Listener Q's & Sloth Poos

It's a listener questions episode which means I answer your questions about animal baldness, skin, and poop! 

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:06):
Welcome to Creature Future production of iHeartRadio. I'm your host
of Many Parasites, Katie Golden. I studied psychology and evolutionary biology,
and today on this show, it's a listener questions episode.
You send me your questions via email or Twitter. I
guess sometimes and I do my best to answer them.

(00:28):
If you are listening to this and you're thinking, hey,
I have a question, why aren't you answering my question? Well,
you can write to me at Creature Featurepod at gmail
dot com. So onto the first listener question. Hey, Katie,
I was just curious. Do you know if any other
animals lose their hair as they age? And if yes,
is it like with humans where it's super selective which

(00:49):
hair disappears in which keeps growing strong right untill we croak?
This is from p K. Thank you for the question.
Baldness is common in humans, and it is actually found
another animals, either as a permanent and useful feature, such
as the bald heads of vultures and buzzards, which keeps

(01:10):
them clean when they are feeding on carrion. There's also
the bald skin of naked mole rats and of course elephants,
which you know their skin. They do have hair on
their skin, but it's very thin and fine. But these
are evolutionary traits. These have adapted over a long period

(01:32):
of time, and so it is something that benefits these animals.
But there is I think the kind of conception of
baldness in humans is something that changes over time due
to age, due to genetics, environment and hormones. So in humans,

(01:52):
pattern baldness is a type of baldness that occurs during aging,
and you usually follows a pattern. It is hereditary, and
it is typically more pronounced in people assigned male at
birth than in female, but it occurs for both males
and females. What happens is the hair follicles shrink over

(02:17):
time and the hair becomes shorter and thinner until it
stops growing thick and full like it used to. So
the follicle isn't dead, but the hair is so thin
and fine it is no longer visible. And so the
reason that pattern baldness isn't as common in furry animals

(02:41):
like you know your cats or what have you, is
that if they have fur, generally there's a good evolutionary
reason for it, and there are selective pressures for them
to keep that fur. In humans, the hair on our
head might keep us marginally warmer or offer some sun protection,
but it's not as article to our survival, especially given

(03:03):
our ingenuity and our social behaviors and being able to
invent things like hats, so we are able to sustain
a large population of people with baldness. So the mechanics
of how pattern hair loss works in humans relates to
the sensitivity of a keratin protein to the androgen hormone

(03:26):
and the lack of this keratin protein on human scalps.
So this is why you can have a hairy chest
or back or other parts as well as like a
fully luxurious beard, while also having a bald head. The
scalp doesn't have the same type of kerotin protein as
these other parts of the body and so a different

(03:48):
type of sensitivity to androgen. So while androgen can cause
hair growth on other parts of the body, it can
actually overstimulate and cause hair loss on the scalp. Androgen
can actually shorten the growth cycle of hair on the scalp,
and that inhibits hair growth while you know, still growing

(04:10):
hair elsewhere on the body. This is also why trans
people who take male hormones can both gain the ability
to grow a beard or other body hair, but can
also paradoxically cause baldness on the scalp, not always but sometimes. Again,
it has something to do with genetics. That is why

(04:32):
pattern baldness is also called androgenetic alopecia. So animals can
experience baldness due to stress or mange. Right. Mange as
a skin infection caused by mites, and it can cause
hair loss all over the animal's body. A lot of
the cryptid sidings that people document, like the chupacabra, are

(04:55):
typically coyotes, dogs, or foxes affected by mange, which alters
their appearance. But this is kind of different from human balding. Right,
Like human balding is not due to a disease, It
is just a natural genetic predisposition to the hair follicles
shrinking in response to androgen So are there animals who

(05:15):
experience this kind of pattern baldness the same kind that
occurs in humans where it happens as you age, And yes,
actually it does. There is an animal called the stump
tailed macaque. It is a primate found in South and
Southeast Asia. It has a red, hairless face, a stubby tail,

(05:39):
and shaggy brown fur. Both male and female stump tailed
macaques experience pattern baldness as they age on their heads,
so their baldness is thought to be caused by similar
factors that affect human baldness, so like the androgenetic alopecia
that occurs in humans. Also, there are certain breeds of

(06:04):
domesticated dogs, usually short, short haired, and pure bred dogs
such as docsins, who also have patterned baldness, but it's
not usually just like on the top of their head.
It would be on the ears, chest, and back legs,
so it Yeah, it does occasionally occur in other animals,

(06:24):
but it is way more common in humans. So yes,
it does occur in other animals, but yeah, it's relatively rare.
It's kind of an interesting, somewhat unique thing that occurs
in humans and the other examples that I mentioned. All right,
onto the next listener question. Hello Katie, long time, first time.

