All language subtitles for through.the.wormhole.s07e03.are.there.more.than.two.sexes.480p.hdtv.x264.rmteam

Boy or girl?

It's the eternal question.

But that question may have
more than two answers.

Science is finding the line

between male and female bodies
is blurred,

identifying the hallmarks
of a transgender brain

and studying people who seem
to change sex spontaneously.

Are some people
neither male nor female?

Are there more than two sexes?

Space, time, life itself.

The secrets of the cosmos
lie through the wormhole.

Captions by vitac...
www.Vitac.Com

captions paid for by
Discovery communications

Everyone who ever
lived was created

from the genes
of one man and one woman.

Those genes blended together
to make a unique child...

With dad's dark hair
and mom's curls,

or with mom's lips
that curl into dad's smile.

One thing, however,
isn't a blend...

The child's sex.

It's either male or female.

But is there
something in between?

Many transgender people,
their friends and families

say there is.

But what does science say?

Today, that question
is playing out

in a very public arena.

For more then 100 years,

athletes have pushed
themselves to the limit

to be the strongest,
the fastest.

And for almost as long,

some have been doing
whatever it takes to gain

that winning edge.

But endocrinologist
Richard Holt is watching them.

He's a pioneer of tests
designed to spot athletes

seeking an unfair advantage.

The difference between
somebody winning

and somebody not winning
is absolutely tiny.

We're talking about
maybe less than 1%.

There are a number
of athletes who might be

just that little bit away,
and they think,

"well, maybe if I just take
a little bit of extra

then I'll be able to reach
the pinnacle of the career."

Richard's human
growth hormone test debuted

at the 2012 London Olympics,

but lately he's entered
a more controversial arena...

Verifying athletes' sexes.

Indian sprinter Dutee Chand
grew up as a woman

and runs against them.

But on the eve of
the 2014 Commonwealth games,

she ran into a problem.

She was found
to have high levels

of testosterone in her blood,

and fell foul
of the regulations.

She was banned from competition.

Men and women both
make testosterone naturally

but in very
different quantities.

According to international
athletic rules,

Chand fell outside
the female reference range.

She did not fit
the definition of a woman.

Imagine we had two
athletes, a man and a woman,

and we looked
at the two together.

We'd see that, on average,

the man would be taller
than the woman,

he'd have broader shoulders
than the woman,

he'd have bigger hands
than the woman.

Men, on average,

have much more lean
body mass than women.

If you've got more
lean body mass,

you've got a stronger engine.

To avoid men sneaking
into women's events,

sporting federations began

in the 1960s
to certify women as women.

They did this
the old-fashioned way...

By visual inspection.

But this led to controversy.

Athletes thought the practice
was indecent and disrespectful.

Since the 2000s,
some women have,

instead, been subjected
to testosterone tests.

But a recent large study

of more than 800
elite athletes found

that testosterone tests can't
always tell men from women.

What they found was
that there are about 15% of men

that had testosterone levels

that were below the typical
normal reference range

and there are about 30%
of women whose testosterone

were above the upper
limits of the female range.

In other words,
there's no clear dividing line

between male and female
testosterone levels.

In fact, there's no evidence
that naturally high testosterone

even gives you
a performance advantage.

If testosterone was really key
to athletic performance,

what we would expect
is that, among men,

men with the highest level
testosterone,

those men
were winning the races,

but I can tell you,

some of them had very, very low
testosterone levels,

and despite having
very low testosterone levels,

they were still capable
of competing

at the very, very highest level.

Dutee Chand fought
the ruling against her,

claiming it was discriminatory
to ban her

for a naturally occurring
condition.

In 2015, she won back
the right to compete.

Testosterone screening
for female athletes

has been suspended
for the moment,

but there's no agreement
on what should replace it.

I think the best way
of actually determining

whether a woman
should be able to compete

as a woman is the way
that she self-identifies.

If she's always seen
herself as a woman,

regardless of what her
testosterone levels are,

I think she should be allowed
to compete as a woman.

