as a greeting
and they perform social grooming of one another, which is key.
(09:26):
We'll be getting back to that in a minute. Yeah,
And for their body size, vampire bats have one of
the largest brains among bats. The neo cortex is about
twice the average size of other bats. And as we
know about the neo cortex and humans, it's really important
in terms of social intelligence and social complexity. So it
(09:48):
would make sense that um it is so very large.
And if they have these very rich bonds with one another.
And we have talked about this before and the other
podcast about bad but a lot of the test to
do with their communication, which is super nuanced. We know
of course they can recognize each other's voices. We also
(10:09):
know that bats share a common gene for communication called
fox P two with us. And we also known, according
to researcher Mere Jean Quinn Child and her colleagues at
the University of Erlingen Nuremberg in Germany, that the younger
great greater sack bats that the baby ones were observed
(10:30):
stringing together screeches, barks, and hisses with no soccial context,
essentially practicing language much like a toddler does when it babbles. Yeah,
so again, you see a lot of parallels with humans.
All right, So let's talk about evolution. Now, mostly we're
interested in the evolution of of vampiresm of depending upon
that blood diet. But but let's let's step it out
(10:53):
a little, uh, a little more and think about the
evolution of the bat itself. Bats and birds. Obviously they
have a great deal in common. Both both are flying organisms,
yet they're very different. In birds, we have the aviens
emerging about a hundred and fifty million years ago during
the Jurassic period, uh, and they go on from there
to fly, swim, trott and borrow all over the world. Meanwhile, uh,
(11:18):
the mammalion bat dates back between seventy hundred million years ago.
But it's hard to say because even though they're one
of the most diverse groups of mammals today, they're one
of the least common groups in the fossil records. Uh.
Part of this is that they have small light skeletons,
they don't preserve all that well. And also, if you're
residing in a tropical environment, as a lot of these
(11:39):
these bats due today and and did historically, these are
not environments where where dead things last long decomposition is yeah,
things that it's breaking down, it's hot, it's moist, things
are eating. Uh, so it's chance the chances of fossilization
are reduced. Again. They're over a thousand different species of
bats in the world. They make up a quarter of
(12:00):
all mammal species. Uh. And among these we have the
mega bats as opposed to the microbats. These are large
bats found in the Old World tropical rainforests Australia, Asia,
and Africa. The biggest bat in the world is the
is the Malayan flying fox found in Asia. Waighs about
two pounds and has a wingspan a fan of about
six feet, and that's one of the fruit eaters. The
(12:20):
smallest bat in the world is Kitty's hog nose bat,
also called the bumblebee bat, and that's stuff found in
Thai land in ways about two grams uh. It's about
as much as a dime, by the way, and it
has a six inch wingspan. So both the bat and
the bird learned to fly in their own way. And
there are other fascinating examples of their covergent evolution. Several
(12:41):
dozen bat species and more than three hundred species of
hummingbird evolved to resemble each other, both anatomically and behaviorally, uh,
solely because they existed in similar environments and exploited a
similar resource name lamely nectar. All right, this is the
sugary liquid bribe of pollen producing plants. But those are
the nectivores. And we're here to talk about bats with
(13:03):
another highly specialized lifestyle for a liquid diet. And we're
talking here, of course about the songlevores, the blood drinkers.
How did the blood drinkers evolve? Well, the first vampire
bats emerged less than twenty six million years ago, according
to genetic evidence, and they are closely related to insect
eating bats that may have gorged on the parasites of
(13:26):
prehistoric beasts. So if you've just feasted on a fat,
juicy tick, let's say, then it's not too far of
a walk in logic to see how some bats may
have begun to have the taste for blood or to
seek it out as as a mean source. Right, And
we we see this to a certain degree in birds. Uh,
(13:49):
there are birds that occasionally or even frequently feed on blood.
