-
>> Why do we --
-
>> Laugh.
-
>> Cry.
-
>> Smile.
-
>> Why do we cry?
-
>> Humans are the only animals that cry.
-
And scientists believe that the
response evolved as an automatic way
-
to signal to others our distress.
-
Watery eyes are our bodies throwing up a
white flag and breaking any eye contact
-
that could be interpreted as combative.
-
>> Why do I cry when I'm happy?
-
>> The tiny part of your brain that controls
emotional responses can't tell the difference
-
between being happy or sad.
-
It just knows that you're overwhelmed.
-
Although we associate tears with sadness, crying
is basically an expression of vulnerability.
-
>> When I'm embarrassed why
do I blush [farting]?
-
>> When you're embarrassed
your body releases adrenaline
-
which triggers the veins in your face.
-
It's believed that we developed blushing
as a physical apology for our mistakes.
-
>> Sorry guys.
-
>> And our vision may have actually evolved
to better detect color changes in skin.
-
>> When I get nervous why do I
get butterflies in my stomach?
-
>> When you're facing an intense
situation, your body prepares itself to act,
-
increasing breathing and blood flow.
-
As a result, blood flows away from the
stomach and out to your lungs and muscles.
-
>> Why do we smile?
-
>> We smile because it makes us feel good.
-
When you smile it causes activity
in the brain's reward circuits.
-
And when you smile along with a friend,
-
it activates the circuits
that control social bonding.
-
>> Why do we laugh?
-
>> Scientists believe that laughing started as
a way for humans to communicate a false alarm.
-
[ Laughter ]
-
Which explains why we laugh
when someone falls but is okay.
-
>> I'm okay.
-
>> Laughter is the expression of relief that
a dangerous situation has turned out okay.
-
[ Music ]