Sporting federations
are still wrestling

with how to draw the line
between male and female bodies.

But Israeli neuroscientist
Daphna Joel has been looking

for telltale differences
in another place...

our brains.

There are many studies
finding differences

between men and women,
in brain structure,

brain connectivity,
brain function,

and also in behaviors,
attitudes, et cetera.

But the question is
whether these differences

add up to create
two types of people.

Do the differences
between the ways men

and women behave trace back

to physical differences
in their brains?

Science has asked this
question for generations.

In the 18th century,
anatomists noticed that men,

on average, had larger skulls.

In the 19th century,

they discovered
that the brains of men

tended to weigh more
than those of women.

These differences quickly
become politicized.

They started using this
to explain female inferiority

when they discovered
that the brain

of males were, on average,

larger than
the brains of females.

Then again,
this was used to explain

why women are not
as intelligent.

There's a long
history of science

being used to justify

and maintain the social order.

Today, we think
we're too sophisticated

to make that mistake.

Studies show that more men
than women like soccer.

We now know,
that doesn't make soccer

an exclusively male sport.

But when we talk
about the brain,

we still fall back on male
and female stereotypes.

For example,
scientists have found that,

on average, a brain structure

called the amygdala
is larger in men.

Because the amygdala
is linked to aggression,

you often hear people say
aggression is a male trait.

The idea that there
is a male brain and female brain

is so popular that people
that write books

about this get
to be millionaires.

These ideas depend
on one big assumption...

That you can look at any brain

and tell whether it belongs
to a man or a woman.

Daphna set out to test
whether this is really true.

She analyzed MRI scans from more
than 1,400 men and women.

She wasn't looking at averages,

she was looking
at each individual brain.

Imagine your brain
is an ice-cream sundae.

You get something blue
for each brain structure

that follows the male pattern.

You get something pink

for each structure
that looks female.

Many different brain structures
go into the sundae.

We assume that all
the differences add up,

one to the other,
to create one type of person...

Men with a male brain
and woman with a female brain.

Daphna's study put this
idea to the test.

If you're female,
will every part of your brain

look female in the MRI?

If you're male, will every part
of your brain look male?

Looking at brains one by one,

Daphna saw nothing like that.

These sundaes should
all look the same

because they are all of women,

but what we actually see
when we look closely,

is that most people had a brain

which was a mosaic,
mosaic of features.

The majority of brains
has a mixture of both male

and female characteristics.

Brains do not have sex,

and we should stop using

the male-brain/
female-brain idea

to explain why men and women
are fundamentally different,

because they are not.

In body and mind,
we are all mosaics...

Pixelated images
of both man and woman.

There's no denying
that most of us grow up

knowing which sex we are,

but on a deep genetic level,

we could be wrong.

Where does our sex come from?

Well, like any biological trait,

the answer lies in our DNA.

There are two sex chromosomes...

One's called the x,

and its little sidekick
is the y.

Usually, women have two x's,

and men have one y and one x.

But a small percentage of babies
are born with chromosomes

in neither
of these arrangements.

The more we learn about
the biology of sex,

the less it seems like
there are only two sexes.

Geneticist Eric Vilain works

with an unusual group
of patients.

They do not fit our normal
definitions of male and female.

One term for them
is "intersex."

I see patients
with intersex conditions.

Their biological sex
does not match

their appearance, their chest,
their genitals.

And sometimes
they're in between.

Their genitalia are ambiguous.

About one in 100 people

have some degree
of intersex condition.

That's roughly the odds

of having green eyes
or red hair.

While those qualities are
visible to the naked eye,

some intersex people aren't even
aware of their condition.

In his research, Eric found
one particularly striking case.

So, I had a patient,
young girl, 17 years of age.

Let's call her Eileen.

And she came to my office

because she didn't
have any periods.

Unlike all her friends,
month after month,

she was waiting...
Nothing.

Eileen looked like
a completely typical girl...

