September 1, 2015 • 44 mins
Tails are a common feature in the animal kingdom, fulfilling just about every role from comfy blanket to instrument of venomous death. Join Robert and Joe as they explore some of the more outstanding uses, including your dog's caudal language and the scorpion that sheds its own tail and anus.
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Episode Transcript
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Speaker 1 (00:03):
Welcome to Stuff to Blow your Mind from how Stuff
Works dot com. Hey, welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Joe McCormick. So, Robert,
I've got a question for you. Okay, shoot, I know
you've heard the old would you rather be able to
fly or be able to turn invisible question? What's your
(00:24):
answer to that? But it's always been invisible? Yeah, that's
the creep's answer. Well, it's the creepy it's you know,
it's the observer's answer. It's this, it's the student of
human behavior's answer. Because if I'm flying around looking at stuff,
I'm going to be scaring wildlife. You know, people are
gonna be staring up at me, and tripped traffic accidents
are gonna occur. But if I've invisible, and if I'm
invisible and I play it safe and I you know,
(00:47):
and ethnically, then you know, I get to observe the
world as it goes about its business. You know. Another
advantage there is that flight can easily be achieved with technology,
but there's no way to become invisible technologically, So that's
the really more magical power. But what I was gonna
ask you is would you rather have wings or a
prehensile tail. This is interesting because I was I was
(01:09):
actually blogging about this a little bit yesterday. I was
looking into because there's a particular plastic surgeon, Joseph Rosen,
who's a real real trends that are real, real, just
amazing intellect in the world of plastic surgery, does a
lot of actual real life work with facial reconstruction and
wounded warriors. But he's also a trans humanist, so he's
he's written a lot about the not only can we
(01:32):
do all these things, we should do them. We will
get to the point where we add tails and wings. Well,
I was coming at this from a somewhat magical perspective
because I don't think humans would necessarily be able to
fly even if they had wings, because we're just too dense, right,
you would, They're like, our beings are much more dense
than birds. Yes, now, there are theoretical ways to transform
(01:54):
the human arm into a bird's wing, and it's would
be a lengthy surgical process, and then they still wouldn't
be able to support you and fly. You would have
to have additional uh tissue, perhaps clone tissue or vat
grown tissue that would be used to to graft on
and create the size of wings necessary to fly. And
(02:14):
then of course you still wouldn't have any arms. You
would just have like the large bat wings. So I mean,
along those lines, I would probably go with the tail
because it would it would change my life less dramatically.
Now would it be more horrifying to not have hands
at all and just have wings like a bird, or
to be like a bat and basically have gigantic hands
(02:36):
that you can't really use as hands but you can
still see some finger bones in there. Um, well, they're both.
They're both fine choices. But wait a minute. This episode
isn't about wings. It's about tails. That's right. We're talking
about tails specifically in this episode, about animal tails, and
then there's gonna be a second episode when we talk
about the absence of tails for the most part in
(02:58):
human beings. Okay, so did you come down one way
or another? Wings or tails? Definitely tails. You'd rather have
a prehensile tail than wings, yes, I mean especially it
was a nice functional tale that, you know, the prehensile
tale that I could utilize in my daily environment. It
wouldn't just be about you know, keeping flies away from me.
I've always thought a prehensile tail would be most useful
(03:19):
to a musician. Yeah, you know, playing a musical instrument,
that's when you really wish you had more hands. Yeah,
if you're a one man band, you could you could
really use that extra appendage, right that that's for your
double bass drum pedal. Yeah, so before we got one
man death metal band? Not but what would it be?
Speed metal, thrash metal? Who uses the double bass pedal?
(03:42):
It's two technical question for me. But you know, when
when it comes to tales, and you know we're already
talking about semi fictional accounts. But but I say a
few examples that come to my mind that make me
also I want to want to go into the prints
off to the prehensile tail direction versus the wing direction. Um.
I think of Minos from Dante's Inferno, who has this
(04:06):
enormous serpentine tail, and when you have a new arrival
in Hell, he wraps this tail around you and he
is able to determine which level of the Inferno you're
bound for based on how many coils wrap around your body.
Now I can't remember. Does this also go into sorting
the virtuous Pagans or is this only once you're definitely
(04:27):
in the hell part. I think this is more about
like definite hell as opposed to the the the limobile
page Pagans and limbo on the outside. Yeah, this is
your inhale. Help now we need to get you where
you go. And Minos is in charge of sorting it. Well,
that's a smart tale. Another one that comes to mind
is u Calabos from Clash of the Titans, the old
(04:48):
Clash of the Titans Harry Hamlin duking it out version.
I assume you've seen this classic film, you know, I
have to admit I actually have not said this is
this is some ray he Housing claimation. Yeah, fabulous, fabulous claimation.
I love that stuff. And I've never seen this movie.
I think I've seen the scene where the where the
Titan comes to life is a huge statue of that
(05:11):
from Clash of the Titan. Well, there's the kracking. This
one has the Kraken, it has Medusa Pegasus, that little
mechanical owl. Of course, Calibus, who's this um, this character
who's twisted by the gods into this sort of caliban
esque creature with horns and a demonic face. And then
a long swinging tale. That's great. We'll have to watch it.
(05:33):
I love the Harry Housing sin Bad movies. Great creatures,
those are wonderful. Yeah, there's one that has um what's
his name? That went imp be doctor who or the
the doctor and Doctor who? Rather um the class. Oh
I don't know, yeah, Tom Baker, Tom Baker? Yeah, which
one is it? I don't know. I saw it a
like a drive in event once and it was It's
fabulous because you get to see him as a dark sorcerer.
(05:55):
Oh that's great. Um. One other fictional tale creature that
I want to mention because it's it's played a role
in my life a lot recently is the Chippendale mup
from Dr Seus's Sleep Book. I don't know what you're
talking about. Oh, well, this is This is a fabulous
Dr Seuss book in that it just takes the soon
hopefully to be a sleep child through this dreamland. Um
(06:17):
or so I guess this awaking dreamland and all these
creatures are going to sleep. And the the overall argument is, hey,
look at all these things that are going to sleep.
You should join this crew in slumber. And the Chippendale
um up is this character who quote, his tail is
so long, he won't feel any pain till the nip
makes the trip and gets round to his brain. So
what happens is this, Um, this creature bites it's exceedingly
(06:39):
long tail right before it goes to sleep, so that
the pain will travel all the way through the tail
and travel eight hours all the way around and back
up the spinal column hit his brain, and then he'll
feel the pain and wake up. And I recently crunch
the numbers on this, and if I'm correct, for this
to work, based on the speed at which pain travels
(07:01):
through a nervous system, uh, the tail would need to
be about a thousand and eight kilometers or six six
miles long. So that's enough. That's so if the thing
we're laying out straight in the Western United States, it
could lay with its nose in Seattle, Washington into tail
in Sacramento, California. Wow. Yeah, I have absolutely nothing to
add to that horrifying children's story. Yeah. Um, beyond that,
(07:26):
I mean, the only other fictional tail that that instantly
comes to mind is, of course the xenomorph tail uh
from Alien and Aliens creature that every every part of
the creature is a is a weapon, and of course
its tail is a rather cinematic weapon as well. Yeah,
it's a it's a barbed spear. If you look at
it, it it looks like it was designed to get stuck
in you. And one thing I have to notice about
(07:48):
that tail. It never seems like you see the tail coming.
It's always suddenly poking out of your torso and you're
looking down at it. And why did this happen? Yeah,
it had whips it around and then right through you.
But those are fictional tales. We should, uh, we we
should start by just talking about the very basics here,
the basics of tales. Yeah, for example, what is a tail?
(08:12):
What is the essence of a tail? It's uh, it's
a harder question than then you then you, you know,
because when you first think of it, especially from a
vertebrate standpoint, you think, well, that's just the other end
of of the vertebrae, right, that's the the tail end
of the verb. It's almost indifficult to think about tails
outside of our language of tales. Yeah. And an interesting
fact is that even animals that don't have tails as
(08:35):
an adult often show a tale at some stage of
their development. So a frog might not have a tail,
but the tadpole that became that frog had a tail.
You might not have a tail, but when you were
in the womb as an embryo, you had a tail.
That's right. And then it it simply goes away, usually
(08:55):
before we're born. Usually we'll get to that, I guess
in the next episode. Yeah, it gets reabsorbed by the body, right, Yeah,
So tales are a huge deal with vertebrates. We just
happen to belong to rather exclusive club of creatures that
do not have tales. Uh. And likewise, you look at
the invertebrate world and tons of fascinating tales there as well,
(09:17):
that exist without the necessity of underlying vertebrate. Now, if
you're an invertebrate and you have whatever we would call
a tale, is that technically a tale or not? Yeah,
it's a It's a more difficult question than than you think,
you know when you start, especially when you look at
some of the specific examples that we're going to roll through.
(09:37):
Um uh, you know, particularly with a scorpion, like trying
to forget where this tail came from and how it
uh eventually evolved into this rather curious form. Now, when
in discussing tales, you basically have two types. There's kind
of and you can sort of think of this as
non functional or barely functional tales versus functional and highly
(09:57):
functional tales. So the first thing I've got to ask
about before we get into these vertebrate tales is what
is going on with the scorpion? Because I love I
love aragnids, and I love scorpions. When I was a
little kid, my dad one time took a trip to
Arizona and when he came back, he had one of
those one of those tourists you know, gifts that that
(10:19):
is a scorpion inside a piece of glass. Oh yeah,
And he he gave this to me, and I used
to just stare at it, thinking like, this is the
coolest thing on planet Earth. Where where does this tail
come from? Why is it so cool? Well, it's a
it's interesting because of course what you what you have
here when you're looking at a scorpion, you have a segmented,
(10:40):
curved tail that's tipped in a venomous stinger which he
uses for self defense, but also against prey that's large
or feisty, like if they're if they're coming up against
something small, they'll often just use their claws and not
even employ the stinger um. And about twenty five different
species of scorpion possessed of venoms capable of killing a human,
(11:01):
and the rest have venoms that are not that potent.