Vampire finches of the Glagos Islands occasionally feed by drinking
the blood of other birds. Meanwhile, there are plenty of
birds that feed on picks and other parasites and large animals,
you know, ox peckers and the like. They're eating the ticks,
they're eating the fleas, whatever. And then if there's a
little blood there from the host organism, they'll they'll go
(14:09):
ahead and cross that line and have some of it
as well. But there's little or no convergence between birds
and bats when it comes to blood. When we're talking
about obligate blood drinking, you don't see uh, any obligate
blood drinking birds. Well, I think imagine the pigeons out there,
so so central are these blood meals to the vampire
(14:31):
bats that they actually have been missing around or modifying
a plasma gen activator gene, which we haven't. Humans have it,
and it protects against heart attack by producing proteins that
bust up blood clots and they clear vessels. Um. But
they actually have this, uh, this gene that they can
activate in their saliva. And David Liberles, a geneticist at
(14:54):
the University of Wyoming and Laramie, studied three species of
vampire bouts and found this modification. And he found that
two species that prey on lifestock acquired additional mutations that
prevent these p A proteins from being silenced by natural inhibitor.
So he says that's a process that humans and other
mammals used to put a harness on blood clotting, but
(15:15):
feeding on mammals, he says, is a key adaptation for that.
So it's just further evidence that this is so important
to them that they've been tinkering over time their genes
say hey, we need to make this process more solid. Yeah,
like thet a genetic level, they are completely committed to
(15:35):
this blood diet and we're going to get into into
some more aspects of this little more. But it's such
a specialized diet that it demands a very specialized physiology.
It's not. And that's something to keep in mind again
when you think of of humanoid vampires, like, what would
it take for a human? Could a human live on
blood exclusively? No, a human couldn't. It would require a
different species of humanoid exactly entirely. Yeah, you'd have to
(15:57):
be a very tiny humanoid first of all. Um. But
I did want a little side note here mentioned that
the anticoagulating enzyme that they produce has been synthathesized by
researchers and it is called draculin. Nice. It isn't that nice,
And it's used in medication for strict victims to keep
tissue damage and a minimum by keeping that blood flow
to the tissues. Yeah, like we discussed when we were
(16:18):
talking about leeches, I believe any animal that that depends
on blood has to be kind of a hacker. And
the and the the bat though it's hard to call
about a parasite. You see people shying away from them
as bat and calling them a carnivore, but still they
have to be able to hack the blood. And so
from a medical standpoint, as we try to figure out
ways to hack the blood, we end up turning to
(16:40):
the to the leeches, to the bats, the parasites of
the world, to the blood drinkers of the world, and
see how they do it. Um. You mentioned the evolution
of the bat and the idea that they evolved from
insect eating bats in prehistory, and I just wanted to
run through UM that that that idea because it gave
me some visual old, didn't it It did? And uh
(17:01):
And specifically I was reading a fantastic book and you
were reading this as well, by Bill Shoot called Dark Banquet,
Blood and the Curious Lives of Blood Feeding Creatures. It's
available on paperback, hardcover, and kindle, and it's it's really excellent,
excellently written, great for just about any any reading level,
in any science level. UM. But he really goes into
(17:23):
this topic and I was. I really enjoyed it so
much I wanted to hit the three uh or so
hypotheses that he mentions. Now, the first hypothesis is, again,
we have these proto vampire bats and they're feeding on
blood in gorge ectoparasites found on large prehistoric animals. So
think of all those crazy prehistoric animals that we covered
in the past. Or you send pictures of um and there,
(17:45):
and there of course loaded with parasites, big old ticks,
big old fleas, other things that are gorging on the blood. Yeah,
it's a feast. And you're a bat, you're you're you
eat insects, and it's a world in which the insects
are are the available prey. And here is a large
animal and it's crawling with these things. So you're you're
gonna you're gonna eat those, right, You're gonna eat those
(18:06):
big blood gorge ticks and whatnot. And so that the
idea here is that they're dining on those and over
time they crossed the line, you know, they start drinking
some blood from the host, and then they reached the
point where they're living exclusively on the blood of the
host animal and ignoring all of those ticks and fleets. Now,
this is supported by the fact as a theory, as
(18:28):
a hypothesis, rather that bats are insectivore. So we know
that that prehistoric bats would have been eating insects, and
there are anecdotal reports of vampire bats praying on vampire moths. Now,
just that's gonna come as a surprise for a lot
of you, because yes, there is a vampire moth um
blood on blood here, yeah, and you'll find him in Malaysia,
(18:50):
you'll find him in Thailand. You're all southern Europe and
and so there. Again, there's anecdotal evidence that vampire bats
have preyed on blood engorged insects, So take that point.