She was tall,
she was good-looking,

she was well put-together.

Even though she looked
completely female,

there's one thing that
was not working properly...

She could not produce eggs,

and she could not
produce female hormones.

We sent some tests for Eileen,

and the first test we sent
for her were chromosomes,

and that's when we discovered

that she had
an x-y pair of chromosome,

and not an x-x.

Eileen was actually male...

At least, according
to her genes.

The human genome is an
incredibly complex molecule.

It's the source of the many
millions of instructions

which our bodies
follow as they grow.

The determination of which sex
we are is just one of them.

In each cell of the human body,

there are 46 chromosomes...

Like this one...

Containing millions
of base pairs,

but only one has something
to do with determining sex.

Our 46 chromosomes
come in 23 pairs.

Half of each pair
comes from our mother,

the other from our father.

Within the chromosomes,

our genes determine
everything from eye color

to the shape of our earlobes.

Hidden among these pillars
of our existence

is one pair of sex chromosomes.

Their combination determines

whether we become male
or female.

Women are x-x, men... x-y.

But if Eileen was male,
why didn't she look male?

Eric went looking
for the root of the problem.

We sent for another
series of tests

looking for mutations in genes

important for
sexual development.

One of these tests looked

for mutations in a critical gene
on the y chromosome

called SRY.

On the y chromosome,

there is this
small gene called SRY

that's only 887 base pairs
in the determined sex.

It was once believed
that many genes

on the y chromosome
worked together

in the womb to make you male.

But we now know
that the tiny SRY gene

does that job all by itself.

If SRY doesn't work correctly,

the child can grow up
looking female.

We identified one base pair

that was different in Eileen.

This one mutation
was responsible

for her being not a boy.

Out of three billion base pairs

in the human genome,

a single one had switched places
with the one beside it.

It's called a point mutation...

The smallest possible alteration
that can be made to a gene.

Since mutations can
be inherited,

Eric invited Eileen's relatives

to come for testing.

He found two more females
who were genetically x-y.

Like Eileen, they had
never had periods

and could not bear children.

Because of one tiny mutation,

they'd lived as women
for their entire lives.

When it comes to SRY,
the main sex-determining gene,

there is no room for error.

One base-pair mutation

and the sexual
development switches

from male to female.

For this handful of patients,

along with millions
of intersex people

around the world,

learning the truth
about their genes

can mark the beginning
of a difficult process.

They're really ashamed
of their situation,

and that's something that
I can't stress enough.

Despite the fact that
these conditions are rare,

they're not unique.

If they're not alone,

then this sense
of shame disappears,

and then they can embrace
their conditions

rather than be ashamed of it.

Most of us can't
imagine the anguish

that the intersexed 1%
must go through,

but some people have even
more challenging transitions...

They hit puberty and their sex
seems to suddenly switch.

We all know that
time changes us.

First, we grow taller,
then a little shorter.

We lose our baby fat,

and then we get
a little of it back.

But for most of us, one thing
doesn't change... our sex.

As we age, we learn
to wear our masculinity

and femininity like an old suit.

But that's not true
for everyone.

Pediatric endocrinologist
Chris Houk lives

on 150 acres in south Carolina.

In this grand laboratory
of nature,

he encourages his kids
to study the birds and the bees.

We live here with chickens

and a horse and bees

and soon-to-be goats.

It allows kids
to connect with nature.

The eggs hatch,
and then they grow up

and become mature
male or female,

and then they make more babies.

And the circle
of life continues.

Chris' research focuses
on the biological process

of growing up...
How girls become women

and boys become men.

A few decades ago,
some intriguing evidence emerged

that not everyone
follows those facts.

Back in the early 70s,

there was a rumor
that circulated,

that there was a village
in the Dominican Republic

where girls turned into boys
at the age of puberty.

The villagers seemed
to know about this.

They had multiple generations,

seven or eight generations,

that they could document
at the time,

to the point that they had
created a terminology for it

called "guevedoce,"
which means "penis at 12."