But of course, you know, allergies and whatnot can play
into reactions. Uh. Now, the interesting thing about scorpions is
that their body is a very old design. It's changed
little over the past four hundred million years, and they
probably evolved from the long extinct sea scorpions. Oh, the euryptorids. Yeah,
the eureptroids. Those are the huge ones, right, Like you
(11:23):
see the fossils of those, and it's just astounding. The
biggest people and uh, the sea scorpions. They also featured
a segmented tale that ended in at least a spike. Now,
it's difficult, perhaps even impossible, to know if these were
venomous or non venomous. It's likely that they used to
use them for propulsion or balance steering swimming, and that
(11:46):
it just eventually evolved into a venomous weapon over time.
This is one of the interesting stories about evolution because
you see this primeval tale emerging in many older forms
of life. Where they've got some kind of appendage coming
out the back of their body. But there are so
many different evolutionary routes this tail could go down in
(12:08):
in later development. Uh, And I guess that's what we're
going to be exploring in in this episode of the podcast.
Today is like eighteen roads diverged in a yellow wood,
and depending on which one you picked, you might have
a tail that communicates your emotions, or a tail that
stabs your prey and injects venom, or a tail that
helps you climb trees, or who knows what I mean.
(12:32):
There are tons of things you can do with a
part of your body that you don't necessarily have to
use for walking or propulsion, though some animals do continue
to use it for that. Yeah, so I definitely challenge
everyone to keep our trans human question in mind as
we move forward. If you were to to have the
chance to gain a tail, might some of these examples
(12:54):
sweeten the deal for you. I think everybody is just
going to go with the xenomorph tail and yeah, but
you know, I don't see the xenomorpha doing a lot
of practical things outside of murder with that tale, right,
it must not be that fulfilling to be a xenomore. Well,
you know, fulfillment is a very human classification, right, I'm
(13:15):
just projecting. I guess well, I think we should first
talk about prehensible tales in the animal kingdom. If you're
not familiar with what they are, I guess you might
have been a little bit lost so far. But a
prehensible tale is a tale that to some degree can
be used for manipulation and grasping. They're usually divided into
fully prehensible or semi prehensible tales, depending on what the
(13:37):
animal can do with and you you might think it
would be really great to have a prehensible tail as
a human because it'd be like having another hand. You know,
you could just do whatever we were talking about it earlier.
You could play more musical instruments or something like that.
But I also want to ask the question of do
you really need one? Because when you look at all
(13:59):
the animals that have prehensile or semi prehensile tails, I
see a common feature. And this might not be the case,
but at least in my observation, they all tend to
live in environments that are kind of like a jungle gym,
where there are branches or sea grass or coral reefs.
And if you look at pictures of animals using their
(14:21):
prehensile tails, sometimes they're used for free object manipulation, you know,
scooping up a bunch of something. But the majority of
what I see is animals using the prehensile tail is
an aid in climbing, or an anchor against some force,
such as hanging from a tree limb, so anchoring against gravity.
Or how a sea horse uses its tail as a
(14:42):
grasping oregan the latch onto things like coral and anchor
itself against the tide so it can just sit there
and wait and and do its thing with its head.
I guess the seahorse doesn't really have hands to work with. Yeah,
the discussion of a jungle gym like environment, it reminds
me of Dan Simon's Hyperion Cantos, his sci fi series.
There's a kind of a subspecies of humans or a
(15:05):
branch of humanity known as the Alsters, and they live
in uh in in in low gravity or zero gravity environments,
and so they're their soldiers particularly will often be seen
with robotic tales added to their suits to to aid
in this very kind of environment. Because you're in a
wait list, like you know, shiphole environment. You are essentially
(15:26):
living in this kind of jungle gym. So we would
be advantageous in that environment to have a tale. Uh,
even if it's just a robotic one, a robotic tale,
you know. I think I've seen people have already created
robotic tales. Have you read about these? No, I was looking.
I've looked at a few different studies that have involved
(15:47):
the biomimicry of say, the sea horse tail. Oh yeah,
but I haven't. I didn't notice in any studies where
anyone's actually fixing this thing under the their posterior. Oh,
not so much studies. There's something I know we've talked
about in for we're thinking that was it wasn't so
much functional as it was decorative, but it was a
tail that would respond to your emotions. Okay, all right,
(16:09):
so the tail of the communicator. You could, Yeah, you
could wag your tail like a dog, which we will
get to in a bit. But of course, I I
said at the beginning, what you can do with the
tail if you don't have to use your tail for movement.
Of course, plenty of animals do still have to use
their tails for movement. They're they're a crucial part of
their locomotion method. We birds, for example, Yeah, I mean snakes,
(16:33):
fish birds in particular, you have a highly specialized tailed,
the feathered tail. The flighted bird contributes to lift as
well as stabilization drag reduction, so it's a very fine
tune part of their anatomy. Yeah, and of course there
are fish. Animals that live in the water often use
tails for propulsion, generating a paddling motion that pushes against
(16:54):
the water in a way that cancels outside to side
motion but generates net thrust in the forward direct And
in fact, if you've never seen it, you should look
up simulations of fish swimming motions and fluent in fluid
dynamics simulators. There. I found a couple of videos of
this on YouTube, and it's really interesting seeing the waves
(17:15):
that are generated by the side to side motion of
a fish's body and tail. As the waves sort of
starts at the head and then gets bigger and bigger
as it goes back towards the tail, and it generates
this upside down y shape of of directional motion. Oh yeah,
it's like a full body movement as opposed to just
you know, a mechanical fish with the tail that goes
(17:35):
back and forth from their your bathtub, right, that'd be
more like a I don't know, a side to side propeller.
I guess that's kind of like sculling in a in
a boat, right, if you just wag the rudder back
and forth. Another interesting fact, if you've never noticed, is
that fish tend to sweep side to side and there swimming,
and marine mammals like dolphins and whales sweep up and down. Uh.
(17:59):
There may be a septions to this, I'm not aware
of them if there are, but it's an interesting artifact
of the divergent and then subsequently re convergent evolutionary pathways
of fish and marine mammals, so that like the whale tail,
the horizontal whale tail versus the vertical shark tail. Yeah.
Or I guess the more apt of comparison would be
dolphins and sharks, as that is the distinction one is
(18:21):
often trying to make at the beach in the water. Yeah.
I don't know why it took me so long in
my life to notice this, but I just never noticed
that difference until I think I was at an aquarium
one time and I was looking at the belugas that
we're swimming through the aquarium, and I was like, what's
wrong with that thing's tail? Oh, it's just not like
fish tails, it goes the other way. Yeah. Of course
(18:43):
we already mentioned that communication is a big deal with
tales and a number of species, and of course what
what manner of communication is more important than than that
involved in courtship? Exactly right, And here we're going to
get to one of the most interesting things I've come
across in in our research about tales, which is the
courtship tail feathers of the p cock. Actually, another pop quiz.
(19:09):
Do you know the generic non gendered term for peacocks
and p hens? No? I don't. It is p foul
foul Okay, that's that's that seems brother neutral. Yeah, I
just thought that was a great word. Fo Yeah, nobody
ever says, let's go look at the p foul though
the peacocks. It's true. Well, it's an unfortunate fact that
nobody cares about seeing the p hens because they do
(19:31):
not have these gigantic, interesting tails. Uh. I'm sure phns
are wonderful. No, no offense to them, but that they
don't put on a display like this, and that's what
we're gonna talk about here. Another interesting fact, did you
know that what we call the peacocks tail is usually
not actually it's tail really yeah, most of the time
this thing you see when you think of a peacock,
(19:53):
what we're talking about is it's covert feathers, which your
feathers that cover the tail feathers. It's also referred to
as a peacock's train. And as you've surely seen before,
when a when a peacock props up and spreads out
its covert feathers, they formed this gigantic, shimmering, iridescent display
of plumage full of spots that look like eyes, and
(20:15):
if you want to use a cool word, those eye
spots are called ocelli. I had always read that the
peacocks train was known to be used for mate selection purposes,
though in reading up on this for today's episode, I
found out that there have been some really interesting questions
and doubts recently thrown into the mix here. But this
(20:36):
is a really interesting story about the complexities of evolutionary
biology and and questioning what we thought we knew. So
there's this mate selection theory of the peacocks train. The
ideas of the most prominent one, this is the one
we've all heard growing up. Yeah, and and Charles Darwin
thought about this. Charles Darwin. If you're Charles Darwin and
(20:57):
you look at a peacock's train, this huge, huge, shimmering,
eyespot covered extravagance, you think, what on earth is this for?
You're you're coming up with this theory of natural selection,
where organisms that are the most adapted to survive and
reproduce in their environment are the ones that survive. How
do you encourage a trait that's so wasteful and pointless.
