Colossal Questions.
Should you pee in a pool?
When you gotta go, you gotta go.
And sometimes you gotta go on a hot summer
day while floating neck deep in the middle of a pool.
It might be tempting to just pee right there in the water,
but you really, really shouldn't.
That's because it's not quite as harmless as it seems.
Here's why.
Experts say that the average residential backyard swimming
pool has about 2 gallons of pee in it at any given time.
Luckily, that's only 100th of 1%.
But even still, a little pee in a pool can go a long way.
You see, pool water is treated with a chemical called
chlorine, which helps kill bacteria and keep
the water nice and clean so that people don't
get sick from swimming in it.
It's also what gives pool water that nice aquamarine color.
The problem is chlorine doesn't react well to things like dirt,
sweat, body oils, and, most of all, pee.
When chlorinated water combines with urine,
it creates a compound that stays in the water.
According to the American Chemical Society,
both red eyes and pool smell that we all
know and don't really like are a result of,
well, you guessed it leftover pee molecules in the pool
water.
So if you've really got to go, just
be sanitary and go pee in the ocean.
Oh, and you might have heard about some special compounds
they put in pools that reveal urine and can catch someone
in the act of peeing.
Yeah, it turns out that's a myth.
Nothing like that really exists.
So if you pee in the pool, no one's
going to know unless they feel that awful warm spot.
What causes some people to go bald and not others?
Lots of people lose their hair.
By 35, 2/3 of American men have started to lose some hair,
even if they don't notice it yet.
By 50, about 85% either have thinning hair
or are completely bald.
And it's not just men, but women and children, too.
80% of women over 60 have some amount of hair loss,
however small.
Even about 3% of kids experience some amount of hair loss.
So, in other words, hair loss also known as alopecia,
is very common, especially for guys.
More often than not, going bald is caused by your genetics,
meaning it's passed down from your parents or grandparents.
Everyone sheds between 50 and 100 hairs per day.
I'm sure you've noticed them in your pillow
and clogging up your shower drain.
Losing hairs daily is no big deal
because your body produces new hair to take its place,
keeping your hair thick.
But for those with alopecia, that doesn't happen.
Your body stops producing the right cells
needed to produce new hairs.
Kids rarely have alopecia, but instead can
develop thinning hair or bald spots
in all sorts of other ways.
Anything from brushing hair too hard to overtreating it
with chemicals to wearing overly tight ponytails
can lead to hair loss for kids.
Today, there are all sorts of products and procedures
for people who want to try and slow or stop their hair loss,
but when it comes to genetics, the reality
is there might not be anything you can do.
Why adults stop growing.
The main reason we stopped growing
is because our DNA tells us to.
Let me explain.
Every person starts as one single cell.
That cell splits and splits and splits millions of times more,
and before you know it, that cluster of cells
is a complex structure.
When you're born, you continue to grow and develop
quickly until the end of puberty,
when your DNA finally tells your body to stop growing.
Once you finally leave puberty, your body
starts producing lots of estrogen,
which is a hormone that basically
fuses shut the receptors in your bones that cause growth.
So that's how your body stops growing.
But why?
Well, scientists aren't positive,
but they do have some theories.
You see, it's actually a disadvantage to be too tall.
It puts a lot of stress on your bones and muscles,
which can lead to arthritis and trouble moving.
It also makes it much harder on your organs
because your heart needs to pump much harder to get blood
all around such a big body.
So would it be fun to just keep growing
until we were all giants?
Well, sure, but just be glad we don't get so tall
that it's hard to live.
Have you ever stopped and wondered
just how old a person can get?
It's not all that uncommon for healthy people
to live to be 100 years old.
In fact, there's almost 500,000 people across the world
right now who are centenarians, which
is a fancy word for someone over 100 years old.
The United States has the highest number of centenarians
living today, around 72,000.
Japan is the second to the US, with around 30,000 people
over a hundred.