It's another scenario that lends support to this idea. Is
the whole grimming thing, right, you had pointed that out.
That's that's important socially that you sit there and groom
(19:11):
each other. So that would be an opportunity to pick
out some nice, juicy morsels, right, That's so that could
lend some support to it. And I said that it
was a sort of short walk in logic to say
you would cross over. But that's also a little simplistic, right,
because that's like saying that if you had to be
a cannibal in this very dire situation as a human being,
(19:34):
that once you had that, you might go cannibal for
the rest of your life, right right. Yeah. We find
it increasingly when you try and apply some sort of
mathematical model for evolution, if you fall into this trap here,
because it's not a situation able X plus y equals
z here so it must be the same here, and
it gets gets complex anyway, Um that expert brock Fenton
(19:55):
disagrees with this, uh, this theory that we've been discussing,
and he argues on some three points. Number one, ectoparasites
are small, Like even if we're talking about a prehistoric animal,
it's it's still gonna have small parasites. It's not like
the giant elephant head giant ticks. So let's take like
thousands of these things. Yeah, you still a lot of them,
(20:15):
and it's gonna be difficult to act. The ectoparasites are
difficult to find on other animals, and vampire bats are
restricted to a very slim portion of the Americans. And
so part of his argument is, if this was really
how things were gonna go down, why didn't it go
down like this in other places? So he presents hypothesis
number two, the idea that proto vampire bats fed on
(20:36):
insects and larva crawling around the gaping wounds of large
prehistoric mammals. So, which is another wondrously grotesque image to
imagine a giant prehistoric creature. It's, you know, it's shambling
through the forest. Maybe it's something that attacked it, had
got into a fight, or it just ripped itself on
some thorns, just got this bleeding hole. So what happens
to a bleeding hole on an animal? Insects come for it, right,
(20:59):
things start laying their squirming larvae in there, and uh.
And so a bat might come and say, well, hey,
I want to hang out where all these delicious insects
are hanging out. And then they end up inevitably drinking
from that font as well, which again is kind of
too easy to walk here. Yeah. Shoot. In his book Counters,
he says that the scenario requires large wound sits on
(21:21):
a regular basis um and uh. And also, as we're
gonna get into a little later, vampire invertebrate blood is
water and protein. There's no fat, so vampire bats can't
store it as fat like non blood drinking bats store
away their their their food. Uh. They need to feed
and consume fifty of their body weight and blood each night.
So you need to be able to find if you're
(21:43):
depending upon wounds, uh, surrounded by insects, you've gotta be
able to find those wounds surrounded by insects on a
regular basis basis, and also echolocation is gonna be useless
in finding these animals. Um It's it's just that there
are a number of holes in this argument as well. Now,
a third hypothesis here is something called the arboreal feeding hypothesis,
(22:05):
and it really focuses on carnivorous members of the neotropical
bat family Philisto muda i found in South America where
formerly there had been vast forests which were then replaced
by grasslands. So what does that mean. That means that
all of a sudden you have very small little islands
of forest area, and you have a lot of big
(22:29):
mammals taking refuge in these trees, sleeping in them at night,
and so all of a sudden you've got a population
of one tree that might be hosting many different hosts
um as opposed to being spread out through the forest.
And this is an opportunity for vampire bats. So what
you're talking about here is a bunch of animals like
sloth taking refuge in these trees, falling asleep, and then
(22:52):
these vampire bats, who are so stealthy by the way,
sneaking up and just saying well you don't mind if
I do, and taking their blood samples there, and then
of course this would encourage that behavior over and again
as an adaptation in this scenario. Because if you've got
that loss of habitat, and all of a sudden you've
got these mammals congregated in the trees, well that makes
easy pickings. So which hypothesis is true? Well, the answer
(23:18):
still open to debate. Uh. That you know, it's possible.
As with a lot of things, it's more of a
combination of these ideas as opposed to one distinct idea.