(21:21):
I mean, it doesn't it takes energy or resources to
develop a train like this. It doesn't seem to provide
any sort of mechanical survival advantage, So it doesn't help
the peacock fly higher, or you know, kick with its
spurs harder or something. In fact, it would actually seem
that feathers like this make the peacocks more vulnerable to predators.
So what's the deal. Why would you have something like
(21:44):
this in an animal? So I've actually read several hypotheses
over the years to explain the the extravagance of the
peacock's train display and the I guess we should start
with the sexual selection effect. This is what's sometimes called
runaway sex sual selection. And the point is that at
some point, way way back in the p fowl's ancestral lineage,
(22:08):
the p hens, the female p foul preferred slightly longer,
more elaborate trains for some reason related to fitness. Maybe
it made the males stronger, more powerful in flight. And
this choosiness kept being magnified more and more over the generations,
until the peacocks were no longer displaying fitness, but they
(22:31):
were just being bred by the females to have longer
and more elaborate trains. In the same way we would
breed a dog to encourage a certain trait to to
intensify over generations, we just end up with a ridiculous
breed of dog that has no clear function anymore other
than to look funny. Yeah, And that's what the p
(22:51):
hens are doing to the pea cocks. Over the generations.
They develop a preference for a certain type of trait
in males, and the males that have that trade get
more mating opportunities, and this gets magnified over the generations,
and if there's not enough of a selection pressure to
counteract the sexual selection, like if there's not a strong
(23:12):
enough force saying okay, males with these big train displays
really are going to get killed all the time, then
they'll just keep getting bigger and bigger. Another evolutionary explanation
that I've read about is that the large extravagant displays
function as a sort of calculated, conspicuous handicap to show
off the fitness of the mail. And it's kind of like,
(23:34):
in human terms, a guy showing off how much money
he has to waste by wearing lots of pointless expensive jewelry,
or like a swordsman demonstrating his superiority by dueling with
one hand tied behind his back. The point is like
I am so fit, I am such a good mate
that I can have this enormous handicap, this pointless waste
(23:55):
of resources, and still be the best that made that
that makes sense. It's like I have the time and
energy to put into this ridiculous, uh cumbersome uh addition
to my body. Another hypothesis that's been developed over the
years is that the ability to produce large, elaborate trains
is an advertisement that the peacock is relatively free of
(24:18):
parasites which would impair his ability to produce and maintain
a large, beautiful train like this. But I want to
talk about some specific studies because, like I said, the
research now seems to have gone back and forth about
the role that the peacock's tail plays in the mating rituals.
So in the early nineteen nineties, the behavioral ecologist Marian
(24:41):
Petrie of Newcastle University carried out some really often cited
research and this is one of the big studies in
this field. One paper and Animal Behavior in nine was
called p Hen's prefer Peacocks with elaborate trains. So what
do what do peacocks do when they want to mate? Well,
they aggregate into something called a leck. I believe I'm
(25:04):
pronouncing that right. It's l e K and that so
the males gathered together and in this case, uh Petrie
and her her team observed one leck that was consisting
of ten males, and they found that there was a
big difference in how much the different males in the
leck got opportunities for mating. So the top male, according
(25:26):
to them, copulated twelve times, while the least successful males
in the leck got no sex whatsoever, and Petrie's team
concluded that quote over fifty percent of the variants in
mating success could be attributed to train morphology. There was
a significant positive correlation between the number of eye spots
(25:47):
a male had in his train and the number of
females he made it with. So they found that the
females didn't mate with the first male they met, but
they would visit several different males and in ten out
of a in cases in their study that ended with
successful copulation. In their terms, I'm trying to imagine what
unsuccessful copulation is, the male that the female chose was
(26:11):
the one with the greatest number of eye spots. So
this seems pretty straightforward. More eye spots on your train
means you get more mating opportunities. Okay, that's pretty straightforward.
It's kind of like more the more jewelry, the more
the fancier the clothes, the more the more money that
the that the individual has to spend on drinks and
nights out translates to the the economics of the development
(26:34):
of these eye feathers. Yeah. Yeah, So this seemed to
be accepted for a while. Until now. That paper was
called p Hen's prefer peacocks with elaborate trains. In two
thousand eight, in the same journal Animal Behavior, there was
a paper called p Hen's do not prefer peacocks with
more elaborate trains. This was carried out by a team
led by Mariko Takahashi, and they were trying to replicate
(26:56):
the original results in a feral population of Indian pe
foul in Japan. Over the course of seven years of observation,
and Takahashi and her co authors claimed to have found
no evidence at all that the phn's expressed any preference
for peacocks with more elaborate trains. That's what they said.
(27:17):
This means the females did not show any noticeable preference
for males with longer trains, more symmetrical trains, or more
eye spots. And those are the three things that are
often cited as as being the you know, the things
you want your train to have. So what does that?
What does that mean? Where does that leave us? Well?
According to them, they concluded that the peacock train display
(27:39):
is it might be a necessary part of successful mating.
So a male that can't show a train display is
not going to get to mate. But they came up
with three concluding points. They said, the train is not
the universal target of female choice. Uh, the trains don't
vary a whole lot across male populations. And then they
(28:02):
also said, quote, based on current physiological knowledge, it does
not appear to reliably reflect the male conditions. So they
don't think that the train is all that much of
an indicator of fitness. And what they ended up concluding
is that it's just an obsolete signal that maybe it
(28:23):
used to correlate to female preference, but it just doesn't anymore.
It's it's tempting to take that and try to apply
it to the human world and and various mating practices
and you know, romance practices that are really kind of
becoming pointless than our modern age. But it's it's part
of traditions, so you kind of have to do it.
(28:43):
I mean, you don't really do it, but every you
don't I mean you don't really have to do it,
but everyone feels a little weird if you don't write. Yeah,
how many common I don't know, dating or courtship practices
are still somehow based on the idea that in a relationship,
a man will be the person who's earning the money
for the couple, when in you know, many or most
cases in the Western world, that's not the case anymore. Yeah,
(29:07):
Or there's so many different little you know, superstitions and
traditions and the wedding ceremony itself. My my wife shoots
a lot of weddings, so I get to hear I
always hear, you know, how did they do a first
look or did they do the whole you know, the
straight up deal where no, the bride in the room
do not see each other till the ceremony, Like that's
something that really had there's no bearing on anything whatsoever.
(29:27):
But when it comes time to put the wedding together,
there's often you know, enough tradition, uh, you know, bouncing
around in your head that you say, I know, we're
gonna we're gonna stick to the old I don't see
you and you don't see me until the moment of
of our of our our actual ceremony, our weddings. The
human version of investing tons of resources in an elaborate
(29:48):
train display. Yeah, I think there's a strong case for that.
So that was what they concluded. But there's still more
to the story because yet another animal behavior study was
published in two thousand eleven that seemed to strike a
note somewhere in between the two that came before, and
said p ns prefer peacocks displaying more eye spots, but rarely.
(30:09):
I can see this study perhaps not getting as much
play and the media. Yeah there, I did read a
good Nature News article about it, but the main takeaway
was and I want to read a quote here to
get it exactly right. They said, p foul mate choice
is clearly more complex than previously thought. Females may reject
a few mails with substantially reduced I spot number while
(30:31):
using some other queue to choose among males with typical trains.
In other words, if you have way fewer eyespots the normal,
if you were obviously I spot deficient, you will not
get sex as a peacock. But there's no real difference
between an average number of eye spots and a much
greater than average number of eye spots. The main takeaway
(30:52):
I got from this is that p foul mate choice
seems to be more complicated than we originally thought. And
actually the main author of the original study from nine,
Marjorie Petrie, said as as quoted in a two thousand
eleven article in Nature News quote, at the end of
the day, we will never know what p hens are
looking at and how they select their mates. You can't
(31:15):
ask them. Now at this point in our discussion of
peacocks and p hen's um, you know, I have to say,
there's got to be a way to spice it up
a little bit. I feel like some some listeners out
there might be saying, all right, I'm I'm ready to
extract from the whole peacock discussion. But wait, right, what
if we throw cyborgs in there? Right? Because you can
(31:35):
answer Marjorie Petriots question in a way you can ask them.
I mean, you can't ask them, but you can take
a look at what p hens are looking at by
making a cyborg p hen with eye tracking devices. In
the Journal of Experimental Biology in April, there was a
paper called Through Their Eyes Selective Attention in p hen's
(31:56):
during Courtship, and the researchers behind the study wanted to
see if they could find out exactly what phn's were
looking at when they were presented with a male doing
his courtship display. So they rigged up what looks like
a cyborg PHN. She's got eye tracking hardware on, and
she looks like something out of those you know, those
Terminator rip off movies that started coming out in the
late eighties where everybody was a cyborg or had had
(32:20):
some kind of like cyborg upgrades for a while. Though
there were so many of them, they were all shot
on the same pseudo industrial setting back lot where everybody
just seemed to wander around factories and alleyways all the time. Anyway,
what did the PHN look at? Curiously? In the video
I saw of this, she spent almost all her time
(32:40):
looking across the bottom of the Peacock's train display, and
the scientist in the video suggests that that means she's
evaluating the width and symmetry of the train. So I
don't know, we're kind of back to the beginning. Yeah, Anyway,
I thought this was very interesting that something that we
originally thought was a pretty settled matter of evolutionary adaptation
(33:04):
turns out as very complicated and we don't fully understand it.
And just one more hypothesis I came across. I don't
know where to fit this into everything else, but this
was that the Peacock's train display makes infrasound as it vibrates,
and this infrasound might play some sort of role in mating. Wow,
so it could be even more nuanced than originally suspected. Yeah.