(06:46):
I just found out about the Morning Gecko and my
mind can't comprehend them. Have you done an episode on
them in the past, and I don't remember it. If
you haven't done an episode on the Morning Gecko, would
you please? I don't understand how they clone themselves, how
they evolve that ability. Are there any evolutionary advantages to
being able to clone yourself? And are there other animals

(07:06):
that can do the same thing or something similar? Thank
you and this is from Tuck so Hey Tech. Thank
you for the really cool question. This is a great question.
There are a few species of reptiles who can do
the same thing as the morning gecko, who can reproduce asexually,
and there are a lot of animals who do so
or go through cycles of cloning and sexual reproduction, like

(07:30):
aphids like coral so whiptail lizards are another reptile who
reproduce asexually and are entirely female. They're very similar in
terms of how their sexual reproduction works to the morning gecko.
So whiptail lizards use three sets of chromosomes to create
heterozygotic offspring. So all this means is that, you know,

(07:56):
we have pairs of matching chromosomes, and chromosome has the
same number of alleles and alleles that line up with
each other, kind of like a zipper lines up with
another half of the zipper. So for heterozygotic organisms, the
aligning alleles are not the same. They can be slightly

(08:19):
different So imagine like a zipper, where each little tooth
represents an allele, and you have the left zipper and
the right zipper, and these are each chromosomes, and each
tooth of the zipper is like a different color, and
this example color is a stand in for like nucleotide
sequence of the allele. So in monozygotic animals, each zipper

(08:42):
tooth is matched with the same color of zipper tooth
on the opposite side, But in heterozygotic animals, each zipper
tooth is matched with a different colored tooth, and they
can still zip together. It still functions, And so this
is how you get sort of dominant and recessive genes
in interacting with each other. You can have a recessive

(09:04):
allele maybe that is negative or something that gets over
rowed by a dominant allele, and then it can protect
you from something like rare disease. And so in the
case of whiptail lizards, they can actually create this heterozygotic
zipper effect even through clonal offspring by having three sets

(09:28):
of chromosomes rather than the usual two, and so they
give their offspring twice the number of chromosomes than sexually
reproducing animals give their offspring. So Now let's talk about
the morning geckos since this was brought up in the question.
They are from Southeast Asia, but they are invasive to

(09:48):
the Americas and Australia. It is a small brown gecko
who looks pretty plain, but their reproductive cycle is really fascinating.
Like the whiptail lizards, they are typically an all female species.
Occasionally they will give birth to an oopsie male baby.
Usually this offspring cannot reproduce and so yeah, these geckos

(10:14):
use parthenogenesis to reproduce. It is asexual reproduction from an
unfertilized egg, and rather than combine their genes with a male,
they will shuffle their own genetic material to reproduce, just
like the whiptail lizard. They are also triploid, so that

(10:35):
means that they have three sets of chromosomes, just like
the whiptail lizard, and that allows them to have their
offspring be heterozygots. So why is it so important to
be a heterozygote. Well, this allows some genetic diversity to

(10:57):
avoid dileterious alleles from stef Say you have an allele
that actually causes an issue, having an opposite allele on
another chromosome, that's slightly different can actually protect an organism
from sort of mistakes stacking up. But because these geckos,
the morning gecko and species like the whiptail lizard are

(11:18):
still clonal and they aren't able to shuffle and replenish
their genetic library like sexually reproducing animals do, they are
still vulnerable to things like environmental change or disease. Because
if one of these geckos is vulnerable to something happening,
say the temperature changing slightly or some fungal infection happening,