Before their daughters
hit puberty,

the villagers trusted their eyes

and raised them as girls.

But when they hit puberty,

sometimes things
went a little haywire.

Similar to humans,
chickens go through puberty...

Testosterone's what initiates
chicken puberty

and establishes sexual maturity,

the ability to reproduce.

To use this analogy,
in guevedoce,

a chick that appears
to be becoming a hen

takes on some of the secondary
sexual characteristics

that one would
only see in a rooster.

When researchers tested
the guevedoces,

they found high levels
of testosterone,

and their sex
chromosomes were x-y.

Biologically, they were male.

Puberty had somehow revealed
their underlying genetic sex.

But how?

Let's use this egg,
for a moment,

to talk about human development.

We'll pretend that
this egg is a womb.

Within it is contained the fetus

and all the materials needed
to make a male or a female.

If we wanted to make a female,
this would be the end of it.

We're done.
We can scramble this up,

we can sunny-side-up,
we can over-medium.

That is a girl egg.

Making a female is
a simple recipe...

Just leave nature's
goodness alone.

But male development calls
for more ingredients.

At a very early time
in human development,

we would need to
add testosterone,

and that will have
a tremendous effect.

But if this is all you do,

you're internal
anatomy will be male,

but no on will know it.

In the guevedoces,
this was the stage

where male development
went off course.

They were missing
a crucial extra ingredient.

You need another, more
potent activator of maleness,

and that would be
a hormone called DHT.

This hormone is at least
100 times as potent

as regular testosterone,

and it's critical for what
we call male development.

In the womb,

DHT is made
from regular testosterone.

It takes an enzyme
called 5-Alpha reductase

to do this job.

In a normal male embryo,

DHT creates structures
we associate with maleness.

At the end of the process,
a baby boy is born.

In guevedoces,
a genetic mutation

prevented them from making DHT.

They looked female
until puberty,

when a surge of testosterone

finally transformed their bodies
into male ones.

This strange discovery
led researchers

to a deep
psychological question...

How will a male see himself

if he's raised as a girl?

We have these two terms,
"sex" and "gender."

They're often used
interchangeably.

But to us in medicine,
they are two distinct things.

Sex generally refers
to the physical appearance

of an individual.

Gender is something
totally different.

It's something sort of ethereal.

It's this internal sense
of "I'm a male"

or "I'm a female"

or "I'm neither,
something in between."

Well into the 20th century,

gender was seen
as something parents

could assign to children.

Raise a girl in a female role

and she will see
herself as female.

But the children
in this Dominican

village shattered this idea.

Of the guevedoces
raised as female,

95% transitioned
to live as male.

This sort of challenged
that prevailing view

that we could assign a gender.

We could assign sex...

You know, how you would
raise the child...

But you could not
really assign gender,

that there's something internal,

something innate about gender.

Our mental sense of whether
we are male or female

is not just an idea we get
from the influence of others.

Gender is rooted,
biologically, deep inside us.

So, what happens in our minds

when our gender
and our sex don't match?

Biology says that sex

is not as simple
as male and female.

Approximately 1 in 300 people

identify themselves
as transgender.

Transgender people feel
their biological sex

doesn't match who
they truly are up here,

which raises a fascinating
scientific question...

Why do body and mind disagree?

Transgender people are becoming

much more visible
in recent years

thanks to evolving social norms.

Many go to great lengths
to alter their bodies,

and ask their families to accept
a different version of them.

But where does the urge

to change one's body come from?

Neuroscientist Ivanka Savić
is trying to understand

the roots of transgender
feelings in the brain.

She studies how we
perceive our bodies

and feel at home in them.

This is a very complex
process for the brain

because it involves
several different areas

that have to do
with cognition, self.

"Who am I?" Is a very high-level
cognitive process.

Ivanka believes
this cognitive process

might be different
in transgender people.

