(introspective music) (narrator) On January the 10th, 2017, the world awoke to find we had a new cousin to join our family of apes, alongside chimpanzees, orangutans, and gorillas.

♪ The new species was identified in Southern China and named the Skywalker gibbon.

♪ There are only about 150 of them, scattered, separated, even from each other.

If single gibbons can find one another, if they like each other, they will sing together across the valleys.

(gibbons squealing) This is an astonishing story about love, loneliness, and being able to connect gibbon couples by phone and a dating app.

(opera singers vocalizing) (gibbons singing) ♪ (birds chirping) (soft piano music) ♪ (leaves rustling) ♪ Gibbons are the smallest ape, and in some ways, the one most like us.

♪ Scientists and locals knew there were a few rare gibbons hidden in Nankang in the Gaoligong Mountains.

Professor Fan Pengfei from Sun Yat-sen University and a forest ranger known as Uncle Yan are up early to search for them.

(birds chirping) If you play recordings of their morning calls, gibbons within a kilometer or so will often sing back thinking they're hearing other gibbons.

(gibbons singing) (soft music) ♪ (speaking Chinese) ♪ (narrator) Over the years, Professor Fan and the rangers have learned to identify families and track them as they move around the forest.

♪ The Skywalker gibbons' jungle reaches up into the clouds.

♪ The far end of the Himalayas descends into the Gaoligong Mountains in China along the border with Myanmar, or Burma.

♪ The gibbon families live in scattered, isolated territories.

♪ (birds chirping) These are the foothills of the Himalayas.

Rich alpine jungle.

Two and a half kilometers above sea level.

The area is little known, rarely visited, and never filmed before.

(orchestral music) ♪ Mother Skywalkers are blonde, fathers and young, dark.

They have a five-year-old youngster and a ten-year-old daughter.

♪ For 15 years, the devoted parents have defended their home with a territorial duet.

(gibbons singing) ♪ We can understand it best as a love song, a dawn aria.

(gibbons shouting) Mammals aren't generally operatic.

There's really just us and them.

(opera singer vocalizing) (gibbons singing) (soft music) ♪ This song contains different sounds and each seems to have meaning, like words that we can't quite understand.

(singing in foreign language) ♪ (gibbons singing) ♪ The couple's morning duet is to each other and a declaration for anyone listening.

(opera singers vocalizing) (gibbons singing) ♪ Every morning, the gibbons have an audience.

♪ The Phayre's leaf monkeys are an equally distant relative to both gibbons and humans.

Gibbons are very different to monkeys.

We are both apes from the same small family.

(gibbons chirping) Gibbons form bonds that last their lifetime.

It's an idyllic world, if you have someone to share it with.

(animals chittering) Not all do.

There's an adult, probably the mother's sister, who's single and lives with the family.

She's listening out for the faraway song of a single male.

She's been listening for 12 years.

Nothing.

(leaves rustling) Scientists first came in 2003, followed later by Professor Fan.

(narrator) It took Professor Fan and his team many years to get close.

(narrator) Comparing them to other gibbons over the years, they seemed different.

(narrator) Professor Fan loves Star Wars, but he also named Skywalker gibbons in 2017 for their treetop dance.

(playful music) ♪ (leaves rustling) ♪ (animals whistling) The little one is still learning.

♪ Gibbons have wrists that can swivel around, and the fingers of each hand form flexible hooks to swing from.

They move around their territory of a few square kilometers at up to 30 kilometers an hour.

In late summer, the monsoon arrives.

Everything is wet for months.

(rain pattering) Gibbons used to live in the valleys, but over the years, farms have pushed them up into the mountains.

It's colder here.

For more than a decade, park and forest rangers have tracked the gibbons with the scientists.

They only have a few days off each year.

(narrator) The early years were tough, but Professor Fan never gave up.

During the first long-term study, a ranger got sick and died.

(introspective music) Locals knew of a gibbon family in the 1990s, but by 2007, they were gone.

It seemed like there were only one or two families left in Nankang.

The oldest ranger, Uncle Yan, knew of only one adult single gibbon, heard once in 2007.

(speaking Chinese) (narrator) By 2009, they had found only a handful more gibbons, many separated by roads, villages, and farms.

(dramatic music) ♪ A road is a serious barrier.

♪ Gibbons can only move through the trees.

♪ There are ways across, but they're hard for the gibbons to find.

(piano music) ♪ A few generations ago, this would've been continuous forest.

Gibbon families are lost in a maze.

♪ Every day, she listens for a single male.

♪ Every day, there's nothing.

(melancholy music) ♪ Sometimes she sings for him, her imaginary love.