(11:43):
and it has a vulnerability to it, well so does
all of the rest of the population. Because they're genetically
so similar, if not identical, so they will be affected
in similar ways. Whereas a population that has more genetic
diversity has more of a chance of their being an
individual or individuals who have some adaptation or difference that

(12:06):
allows them to deal with environmental stressors. So the question
would be why would you ever want to be a
clonal species? Well, I mean the main thing is just
that you don't have to date. You don't have to
be in the dating pool. Not having to find a
partner or compete to find a partner means that you

(12:26):
can simply drop your little lizard pants and lay an
egg when the conditions are right. This allows them greater
ability to reproduce without constraints. So this is one of
the reasons they are such an invasive species. All they
need is one individual to land on an island or
new continent to establish a population there. They don't even

(12:47):
need to find a partner to reproduce, so that is
a benefit. But then you know, so these these geckos
and lizards have kind of comp and stated for the
fact that clones are less genetically diverse by using that
three chromosome trick. But other species I mentioned earlier, like

(13:09):
aphids coral, they will have both a sexual and sexual
reproduction and sometimes it happens in seasonal cycles or depending
on the environment, And that's another way that a species
can try to compensate for the downsides of both sexual
and a sexual reproduction. So like with sexual reproduction, you

(13:33):
know you have to find a partner, it can be
tricky and you can't create as many offspring as quickly,
whereas with a sexual reproduction you can create a lot
of offspring. And so kind of combining both systems for
these organisms allows them to introduce some genetic diversity while
also pumping out a lot of babies, which is, you know,

(13:56):
important if you're an avid, because gosh, you're just a
tiny little jellybean of the natural world. Everybody likes to eat,
especially ladybugs. Anyways, we're gonna take a quick break and
when we return we will answer another couple listener questions.

(14:16):
All right, onto the next email. I have a burning question.
Why is dog skin like that? You can just grab
a handful of dog skin. You can't do that to
a human it hurts, but dogs like it. You can
grab fistsful of dog skin on the back of their neck,
which makes sense for scruffing puppies, but you can also

(14:37):
do it on their butt, legs and belly. It's like
it's hardly attached. The only place you can do that
on a human is the elbows, and it's the same
with cats too. I don't know for sure, but I
was traumatized by Michael Moore's Roger and Me, and I'm
guessing that you can grab a fistful of buddy skin too.
How come some animal skin is all loose like that?

(14:58):
Thanks will Well, will I I have not seen that movie,
and I don't know what you're referring to, and I'm
going to keep it that way because I do like bunnies.
So yeah, as you pointed out, dogs, bunnies, cats, a
lot of other animals actually have looser skin than humans.
Like if you try to sort of scruff your own neck,
you're gonna have a bad time. And as you point

(15:19):
it out in your question, one reason that dogs, bunnies,
and cats skin is loose on their neck is that
as puppies and kittens, they can easily be transported by
the neck by their mother. Now, don't do that with
adult dogs or cats or well, actually I don't know
too much about handling rabbits, but yeah, if you scruff

(15:41):
an animal that is an adult without supporting them properly,
you can hurt them. Because it's really only meant for
kittens and puppies because they're lighter and so there's less
pressure on that neck scruff. So yeah, always always grab
your animal's skin with care you cut, Like if you
own a dog, you kind of know, like you can

(16:02):
usually like sort of massage your dog's neck and like
there's skin that kind of is loose there, and they're
happy enough to have their skin kind of massaged in
a way that would maybe be uncomfortable for a human.
But you know, aways, always be gentle with your dog
skin because even though it's looser, it can still be sensitive,
especially in places like on their bellies or on their haunches.

(16:25):
But yeah, so it is definitely looser than human skin,
and loose skin in animals has a variety of purposes,
including protections. So loose skin around the throat or other
vital organs can prevent an animal from being injured or
killed if they're clad or bitten by another animal, so

(16:48):
basically their skin will be grabbed while their organs will
be safe. In fact, some animals go to the extreme
when it comes to this type of defense. The hagfish have,
which are basically these like deep sea fish that look
like gross slimy tubes, and hagfish have such loose, detached skin.