And uh, and we have to remember that it's it's
it's it's difficult to avoid falling into the trap of
thinking of evolution as this clockwork predictable scenario. Again, if
it's X here, then it's X there. Uh. If we
(23:40):
turn back the clock and did it again, everything would
come back to the same place that we get the
same results. And that's that's likely not how it goes.
Um For whatever reason, a single group of New World
leaf nose bats evolved as the only vertebrate obligate sangle bores.
And it's pretty amazing. All Right, we're gonna take a
quick break. When we get back, we're gonna talk more
(24:01):
about the hard knock life and uh blood letting. All right,
we're back. Let's talk about these vampire bouts because if
you made it this far in the Vampire About Territory,
you're about to get this serious blood payoff. Because this
(24:22):
is fascinating stuff. And uh, maybe we should start this
section as like, you imagine you are the vampire bout,
dear listener. Yeah, I imagine that you have sort of
gone down this uh almost evolution. I wouldn't almost say
an evolutionary dead end, but you've you've gone down far
enough that you're you're in this very niche area and
(24:44):
there's no there's no turning back. It's like that line
in Macbeth where Shakespeare says, you know, if I've waited
that the main character says, I've waded through blood so
far that if I were to turn back, it would
be just as much work to keep going. And that's
where the vampire bad is. It's a hard knock life
that the vampire back has evolved into, but there's no
turning and turning back at least not anytime soon, that's right.
(25:04):
So you are stuck with this blood diet and the
bad news here is again and We've talked about it before.
Blood just doesn't have much to it in terms of nutrients.
In fact, a percent of it is water. So what
do you have to do Every night? You must go
out and hunt and lap up of your body weight.
And this is this is a hard thing to do
(25:26):
because you can't store any fat that it might have
because it doesn't have any fats. So you every night
are obligated to go out. You can't sleep it off,
you know. You Also you can't hybrid it. You can't
build up stores for later. You're there's no uh, there's
no preparing for the winter. If winter comes, you're you're
gone if you can't get blood. So and that's why
(25:46):
we see these three species of vampire bats living in
tropical areas. They cannot knack it in areas that have
cold climates. So that's right, you cannot hack the cold weather.
You have to take advantage of these areas that have
warmer web other and you must be really wildly. So
it's not just like, hey, I gotta go out and
get some blood. No, you're gonna be the best at
(26:08):
getting blood. Is any blood getting mammal is gonna get. Yeah,
you've got to use your stealth to the highest degree
because you need to prey on sweeping animals. You need
to not wake them up while you're drinking their blood.
And you can't exert a tremendous amount of effort and
energy finding your prey because again you're you're you're on
a very tight budget here. You have to eat every night,
(26:32):
and you can't spend too much energy because you can't
store that much energy. So you can't go on long
drawn old hunts covering you know, vast miles of of area.
You have to you have to really hone in. You
gotta make it work, and you've got to You've gotta
get defeating, that's right. And so as a result, you
have this exquisitely sensitive heat detecting molecule covering nerve ending
on your nose, and this allows you to detect infrared
(26:55):
heat that is just beaming from areas on a livestock's
body and and that that's sort of like the the
area that you know you're going to hone in on,
because as you said, you don't have tons of energy here.
You gotta be fast. Yeah, you gotta go right for
the vein. There's no just crawling around on it's romp
until you find an area that's that's that's right. You
can't feel it out, you gotta see it. You gotta
(27:16):
focus in on it, and luckily the vampire back can
douce that. Yeah, and these guys that mostly attack from ground,
though sometimes it's from the trees, but they can actually run.
It's only like two point five miles per hour or something,
but still that's pretty fast, and that they think. The
reason for that, researchers think, uh, is because if they're
around something like a horse or a cow, it's easy
(27:36):
to get trampled upon, So you gotta get out of
their fashion. Good people to hop away. But it's pretty
amazing to see them running, all right. See you land
next to the cow. You hit the ground running more
or less than you you you scamper up there right
to the place that that hot spot that you've you've
seen with your your your fantastic heat vision. And this
is where you're gonna feed. What do you do? Well,
(27:58):
first thing you do is you lick that area where
where you're gonna apply the incision the saliva anticoagulants. Yes,
because the saliva here is key and is really amazing
to quote Bill Shoot from his book Dark Banquet, the
process actually consists of a maddening cascade of chemical reactions
(28:18):
that must occur before clot forms. Because again, you're making
when you make your incision now with your your sharp teeth,
you're making a very small wound. You're not just you know,
you're not making this enormous font from which to drink.