(33:27):
Now I want to talk just briefly about the hippo tale. Um,
because this is a tale that is easy to miss,
is easy to you to forget to draw. When you're
drawing hippo's for a child, as I often do, I'm
picturing a hippo tail. It's not very big. No, it
doesn't make a courtship display. No, it doesn't seem to
(33:49):
communicate a whole lot. Maybe it communicates a little. So
what's the point. It's just a little dangly tiny thing. Yeah,
like barely covers the hippo anus really. Um, Well, here's
the here's the thing. If you see, if you see
a hippo in a while, if you see a hippo
at the zoo, uh. The what the tail does is
that as the hippo releases its bowels, uh, the tail
(34:09):
flips back and forth in order to fling poop like
some sort of fecal sprinkler system. And it's suspected that
this is how male hippos wou mates and territory, So
it could be a form of communication, a fecal communication system. Uh.
Though there's another theory out there then. This theory is
(34:30):
that it's a means of flinging parasites away from the
hippo's body, such as the place of dell Odeo's Dieger
Skio Delhi leech a special leech that feeds exclusively on
the rectal tissue of a hippopotamus. So what's it like
to be that leech. It's a very specific lifestyle. I mean,
(34:50):
there's so many different types of leech leeches out there
with the very specific hosts in some cases, uh, and
some actually eat worms as opposed to the on blood.
But this leech knows what it wants it and it's
hippo rectum. So it's possible that the hippo tail is
as much about just flinging those away from its body
(35:11):
as possible, and certainly in other large herbivores, we see
the use of the tail as a means of keeping
flies away from the rectum as well, and ultimately about
you know, keeping parasites away from that delicate area of
the anatomy that is otherwise difficult to reach. Now. I
want to get back to monkeys for a second, because
when I talked about monkeys and their prehensile tails, obviously
(35:34):
not all monkeys have preensile tails, but the New World
monkeys that have them, I talked about them using them
in climbing. And there are multiple ways actually that a
tail could come into climbing behaviors. It wouldn't necessarily just
have to be for gripping branches or for bracing against
trunks and limbs, right, yeah. It can be used as
(35:56):
a as a balance, as a counterweight. Ah there you yeah,
and and certainly you can imagine this, but I just
imagine yourself balancing on a beam and the various things
you use your arm for, you know, spreading your arms
out and all that. If you had a tail, that
would just be another part of your body that you
could utilize in such a fashion. Even something like your
modern house cat will utilize it's its tail for balance. Yeah.
(36:21):
But another animal that uses it not only uses its
tail for balance, but also for propulsion and uses it
for pulp for propulsion on land is of course the kangaroo.
You know, they have that large tail, uh, sticking out
behind a huge muscular tail, and according to a two
fourteen study published in the journal Biology Letters, the kangaroo
(36:43):
utilizes its tail as a true fifth leg. The researchers
found that the tail of a walking kangaroo works as
hard as the leg of a comparably sized human moving
at the same speed. Wait, so the tail makes contact
with the ground. Yes, it does, and I'll get to it.
To to that part in a second. For the most part, though,
(37:04):
as it hops, the tail lashes up and down, helping
the creature stabilize while also serving as a motor to
lift and help accelerate the kangaroo's body. So it's almost
it's almost like a ficio's tail, except it's uh, it's
just it's moving in the air, and it's about, you know,
thrusting the body as opposed to actually making contact with anything. However, However,
(37:28):
to your point, though, the that that fifth lag, that
giant tail can support the kangaroo's full body, and you'll
you'll often see this occur when when male kangaroos are
kicking at each other, they'll kick up, you know, they
do that kangaroo kick and uh, and in doing so,
they actually come up on the tail. Now, of course,
a lot of the rest of the time, the creatures
(37:49):
are not doing high speed hops and they're not kicking
each other. They're just you know, gently browsing um for
stuff to eat. And in those those situations, the tail
just kind of, uh, you know, faces into the background
for a little bit. But it's a really really remarkable
tale when you when you look at at at its
high speed hopping behavior and its ability to just rear
(38:12):
up on that tail and kick with its feet. When
I was a kid, I remember I thought kangaroos were
one of the coolest animals, and I think that simply
had to do with the obvious athleticism you see in
in a kangaroo bounding, and I never really thought about
the role it's tail played. Yeah, it's easy because they have,
you know, pretty remarkable physiologies. Otherwise that nothing really looks
(38:33):
like a kangaroo um. But yeah, when they're that challenge
anyone to next time you're watching a kangaroo run, either
at at a zoo or or just looking up you
know videos on YouTube, observe the tail. I mean, what
the kangaroo is doing. It's a full body movement obviously,
and the tail plays an enormous role in that movement,
even if it's not making contact with the ground. Um.
(38:56):
I have to admit the kangaroo is a creature I
kind of took for granted because because you would see
cartoons where they get in boxing matches, you'd see footage
of them running. But then you go to the zoo
and you see captive kangaroos and they're just all, you know,
lying on the ground and kind of splayed, and they
kind of look like old men, like naked, furry old
(39:16):
men laying around. I can think of it as a
kanger danger. You know, you just want to look around,
look away, and tell the children not to make eye
contact with the creepy kangaroo. Yeah, there is something kind
of sad about seeing bounding animals in captivity, and yeah,
well it's it's almost the equivalent, though not quite the same,
of hunting animals in captivity. I'm sure you've seen those
(39:39):
YouTube videos where a tiger will see a child at
the zoo and come up and through the glass and
try to eat the baby. Yeah. Yeah, it's far more,
far more depressing with the with a large carnivores for sure,
and and certainly any animal that depends on you know
a large territory in which to range about. Now I'm
gonna also and throw the fox in here. There's not
(40:02):
a lot to this one, but with the fox, you
do see them using their big bushy tails as a
warming wrap. So there's another use right there. Of course,
the tail can play a role in some kind of
energy conservation. Another way it could play a role in
energy conservation is storage of fat, like you might see
this in an alligator that stores fat at the base
(40:23):
of its tail. I was trying to find information about this,
and when I googled alligator tail, almost all of the
results were about meat. I thought that was interesting. For example,
a grocery item on Amazon called alligator tail meat five
pounds and have very good reviews. Uh. But apparently alligators
aren't the only ones who will put some fat in
their tail store it for later. Yeah. For instance, sheep
(40:46):
also keep a fat reserve in their tail. And really,
if there's if there's room for fat in an animal's tail,
it's essentially serving that purpose. And that's one of the
things when you start looking at tails um with various creatures,
there's often like a very predominant talking point purpose for
the tail. But then there are various other uses as well,
like you could be a prehensile tail, but if there
(41:08):
is room for any fat storage in there, well, then
it's it's also achieving that go as well. Another way
that a tail can be fat without necessarily being fatty
or having fat cells in it is tail volume. Yeah.
I was interested in the question of what creature in
the world has the biggest tail, But then I realized
that's actually not very interesting because and I can't find
(41:30):
any documentation to confirm this. I have to assume that
it's probably just the blue whale, since the blue whale
has the biggest of everything it has. That would I
think that would be a very sick that But if
you know otherwise, please email us that blow the mind
at how stuff works dot com and let us know.
But I did think of the question of what land
mammal has the largest tail in relation to its body,
(41:51):
So the largest tail to body ratio, and if you
count the volume of fluff rather than mass, the trophy
seems to go to the tufted ground squirrel of Borneo
or Rathroscurus macrotis. I found a great feature in Science
from June about this bizarre animal and what they said,
(42:12):
is that it First of all, it's about twice the
size of most tree squirrels, and they say it reputedly
has a taste for blood. But like for real or
just in like folklore. I think it's folklore. But we'll
get to that in a second. So the size of it,
it's about like thirty five cis long. It has the
bushiest tail to body size ratio of any mammal, with
(42:32):
the tail being thirty percent greater by volume than the
rest of the squirrel's body. Wow, that's a big tail.
Is a big tail, So why is the tail so bushy?
One of the scientists referenced in that in that science
article hypothesized that this giant puff ball of a tail
could confuse or distract predators like leopards, or it could
(42:52):
simply prevent the predator from getting a good grip on
the squirrel if I'm just trying to catch it. Also, apparently,
like I said, squirrel has this messed up reputation. In
local legend, hunters claim that it attacks much larger animal
like deer, it slashes them to death and then tears
their guts out. Well, I certainly want to believe that story.
(43:15):
Like the blood crazed killer squirrels. He reminds me of
a certain rabbit from Monty Pyth. Right, Yeah, it's the
only squirrel you know of that might harvest your organs.
But it looks like the scientists are skeptical that this
is true. All Right, we're gonna go and cut the
tail off here, Okay, But next time, in in part
two of our two parter about tales, we're going to
(43:36):
talk about using tales in communication. We're going to talk
about the strange world of autotomy. Am I pronouncing that right? Autotomy? Tommy?
But yeah, and the scorpion will come back up again
as promised. Um. And then of course humans human, why
don't we have tales? Where's our tail? We will discuss
in the meantime. If you want to check out more
(43:56):
content from Stuff to Blow your Mind, hadn't over to
stuff to Blow your Mind dot com. That's the mothership.
That's where we'll find all the podcast episodes, all the
blog posts, various videos. This one links out to our
social media accounts that we we keep all our eyes on.