(17:13):
They're basically like a long, tough, mucas y water balloon
filled with organs, which makes it really hard for a
predator to puncture their internal organs because they can grab them,
but they're basically just like grabbing the skin while the
organs shift around inside them. So this is protection for
the hagfish. Another interesting species is the African spiny mouse.

(17:39):
So African spiny mice have this adaptation, which is detachable skin.
Their skin can actually be built, pulled off and grow back,
allowing them to escape predation by the skin of their teeth,
which I guess technically it's just the skin everywhere, but
it's sort of like that the the technique that some

(18:01):
lizards have where their tails can pop off. So yeah,
it's their skin can basically come off, come loose, and
the mouse can live another day. It regrows the skin
and is able to survive predation. So really there's a
lot of good reasons to have loose skin. So the
better question is why humans and some other animals have

(18:24):
really tight skin, since it puts us at greater risk
of a predator or competitor biting our organs. Right, we
don't have that same defense technique that say a dog has,
so humans and some animals like pigs have very firmly
attached skin. Actually, pig skin is similar to humans, and

(18:46):
it's often used in research sort of to examine it
in place of human skin because of how similar it is.
So we also have a limited paniculous noosis, which is
a thin layer of muscle attached to the skin. So
you have you noticed like your dog or a horse

(19:08):
can like twitch its hind legs, say, like a fly
lands on a horse a horse's butt, and it's skin
just kind of like flicks around, twitches around to kind
of ward off this fly. We can't really do that.
We have a very limited muscle control of our skin.

(19:28):
And so you know, this is a limited thing that
we cannot do. So why again, why have we lost
this ability? So this is it's a big question. So
one of the possible benefits of more firmly attached skin
may have to do with our need for sweat glands.

(19:49):
You know, like maybe we are more kind of endurance hunters.
We need to have a lot of sweat glands. We
need to be able to have our skin get kind
of like evenly coated and sweat to cool off if
we're doing sort of these this sort of endurance hunting. Also,
it could have something to do with the immune function

(20:11):
of our skin. Uh, Honestly, I am not entirely certain
why this is, and I really want to find out more.
If there are any dermatologists or skin experts out there
who have an answer, you can write to me at
Creature featurepod at gmail dot com. In the meantime, I
will continue to keep my eyes peeled for skin news.

(20:36):
That's right. I will keep reading the news to see
if any more discoveries come out about human skin and
why why we don't gotta lose saggy baggy skin seems
like it'd be fun. You could just kind of like
slide around in it, you know. Can you imagine if
we had naked mole rat skin and we were just no,

(20:57):
there would be no more marketing to get rid of
or wrinkles, because we'd all have wrinkles by design, and
we'd think they look sexy, and that would be great.
It'd be liberating. We should be allowed to have wrinkles
in age. In fact, we should come out all Benjamin
buttony and just get older. That's how I feel. Let's

(21:18):
move on to another listener question. So here it is, Hi, Katie.
I just saw this short video of a spider tailed
horned viper and was truly horrified, But I thought it
might inspire you to do a show on some of
the most amazing or horrifying cases of memoricry. This is
from Amanda m Hi Amanda, So the spider tailed horned

(21:41):
viper is indeed an amazing mimic It is a viper
that lives in the mountains of Iran and Iraq, with
a tail tip that looks uncannily like a spider, even
with these little sort of dingly bits that look like legs.
So it will wiggle this tip of its tail until

(22:02):
it grabs the attention of a bird or other small insectivore,
and the bird will come down try to eat this spider,
but hey, that's just part of a snake. And then
at this point the viper will strike and it will
get its lunch. So I did actually talk about this
snake a while back on an episode called the Go

(22:22):
Home Nature, You're Drunk, which aired August fifteenth, in twenty nineteen.
So that was a really long time ago. I was
just a little baby, little baby podcaster and my little
podcasting diapers. I didn't know what I was doing at
that point, but yeah, you could listen to it Go
Home Nature, You're Drunk, August fifteenth, twenty nineteen. But yeah,

(22:43):
I definitely will do more cases of horrifying mimicry. I
love mimicry. I think it's really fascinating. So yeah, keep
your ears peeled. For that, I guess you don't peel
your ears. What's the term for that? Keep your ears perked?
We can't even perk our ears. We've lost so much

