
Spanish: 
[Vsauce]
Hola, Vsauce. Soy Michael
y hoy nos haremos una pregunta:
¿por qué los animales no tienen ruedas?
Los animales usan una plétora
de técnicas locomotoras complicadas—
aletas, patas, alas—
pero ninguno tiene ruedas.
Lo paradójico de esta pregunta
es que los humanos parecemos estar
bastante avanzados en cuanto a la tecnología.
Hemos creado la rueda,
pero deberíamos diseñar algo
que saque ventaja de las extremidades.
Es por esto que esto luce tan espeluznante.
Es lo más parecido que hemos llegado
a crear para imitar
algo que en la naturaleza es bastante normal.
Por supuesto, la naturaleza, la fuente
de estas milagrosas extremidades
que aún queremos reproducir,
no utiliza ruedas.

English: 
Hey, Vsauce. Michael here. And today we are going to talk about why we dream.
What's going on inside our brains?
The scientific study of dreaming is called oneriology.
And for most of history, it didn't really exist,
because you can't hold a dream.
It's difficult to measure a dream, you can't taste it.
You can't see other people's dreams,
and if you ask them to tell you what they dreamt,
the results are almost always unreliable.
In fact, it's estimated that we forget 85 percent
of the dreams we have, especially within the first ten minutes of having them.
But then, in 1952, something amazing happened.
Researchers at the University of Chicago found this.
It's a unique type of electrical activity
that occurs during a certain stage of a person sleeping.
When researchers awoke people during this stage,
they almost always reported that they had been dreaming.

English: 
Also, at the same time, during this stage, people's eyeballs are going crazy,
rapidly darting all over the place underneath their eyelids.
You can actually see this happening if
you watch people sleep like I usually do.
During REM sleep, some pretty bizarre stuff happens.
If you look at the electrical activity of a brain
that is in REM sleep, it almost exactly mimics
the way the brain acts when it's awake.
The biggest difference being that the production of chemicals inside the brain
like norepinephrine, serotonin, and histamine
is almost completely blocked,
and that causes the muscles to stop moving,
which is why you can dream about flying or running around
or fighting ninjas, but your body doesn't move.
People who have a disorder achieving complete REM atopia
move around in their sleep and act out their dreams.
They can even get out of bed and sleep walk.
Oh, before we move forward, I should say two things.
One is that it's possible to wake up and not be able to move your body
because you're still in REM atopia.
You're completely conscious and you know that you're awake,
but your body is not ready to move.

Spanish: 
La rueda le da una ventaja mecánica al usuario
y le permite mover cosas pesadas
sin mucho esfuerzo,
pero si la rueda es tan básica
y luce tan sencilla,
¿por qué los animales no tienen?
Para asegurarnos, miremos a la araña que rueda.
Cuando escapa de un predador,
esta araña convierte su cuerpo
en un neumático y gira cuesta abajo.
Piensen en los cardos rusos.
Giran con el viento dejando semillas por doquier.
Otro ejemplo es el escarabajo pelotero,
que toma pedazos de excremento
y los convierte en pelotas
que son muy sencillas de mover.
Pero esos son ejemplos de cosas que ruedan,
no de las ruedas en sí
como las conocemos hoy.
Ruedas en ejes—algo que es una parte del total,
pero existe de forma independiente
y puede girar indefinidamente
en una dirección
sin la necesidad de empujarse nuevamente.

Spanish: 
Los flagelos bacterianos
funcionan de esta manera,
pero no los vemos en ninguna forma de vida
más grande,
lo que nos dirige al primer problema,
encontrar ruedas en animales.
¿Cómo puede hacer una rueda con vida
para estar separada del animal
y aun así recibir nutrientes y expulsar deshechos?
O, si la rueda se hizo a partir del tejido muerto
que el animal produjo,
como uñas o cabello,
¿cómo podría tomar la forma de una rueda
y seguir estando separado del animal?
Pensemos, ¿cómo puede ayudarte
tener una rueda
en el cuerpo?
Bueno, piensen en la jirafa.
Tener un cuello
un poco más largo significa
que puedes alcanzar la comida
que está un poco más alto.
Tendrías más comida,
vivirías más tiempo
y tendrías más bebés que harían
que el cuello largo sea normal.
Pero si tu mutación fuera una rueda
que es solo un poco redonda,
no te daría el mismo beneficio.
No es lo mismo que tener bebés.

English: 
On the flip side, you can also be inside a dream
and know that you're dreaming.
This phenomenon is known as lucid dreaming,
and it's particularly attractive, because
while in an illusive dream,
I can make conscious decisions about what I do.
I can go fly to wherever I want, or I can
have a tea party with Abraham Lincoln.
I'm in control, but achieving illusive dream is quite illusive.
Howcast has a great video, which
I've put in the description
that gives some tips and tricks on how to achieve one.
Researchers were able to deprive
mice of REM sleep by using this
inverted inside a tub of water way up to the tippy top,
meaning that the mouse was only able to sit
right on top of this little tiny surface.
When that happens, the mouse can still
fall into non-REM sleep,
but as soon as they reach REM sleep
and their muscles relax,
they fall off the platform into
the water waking up.
What they found was that when mice
are not allowed to achieve REM sleep,
they have an incredibly amount of trouble

English: 
remembering things.
This happens in humans too.
If you have people remember word pairs and then you don't allow them to sleep,
the next day, their memory for that stuff is incredibly terrible.
But memory and REM does not stop there.
If a person learns a difficult new task during the day,
say a new instrument or a new type
of difficult puzzle,
you can measure the electrical activity in their brain
while they do that, and then while they sleep that night,
whether they know it or not, their brain replays
those electronic impulses.
Many popular theories about why we dream
are variations on the idea that while we sleep,
the unconscious part of our
brain is busy organizing memories,
and strengthening connections from the day before that we need in the future
while getting rid of the junk that would otherwise clog the brain.
Now, so the theory goes,
these electrical impulses are detected by
our conscious brain, and our cortex freaks out.
It doesn't know what it means, and so it tries its best to create a cohesive story,
creating a dream.

