which I've spent the better half of this decade

kind of living within them.

And what is important about them is that you observe people behaving

with that certain kinds of pressures

and how that scales out to the outside world.

So, first of all: what is a nightclub?

Nightclubs have been around for about forty, fifty years maybe,

and they are relatively small rooms, you are filling it with this species

that's been evolving for millions and millions of years,

so, in terms of evolutionary time, that's a really short sliver.

And when you apply certain variables to people, they act in certain way.

They only exist in highly urbanized metropolises,

and although they sell alcohol, the real commodity that a nightclub sells

is actually sex and social status.

Because of that, they are catered towards men,

which is why the gender issue is skewed, it's always

sixty percent women to the forty percent men in a night club

And most importantly, there is a door policy.

It is one of the only businesses in the world where they can just refuse entry

based on whatever, what you look like,

if you're not dressed appropriately, etc.

And so, there is a couple of variables

that go into a nightclub:

the first is music and lighting,

which, in fact is that at the sensory level, it's data coming in

through our eyes and through our ears.

The next is drugs and alcohol, which affects perception,

so not only how you're perceiving the night,

but also how the memories are physically being encoded

and how you're going to remember it later on.

And then, sex and social status

which are the commodities that we discussed before,

there is a difference as a social rules, so if you wanted to

walk up to somebodyone and initiate a conversation,

then you can do that, but you might not

feel comfortable doing that in a place like a grocery store.

There is also a different set of laws within them,

because the immense social power

and influence and the amount of money

and overall wealth in these clubs,

these people can kind of get away with whatever they want.

So laws are broken all the time,

and nobody really gets in trouble for anything.

So, my passion is music,

because music is cross-cultural,

it's been in every single society and civilization,

that's known to man.

You'll be hard pressed to find someone that you know

who doesn't listen to any sort of music at all,

and because of that, in terms of natural selection,

it means it was selected for.

So basically, if you liked music, you lived to pass on your genes to your offspring,

and if you didn't like music, well you died and didn't pass your genes on.

So, we have our biology and sociology,

and they're constantly at war pushing against each other,

but the interesting thing about alcohol is,

as a chemical, we don't really know how it works,

but one of the effects is disinhibition.

It makes people more outgoing and louder.

It does this by removing the top level

or the more recent cognitive processes that evolved.

So we evolved these certain hard wired traits,

that are meant to keep us safe,

but alcohol removes these traits,

like etiquette and our biology takes over.

So when I say a nightclub is stereotypically the most dishonest

business that you can get into, it's true,

but the irony in that statement is that people actually behave

really really honestly once they are inside them,

so it's just an interesting lens to look at society through.

So, in exposing the primitive drives,

there is food, water, sex and aggression.

So, with alcohol unless these social norms holding us back,

it's exposing more or less these biologicaly

primitive drives from the oldest part of our brain,

they call it "the lizard brain."

So food: after the bar, typically people go and get a burger,

nobody really craves a salad that late at night

after they have been drinking,

and that's because evolution selected for us

to opt for the carbohydrates and fats, because they have more energy,

and it's enhancing your likelihood of survival.

Water is kind of taken out of the situation,

because everybody is drinking all night.

Sex, when I say that more sex happens after a nightclub

than in any other business around the world,

it is not an understatement.

And aggression, when you take a look at stats,

that over 50 percent of violent crimes are committed

under the influence of alcohol, you can see why.

Another thing is called "the rock star effect",

which is really important when it comes to nightclubs and any kind of music.

The "rock star effect" is the release of oxytocin during singing.

Oxytocin is a hormone that produces feelings of trust and love in humans.

It's released by both sexes during intercourse

and makes pair bonding as a way of increasing the likelihood

essentially that the father is going to stick around

so that if a baby is born,

that there is two people to raise it

instead of one, because having two parents to raise the offspring,

drastically increases the survival than having one parent.

Dr Paul Zack just spoke about oxytocin at TED Global

and his lab showed that it wasn't only responsible

for trust and love, but for morality,

and morality is something that makes us human.

So we are the only creatures that listen to music,

and we are the only creatures with any sort of morals,

and these all kind of revolve around this hormone oxytocin,

so there is something really special about that.