You're making something that giving its own devices, given the
body's own defenses, this would normally close up in a
couple of minutes. This is not You're not just you know,
(28:39):
opening a jugular here and dancing around the fountain. You're
creating a small wound, but anticoagulants in the blood prevented
from clotting, allowing you to feed there for the amount
of time necessary to get that full meal. Yeah, in
this case about minutes. And if you think about their incisors,
they are knife sharp um. In fact, Bruce Patterson, a
(29:00):
zoologists at Field Museum in Chicago, says, you can actually
cut yourself handling a bat skull in a museum. They're
that sharp. Because again we're talking about efficiency here, getting
in and getting in quick, and their tongues also get
into the game here because they contain a specialized groove
that allows a blood meal to flow via capillary action.
(29:21):
So they do not suck, they slurp, They lap up,
which is another thing to keep in mind because again
it's it's a small wound. It's not going to be
held open by suction. And uh and to your point
about the teeth, that's another aspect of this too, is
that it's such a small cut in with such a
sharp knife you barely feel it while you're sleeping. UM.
In his book, Bill Shoot talks about an encounter with
(29:44):
a bat and a hen that had him reeling. And
I love this, you know what I'm talking about. So
I was thinking about this. Not only does the bat
have data from UM from the infrared molecule and data
from the breathing pattern of the livestock, but also has
been observing it and perhaps taking those observations and passing
(30:06):
them down among its young and so on and so forth.
And what I mean is that Bill Shoot saw this
bat sidle up to a hen. Thought the hen was
going to be like, no way getaway, but it did not,
because the bat then went and cuddled up to the
hen right at this area it's called UM I think
it's called a brood patch. It's where chicks will go
(30:28):
because there's more heat and more capillaries that are congregated there,
so there's more heat available. So essentially, this bat is
mimicking a chick and cozing up with the hen. And
what he said is that he saw the hen like
visibly looked to be relaxed and then settled down, and
then the bat kind of burrowed down a little bit more,
(30:50):
and a couple of minutes later he saw evidence of
that blood from underneath the hen where that bat had
been suckling a the vein. I mean, I think it's
amazing that essentially said hello, hen, I know I look
like a bat, but really I'm a sweet little chick
who just needs a little warmth. That is amazing. Now
(31:12):
you mentioned the tongue earlier, and the tongue is also
really key here. Again, the bat is not sucking the blood.
It's it's lapping the blood. But but lapping. It's easy
to just say, oh, lapping and just sort of have
this loose idea in your mind of a dog or
a cat lapping up the milk or water, which even that, incidentally,
if you slow it down and look at the video
is a far more complicated process than we than we
(31:34):
give the credit. With the bat, you have this piston
like motion of the tongue and it causes the blood
to flow along a pair of grooves on the bottom
of the tug and into the mouth through that cleft
in the lower lip that we mentioned earlier. So you
have to imagine that again. It's like this piston action
of the tongue just and you get this flow going
(31:55):
out of the wound into the bat's mouth. Yeah, we're
talking about a tablespoon when it's all um done. But again,
that's half of the bat's body weight. So after it
leaves the tongue, it goes into the esophagus and down
into the stomach, which is richly lined with blood vessels
that absorb that water and that shunts it straight to
(32:16):
the kidneys before it actually goes to the intestines. So
that something is really important here because it is absorbing
all of that water. But the reason is is because
they have to work fast, these bats in terms of
digesting and expelling this stuff from their systems. Yeah, again,
they're loading up on blood and they have to be
ready to escape at a moment's notice, you know that
(32:37):
cow might wake up, uh anything at any time, and
you're gonna have to get away. You're gonna have to
then fly away. And you cannot be weighted down with
all of this waterway because again we're talking about just
just consuming you know, half your body weight and food
and you're and you're gonna have that that stomach just
filled with water. So you've got to get rid of it.