And if you want to follow up on any of
the rabbit trails we went down about tales today, or
if you just have an interesting tale fact you'd like
(44:16):
to share with us. You can email us at blow
the Mind at how stuff works dot com. For more
on this and thousands of other topics. Is it how
stuff works dot com
Welcome to Stuff to Blow your Mind from how Stuff
Works dot com. Hey, welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Joe McCormick. So, Robert,
I've got a question for you. Okay, shoot, I know
you've heard the old would you rather be able to
fly or be able to turn invisible question? What's your
(00:24):
answer to that? But it's always been invisible? Yeah, that's
the creep's answer. Well, it's the creepy it's you know,
it's the observer's answer. It's this, it's the student of
human behavior's answer. Because if I'm flying around looking at stuff,
I'm going to be scaring wildlife. You know, people are
gonna be staring up at me, and tripped traffic accidents
are gonna occur. But if I've invisible, and if I'm
invisible and I play it safe and I you know,
(00:47):
and ethnically, then you know, I get to observe the
world as it goes about its business. You know. Another
advantage there is that flight can easily be achieved with technology,
but there's no way to become invisible technologically, So that's
the really more magical power. But what I was gonna
ask you is would you rather have wings or a
prehensile tail. This is interesting because I was I was
(01:09):
actually blogging about this a little bit yesterday. I was
looking into because there's a particular plastic surgeon, Joseph Rosen,
who's a real real trends that are real, real, just
amazing intellect in the world of plastic surgery, does a
lot of actual real life work with facial reconstruction and
wounded warriors. But he's also a trans humanist, so he's
he's written a lot about the not only can we
(01:32):
do all these things, we should do them. We will
get to the point where we add tails and wings. Well,
I was coming at this from a somewhat magical perspective
because I don't think humans would necessarily be able to
fly even if they had wings, because we're just too dense, right,
you would, They're like, our beings are much more dense
than birds. Yes, now, there are theoretical ways to transform
(01:54):
the human arm into a bird's wing, and it's would
be a lengthy surgical process, and then they still wouldn't
be able to support you and fly. You would have
to have additional uh tissue, perhaps clone tissue or vat
grown tissue that would be used to to graft on
and create the size of wings necessary to fly. And
(02:14):
then of course you still wouldn't have any arms. You
would just have like the large bat wings. So I mean,
along those lines, I would probably go with the tail
because it would it would change my life less dramatically.
Now would it be more horrifying to not have hands
at all and just have wings like a bird, or
to be like a bat and basically have gigantic hands
(02:36):
that you can't really use as hands but you can
still see some finger bones in there. Um, well, they're both.
They're both fine choices. But wait a minute. This episode
isn't about wings. It's about tails. That's right. We're talking
about tails specifically in this episode, about animal tails, and
then there's gonna be a second episode when we talk
about the absence of tails for the most part in
(02:58):
human beings. Okay, so did you come down one way
or another? Wings or tails? Definitely tails. You'd rather have
a prehensile tail than wings, yes, I mean especially it
was a nice functional tale that, you know, the prehensile
tale that I could utilize in my daily environment. It
wouldn't just be about you know, keeping flies away from me.
I've always thought a prehensile tail would be most useful
(03:19):
to a musician. Yeah, you know, playing a musical instrument,
that's when you really wish you had more hands. Yeah,
if you're a one man band, you could you could
really use that extra appendage, right that that's for your
double bass drum pedal. Yeah, so before we got one
man death metal band? Not but what would it be?
Speed metal, thrash metal? Who uses the double bass pedal?
(03:42):
It's two technical question for me. But you know, when
when it comes to tales, and you know we're already
talking about semi fictional accounts. But but I say a
few examples that come to my mind that make me
also I want to want to go into the prints
off to the prehensile tail direction versus the wing direction. Um.
I think of Minos from Dante's Inferno, who has this
(04:06):
enormous serpentine tail, and when you have a new arrival
in Hell, he wraps this tail around you and he
is able to determine which level of the Inferno you're
bound for based on how many coils wrap around your body.
Now I can't remember. Does this also go into sorting
the virtuous Pagans or is this only once you're definitely
(04:27):
in the hell part. I think this is more about
like definite hell as opposed to the the the limobile
page Pagans and limbo on the outside. Yeah, this is
your inhale. Help now we need to get you where
you go. And Minos is in charge of sorting it. Well,
that's a smart tale. Another one that comes to mind
is u Calabos from Clash of the Titans, the old
(04:48):
Clash of the Titans Harry Hamlin duking it out version.
I assume you've seen this classic film, you know, I
have to admit I actually have not said this is
this is some ray he Housing claimation. Yeah, fabulous, fabulous claimation.
I love that stuff. And I've never seen this movie.
I think I've seen the scene where the where the
Titan comes to life is a huge statue of that
(05:11):
from Clash of the Titan. Well, there's the kracking. This
one has the Kraken, it has Medusa Pegasus, that little
mechanical owl. Of course, Calibus, who's this um, this character
who's twisted by the gods into this sort of caliban
esque creature with horns and a demonic face. And then
a long swinging tale. That's great. We'll have to watch it.
(05:33):
I love the Harry Housing sin Bad movies. Great creatures,
those are wonderful. Yeah, there's one that has um what's
his name? That went imp be doctor who or the
the doctor and Doctor who? Rather um the class. Oh
I don't know, yeah, Tom Baker, Tom Baker? Yeah, which
one is it? I don't know. I saw it a
like a drive in event once and it was It's
fabulous because you get to see him as a dark sorcerer.
(05:55):
Oh that's great. Um. One other fictional tale creature that
I want to mention because it's it's played a role
in my life a lot recently is the Chippendale mup
from Dr Seus's Sleep Book. I don't know what you're
talking about. Oh, well, this is This is a fabulous
Dr Seuss book in that it just takes the soon
hopefully to be a sleep child through this dreamland. Um
(06:17):
or so I guess this awaking dreamland and all these
creatures are going to sleep. And the the overall argument is, hey,
look at all these things that are going to sleep.
You should join this crew in slumber. And the Chippendale
um up is this character who quote, his tail is
so long, he won't feel any pain till the nip
makes the trip and gets round to his brain. So
what happens is this, Um, this creature bites it's exceedingly
(06:39):
long tail right before it goes to sleep, so that
the pain will travel all the way through the tail
and travel eight hours all the way around and back
up the spinal column hit his brain, and then he'll
feel the pain and wake up. And I recently crunch
the numbers on this, and if I'm correct, for this
to work, based on the speed at which pain travels
(07:01):
through a nervous system, uh, the tail would need to
be about a thousand and eight kilometers or six six
miles long. So that's enough. That's so if the thing
we're laying out straight in the Western United States, it
could lay with its nose in Seattle, Washington into tail
in Sacramento, California. Wow. Yeah, I have absolutely nothing to
add to that horrifying children's story. Yeah. Um, beyond that,
(07:26):
I mean, the only other fictional tail that that instantly
comes to mind is, of course the xenomorph tail uh
from Alien and Aliens creature that every every part of
the creature is a is a weapon, and of course
its tail is a rather cinematic weapon as well. Yeah,
it's a it's a barbed spear. If you look at
it, it it looks like it was designed to get stuck
in you. And one thing I have to notice about
(07:48):
that tail. It never seems like you see the tail coming.
It's always suddenly poking out of your torso and you're
looking down at it. And why did this happen? Yeah,
it had whips it around and then right through you.
But those are fictional tales. We should, uh, we we
should start by just talking about the very basics here,
the basics of tales. Yeah, for example, what is a tail?
(08:12):
What is the essence of a tail? It's uh, it's
a harder question than then you then you, you know,
because when you first think of it, especially from a
vertebrate standpoint, you think, well, that's just the other end
of of the vertebrae, right, that's the the tail end
of the verb. It's almost indifficult to think about tails
outside of our language of tales. Yeah. And an interesting
fact is that even animals that don't have tails as
(08:35):
an adult often show a tale at some stage of
their development. So a frog might not have a tail,
but the tadpole that became that frog had a tail.
You might not have a tail, but when you were
in the womb as an embryo, you had a tail.
That's right. And then it it simply goes away, usually
(08:55):
before we're born. Usually we'll get to that, I guess
in the next episode. Yeah, it gets reabsorbed by the body, right, Yeah,
So tales are a huge deal with vertebrates. We just
happen to belong to rather exclusive club of creatures that
do not have tales. Uh. And likewise, you look at
the invertebrate world and tons of fascinating tales there as well,
(09:17):
that exist without the necessity of underlying vertebrate. Now, if
you're an invertebrate and you have whatever we would call
a tale, is that technically a tale or not? Yeah,
it's a It's a more difficult question than than you think,
you know when you start, especially when you look at
some of the specific examples that we're going to roll through.
(09:37):
Um uh, you know, particularly with a scorpion, like trying
to forget where this tail came from and how it
uh eventually evolved into this rather curious form. Now, when
in discussing tales, you basically have two types. There's kind
of and you can sort of think of this as
non functional or barely functional tales versus functional and highly
(09:57):
functional tales. So the first thing I've got to ask
about before we get into these vertebrate tales is what
is going on with the scorpion? Because I love I
love aragnids, and I love scorpions. When I was a
little kid, my dad one time took a trip to
Arizona and when he came back, he had one of
those one of those tourists you know, gifts that that
(10:19):
is a scorpion inside a piece of glass. Oh yeah,
And he he gave this to me, and I used
to just stare at it, thinking like, this is the
coolest thing on planet Earth. Where where does this tail
come from? Why is it so cool? Well, it's a
it's interesting because of course what you what you have
here when you're looking at a scorpion, you have a segmented,
(10:40):
curved tail that's tipped in a venomous stinger which he
uses for self defense, but also against prey that's large
or feisty, like if they're if they're coming up against
something small, they'll often just use their claws and not
even employ the stinger um. And about twenty five different
species of scorpion possessed of venoms capable of killing a human,
(11:01):
and the rest have venoms that are not that potent.