Nowadays, people are living longer and longer,
and if that continues at its current rate,
there will be almost a million people
in the United States alone over a hundred years old by 2050.
Right now, about 1 in every 1,000 centenarians
live long enough to become super-centenarians,
at 110 years or older.
The rarest feat of life is someone who lives to be 115.
As of today, there's only 47 people
in recorded history who can confirm they lived that long.
As of early 2019, the oldest living person on Earth
is a Japanese woman by the name of Kane Tanaka,
at 116 years young.
OK, so now you know how old people can live,
but what can we do to try and live longer?
Well, some experts have actually found special spots
all around the globe where an unusually high number of people
live extra long.
These regions are called blue zones,
and there's thought to be five of them on Earth.
Okinawa, Japan; Sardinia, Italy; Nicoya, Costa Rica;
Icaria, Greece; and Loma Linda, California, in the US.
The theory goes that people living in these five blue zones
often live much longer and healthier lives because
of a few key things they all have in common.
They all tend to smoke less, eat mostly plants,
very little meat, and, most importantly, legumes,
like beans.
On top of their clean diet, these five regions
tend to put a huge emphasis on family, staying physically
active every day, and, most importantly,
they have strong communities where
people interact with their neighbors
and help each other out.
So how do we stay young as we grow old?
Well, if these blue zones tell us anything
about living longer, the keys are everyday exercise,
a nice healthy diet, and lots of people to love.
What causes our eyes to be different colors?
The color of your eyes has to do with the amount of melanin
you have in your iris.
Melanin is a pigment, or natural coloring,
found in animal tissue.
It gives our skin and hair their color,
and our eyes are no different.
Having less pigment gives you blue eyes.
Having a little bit more will make your eyes green,
and if you have lots of pigment, it leads to brown eyes.
You or someone you know might have different colors
or patches within one eye.
For instance, blue eyes with green around the edges,
or green eyes with Brown around the irises are common.
When this happens, it's because different areas
within the actual eye make different amounts of melanin,
changing the colors.
What color eyes you end up with is genetic,
meaning it's passed down from your parents,
even if you don't share the same eye color.
Science is still trying to understand
exactly what genes in our eyes get passed down
to determine our eye color.
So far, the key gene in brown eyes has been discovered,
but experts have had no luck so far uncovering
the gene for green eyes.
OK, so that's why people have different-colored eyes,
but one question remains.
What about the 1 in every 100 Americans
who have two different-colored eyes?
Just about every baby is born with gray eyes,
but in the first several months after you're born,
the color in the irises develops,
giving you your eye color.
The melanin levels in a baby's eyes
determine how dark their eyes become.
However, for those 1 in 100, the amount of melanin in each eye
isn't uniform.
This is called heterochromia.
Complete heterochromia happens when
each eye is one distinct color.
Central heterochromia, on the other hand,
is when your eyes have multiple colors mixed across the two.
But don't worry.
Not only is heterochromia a completely harmless condition,
but it can look kind of cool, too.
What causes some people to have straight hair,
and others to have curly?
It turns out that whether you have
super-straight hair or a bunch of tight curls,
you can Thank your genes.
But how exactly?
Experts are still trying to determine
exactly how our genes work to make our hair look
a certain way, but studies have shown that your DNA is
definitely a huge factor.
Let's start with the basics.
Every hair on your body grows out
of its own hair follicle, which are tiny little organs just
below the surface of your skin.
Cells inside the follicles divide and multiply,
slowly pushing upwards and hardening along the way.
By the time the hardening cells get long enough
to poke out of your skin, they've hardened into a hair.
How curly a single strand of human hair
gets depends on the hair follicle it's growing out of.
If a follicle isn't quite symmetrical,
it produces a strand of hair in a slightly oval shape, which
tends to naturally curl the longer it gets.
If a follicle is symmetrical, the hair it makes
will come out round and stays straight
no matter how long it gets.
And the shape of your hair follicles, it turns out,
are determined by the genes you inherit from your parents.