And that's why you have this rapid uh removed oval
(33:00):
of the water, shut it through the kidneys. And then
the bat vampire bat is urinating as it's feeding, Like
shortly after it starts feeding, it starts urinating because it's
it has to prepare for takeoff. Yeah, to add insult
to injury here, and it avoids soiling itself by extending
one hind limb sideways and downward. So it's like, I'm
(33:21):
not gonna get on any on me, but hey, you
sorry about that. And it's also an interesting scenario when
you start thinking about about the urine itself and it
has to the urine that the bat is pumping out
is getting increasingly concentrated as it goes. Because part of
the whole deal with our urine. Of course, we're getting
rid of these toxic aspects of our meal and uh,
(33:42):
and that's what the bat is doing as well. But
it's doing in such a such a such a fast
process at play here that you just have the concentration
of the urine is just building up and building up
the more that it urinates. And you get into this
interesting area here too, where despite the fact that the
vampire bat has this this liquid diet, and despite the
(34:04):
fact that it lives in the tropics exclusively, it lives
in its own kind of personal physiological desert, there's always
this risk of dehydration because it has to get rid
of so much of the water that it consumes through
its meals. That that that that again factors into the
economy of the vampire bat. It can't it can't live
(34:25):
in a place where it's any kind of dryness, because
it does it it's living, it's living with such a
slim margin um between it's it's it's life and complete dehydration. Yeah,
that's a that's a really complex balancing game there, And
I think it speaks again to this idea, or at
least in my head, that they almants feel like they're
cursed in a sense like in and of course I'm
(34:46):
evoking uh, vampire lore here, but you know you can't.
You can't hibernate. You have to live in this very
specific area, um and kind after night you must go
out and kill, well not the kill perpect blood. One
thing that makes me think about you. You've done freelance work,
(35:06):
of course, freelance writing, uh and I have as well.
And at times you do you like like like myself,
You've probably ticket You've thought yourself, well, could I just
depend up solely on freelance writing? And I feel like it.
You end up getting into this sort of vampire bat
situation where you're like, yes, if I, if I pray,
if I get enough gigs on a regular basis in
the in the just the right environment, and I never sleep,
(35:29):
never hibernate, then I can make it work. I can
just barely make it work, and I can survive and
and and pay all my bills. And then you end
up just defecating and urinating on yourself all the time
to avoid having to deal with any loss of energy, right,
and you're always looking for that that next that next kill,
that next job. Yeah, it is. It's kind of I
(35:50):
like that analogy. Yeah, the vampire bat is living on
the margins here, you know, it's just it's it's it's
found this niche. But it is a hard niche to
exist in. Indeed, it is. I want to point out
that we do have a few fossil vampire bats, including
the biggest vampire bat that that ever existed as far
as we can tell from the fossil record, and that's
(36:10):
the thirty percent larger uh do Modus dracula, which is
of course a great great name for a vampire bat
or some sort of a you know, Gothic band uh
And they were they were total vampires. They were not
any kind of transitional form, and they existed farther up
into the America's But the idea is, this larger bat
is depending on the blood of larger species, and if
(36:33):
those species died out in these sorry times, so did
this And so the domain of the vampire bat was
once larger and contained more species than it shrinks. And
it's then it's confined to these these hot tropical zones
and the few animals that they can still prey on
for blood. Ah. But what of global warming, which is
actually warming up many parts of the world, and this
(36:57):
has led some people to say, hey, we think that
there is going to be an increase in the vampire
bat population, specifically in North America, in Texas and some
parts of Louisiana in the next couple of decades, so
they might be coming to a city near you. Yes,
all right, so, um, we've given you guys a description
(37:19):
of these bats, but if you would like to see
them specifically on a vamp cam, you can at this
very moment. In fact, there's a there's a camera in
there twenty four hours a day you can observe these
and this is at the Organization for Bat Conservation, So
that's bad Conservation dot Org. Yeah. I was looking at
the other day and they're they're really adorable where they're
(37:40):
scurrying around. That's the thing about the vampire bad It's
like part of this responds to them, and we with this,
uh this something kind of cute about them, But then
there's also something that in the very depth of our
genes we we can't help but find a repugnant. They
walk that line. Well, the distance though of the vamp
cam makes it all sorts of adorable. Sure, like my
(38:01):
hand's nut in that cage with them, So that's so
cute that they're cuddling right now. And it's not full
color either, so it's got that going for it. So
there you go, the vampire bat, the evolution of the
vampire bat, the physiology of the fampire bat. I I
hope it it allows everyone to have even more respect
for these amazing creatures and just rethink the vampire equation
(38:23):
in general. Like it really made me rethink our ideas
of a vampiric human and what that would be like.