Transgender people, they look
at themselves in the mirror

every morning
and feel uncomfortable

because they, of course,
recognize the image,

but they don't feel this is
the image that represents them.

In a way,
they see somebody else.

As a neural scientist,

Ivanka knows that connecting

with your own body
is a complex mental ballet.

Our visual world overflows
with information...

Colors, forms, movements...

But our brains impose
a kind of order,

identifying those things
which are most important to us.

It starts with
the visual cortex,

which takes in
everything we see.

That information flows

to more specialized
brain regions...

One identifies bodies,
another identifies faces.

And yet another region,

the temporo-parietal
junction,

identifies whether those
faces and bodies belong to us.

But it takes one more region

to pull all
these I.D.S together...

The brain's identity center.

The prefrontal cortex
must conclude

"this image feels like me."

This is the mental network

that allows us to recognize
our own bodies

and feel at home in them.

And it operates
completely unconsciously.

This all-body perception
is so automatic,

so we don't even
consciously reflect upon it.

I look at my hand.
It's my hand.

I look at my face.
It's my face.

To recognize and know ourselves

is something we take
for granted everyday.

But in some people, it may
work a little differently.

Many transgender people
do not identify

with the bodies
they are born with.

And in many cases,

it doesn't seem to be
a matter of choice.

In many, many people
who are transgender,

this occurs very early
during the childhood,

and it's very strong.

And that's why
it's very important

to take this seriously.

Ivanka thought
transgender people might see

in their mind's eye

a body that's different
from their physical image.

In an experiment,
she showed transgender subjects

photos of themselves.

In some of these photos,

she had subtlety
altered their physiques.

Many, many body images
are presented

during a very short time,

and for each image,
they have to determine

"how much is it me?"

Ivanka gave her subjects
very little time to reflect,

but they consistently
identified with the photos

that altered their outward
sex characteristics,

and they made
their choices so quickly,

Ivanka suspected
the unconscious process

of own-body perception

was working
differently for them.

So she used MRI imaging to look

at the connections
in their brains.

Think about what it takes
to make a self-portrait.

It's a dialogue between
what your eyes tell you

and what you think
should be there.

That's not unlike
the unconscious dialogue

that goes on between
regions of your brain.

People with transgender feelings

don't have any
visual impairment.

They don't see the world
any differently,

but when Ivanka looked
at their brains,

she noticed two regions

that weren't communicating
in the usual way.

We could see that there
was a weaker connection

between the area of the brain

that represents self
and the area of the brain

that represents their own body.

It could, somehow,
explain these perceptions

of seeing own body,
recognize own body,

but at the same time,

feeling that this
is not part of the self.

The struggle to feel
like yourself

when you look at your own body

is at the core
of trans identity.

Ivanka's research has
uncovered the roots

of this struggle in the brain.

To live happier lives,

transgender people often correct

their physical appearance

through hormone therapy
or surgery.

It's a tall order
to switch sex anatomically,

but new research is showing it
soon could get easier

because, on a hidden level,

our bodies are constantly
trying to switch.

Hermaphrodite... it's an animal
that has both male

and female sex organs,

like these snails.

When they mate,

either one can take
on the biological role

of the male or the female.

New research is revealing

that we all might be
hermaphrodites, in a sense.

Down at the level of our cells,

there's a war between
male and female

raging inside all of us.

Geneticist David Zarkower looks

at how cells in our
reproductive organs

choose to be one sex
or the other,

and whether they can
change their minds.

Our interest is in how sexual
differentiation happens,

so how cells come to be
either male or female.

And so what we do
is we find genes

that might play an important
role in that process,

and we break them,
and we see what happens.

SRY is the gene on the y
chromosome that decides

whether you'll become
male or female,

and if SRY has been active,
male development occurs.

But David and his team
decided to look beyond SRY

to another gene called dmrt1.

Dmrt1 helps the testes develop,

but David wondered why it
stayed active in adulthood.

If the sex of male cells

is supposed to be fixed
before birth,

why was this gene still working?