But of course, you know, allergies and whatnot can play
into reactions. Uh. Now, the interesting thing about scorpions is
that their body is a very old design. It's changed
little over the past four hundred million years, and they
probably evolved from the long extinct sea scorpions. Oh, the euryptorids. Yeah,
the eureptroids. Those are the huge ones, right, Like you
(11:23):
see the fossils of those, and it's just astounding. The
biggest people and uh, the sea scorpions. They also featured
a segmented tale that ended in at least a spike. Now,
it's difficult, perhaps even impossible, to know if these were
venomous or non venomous. It's likely that they used to
use them for propulsion or balance steering swimming, and that
(11:46):
it just eventually evolved into a venomous weapon over time.
This is one of the interesting stories about evolution because
you see this primeval tale emerging in many older forms
of life. Where they've got some kind of appendage coming
out the back of their body. But there are so
many different evolutionary routes this tail could go down in
(12:08):
in later development. Uh, And I guess that's what we're
going to be exploring in in this episode of the podcast.
Today is like eighteen roads diverged in a yellow wood,
and depending on which one you picked, you might have
a tail that communicates your emotions, or a tail that
stabs your prey and injects venom, or a tail that
helps you climb trees, or who knows what I mean.
(12:32):
There are tons of things you can do with a
part of your body that you don't necessarily have to
use for walking or propulsion, though some animals do continue
to use it for that. Yeah, so I definitely challenge
everyone to keep our trans human question in mind as
we move forward. If you were to to have the
chance to gain a tail, might some of these examples
(12:54):
sweeten the deal for you. I think everybody is just
going to go with the xenomorph tail and yeah, but
you know, I don't see the xenomorpha doing a lot
of practical things outside of murder with that tale, right,
it must not be that fulfilling to be a xenomore. Well,
you know, fulfillment is a very human classification, right, I'm
(13:15):
just projecting. I guess well, I think we should first
talk about prehensible tales in the animal kingdom. If you're
not familiar with what they are, I guess you might
have been a little bit lost so far. But a
prehensible tale is a tale that to some degree can
be used for manipulation and grasping. They're usually divided into
fully prehensible or semi prehensible tales, depending on what the
(13:37):
animal can do with and you you might think it
would be really great to have a prehensible tail as
a human because it'd be like having another hand. You know,
you could just do whatever we were talking about it earlier.
You could play more musical instruments or something like that.
But I also want to ask the question of do
you really need one? Because when you look at all
(13:59):
the animals that have prehensile or semi prehensile tails, I
see a common feature. And this might not be the case,
but at least in my observation, they all tend to
live in environments that are kind of like a jungle gym,
where there are branches or sea grass or coral reefs.
And if you look at pictures of animals using their
(14:21):
prehensile tails, sometimes they're used for free object manipulation, you know,
scooping up a bunch of something. But the majority of
what I see is animals using the prehensile tail is
an aid in climbing, or an anchor against some force,
such as hanging from a tree limb, so anchoring against gravity.
Or how a sea horse uses its tail as a
(14:42):
grasping oregan the latch onto things like coral and anchor
itself against the tide so it can just sit there
and wait and and do its thing with its head.
I guess the seahorse doesn't really have hands to work with. Yeah,
the discussion of a jungle gym like environment, it reminds
me of Dan Simon's Hyperion Cantos, his sci fi series.
There's a kind of a subspecies of humans or a
(15:05):
branch of humanity known as the Alsters, and they live
in uh in in in low gravity or zero gravity environments,
and so they're their soldiers particularly will often be seen
with robotic tales added to their suits to to aid
in this very kind of environment. Because you're in a
wait list, like you know, shiphole environment. You are essentially
(15:26):
living in this kind of jungle gym. So we would
be advantageous in that environment to have a tale. Uh,
even if it's just a robotic one, a robotic tale,
you know. I think I've seen people have already created
robotic tales. Have you read about these? No, I was looking.
I've looked at a few different studies that have involved
(15:47):
the biomimicry of say, the sea horse tail. Oh yeah,
but I haven't. I didn't notice in any studies where
anyone's actually fixing this thing under the their posterior. Oh,
not so much studies. There's something I know we've talked
about in for we're thinking that was it wasn't so
much functional as it was decorative, but it was a
tail that would respond to your emotions. Okay, all right,
(16:09):
so the tail of the communicator. You could, Yeah, you
could wag your tail like a dog, which we will
get to in a bit. But of course, I I
said at the beginning, what you can do with the
tail if you don't have to use your tail for movement.
Of course, plenty of animals do still have to use
their tails for movement. They're they're a crucial part of
their locomotion method. We birds, for example, Yeah, I mean snakes,
(16:33):
fish birds in particular, you have a highly specialized tailed,
the feathered tail. The flighted bird contributes to lift as
well as stabilization drag reduction, so it's a very fine
tune part of their anatomy. Yeah, and of course there
are fish. Animals that live in the water often use
tails for propulsion, generating a paddling motion that pushes against
(16:54):
the water in a way that cancels outside to side
motion but generates net thrust in the forward direct And
in fact, if you've never seen it, you should look
up simulations of fish swimming motions and fluent in fluid
dynamics simulators. There. I found a couple of videos of
this on YouTube, and it's really interesting seeing the waves
(17:15):
that are generated by the side to side motion of
a fish's body and tail. As the waves sort of
starts at the head and then gets bigger and bigger
as it goes back towards the tail, and it generates
this upside down y shape of of directional motion. Oh yeah,
it's like a full body movement as opposed to just
you know, a mechanical fish with the tail that goes
(17:35):
back and forth from their your bathtub, right, that'd be
more like a I don't know, a side to side propeller.
I guess that's kind of like sculling in a in
a boat, right, if you just wag the rudder back
and forth. Another interesting fact, if you've never noticed, is
that fish tend to sweep side to side and there swimming,
and marine mammals like dolphins and whales sweep up and down. Uh.
(17:59):
There may be a septions to this, I'm not aware
of them if there are, but it's an interesting artifact
of the divergent and then subsequently re convergent evolutionary pathways
of fish and marine mammals, so that like the whale tail,
the horizontal whale tail versus the vertical shark tail. Yeah.
Or I guess the more apt of comparison would be
dolphins and sharks, as that is the distinction one is
(18:21):
often trying to make at the beach in the water. Yeah.
I don't know why it took me so long in
my life to notice this, but I just never noticed
that difference until I think I was at an aquarium
one time and I was looking at the belugas that
we're swimming through the aquarium, and I was like, what's
wrong with that thing's tail? Oh, it's just not like
fish tails, it goes the other way. Yeah. Of course
(18:43):
we already mentioned that communication is a big deal with
tales and a number of species, and of course what
what manner of communication is more important than than that
involved in courtship? Exactly right, And here we're going to
get to one of the most interesting things I've come
across in in our research about tales, which is the
courtship tail feathers of the p cock. Actually, another pop quiz.
(19:09):
Do you know the generic non gendered term for peacocks
and p hens? No? I don't. It is p foul
foul Okay, that's that's that seems brother neutral. Yeah, I
just thought that was a great word. Fo Yeah, nobody
ever says, let's go look at the p foul though
the peacocks. It's true. Well, it's an unfortunate fact that
nobody cares about seeing the p hens because they do
(19:31):
not have these gigantic, interesting tails. Uh. I'm sure phns
are wonderful. No, no offense to them, but that they
don't put on a display like this, and that's what
we're gonna talk about here. Another interesting fact, did you
know that what we call the peacocks tail is usually
not actually it's tail really yeah, most of the time
this thing you see when you think of a peacock,
(19:53):
what we're talking about is it's covert feathers, which your
feathers that cover the tail feathers. It's also referred to
as a peacock's train. And as you've surely seen before,
when a when a peacock props up and spreads out
its covert feathers, they formed this gigantic, shimmering, iridescent display
of plumage full of spots that look like eyes, and
(20:15):
if you want to use a cool word, those eye
spots are called ocelli. I had always read that the
peacocks train was known to be used for mate selection purposes,
though in reading up on this for today's episode, I
found out that there have been some really interesting questions
and doubts recently thrown into the mix here. But this
(20:36):
is a really interesting story about the complexities of evolutionary
biology and and questioning what we thought we knew. So
there's this mate selection theory of the peacocks train. The
ideas of the most prominent one, this is the one
we've all heard growing up. Yeah, and and Charles Darwin
thought about this. Charles Darwin. If you're Charles Darwin and
(20:57):
you look at a peacock's train, this huge, huge, shimmering,
eyespot covered extravagance, you think, what on earth is this for?
You're you're coming up with this theory of natural selection,
where organisms that are the most adapted to survive and
reproduce in their environment are the ones that survive. How
do you encourage a trait that's so wasteful and pointless.
(21:21):
I mean, it doesn't it takes energy or resources to
develop a train like this. It doesn't seem to provide
any sort of mechanical survival advantage, So it doesn't help
the peacock fly higher, or you know, kick with its
spurs harder or something. In fact, it would actually seem
that feathers like this make the peacocks more vulnerable to predators.