I feel like we focused, we focus far too much
on the supernatural aspects of of a humanoid vampire. We
focus on the viral aspects of like vamp vampirism as
a disease in these fantasy and scenarios, and of course
(38:44):
we end up fantasizing and focusing on like the sexy
and alluring aspect of some sort of a fictional vampire,
whereas if we look to the biological example, if we
look to the vampire bat, it paints an entirely most
entirely different idea about what evampiric human would look like.
(39:04):
I think the closest we've come is the nos Ferato
of the classic film and some of the rehashes we've seen,
which is kind of like this withered figure. Um, not
this robust character wearing shades and a leather jacket and
like ruling the night. No, because even the vampire bat
does not rule the night. It knows it. I mean,
(39:25):
I'm I'm anthromorphizing here. It knows it doesn't rule the night.
It has to stick to the shadows as a conservative energy,
and it has to get the easiest, uh most filling
meal it can. So the idea of this slim, ghastly
corpse like nos Ferato, you know, reeling in the shadows
like that's that's I feel like that's the corporate we've
(39:45):
we've managed to get. I agree. I wish that Jim
Jarmus is a new movie. Only Lovers Left Alive would
have explored that idea, would you explored in a blog
post by way Um, So check that out af if
you want to kind of do some reimagining of Dracula
and popular Lure. Yeah, I do want to see Only
(40:07):
Lover's Left Alive. I didn't think that I would want
to see another vampire film, but that one looks pretty good.
Till the Swinton The Magical unicorn of a human is
in it, so you kind of I mean, I have
to see it just for that alone. Yeah, I want
to see that. I also want to see Neil Jordan's Byzantium,
which sounds in like, on the surface, it sounds like
just another scenario of like to two vampires, like a
(40:28):
mother and a daughter vampire and they they're, you know,
trying to find their way in a world of vampires
living in the shadows. But it's it's misunderstanding each other. Yeah,
but it's her mother daughter, but it's it sounds more
interesting because it's like strong, supposedly strong female characters based
on a play by a female play right, So there's
there's something about that that I want to give that
(40:49):
one a shot as well. All right, So what about
you guys and gals out there, what do you think
about the science of a vampire bat the physiology and
evolution of vampire bat um. How does that make you
rethink these curious creatures? How does it make you rethink
the myth of the vampire as it exists in folklore
and in popular culture. Um, we'd love to hear from you,
(41:10):
and you can find us at all the normal places
there is, of course, Stuff to Blow your Mind dot com.
That's the mothership that should be your your first stop
when you think yourself, I wonder what those guys are
up to? Well, go to Stuff to Blow your Mind
dot com. That's where we will get the full dosage
of all of our activities, including our blog posts, are podcasts,
our videos, links out to our various social media accounts
(41:31):
such as Facebook, Twitter, Tumbler, Google plus, um, our YouTube
account which is mind Stuff Show. If you haven't followed
us there, if you're a regular YouTube user, go there
and give us a follow. Let's check out some of
our videos there. We have a number of cool new
projects that we're pushing out in the weeks ahead. Indeed,
and if you would like to get in touch with
us in the meantime, you may do so a blow
(41:53):
the mind at Discovery dot com. For more on MISS
and thousands of other topics, visit how staff works dot com.
H
Stuff To Blow Your Mind News
Hosts And Creators
Robert Lamb
Joe McCormick
Popular Podcasts
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations.
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
The Nikki Glaser Podcast
Every week comedian and infamous roaster Nikki Glaser provides a fun, fast-paced, and brutally honest look into current pop-culture and her own personal life.