(gibbons singing) Recording the Nankang single female's song is Lee Xingyu, a musician working on a gibbons singing project.

Dr. Fei Hanlan will also use the recordings for scientific analysis.

(gibbon singing) They wonder what she's looking for in a mate.

(narrator) They all want one thing for her: to find her the single male she needs, any way they can.

(gibbons singing) (soft piano music) ♪ (animals chittering) ♪ (narrator) Skywalker gibbons have reached the end of the road.

♪ Fan can't see a way through.

He fears that he's identified our newest cousin, only to announce its imminent extinction.

♪ (gibbons singing) ♪ (leaves rustling) ♪ Every morning, the darker father and lighter mother duet.

(gibbons singing) The song is complex.

There are stylized phrases.

The female's great call and the male's reply, with more variable conversational moments between verses.

(gibbons singing) Professor Fan's research compares gibbon songs to human speech.

In 2019, he showed that gibbon calls obey some of the key rules of human language.

In effect, what Professor Fan and his colleagues are saying is that a gibbon's morning aria is more than just music.

It has lyrics.

It's opened the door to a scientific study that uses data algorithms to decode gibbon calls, like a translation app.

(leaves rustling) (gibbons crying) The song is the key to understanding them and their relationships, and may contain the solution to saving Skywalker gibbons from extinction.

You can't move the singers, but maybe you can move the song.

(soft music) Fan and the team will become gibbon matchmakers.

♪ To the translation app, add a dating app.

The first stage is a singles database.

For that, he needs an army of helpers to venture deeper into the jungle, searching for the last of the Skywalker gibbons.

♪ Dozens of volunteers, rangers and students, come to help.

Professor Fan lists rumors of sightings and of where one was shot by a Burmese poacher.

(indistinct conversations) The teams are armed with GPS systems, radios, notebooks, and rations.

They cover hundreds of square kilometers.

(dramatic music) Pockets of protected forest are hemmed in by farms and villages.

♪ Beyond the reserve, the gibbon'' forest is disappearing.

♪ (sirens wailing) ♪ They map the 150 or so Skywalker gibbons left.

That's about 40 families.

Some teams head north while others go west to the little known cluster of families near the border with Myanmar, or Burma, searching for any single adults.

No unattached male gibbons are found, but the team is able to get to know one new family.

(gibbons squealing) ♪ There's a son who's too young to be dating, and a father and mother who sing at sunrise.

(gibbon crying) They have a female teenage daughter with a strange hairstyle.

(gibbons singing) The teenager is almost ready to leave home, but she's another lone female who will need a mate.

Even if the team finds a single male here, they should leave him for her.

(soft music) (gibbons singing) ♪ Efforts instead are concentrated 15 or so kilometers north of our original Nankang family in a forest that slopes around a village.

♪ It's a wilder area, less accessible, with more scattered gibbons that are harder to find.

In contrast, leaf monkeys are everywhere.

(monkeys chirping) They mess around on vines and lick rocks for salt.

(cheerful music) ♪ There are more elegant neighbors.

♪ The Great Hornbill has a lifelong mate, like gibbons.

But he keeps her in a hole in a tree.

♪ He's sealed her in with mud.

She's walled in for three months, and he feeds her through a slot.

Inside, the female hatches a chick.

He'll keep them both fed until the chick is ready, when they'll break out together.

♪ Here in the north live a gibbon couple, retired as it were.

She's old with a damaged eye.

(animals chittering) Perhaps her mate could be tempted away for the good of the species.

No, gibbons are loyal.

He'll never leave her.

A decade ago, she had two sons, and that's the reason the team have come.

It's possible that her sons are still here somewhere.

Gibbons are territorial.

It's not possible to anesthetize them and relocate them by force or lure them with food.

(rain pattering) It seems hopeless.

(solemn music) ♪ But without hope, without the singing gibbons, the magic of the forest dies.

♪ We can understand them best as the animal most like us.

Their relationships, too start with music and language.

♪ The team finds a single male.

One of the old couple's grown-up sons.

♪ At dawn, Dr. Fei and Lee Xingyu play him the recording of our single female from Nankang.

(gibbon singing) ♪ There's no reply.

(animals chittering) Playback works between territorial families, but single gibbons may communicate very different messages.

Random bits of her singing don't arouse his interest.

They don't know if the recorded song was for a mate.

Perhaps it was about food or family or territory, or it's too short or the wrong part.

If the single male doesn't understand her song, he's unlikely to respond.

(indistinct conversations) Maybe he'll only reply if she's singing the right part of a genuine courtship duet.

(soft music) ♪ The duet doesn't have to start with him.

There is another candidate, a stand-in to help get things going.