And because oxytocin is releasing these feelings of trust,

morality and love, which are all high demand

by mates and members of the opposite sex,

that's the reason why you hear people

wanting to sleep with the lead singer of the band

or thousands of girls crying over

Justin Bieber every day.

It's also one of the only things that can put

a 100.000 people in one place at a time,

music festivals can easily attract these kinds of numbers, like Coachella.

It is also the reason "American Idol" is

one of the most watched television shows of all time,

and why guitar hero outsells like every other video game.

It's because the music and the emotional attachment.

So I'm going to play a couple of songs for you now.

Every song has a bunch of fundamental characteristics:

there is tempo and key.

So tempo is the speed in beats per minute

that a song is playing at,

and key is either minor or major,

and even an untrained ear can tell you

that minor key sounds sad,

and major key sounds happy.

So, I'm going to play two samples for you right now

and I want you to listen and be able to tell me

which one is the happy sounding one.

(Piano music)

So that was number one.

(Piano music)

So, who thought number one

was the happier sounding sample?

OK so that is the entire room,

so that's your proof that everybody can detect emotion within a song,

which is really important, because nobody is trained to do that,

yet, somehow we are able to.

So, right around the time of the 2008 recession

I was playing in this club,

I was a DJ for a while,

and I knew this room inside and out.

I knew what people wanted to hear,

I knew what kind of styles they wanted,

and my job is to play the music that they want,

and to not play the music that they don't want,

that's what makes an effective DJ

You have to read the room, you can't play for yourself.

So, week after week I saw these people,

then the stock market crashed

and for two weeks nobody was going out,

they said, "Don't even bother coming in to work."

And the week after I went in,

and it's the same people, the same faces,

but they were not into the same music that was going on two weeks ago,

they wanted this fast paced electro music.

Which is when a lot of you probably listened

to electro out there, which used to be an underground genre,

and it broke through to the main stream.

And one of the characteristics of electro is that

it's has actually a lot of minor keys.

And so it sounds sad to everybody, even an untrained ear.

So I texted all my other buddies that were DJ-ing,

in New York, Toronto or Los Angeles,

they all said the same thing was happening,

so, there was something more at work.

And so, what I did was: I took the Down-Jones industrial average

as an index of the stock market,

but also as a way of measuring how people feel, kind of globally.

And I cross referenced that with every hot 100 track

that had ever touched ground on the billboard charts,

and I classified it by tempo and key.

But essentially, to 87 percent accuracy,

the stock market was dictating what was hot on popular charts.

So economic busts were associated with up tempo,

and sad sounding music, minor keys,

whereas booms were associated with down tempo and major keys,

to such a highly statistical number

that it just had to be true.

So, you have a correlation there,

you don't necessarily have the causality

and they are not always the same.

So, we are going to go into the causality.

If you think of money, as resources,

which affect our mood, our friends' moods,

and it affects global moods,

under times of stress, we have a fight or flight response,

which is basically: if you're walking down the street,

and a bear pops out,

you have to decide whether or not you're going to run,

it releases a bunch of neurotransmitters

like adrenaline, and natural pain killer,

so that whether you're fighting or running, it's the same response.

So, when we're under this kind of economic stress

which is literally challenging our survival,

these same chemicals are peculating into our brain at a smaller rate

so we're not having panic attacks,

but if you remember how you felt during the time of the recession,

people were for sure a little more on edge.

So just to reiterate:

economic booms were happier, and the music is slower, more relaxed.

Economic bust, were a little bit more on edge

and the music sounds faster and sinister.

So this goes into resource theory,

which affects every single mammalian model in the world

and a lot of other insect species and aquatic.

But it has to do with men competing for access to females.

So in terms of mate selection, the number one thing

cross-culturally that men look for in a woman is good looks

and the number one thing cross-culturally

that women look for in a man is access to resources.

It's superficial and shallow but there are countless studies

that prove that, so that is what the data says.

And, so we can see that this kind or resource theory

in other societal projections.

So "less is more."

If you understand this, you'll understand a lot about human behavior,

but it's basic supply and demand.

When demand increases,

supplies goes down and the price goes up,

the more expensive something becomes,

the less people can afford them,

and so, by wearing those things they are sending

a very specific message to the outside world.

So this is how the economy influences fashion trends.

So, this is called the "Hemline Index."