We have something special for you today.

We've been hard at work on a new series with Netflix called "Explained."

If you like our YouTube, you're gonna love this.

The reason we're making this show is because of you.

You, our subscribers.

So they let us share the entire first episode right here.

There's two more episodes on Netflix at netflix.com/explained.

You can go right now, they are there for you to watch.

Every Wednesday there is going to be a new story.

Add it to your list and enjoy.

[SINGING] 'Cause I'm in love...

From virtually the moment we're born, there's a story that's preached across cultures

and continents.

It's a familiar fairy tale...

She was even more beautiful than he had thought.

That finding one, true, love is the key to a fulfilled and happy life.

I've been doing a lot of thinking.

And the thing is, I love you.

I love you.

I love you.

Ditto.

As an adult, we're forced to reconcile the messaging on monogamy with one simple

fact...

Humans are terrible at it.

It's kept Jerry Springer on the air for 25 years.

Ohhhhh!

I've been... ...sleeping with Eddie.

He cheated on me with her?

I have your name tattoed on me!

How many girls you take from me, Aaron?

In 2016, 2.2 million U.S. couples got married.

But over 800,000 called it quits.

Our quest for – and failure at – monogamy has caused so much pain and heartbreak.

If it's so hard for humans to be monogamous, why do most of us, all around the world, make

it one of the most central goals of our lives?

I start asking myself, "Is he right for me?"

If you ask couples why they chose monogamy, you'll hear one answer again and again.

They fell in love.

We met in a candy store.

1946.

We went to college together.

We were both in a relationship then...

We didn't cheat.

You look so guilty every time we talk about this.

I'm bad at talking about this.

It's arranged marriage, whatever they selected for me, it was good.

And I am very happy with that.

We had a study date one night, and that study break turned into anatomy, I guess.

I've never felt this way about anybody before.

I feel God has blessed us.

We found true love.

Of course we did.

We're still here, 70 years, what do you expect.

25 years I would've gotten out on good behavior.

I would like to think that soul mates are

real, but...

She's my soul mate.

Well, you're mine too.

But monogamy and love aren't the same thing.

We are so psychotically welded to this idea

that monogamy means love, and love means monogamy,

and in the absence of monogamy, there is not love.

Love is a feeling.

Monogamy is a rule.

You'll only have sex with this one person, and most people live in a culture where they're

expected – at some point – to make that rule a legal contract called marriage.

In many countries, breaking that rule is a crime.

In the U.S., adultery is illegal in at least 20 states, and although they're rarely enforced,

punishments can range from a $10 fine to three years in prison.

If you are in a monogamous relationship for 50 years and you fell down once, you cheated

once – the whole relationship was a lie and a failure.

Most human beings have ambivalent impulses that it's nice to have someone you can rely

on, but there's also the temptation of novelty.

Why would humans all around the world invent a rule that's so difficult to follow, and

treat breaking it as such an enormous betrayal?

Should a male have on his clothing so much as a strand of hair from a female not his

wife, a serious crisis may result.

For more than a century, there's been a culturally accepted explanation.

Sound check.

One, one, one, one, one, one, one.

The standard narrative is the story that everybody knows: that men want to be free sexually and

spread their seed around the world, and women want to be very exclusive and particular and

choose a provider, because they're vulnerable and the children need someone to take care

of them, and all that.

Women trade sexual fidelity to men in exchange for goods and services essentially.

In this narrative, there's another reason why men wouldn't want women to sleep around.

If a baby comes out of a woman's body, there is no question but that she is genetically

related to that baby.

The male has to take the woman's word for it.

Biologists have known for a very long time that men are far more inclined to seek multiple

sexual partners.

And the reason for that is is really quite clear.

Now in the first place, remember that the male sperm cells are being produced all the

time.

While only one egg cell is produced each month.

There's a very good – and I don't mean ethically good – but very understandable evolutionary

payoff for males as being randy bastards.

But there's one big issue with that explanation – of promiscuous, possessive men and demure

women.

At lots of points in time, and places in the world, people didn't follow it.

Anatomically modern human beings have existed for at least 300,000 years.

And for more than 90% of that time, we lived as hunter-gatherers.

Anthropologists refer to them as fiercely egalitarian.

There's no reason to think that our ancestors shared everything except sexual partners.

Of course we can't go back and interview our foraging ancestors, but we have the accounts

of explorers and Europeans who first developed and saw these societies before they'd been

much touched by outsiders, and their surprise and shock at the difference in sexual mores.

There's a wonderful story that a Jesuit who lived with the Naskapi Indians for some time

and he would ask, "If you let your wives have this much freedom, how do you know that the

child she bears will belong to you?"

And he recorded the answer of the Indian:

"Thou has no sense."

The guy said, "You Frenchmen love only the children of your body, but we love all the

children of the tribe."

If a child is crying, the adult nearest to that child picks it up.

Nobody says, "Hey, hey your kid's crying."

No, it's – there's a commonality to parenthood among hunter-gatherers.

One of those groups are the Bari of Venezuela, where every man who sleeps with a woman while

she's pregnant is considered a father of the child, and helps provide for it.

Now in our society, that would probably not work very well, I'm not recommending it.

But in that society, a child who had several fathers named, because she'd slept with several

fathers, actually had a much better chance of surviving to adulthood because those men

contributed.

Did you ever think of going with somebody else after you married me?

What are you, crazy?

We don't like to say that we're open, we like to say we're slightly ajar.