(23:05):
through evolution in terms of moving our skin and our
ears around. All right, So last listener question. One question
I have is why some sloths have to climb down
to the ground to poop, exposing them to overwhelming danger.
Why don't they just poop from the skies like most birds,

(23:25):
which is a worse calamity to your hat than most droppings. So,
Michael D. From Sacramento, thank you for this question. I
always love a poop question. Keep them coming. So before
I answer the question directly, here's some background that will
help you understand. There is this interesting thing that happens
when sloths descend and poop. They are able to facilitate

(23:51):
the life cycle of a symbiotic moth that lives on
the sloth spur. The moth that lives in the sloths
fur actually poops on the sloth and will dye sometimes
in its fur, which sounds gross like you have a
bunch of moth poop and corpses in your fur, But
actually what that does is provide fertilizer for another symbiote

(24:14):
that lives on the sloth, green algae. So green algae
lives on the sloth. You can actually see algae sometimes
on sloth. They'll have a greenish tint to their fur.
And this algae feeds on the moth droppings or even
the moth corpses. And the algae is beneficial to the

(24:34):
sloth because it grows on the sloth skin and fur,
and the sloth can actually absorb vitamins and nutrients through
its skin from this algae that it otherwise can't get
through its diet. So ecologist Jonathan Polly and his team
at the University of Wisconsin think that this algae moth

(24:56):
connection may be a reason for the sloth inefficient pooping
method of climbing all the way down from the tree
onto the ground. So Polly describes the sloth descending the
tree to poop as quote, it's like if you had
to go to the bathroom and you were programmed to
go run a five k on the interstate before you
could go to the bathroom, which you know, man, I've

(25:20):
I've been camping, and the worst part of camping is
like trying to go to the bathroom in the middle
of the night, either walking all the way to the
one bathroom on the campsite or finding like a secret
spot when you're really out there. I did that once,
had like a mouse run across my foot as I
was trying to do a little bit of pee, and

(25:40):
that was horrible. Don't recommend. I mean, I still enjoy
the great outdoors, but I do love a convenient bathroom.
I think humans really nailed that. So back to the moth. Uh. Basically,
when the back to the moth, back to the sloth.
When the sloth the sinds to poop, the moth can

(26:03):
then lay its eggs in the sloth poop. So the
moth hops off of the sloth, lays its eggs in
the sloth poop, and that is where the new generation
of moths will hatch. And then those as the sloth
is doing its business pooping, the new generation of moths,
the moth larvae can actually crawl onto the sloth, and

(26:27):
so the sloth gains these passengers, and these are helpful passengers.
This is a mutualistic, symbiotic relationship where the sloth provides
the moth a home and the moths provide the sloths. Well,
it's like a complicated symbiosis, right, because it involves at
least three organisms, where it's the sloth, the moth, and

(26:49):
the algae, and so the moth helps grow the algae
which helps the sloth, and the sloth provides a home
for the moths. It's beautiful, it's a beautiful relationship. It's
a pollocule, a natural pollocule. So there have been other
explanations proposed for why sloths to send all the way
to poop, and none of these are mutually exclusive. They

(27:11):
could all be factors. So one is that, like maybe
they want to go down so that they make less noise.
I guess if they pooped from the tree, it might
make a plopping sound, and they don't want to be conspicuous.
Another theory is that it's a social activity, a way
to meet other sloths, other sexy singles in your area.
I do love a singles bar just called the poop

(27:34):
floor where you get over all of your embarrassments and
hang ups from the beginning because you all go just
you know, to poop on the forest floor and meet
other sloths. That's great for them. I'm really happy for them. Anyways,
that'll do it for our listener Questions episode. If you
have a question that you would like me to answer,

(27:55):
you can write to me at Creature featurepot at gmail
dot com. I am also exciting submissions of pet photos
for me to look at. And it's not like a contest.
You don't win anything. You don't really gain anything at
all by sending me these photos. But guess what, I
get a bunch of cute photos of animals. So hey

(28:16):
works out for me. Anyways, Thank you guys so much
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(28:39):
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