What do parasites and razor burn have in common?

A recent theory about human hairlessness cites parasites as the cause. Find out how parasites relate to hair -- and some fascinating facts about shaving habits -- in this podcast from HowStuffWorks.com.

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Episode Transcript

Speaker 1 (00:00):
Brought to you by the reinvented two thousand twelve Camray.
It's ready. Are you welcome to stump Mom never told
you from house Stop works dot com. Hey, and welcome
to the podcast. This is Molly and I'm Kristen Kristin.
Here's a question for you. All right, how about you

(00:22):
tell us all the top three traits you look for animate? Okay, um,
I guess they're pretty typical. Uh. And by the way,
Molly did not prep me for this question, so that's
the question it might be taking. This is just off
the top of my head. I gotta say. Physically, I
like a strong jawline, okay, I do. And a sense

(00:45):
of humor. It's good. Okay, someone to make me laugh, gotcha,
So so I'll stop crying. And Third, oh god, I
don't know tall. I'm a pretty tall person, and I
would like for my mate to be taller than I
am when I am wearing heels once a year. That's

(01:05):
a pretty reasonable list. Yeah, it sounds pretty superficial. But
that's off the top of my head. Do you know
what I look for? What, Molly, someone who's free of parasites.
That's wise of you, I think, so. Yeah, because you know,
when you go in for the first kiss, you don't
want to parasite to jump on. I know, I don't
want to ruin the moment exactly. The reason I have

(01:26):
parasites on my mind is there's this new show on
and all Planet Monsters inside me. It's all about parasites.
It's about how they get in us, get on us.
And it just got me thinking that I will love
a parasite free lifestyle and I want my mate to
do the same as well. But did you know that
parasites maybe the reason why we don't have body hair? Well, yes, Molly,

(01:47):
I do. It's one of the newest theories I believe
in this whole question of why humans are so hairless.
We might not think of ourselves as being hairless when
we have to shave our legs and shave our beards
and etcetera, etcetera. But compared to other mammals, we are
quite bare. Yes, very few mammals have his little hairs

(02:08):
us and the ones that do are mainly aquatic creatures
like a hippopotamus. They go into the water, so you know,
they don't need to be having hair. It's not very
good for swimming, right, and you've got elephants who are
also pretty hairless, and they're big floppy ears help cool
them off as well. Yeah, they live in hot climates. Now,
both of those reasons water and temperature relate to sort
of the predominant theories as to why we're hairless, because

(02:30):
basically before this parasite theory came along, there were two
other schools of thigh as to why humans don't have hair.
One was that and this is my favorite phrase of
the week. One was is that we were at one
time water dwelling apes, like early humans might have been
sort of semi aquatic, and so when we were semi
aquatic water dwelling apes, we lost the body hair. It

(02:53):
would need to need the fur to insulate us because
we were in the water could cool off. Is that
is that? What? Well, it's just just bad for swimming. Ah,
it holds you back. It's like when swimmers shaved their
legs and in exchange for getting rid of the fur,
if we were what was your favorite phrase water dwelling,
water dwellings. So, Kristen, you water dwelling apes. That's how
I would use it. That's the context. Thank you, Thank

(03:15):
you for putting that in context. Um, But I think
according to that theory, since we lost the fur, we
got body fat instead to help inslid us in to
make us more buoyant. The other theory goes along with
what you're talking about with elephants, and that if you
live in a hot temperature, you don't need all this
hair like heating me up right, if I am going
on a trip to the beach, I'm not going to

(03:37):
pack my your fury suit my first suit. Are we
gonna leave it at home? So the first suit. So
the theory is is that if we lived on the
African savannah, as it's believed the early humans did, we
wouldn't have need that needed that much hair. And additionally,
when we started walking upright, our backs weren't exposed to
the hot sun, so we didn't need as much protection

(03:59):
from the sun. Right, And I think that all of
this is pointing to a little little word called thermoregulation.
Our ability too, as warm blooded animals to regulate our
own body temperature internally maintained at nine eight point six
degrees inside. Sweating also helps with that. Sweating and cooling.