David works on mice
as stand-ins for humans,

as their biology
is very similar.

And he did what geneticists do,

he let mice grow to adulthood,

then broke the dmrt1 gene
to see what would happen.

In this microscopy room,
we look at mouse tissue samples,

and we use specific stains
to ask whether male-

or female-specific proteins
are active.

The color scheme is simple...

Green for male cells,
pink for female.

When David eliminated
the dmrt1 gene

then looked at the gonads
of his mice,

he saw something surprising.

You can see that
there's still some male cells...

Which is these...
But there are many,

many more intensely
pink staining cells.

Deleting just one gene

caused the cells to change sex.

Ovaries were developing
in the bodies of males.

And he found this process
works in both directions.

At first we didn't
really believe it,

because this was
supposed to be a testis,

but there was
all this expression

of female-specific genes,

and so we repeated
the experiment,

but it was clearly true.

This testis was, essentially,
directly transforming

into something that was
very much like an ovary.

It's a discovery that shakes
the very foundations of sex.

The cells which
makes us male or female

don't have to stay that way.

Could a woman produce sperm

to make a baby
with another woman?

And could a man produce eggs?

We all start with genes

that could pull us
toward male or female.

For the first six weeks
in the womb,

a tenuous balance exists,

neither side is winning.

The embryo seems
neither male nor female.

But after six weeks,

if the embryo
has a y chromosome,

the SRY gene kicks into action.

The gene called SRY
is the difference-maker.

With SRY as anchor,

the pro-male genes
swing into action...

Overwhelming their competition,

pulling the fetus
to develop as male.

With sex determination complete,
SRY hands over the reins.

Here you go.

Dmrt1 sees to it that
a male child remains male.

But if dmrt1 should
ever leave his post,

a gene called foxl2

will seize the opportunity

and start working
to make the body...

Let's go, ladies.

Female.

Like SRY, foxl2 spurs
other genes into action...

One, two, three, pull.

Which overpower the male genes

and start making female cells.

We have this lifelong battle
between dmrt1 and foxl2

over whether the gonad
will remain male

or will, instead, become female.

This is really different
from the way

we thought
about things previously.

Dave's genetic
tinkering found a battle

of the sexes going on inside us

that never truly ends.

In theory, an adult
human body can be coaxed

to make opposite-sex hormones.

A new era of gender therapy
is on the horizon.

But consider the dark side.

Could this technology
be misused?

Could people with anomalies

in their sex
chromosomes be forced

to accept genetic alteration,

to make them fit
into traditional male

and female molds?

Children who are intersex
may be coerced

into being assigned one sex
or the other.

This has been
a historical problem.

This technology could
potentially make that worse.

So it'll have to be
used responsibly.

On the other hand,

this new knowledge
offers immense hope

for transgender
and intersex people

who want to transition
from one sex to another.

The ultimate goal
of gender transformation

would be to allow
somebody to become

a reproductive individual
of the opposite sex.

It's a ways off, but now
there's some reason to think

that it might be possible
for two men to have a baby,

with one making sperm
and the other one making eggs.

Some day, our society

may contain many new kinds
of happy families.

Our children may be born

with more ways of changing
their bodies' sex,

if it doesn't seem to fit.

Sex could soon be more fluid

than we ever thought possible.

But the animal kingdom
is already showing

that our understanding of sex

could evolve even further.

These scientists
are exploring a world

where making babies

needs more than one male
and one female.

Sex and gender were long seen
as male or female.

However you thought of yourself,

you could only use
one bathroom door,

but we now know
the gender you feel you are

can disagree with your anatomy.

As a society, we're beginning
to accept that sex

and gender can be male,

female, both,
or somewhere in between.

But in the future,

we may choose to make sex
even more complex than that,

creating more than one type
of male and female

and even more
possibilities in between.

Good morning.

Hey. Would you like
to get a colony out?

Sure.