Spanish: 
Y, aunque me cueste mucho admitirlo,
la rueda está un poco sobrevalorada.
Piénsenlo de esta manera:
para que la rueda
sea útil para mover elementos,
necesita
otra invención: la carretera.
Sin una superficie llana para moverse,
como una carretera o unas vías,
la rueda se queda atrás
y las alas, aletas y extremidades
hacen un mejor trabajo
en cualquier superficie de la Tierra.
Aun cuando los humanos conocían la rueda,
no pudieron usarla en superficies desiguales
o fangosas o calles de ripio.
Es por esto que la gente rica
en el pasado
se trasladaba en literas—
sí, literas—
vehículos que no tienen ruedas
y son llevados por personas o animales.
La gente rica y elegante
se transportaba
en berlinas,
pero también existía otro tipo de litera
que era un cabestrillo
hecho de tela
que ayudaba a transportar soldados heridos
en los campos de guerra.

English: 
This would explain why dreams are often so
fantastic and seemingly random.
They're not supposed to make sense,
they're  not an actual message from our brain.
It's just the results of our cortexes trying to synthesize the noise
coming from all the work being done back in the unconsciousness.
Under this way of thinking, dreams are an epiphenomenon.
They're not a primary process that has a purpose.
Instead, they're the accidental result
of a more important process
going on behind the conscious brain.
But some researchers don't believe that.
They believe the dreams serve a primary purpose,
and that purpose is to prepare us for threats.
They think this because the most prevalent emotions felt during dreams are negative.
Abandonment, anger, and the most common of all, anxiety.
Theory goes like this: back when we were early humans especially,
we had no idea what kind of threats we might encounter during the day.
And so, to prepare us,
our brain would simulate anxieties while we slept

Spanish: 
La camilla de hoy en día
es un ejemplo de una litera.
Entonces, para que las ruedas
en tu cuerpo sean útiles,
debes construir carreteras.
Entonces, animales, ¿por qué nunca
construyeron carreteras?
Son capaces de hacer cosas asombrosas—
madrigueras, nidos y represas complejas—
¿por qué nunca construyeron carreteras?
Esta pregunta es fundamental
para el análisis de Richard Dawkins
acerca del problema del animal con ruedas.
Él dice que el problema con las carreteras
es que no son lo suficientemente egoístas.
Un nido, una madriguera o una represa—
son cosas que puedes defender;
que puedes construir y usar
para tu propio beneficio.
Porque fuiste inteligente y un gran trabajador
para lograr construirlo,
porque las carreteras se pueden utilizar
por cualquiera.
Perdiste energía y recursos para construirla
y un vago puede venir y utilizarla
y así ahorrar tiempo para tener bebés y prosperar.

English: 
to make us better prepared for that feeling in the real world.
So people who had terrifying dreams
were better at dealing with anxiety in the real world,
and had stronger genes.
All right, so the theories we discussed today are quite popular,
but they don't really enjoy a consensus.
Not everyone agrees on them, and they barely scratch the surface
of scientific thought about dreams.
But that's kind of the cool thing about dreams.
Think of it like this.
Here is the eagle nebula—a giant structure in outer space
6,500 light years away.
Despite its distance, we pretty much
know what it's made out of.
We know that it's 100 trillion kilometers tall,
we know what caused it, and we know
where it's going to be in 750 million years.
But last night, I had dreams,
and no one really knows why or for what reason.
And that's pretty cool, and that's why—
thanks for watching.

Spanish: 
Así que la carretera es un gran ejemplo
de cómo los humanos se beneficiaron
al romper el molde
y hacer cosas
no solo para sí mismos,
sino que para todos.
De hecho, entre todos los animales,
solo los humanos
han inventado impuestos—
dinero que forzamos a otros a pagar
para construir servicios
que tal vez nunca usen.
Así que, la próxima vez que vean una rueda,
digan: "Gracias, rueda.
Eres un gran símbolo del hecho
de que los humanos pueden cooperar
y no ser egoístas."
Y, como siempre, gracias por mirar el video.
Ruedalmente les agradezco.
[♪ música ♪]
[Vsauce]
[@Tweetsauce]
[Facebook.com/VsauceGaming]
[♪ música ♪]

English: 
If you want to learn more about the world, I highly recommend
Smarter Every Day, it's a show here on YouTube
by a guy named Destin
who I've met, he's awesome, I've learned a lot from him.
He's the guy who did the chicken thing
from the lean back.
He's also studied what causes poop splash,
slow motion water balloons,
and has a lot of guns and explosions.
What more could you ask for?
Do me a favor and go check it out
and subscribe if you like it.
And if you haven't seen it yet, go check out
What's What's review of my beard.
I've got that in the description, and as always,
thanks for watching.