(04:20):
So those are sort of the two main theories you
might have learned in school as to why humans didn't
have as much body hair. But then in two thousand three, Kristen,
we had some guys come along to blow our minds. Yes,
I believe you're referring to a doctor Mark Pagel and
his colleague Walter Bottomer, thank you. They published a paper
in the Proceedings of Royal Society in two thousand three

(04:42):
positing that as humans evolved, we had all this, you know,
we had our fur, our fury suits, our furry suits,
um like other primates, and since parasites thrive more in
in the fur, in the furry environment, we gradually shed

(05:02):
our fur in order to lose the parasites, get rid
of all those parasites and the more importantly, the diseases
that they carry along with them. Yeah, because traditionally, you know,
species die out because parasites give them disease. And when
you think about how the plague spread with like these
little fleas, possibly, you know, you don't really want to
be carrying around a magnet for for little bugs, right,

(05:24):
And they were saying that around the same time that
humans started living in shelters and started wearing clothes, uh,
that corresponded with with this whole furlessness evolution. Yeah, the
clothes helped because while you know, a parasite can get
on like a shirt, you can change your shirt and
you can wash it. You can get rid of the parasites,
whereas if it's in your fur, that's just it's just

(05:47):
bad new spears. Right. And according to this parasite theory,
as humans eventually lost their fur, it became a part
of the entire like sexual selection. Uh, you know, the
people who were the least harry were more attractive because
they seemed healthier because they wouldn't have had as many parasites,
so you would be more inclined to want to mate

(06:09):
with them. Yeah, you can get all up close because
they don't have any things and there no nits, no
nitnits to pick out. And this might also explain why
women are generally less hairy than men, right, Yeah, because
in our species, males can be choosier basically, and so
they when they started picking these females that didn't have
as much body hair than hairlessness became a more attractive trait. Right,

(06:32):
And hairlessness is also related to our body hair is
related to testosterone, which is a predominantly male hormone. So
for men, a little bit more body hair might be
a sign of virility, and for women, the more beer
you are might be more inherent sign of femininity. Yeah,
and so they think that this parasite there, it kind

(06:54):
of explains why women have less body hair overall. But
they also cover something that previous the areas of UH
hairlessness didn't cover, and that was the pubic hair. Okay,
everyone's favorite hair. I guess well, we've got We did
evolve to be bare except for three main areas, obviously,
the pubic hair as as you mentioned, and our under

(07:15):
arms in our head. So the parasite theory explains pubic
hair in away with the other two theories don't. Because
the thinking is is that pubic hair still serves UH
purpose in sexual attraction. That there's a high concentration of
sweat glands down there, and so when we sweat, it
gets sort of caught in the hairs, and this sort
of helps us release and hold these pheromones that are

(07:36):
attractive to potential mates. Right, And the same thing goes
for the underarm hair, the high concentration of sweat glands.
As anyone who has been incredibly nervous before meeting or
stuck outside on a hot day, knows you know, you're
gonna get the under arm pit stains, which you're really pleasant,
but like the like the pubic hair, that's also the

(07:57):
underarm hair down there could also be a uh wafting
pheromone machine to also attract mates, although I don't know
if my bio on a hot day is is you know,
come on? But but the thing about it is that
we've probably been trained by society to think that it's not.
You know, there are plenty of cultures where you don't

(08:17):
shave your under arm hair and they still get together
just fine. So why are we so obsessed with this
hairlessness when you know nature has given us hair in
certain places. Right, there was an article that came out
in The Economist about this whole human evolution towards being
more bare, And it's talking about this whole phenomenon of
women waxing their whole bodies and men too, waxing and

(08:39):
shaving and de pilatory dreams and all the things that
we do might just be this ingrained, like evolutionary urge
to be as bare as possible. Yeah, and it might
all go back to the parasites. So let's go back
to this original question that we had of what do
parasites and razor burn have in common? We know now
that according to this parasite fear, that they may be