So what's the deal. Why would you have something like
(21:44):
this in an animal? So I've actually read several hypotheses
over the years to explain the the extravagance of the
peacock's train display and the I guess we should start
with the sexual selection effect. This is what's sometimes called
runaway sex sual selection. And the point is that at
some point, way way back in the p fowl's ancestral lineage,
(22:08):
the p hens, the female p foul preferred slightly longer,
more elaborate trains for some reason related to fitness. Maybe
it made the males stronger, more powerful in flight. And
this choosiness kept being magnified more and more over the generations,
until the peacocks were no longer displaying fitness, but they
(22:31):
were just being bred by the females to have longer
and more elaborate trains. In the same way we would
breed a dog to encourage a certain trait to to
intensify over generations, we just end up with a ridiculous
breed of dog that has no clear function anymore other
than to look funny. Yeah, And that's what the p
(22:51):
hens are doing to the pea cocks. Over the generations.
They develop a preference for a certain type of trait
in males, and the males that have that trade get
more mating opportunities, and this gets magnified over the generations,
and if there's not enough of a selection pressure to
counteract the sexual selection, like if there's not a strong
(23:12):
enough force saying okay, males with these big train displays
really are going to get killed all the time, then
they'll just keep getting bigger and bigger. Another evolutionary explanation
that I've read about is that the large extravagant displays
function as a sort of calculated, conspicuous handicap to show
off the fitness of the mail. And it's kind of like,
(23:34):
in human terms, a guy showing off how much money
he has to waste by wearing lots of pointless expensive jewelry,
or like a swordsman demonstrating his superiority by dueling with
one hand tied behind his back. The point is like
I am so fit, I am such a good mate
that I can have this enormous handicap, this pointless waste
(23:55):
of resources, and still be the best that made that
that makes sense. It's like I have the time and
energy to put into this ridiculous, uh cumbersome uh addition
to my body. Another hypothesis that's been developed over the
years is that the ability to produce large, elaborate trains
is an advertisement that the peacock is relatively free of
(24:18):
parasites which would impair his ability to produce and maintain
a large, beautiful train like this. But I want to
talk about some specific studies because, like I said, the
research now seems to have gone back and forth about
the role that the peacock's tail plays in the mating rituals.
So in the early nineteen nineties, the behavioral ecologist Marian
(24:41):
Petrie of Newcastle University carried out some really often cited
research and this is one of the big studies in
this field. One paper and Animal Behavior in nine was
called p Hen's prefer Peacocks with elaborate trains. So what
do what do peacocks do when they want to mate? Well,
they aggregate into something called a leck. I believe I'm
(25:04):
pronouncing that right. It's l e K and that so
the males gathered together and in this case, uh Petrie
and her her team observed one leck that was consisting
of ten males, and they found that there was a
big difference in how much the different males in the
leck got opportunities for mating. So the top male, according
(25:26):
to them, copulated twelve times, while the least successful males
in the leck got no sex whatsoever, and Petrie's team
concluded that quote over fifty percent of the variants in
mating success could be attributed to train morphology. There was
a significant positive correlation between the number of eye spots
(25:47):
a male had in his train and the number of
females he made it with. So they found that the
females didn't mate with the first male they met, but
they would visit several different males and in ten out
of a in cases in their study that ended with
successful copulation. In their terms, I'm trying to imagine what
unsuccessful copulation is, the male that the female chose was
(26:11):
the one with the greatest number of eye spots. So
this seems pretty straightforward. More eye spots on your train
means you get more mating opportunities. Okay, that's pretty straightforward.
It's kind of like more the more jewelry, the more
the fancier the clothes, the more the more money that
the that the individual has to spend on drinks and
nights out translates to the the economics of the development
(26:34):
of these eye feathers. Yeah. Yeah, So this seemed to
be accepted for a while. Until now. That paper was
called p Hen's prefer peacocks with elaborate trains. In two
thousand eight, in the same journal Animal Behavior, there was
a paper called p Hen's do not prefer peacocks with
more elaborate trains. This was carried out by a team
led by Mariko Takahashi, and they were trying to replicate
(26:56):
the original results in a feral population of Indian pe
foul in Japan. Over the course of seven years of observation,
and Takahashi and her co authors claimed to have found
no evidence at all that the phn's expressed any preference
for peacocks with more elaborate trains. That's what they said.
(27:17):
This means the females did not show any noticeable preference
for males with longer trains, more symmetrical trains, or more
eye spots. And those are the three things that are
often cited as as being the you know, the things
you want your train to have. So what does that?
What does that mean? Where does that leave us? Well?
According to them, they concluded that the peacock train display
(27:39):
is it might be a necessary part of successful mating.
So a male that can't show a train display is
not going to get to mate. But they came up
with three concluding points. They said, the train is not
the universal target of female choice. Uh, the trains don't
vary a whole lot across male populations. And then they
(28:02):
also said, quote, based on current physiological knowledge, it does
not appear to reliably reflect the male conditions. So they
don't think that the train is all that much of
an indicator of fitness. And what they ended up concluding
is that it's just an obsolete signal that maybe it
(28:23):
used to correlate to female preference, but it just doesn't anymore.
It's it's tempting to take that and try to apply
it to the human world and and various mating practices
and you know, romance practices that are really kind of
becoming pointless than our modern age. But it's it's part
of traditions, so you kind of have to do it.
(28:43):
I mean, you don't really do it, but every you
don't I mean you don't really have to do it,
but everyone feels a little weird if you don't write. Yeah,
how many common I don't know, dating or courtship practices
are still somehow based on the idea that in a relationship,
a man will be the person who's earning the money
for the couple, when in you know, many or most
cases in the Western world, that's not the case anymore. Yeah,
(29:07):
Or there's so many different little you know, superstitions and
traditions and the wedding ceremony itself. My my wife shoots
a lot of weddings, so I get to hear I
always hear, you know, how did they do a first
look or did they do the whole you know, the
straight up deal where no, the bride in the room
do not see each other till the ceremony, Like that's
something that really had there's no bearing on anything whatsoever.
(29:27):
But when it comes time to put the wedding together,
there's often you know, enough tradition, uh, you know, bouncing
around in your head that you say, I know, we're
gonna we're gonna stick to the old I don't see
you and you don't see me until the moment of
of our of our our actual ceremony, our weddings. The
human version of investing tons of resources in an elaborate
(29:48):
train display. Yeah, I think there's a strong case for that.
So that was what they concluded. But there's still more
to the story because yet another animal behavior study was
published in two thousand eleven that seemed to strike a
note somewhere in between the two that came before, and
said p ns prefer peacocks displaying more eye spots, but rarely.
(30:09):
I can see this study perhaps not getting as much
play and the media. Yeah there, I did read a
good Nature News article about it, but the main takeaway
was and I want to read a quote here to
get it exactly right. They said, p foul mate choice
is clearly more complex than previously thought. Females may reject
a few mails with substantially reduced I spot number while
(30:31):
using some other queue to choose among males with typical trains.
In other words, if you have way fewer eyespots the normal,
if you were obviously I spot deficient, you will not
get sex as a peacock. But there's no real difference
between an average number of eye spots and a much
greater than average number of eye spots. The main takeaway
(30:52):
I got from this is that p foul mate choice
seems to be more complicated than we originally thought. And
actually the main author of the original study from nine,
Marjorie Petrie, said as as quoted in a two thousand
eleven article in Nature News quote, at the end of
the day, we will never know what p hens are
looking at and how they select their mates. You can't
(31:15):
ask them. Now at this point in our discussion of
peacocks and p hen's um, you know, I have to say,
there's got to be a way to spice it up
a little bit. I feel like some some listeners out
there might be saying, all right, I'm I'm ready to
extract from the whole peacock discussion. But wait, right, what
if we throw cyborgs in there? Right? Because you can
(31:35):
answer Marjorie Petriots question in a way you can ask them.
I mean, you can't ask them, but you can take
a look at what p hens are looking at by
making a cyborg p hen with eye tracking devices. In
the Journal of Experimental Biology in April, there was a
paper called Through Their Eyes Selective Attention in p hen's
(31:56):
during Courtship, and the researchers behind the study wanted to
see if they could find out exactly what phn's were
looking at when they were presented with a male doing
his courtship display. So they rigged up what looks like
a cyborg PHN. She's got eye tracking hardware on, and
she looks like something out of those you know, those
Terminator rip off movies that started coming out in the
late eighties where everybody was a cyborg or had had
(32:20):
some kind of like cyborg upgrades for a while. Though
there were so many of them, they were all shot
on the same pseudo industrial setting back lot where everybody
just seemed to wander around factories and alleyways all the time. Anyway,
what did the PHN look at? Curiously? In the video
I saw of this, she spent almost all her time
(32:40):
looking across the bottom of the Peacock's train display, and
the scientist in the video suggests that that means she's
evaluating the width and symmetry of the train. So I
don't know, we're kind of back to the beginning. Yeah, Anyway,
I thought this was very interesting that something that we
originally thought was a pretty settled matter of evolutionary adaptation
(33:04):
turns out as very complicated and we don't fully understand it.
And just one more hypothesis I came across. I don't
know where to fit this into everything else, but this
was that the Peacock's train display makes infrasound as it vibrates,
and this infrasound might play some sort of role in mating. Wow,
so it could be even more nuanced than originally suspected. Yeah.