But he's in Beijing.

♪ (narrator) Linlin was born in captivity.

He knows nothing else.

♪ Lee Xingyu originally went to the jungle to record calls for a song about the lonely gibbon in all of us.

Lee plays it at his concerts.

(crowd cheering) (mellow music) ♪ ♪ Someone's singing ♪ ♪ No one's there ♪ ♪ Someone's listening ♪ ♪ ♪ Someone longing, someone waits ♪ ♪ Someone's singing ♪ ♪ ♪ Every day, so early ♪ ♪ She's still waiting ♪ (gibbons singing) ♪ Every day, so early ♪ ♪ She sings ♪ (gibbon singing) (narrator) Finding a partner these days can be difficult.

Everyone has moved around so much.

Many of us feel isolated, hard to be heard.

Lee plays the single female gibbon's song to the zoo male.

(gibbons singing) The response is immediate.

(playful music) (gibbons singing) ♪ He records the male's reply.

(gibbons singing) ♪ Lee always streams his own songs live.

An idea is starting to form.

♪ Back in Yunnan, musician Lee Xingyu and scientist Dr. Fei Hanlan are with our original family in Nankang.

The father is looking after the youngsters.

The mother's single sister is at her post listening.

(gibbons chirping) Finding a partner for her has become something of an obsession.

(animals chittering) The plan is to play her the zoo recording.

(gibbons crying) It's the reply to her song, after all, even though it was recorded 3,000 kilometers away.

She responds slowly, puzzled maybe.

(speaking Chinese) (narrator) She moves nearer.

(gibbons singing) Her reply is tentative, almost shy.

She waits for his answer.

Lee and Fei have no appropriate response.

(tense music) For a conversation, you need more than just recordings.

♪ The suggestion, a new hope, never tried before, is to create a live internet link to the zoo, a communication app for a wild animal.

♪ The team stay with the family, thinking about the ethics of the idea.

Scientists are not supposed to interfere with animals' lives.

They should just observe.

A sister waiting for a husband.

(solemn music) A daughter growing up.

♪ A baby who needs his father and loves his teenage sister.

♪ It's hard not to get involved.

♪ There are also technical challenges.

There is cell phone coverage for the villages, but isolated valleys need testing.

(indistinct remarks) If they are to connect the two gibbons 3,000 kilometers apart, they need to fix any delay on the line or echoing feedback.

(speaking Chinese) (narrator) Some places may need a satellite link to bring the single gibbons together.

(indistinct conversations) The satellite phone is often a lifesaver.

Now, it could be a species saver.

It's worth a try.

(indistinct conversations) (thunder rumbling) (piano music) ♪ When Bell, Marconi, or Edison made the first distant human connections, they changed the world.

To the team, it feels the same.

♪ Multiple song feeds from two or more mobile phones link to a chat room dating app that can merge them into a live broadcast that anyone can log in to and listen.

♪ (indistinct remarks) Cell phone coverage is out of range, so they'll use the satellite system.

(indistinct conversations) ♪ She's not heard a single male's song for as long as they've known her.

♪ (gibbons singing) ♪ Probably, Linlin is about to become the first animal in history to be linked to another by phone.

The connection works.

He'll be the only animal to have a first date through an app.

(gibbon crying) The sound is very distorted.

It's strange.

(speaking Chinese) (gibbon crying) (narrator) The satellite link has a low bandwidth.

To the team, it sounds more like a bird.

(indistinct conversations) However distorted it is to our ears, the gibbons seem to hear something.

There's a reaction.

(indistinct chatter) An update is sent down one of the lines to the zoo.

(gibbon squealing) (speaking Chinese) (narrator) The female is listening.

She's getting ready to sing.

(gibbon singing) The teams at each end can hardly believe it as the gibbons sing together.

(gibbons singing) Parts of the call sound new, never heard before.

(animals chittering) Then, as if by agreement, the singing stops and conversation finishes.

(indistinct remarks) (uplifting music) (narrator) The conversation lasted 22 minutes.

It's the 14th of December, 2018.

♪ In Beijing on Earth Day, artist Lisa Roet's Skywalking Gibbon sang out recorded songs over the city.

♪ In Guangzhou, scientists from all over the world came to talk about gibbons and their problems.

(speaking Chinese) ♪ (laughing) (applause) ♪ (gibbons singing) (narrator) While Fan is away, Fei and Lee continue to connect the wild female and zoo male.

They find that the normal cellular network distorts much less than the satellite phone and in many places, there's a good signal.

With each connection, the zoo male and wild female are slowly building each other's confidence.

There's discussion about introducing the zoo male into the wild, but that's difficult.