(09:01):
the cause for us losing our quote unquote for you know,
and also the inner drive for us keeping ourselves shaven
is to look healthy to potential mates. But let's go
into this razor burn thing, because you brought up a
good point about other cultures, for instance, not shaving their
under arms, and how we might be more trained by

(09:23):
society to shave. Yeah. I was looking at, um, the
history of shaving, and it's pretty fascinating. From the beginning
of time, you know, even though we lost the for
people were still kind of obsessed with taking the rest
of the hair they had off. In four thousand BC,
women were making these sort of homemade creams to get
their hair off, and they would have ingredients like arsenic

(09:44):
So that's not good, um, but it's just kind of
developed through time, Like I know, for men, Alexander the
Great was a very uh, very big pioneer and being
completely shaven because he hated to go into battle with
any facial hair at all. Um. And then what the
underarm thing? Is really sort of a US phenomenon that
happened during World War One when a shaving company put

(10:06):
an ad in a woman's magazine. It had a woman wearing,
you know, a sleeveless dress and she had her arms
up and you could see her bare under arms. And
the whole campaign was designed to teach women under arm
hair was unhygienic and that it was unfeminine, and as
a result, Razor sales went through the roof. I mean,
it's much like we were discussing with diamonds and our
Diamonds podcast is basically, women have been trained by marketing

(10:29):
executives to think that something is either good or bad,
in this case, that under arm hair is bad. And um,
speaking of all of this shaving, um, you know, women
complain a lot about having, you know, if they shave
their legs, Like men don't know what we have to
go through. We're shaving like half of our bodies. But
one interesting thing that I've found out about shaving is
that men actually might have it worse than women because,

(10:53):
according to this article in the Economists, even though the
legs and the under arms are about nine times more
surface area than men's facial areas. There's actually just as
many hair follicles in in both the facial area and
the legs and arms, and they're denser. The men's facial
hair is denser and grows faster, So while we may

(11:16):
have more territory to cover, they have just as much
hair to get rid of. Wow. Yeah, that's a good factoid.
And um men's spend I think it is thirty three
days of their life just shaving their beards. Wow. On average.
Think about that the next time you shave. But I
do have one thing to share, is uh, you know,
it might be a little bit more culturally acceptable for

(11:38):
a guy to walk around with a beard. As we
were saying, hair of all types can play a role
in sexual attraction. Beards and mustaches definitely do it for
some ladies. But have you ever seen a guy shave
with sand paper? Not that I know of, No, I mean,
I that's sort of a dumb way to ask the question.
But did you know that a World War two and
there was no metal left because they sent it off

(11:58):
to the war, women shave their legs with sandpaper? Oh man,
we just buffed our buffed our hair down. Well, that's
obsess we are with being hairless. Thanks parasites, Yeah, thank you,
thank you parasites and ticks. But you know I'm clean,
sandpaper or for take your pick. I guess I'm I
guess I'm good with where I am. Yeah, fur less

(12:19):
like a rhino or molly. To throw it back to
your phrase of the week, hairless like a water dwelling ape. Nice, Kristen,
that one was for you. I appreciate it. Uh. Well,
if water drawing ape doesn't float your boat, maybe learning
more about parasites and razor burn one. Yeah, and if
you want to get really grossed out about parasites, don't

(12:40):
forget to check out Monsters Inside Me on Animal Planet
on Wednesdays at nine o'clock pm Eastern and Pacific. And
if you want to learn more about parasites, Chris and
I have both been wrying about them on our blog
how to Stuff. So if thank you have any parasite
knowledge anec does to share, head on over there and
leave us your comments at how to stuff on how

(13:00):
stuff works dot com. For more on this and thousands
of other topics, is it how staff works dot com.
Want more how stuff works, check out our blogs on
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(13:22):
are you