Biologist Joel Parker

and evolutionary ecologist
Sara Helms Cahan

were once classmates.

Now a tiny species has
brought them back together...

a species which could reveal
where we ourselves are headed.

- Okay.
- Are you ready to touch 'em?

- Yeah, well, don't get stung.
Ah, remember... yes.

You're braver than I am.

I remember you were always
squeamish about this.

Throughout the desert southwest,

there are many different species
of seed-harvester ants.

One of the most common
is a pogonomyrmex.

It means "bearded ant."

"Pogo" meaning "beard."

It was here,
in the pogo's desert habitat,

that Joel came across a paradox.

He found two different
species of pogos,

a red type and a black type.

Their colonies looked normal,

with reproductive queens
and males

and hoards of sterile workers.

But the two species
shared a mysterious quirk.

If you mated a queen
with a male from her colony,

you wouldn't get all
the offspring the colony needed,

you would only get
female reproductives.

You wouldn't get workers.

So where did those workers
all come from?

Did they fall from outer space?

Or did their appearance
on the scene

have a more earthy explanation?

It was a mystery Joel and Sara
were determined to solve.

A normal ant colony gets started

when a newly mated queen
goes off after she mates

and digs a little hole.

She'll crawl into the hole
then lay eggs

that will become the first
generation of workers.

Workers are
the backbone of an ant colony.

These sisters forage for food

and maintain the nest,

but they can't reproduce.

Reproductive females come later,

and then the colony
is established.

They're cared for
and fussed over

like the future queens
they are destined to be.

You could think of them
as princesses.

And finally come the males,
the colony's lowliest members.

Males have a very sorry
lot in the insect world.

They're very small.

They basically only have
two functions in life...

To fly and to mate.

But mating for these two species

is where the system
appears to break down.

Joel discovered that
each species

wasn't being faithful
to its own kind.

They were flying off
to have flings

with the species next door.

In a pogo mating swarm,

different couplings produce
different types of offspring.

When a female mates
with her own species,

she makes another
reproductive female,

a future queen.

But to make one
of the much-needed workers,

she must mate with a male
from the other species.

Usually when you think
of a sexual system,

you think of males and females.

With our ants,
we have a situation

where there's two
different types of males

and two different
types of females

that are required to keep
this population going.

So you can think of it
as like one species,

then, that has
four different sexes.

In a species with four sexes,

there is more than
simply male and female.

Joel and Sara believe
this system

helps ants in a colony

become more specialized
in their roles,

and they think
it offers a preview

of what may happen with humans,

in the future.

The thing that blows me
away about ants is

when you actually start
looking at 'em

from a biological point of view,

they are more highly advanced
evolutionarily than humans.

Ants started farming
100 million years before we did.

They don't have to be
taught how to farm.

It's all in their genes.

We have ranching,
we keep cattle.

Ants tend their
own kind of cattle,

which are tiny little
insects called aphids.

We have soldiers that we
send out to fight our wars.

Ants also have soldiers

that they send out
to fight their wars.

Where ants have gone,
humanity has followed.

Joel and Sara think
it is happening again.

Today, every human baby
is made from the genes

of just two people.

But we are now experimenting

with modifying the human genome,

inserting genes
from other sources.

A baby made this way would have
more than just two parents.

I can't even think what our
sexual system will be like

when we start using
some of these new technologies

to put foreign DNA
into our germ line.

But when that happens, how
many parents are we gonna have?

I think
we are going to move beyond

the simple binary
of mother and father.

I could see it becoming
more difficult

to be able to easily define

who is the parent
of a given child.

The poet Audre Lorde once wrote,

"it is not our differences
that divide us,"

it is our inability
to recognize, accept,

"and celebrate
those differences."

One day, we may find ourselves

embracing a rainbow
of different sex identities.

Medical techniques could expand
the definitions of sex

and allow us to accelerate
the evolution of our species.

Perhaps the question isn't

whether there are more
than two sexes,

but whether there
are more possibilities

than we ever imagined.