(33:27):
Now I want to talk just briefly about the hippo tale. Um,
because this is a tale that is easy to miss,
is easy to you to forget to draw. When you're
drawing hippo's for a child, as I often do, I'm
picturing a hippo tail. It's not very big. No, it
doesn't make a courtship display. No, it doesn't seem to
(33:49):
communicate a whole lot. Maybe it communicates a little. So
what's the point. It's just a little dangly tiny thing. Yeah,
like barely covers the hippo anus really. Um, Well, here's
the here's the thing. If you see, if you see
a hippo in a while, if you see a hippo
at the zoo, uh. The what the tail does is
that as the hippo releases its bowels, uh, the tail
(34:09):
flips back and forth in order to fling poop like
some sort of fecal sprinkler system. And it's suspected that
this is how male hippos wou mates and territory, So
it could be a form of communication, a fecal communication system. Uh.
Though there's another theory out there then. This theory is
(34:30):
that it's a means of flinging parasites away from the
hippo's body, such as the place of dell Odeo's Dieger
Skio Delhi leech a special leech that feeds exclusively on
the rectal tissue of a hippopotamus. So what's it like
to be that leech. It's a very specific lifestyle. I mean,
(34:50):
there's so many different types of leech leeches out there
with the very specific hosts in some cases, uh, and
some actually eat worms as opposed to the on blood.
But this leech knows what it wants it and it's
hippo rectum. So it's possible that the hippo tail is
as much about just flinging those away from its body
(35:11):
as possible, and certainly in other large herbivores, we see
the use of the tail as a means of keeping
flies away from the rectum as well, and ultimately about
you know, keeping parasites away from that delicate area of
the anatomy that is otherwise difficult to reach. Now. I
want to get back to monkeys for a second, because
when I talked about monkeys and their prehensile tails, obviously
(35:34):
not all monkeys have preensile tails, but the New World
monkeys that have them, I talked about them using them
in climbing. And there are multiple ways actually that a
tail could come into climbing behaviors. It wouldn't necessarily just
have to be for gripping branches or for bracing against
trunks and limbs, right, yeah. It can be used as
(35:56):
a as a balance, as a counterweight. Ah there you yeah,
and and certainly you can imagine this, but I just
imagine yourself balancing on a beam and the various things
you use your arm for, you know, spreading your arms
out and all that. If you had a tail, that
would just be another part of your body that you
could utilize in such a fashion. Even something like your
modern house cat will utilize it's its tail for balance. Yeah.
(36:21):
But another animal that uses it not only uses its
tail for balance, but also for propulsion and uses it
for pulp for propulsion on land is of course the kangaroo.
You know, they have that large tail, uh, sticking out
behind a huge muscular tail, and according to a two
fourteen study published in the journal Biology Letters, the kangaroo
(36:43):
utilizes its tail as a true fifth leg. The researchers
found that the tail of a walking kangaroo works as
hard as the leg of a comparably sized human moving
at the same speed. Wait, so the tail makes contact
with the ground. Yes, it does, and I'll get to it.
To to that part in a second. For the most part, though,
(37:04):
as it hops, the tail lashes up and down, helping
the creature stabilize while also serving as a motor to
lift and help accelerate the kangaroo's body. So it's almost
it's almost like a ficio's tail, except it's uh, it's
just it's moving in the air, and it's about, you know,
thrusting the body as opposed to actually making contact with anything. However, However,
(37:28):
to your point, though, the that that fifth lag, that
giant tail can support the kangaroo's full body, and you'll
you'll often see this occur when when male kangaroos are
kicking at each other, they'll kick up, you know, they
do that kangaroo kick and uh, and in doing so,
they actually come up on the tail. Now, of course,
a lot of the rest of the time, the creatures
(37:49):
are not doing high speed hops and they're not kicking
each other. They're just you know, gently browsing um for
stuff to eat. And in those those situations, the tail
just kind of, uh, you know, faces into the background
for a little bit. But it's a really really remarkable
tale when you when you look at at at its
high speed hopping behavior and its ability to just rear
(38:12):
up on that tail and kick with its feet. When
I was a kid, I remember I thought kangaroos were
one of the coolest animals, and I think that simply
had to do with the obvious athleticism you see in
in a kangaroo bounding, and I never really thought about
the role it's tail played. Yeah, it's easy because they have,
you know, pretty remarkable physiologies. Otherwise that nothing really looks
(38:33):
like a kangaroo um. But yeah, when they're that challenge
anyone to next time you're watching a kangaroo run, either
at at a zoo or or just looking up you
know videos on YouTube, observe the tail. I mean, what
the kangaroo is doing. It's a full body movement obviously,
and the tail plays an enormous role in that movement,
even if it's not making contact with the ground. Um.
(38:56):
I have to admit the kangaroo is a creature I
kind of took for granted because because you would see
cartoons where they get in boxing matches, you'd see footage
of them running. But then you go to the zoo
and you see captive kangaroos and they're just all, you know,
lying on the ground and kind of splayed, and they
kind of look like old men, like naked, furry old
(39:16):
men laying around. I can think of it as a
kanger danger. You know, you just want to look around,
look away, and tell the children not to make eye
contact with the creepy kangaroo. Yeah, there is something kind
of sad about seeing bounding animals in captivity, and yeah,
well it's it's almost the equivalent, though not quite the same,
of hunting animals in captivity. I'm sure you've seen those
(39:39):
YouTube videos where a tiger will see a child at
the zoo and come up and through the glass and
try to eat the baby. Yeah. Yeah, it's far more,
far more depressing with the with a large carnivores for sure,
and and certainly any animal that depends on you know
a large territory in which to range about. Now I'm
gonna also and throw the fox in here. There's not
(40:02):
a lot to this one, but with the fox, you
do see them using their big bushy tails as a
warming wrap. So there's another use right there. Of course,
the tail can play a role in some kind of
energy conservation. Another way it could play a role in
energy conservation is storage of fat, like you might see
this in an alligator that stores fat at the base
(40:23):
of its tail. I was trying to find information about this,
and when I googled alligator tail, almost all of the
results were about meat. I thought that was interesting. For example,
a grocery item on Amazon called alligator tail meat five
pounds and have very good reviews. Uh. But apparently alligators
aren't the only ones who will put some fat in
their tail store it for later. Yeah. For instance, sheep
(40:46):
also keep a fat reserve in their tail. And really,
if there's if there's room for fat in an animal's tail,
it's essentially serving that purpose. And that's one of the
things when you start looking at tails um with various creatures,
there's often like a very predominant talking point purpose for
the tail. But then there are various other uses as well,
like you could be a prehensile tail, but if there
(41:08):
is room for any fat storage in there, well, then
it's it's also achieving that go as well. Another way
that a tail can be fat without necessarily being fatty
or having fat cells in it is tail volume. Yeah.
I was interested in the question of what creature in
the world has the biggest tail, But then I realized
that's actually not very interesting because and I can't find
(41:30):
any documentation to confirm this. I have to assume that
it's probably just the blue whale, since the blue whale
has the biggest of everything it has. That would I
think that would be a very sick that But if
you know otherwise, please email us that blow the mind
at how stuff works dot com and let us know.
But I did think of the question of what land
mammal has the largest tail in relation to its body,
(41:51):
So the largest tail to body ratio, and if you
count the volume of fluff rather than mass, the trophy
seems to go to the tufted ground squirrel of Borneo
or Rathroscurus macrotis. I found a great feature in Science
from June about this bizarre animal and what they said,
(42:12):
is that it First of all, it's about twice the
size of most tree squirrels, and they say it reputedly
has a taste for blood. But like for real or
just in like folklore. I think it's folklore. But we'll
get to that in a second. So the size of it,
it's about like thirty five cis long. It has the
bushiest tail to body size ratio of any mammal, with
(42:32):
the tail being thirty percent greater by volume than the
rest of the squirrel's body. Wow, that's a big tail.
Is a big tail, So why is the tail so bushy?
One of the scientists referenced in that in that science
article hypothesized that this giant puff ball of a tail
could confuse or distract predators like leopards, or it could
(42:52):
simply prevent the predator from getting a good grip on
the squirrel if I'm just trying to catch it. Also, apparently,
like I said, squirrel has this messed up reputation. In
local legend, hunters claim that it attacks much larger animal
like deer, it slashes them to death and then tears
their guts out. Well, I certainly want to believe that story.
(43:15):
Like the blood crazed killer squirrels. He reminds me of
a certain rabbit from Monty Pyth. Right, Yeah, it's the
only squirrel you know of that might harvest your organs.
But it looks like the scientists are skeptical that this
is true. All Right, we're gonna go and cut the
tail off here, Okay, But next time, in in part
two of our two parter about tales, we're going to
(43:36):
talk about using tales in communication. We're going to talk
about the strange world of autotomy. Am I pronouncing that right? Autotomy? Tommy?
But yeah, and the scorpion will come back up again
as promised. Um. And then of course humans human, why
don't we have tales? Where's our tail? We will discuss
in the meantime. If you want to check out more
(43:56):
content from Stuff to Blow your Mind, hadn't over to
stuff to Blow your Mind dot com. That's the mothership.
That's where we'll find all the podcast episodes, all the
blog posts, various videos. This one links out to our
social media accounts that we we keep all our eyes on.
And if you want to follow up on any of
the rabbit trails we went down about tales today, or
if you just have an interesting tale fact you'd like
(44:16):
to share with us. You can email us at blow
the Mind at how stuff works dot com. For more
on this and thousands of other topics. Is it how
stuff works dot com
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