Exactly.

That's not good, in my way.

In our language also they say Pati parmeshwar.

That means husband is like God.

This is our culture.

We actually kind of met through the non-monogamy community.

I define this relationship as, this is my cohabitating partner and we call each other

otters.

We are our primary partners and our other partners are secondary partners.

I find it really fascinating.

I think about a lot like if I could ever do that, and I don't know if I could.

I had a threesome with, like, two friends of mine that I initiated.

I decided that it would be cool to experiment with multiple people with, like, somebody

that I really loved and cared about.

The queer community has been berated with the idea that our relationships are lesser,

and that they're not actually up to par and that standard of – you know, the heteronormative

standard, and all that's bull.

"We shouldn't be surprised that some cultures practice non-monogamy.

Because in the animal world, true sexual monogamy is virtually unheard of."

The most romantic creature might be the diplozoon paradoxum.

A parasitic tapeworm that literally fuses together with its partner for life.

But humans aren't tapeworms.

We're apes.

And our closest relatives in the animal world are chimps and bonobos.

We're more closely related to chimps and bonobos than the Indian elephant is to the African

elephant.

The close comparison exists in bone and muscle structure, and in the capability of responding

to stimuli and solving problems.

Clearly chimps and bonobos are anything but monogamous.

Bonobos have sex at the drop of a hat.

[SINGING] I know – I know – that I just met you...

They have sex to say hello, they have sex to say goodbye, they have sex when they're

stressed out.

For both the male and female bonobos, that free love philosophy makes evolutionary sense.

The males get to spread their seed, and the females get to take in the seed of multiple

males – which then compete against each other to fertilize her egg.

It's survival of the fittest – for sperm.

There are aspects of bonobo anatomy that seem adapted to promiscuity.

And intriguingly, you can also find a lot of them in humans.

Suggesting we may have evolved to be non-monogamous, too.

There's body dimorphism...

In species that are more promiscuous, the males tend to be 15 to 25 percent larger than

the females.

And in theory, if there are males battling to impregnate women, testicles would be bigger

and stronger.

You'll see that human testicles are intermediate between very large testicles in bonobos and

chimpanzees, and very small testicles in gorillas for example.

There's the human penis – tied for the biggest among all primates – which has a

unique shape.

We have this much thicker penis with the flared head.

This shape creates a vacuum in the female's reproductive tract that tends to pull any

sperm that's already there, it pulls it down away from the ovum.

Thereby giving an advantage to the sperm of the man who's having sex at the moment.

There's also female copulatory vocalization – a phenomenon so well- known and accepted,

it's a standard feature of movie sex scenes.

Oh!

Oh!

Ahh!

Oh.

What we see is that female copulatory vocalization is common among primates that engage in sperm

competition.

Then there's the fact that humans and bonobos have sex to bond, and not just to have children

– which might explain the way we face each other during intercourse.

You see humans and bonobos are the only two that face each other while they're having

sex.

And why we have a lot more of it than most mammals.

So clearly when people say so-and-so had sex like an animal, they're getting it backwards.

And there's now a lot of evidence that monogamy is a more recent invention than most of us

would expect.

Around 12,000 years ago – when most humans stopped being hunter- gatherers, and figured

out how to farm.

You get a very overpowering concern with property rights.

As the Greeks put it, you don't want a foreign seed introduced into your soil.

For thousands of years, marriage was the main way that you increased your family labor force,

you made peace treaties, business alliances.

The more I've studied the more I became convinced that marriage was invented not to do with

the individual relationship with the man and the woman, but to get in-laws.

You know, and it's amusing because today we see in-laws as a big threat to the solidarity

of the man and the woman.

But that's what marriage was about.

You look back at Anthony and Cleopatra, that was not a love story at all.

That was two people from the most powerful empires in the world trying to figure out

how they could get together and rule both of those empires.

The idea of marrying someone for love?

Coontz says western societies only started doing that a few hundred years ago.

As we made a transition to the idea that marriage should be on the basis of love, it scared

people.

Defenders of traditional marriage said, "Oh my gosh, how will we get a woman to marry

at all if she says, 'Ew I don't love him.'

How will we stop people from getting divorced?"

So a new idea took hold: men and women needed to find love and marry, because they were

two parts of a whole.

Men were aggressive and protective.

Women were nurturing and demure.

They were opposites who completed each other.

The field of evolutionary biology also developed around this time; pioneered by male scientists,

who used their theories on sexual selection to explain Victorian gender roles.

As Charles Darwin wrote in “The Descent of Man”:

“Woman seems to differ from man in mental disposition, chiefly in her greater tenderness

and less selfishness...Man delights in competition, and this leads to ambition..."

"Thus man has ultimately become superior to woman.”

And it's possible his ideas became so popular and survived so long, because it made sense

to us in the societies we were living in.

But if monogamy is all a made-up construct, a way to enforce gender roles and social order,

how do we explain that visceral, deep-rooted feeling we get when our loved ones stray?

Tell me something: are you the jealous type?

I feel like we don't really deal too much with jealousy.

I don't know why that is.

I think it's just 'cause we're sluts, to be honest.

I don't get, like, jealous like that, you know.

It's important I think to understand why you're feeling jealous, because jealousy is not just

a – it's not a feeling, it's usually rooted in some other sort of thing.

It's not a descending guillotine.

It's like, jealousy is an event.

What's the best way to deal with that event?

Who were you really with?