Usually, curly hair is a bit more dry than straight hair
because oils from your scalp have an easier time traveling
down a straight strand of hair, but this also
means that straight and wavy hair have a tendency
to get a lot greasier than curly hair because of all that oil.
So no matter what kind of hair you
have, straight and oily, or curly and dry,
you only have your family to thank for it.
What causes us all to be such different sizes?
For the most part, how tall any of us will be mostly
comes down to genetics mixed in with your diet, health,
and environment as a kid.
According to experts, somewhere between 60% to 80%
of our height is decided by our genes.
You get all your genes from your parents, about half
from each one of them.
So if you have super-tall parents,
you're more likely to be told yourself,
and same if your parents are short.
Experts say that the mix of genes that make up your height
is complex.
So gauging how tall you'll be based on your mom and dad
is a decent indicator, but it's also
a bit of an inexact science.
That leaves just 20% to 40% of your height that's
influenced by environmental effects, like how well you eat,
your sleeping habits, exercise, and things like that.
That means eating plenty of healthy foods
and getting a good night's sleep isn't just something
your mom nags about.
It actually helps you grow taller and stronger
as you grow up.
OK, so that's how people end up either tall or short, but why?
Why are some people genetically tall or short?
To answer that, we have to travel back,
way back, way back, to our ancient ancestors living
in Africa almost 2 million years ago.
They were genetically quite tall,
with thin bodies and long legs, to help
keep cool while traveling long distances in the sun.
But as people made their way closer and closer
to the frigid polar regions, they
evolved to be a bit shorter and stockier to help
conserve heat and keep warm in the cold winter months.
Nowadays, kids grow about 2 inches or so per year from age
three until they hit puberty.
That's when the growth spurts start, where you might grow up
to 4 inches a year.
Double the speed.
So if you're not quite tall enough
to ride the craziest coaster at the park,
maybe just eat well and hope for puberty to it.
Just be careful what you wish for.
When did we start shaking hands?
It probably seems like people have been shaking hands
to say hello forever, and in some ways, they have.
Archaeologists have uncovered depictions of handshakes
on vases, graves, stone slabs, statues, paintings,
and all sorts of ancient art, but that classic greeting
wasn't used in quite the same way we use it today.
You see, for most of history, the handshake
was mainly used to seal a pact or swear an oath rather than as
a casual greeting.
Some believe it could have started as a sign of peace
between enemies or rivals.
After all, clasping someone's hand or wrist
is a half-decent way to prove that you
aren't carrying some kind of a concealed weapon
up your sleeve.
According to experts, it wasn't until the mid-1800s
that people actually started shaking hands to say hello.
And even back then, it was considered a little too casual
a greeting, meant just for close casual friends,
kind of like the 19th-century equivalent of a fist bump.
So the handshake we know and love
today was finally a fairly common greeting by the 1800s,
and who actually started shaking hands to say hello?
Well, no one can say for sure, but the Quakers
are often given credit.
Quakers were a religious group who left Britain for America
in the 1600s, believing the Church of England
had become too materialistic for its own good.
Back in England, a bow, curtsy, salute,
and all other forms of saying hello
were common and expected when creating a powerful person.
The Quakers believed that everyone was equal
and decided they needed a new greeting
that anyone could use regardless of their wealth or influence.
Scientists can't say for sure exactly why the handshake stuck
around, but there is one theory that it might have something
to do with smell.
You see, a handshake may actually
be a way for us to reflexively sniff
for subtle smells on other people
since it forces you to touch and get near each other.
Think of it a bit like dogs sniffing each other
when they first meet.
Every person gives off chemical signals in the form of smells
that others detect and helps us communicate basic subconscious
info without even talking.
Or in other words, we like to sniff people out when we first
meet them, literally.
So next time you meet someone new
and you have an almost automatic urge
to reach out and shake their hands to greet them, just
remember, you might be sniffing them,
and they might be sniffing you too.
Weird, right?
[dog sniffing]
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