(gibbon crying) Maybe they could use the zoo male's duet to lead her towards the wild male.

They'd move the megaphone north and she'd follow.

(gibbons singing) The wild female seems to have overcome any shyness and is increasingly enthusiastic.

(gibbons crying) Suddenly, for the zoo male, it all becomes a bit much.

(melancholy music) Linlin is a bit freaked out by the wild female.

♪ If they were people, we'd say she came on too strong and scared him off.

♪ The relationship and the connection both are ended.

She waits for a while, but the line is dead.

♪ The outside world is too much for him.

♪ The mother's lonely sister is not the only single female in the family.

The ten-year-old daughter is growing up.

She'll turn blonde soon and will start to listen out for a mate for herself.

(birds chirping) It must be hard for them both.

The leaf monkeys have new babies.

They start life orange.

(upbeat music) ♪ (animals chittering) ♪ Monkeys live promiscuous, high-octane lives... ♪ ...full of complicated, changing relationships.

♪ (birds chirping) The team's concerns about interfering with animals' lives were justified.

It didn't help.

(mellow music) Science is perhaps better just observing and trying to understand them.

♪ Hundreds of different trees and vines flower and fruit in turn.

Our Nankang family fiercely defend their food.

♪ All apes, including us, search for plants that contain rare nutrients or have chemical protection from bacteria, viruses, or fungi.

Gibbons eat medicinal plants and insects in small doses.

The teenager is fond of epipremnum, which has an antibiotic ingredient.

Orange climber is said locally to help fever and rheumatism.

(unclear) is thought to protect from neurotoxins.

The family moves on to a false pepper vine, a traditional memory improver.

The teenager selects each mouthful as carefully as a pharmacist.

Orchid flowers are eaten by locals for the immune system.

Melodinus fruit may kill parasites.

Gnetum is used as an anti-inflammatory.

The father has caught a rare treat, a lizard.

Gibbons occasionally hunt.

It's worth searching through the moss and under branches.

After lunch, rhododendron flowers.

They contain a psychoactive grayanotoxins.

People from Turkey to Nepal use it as a hallucinogen.

(birds chirping) The squirrels may be unaffected, but we primates have to be more careful.

(gibbon squealing) (soft music) ♪ Fan and the team research the family's diet, they're singing and language, and discover each member of the family's different character.

♪ The mother's lonely single sister is still waiting to hear a faraway male.

♪ The teenager and her little brother are close.

♪ (speaking Chinese) (narrator) The teenager's instinct to start her own family is growing.

♪ Scientists and rangers don't mean to get emotional.

They study the gibbons to understand why the family shows more affection and loyalty than any other animal they can think of.

♪ (speaking Chinese) ♪ (narrator) August is humid and full of insects.

(insects buzzing) Even the monkeys are feeling it.

(thunder rumbling) The summer breaks with the return of the monsoon.

(dramatic music) ♪ It's the father's turn to babysit the five-year-old.

Fathers take an equal share in looking after the young.

He tends to spend more time with the teenager, but plays with the baby every day.

♪ The teenager is learning what it will take to be a good parent.

(vocalizing) ♪ The important role of a father here seems very human and barely exists in any other apes.

♪ Everything comes back to the heart of their lives.

The perfect partner really matters.

♪ On good days, she sings.

(gibbon singing) ♪ Somewhere out there is a single male.

♪ Sometimes nature surprises you.

(solemn music) ♪ (leaves rustling) (gibbons singing) The surprise, when it comes, is terrible.

The teenage daughter is discovered dead by one of the ranger teams.

(somber music) ♪ (beeping) ♪ She's found later to have genetic abnormalities, liver and other problems.

♪ Her DNA results are disturbing.

♪ The family has a dark secret.

Hemmed in by farms and roads, the parents had inbred.

They are close relatives, probably brother and sister.

They must have had no other choice.

♪ The problem is worse than anyone thought.

Inbreeding is killing them.

The future of their tiny, fragmented population is grim.

♪ Their problem is not unique.

It's commonplace, found in pockets of wildlife all over the world.

♪ Though scientists are never supposed to intervene, in a silent moment, we may all wish we'd done more.

(birds chirping) The mood is somber and determined.

The team must find the lone male up north and try to be matchmakers again.

(thunder rumbling) He hasn't gone far.

(playful music) ♪ His stand-in in Beijing was not a romantic success, but the technology works.

♪ The app will make the live connection to our lone female 10 or 15 kilometers to the south.

♪ Fei and Lee find the single male.

The plan is to link them together in stages.

First, Lee and Fei play him the recordings of the lone female singing to the zoo male.

(gibbon singing) Maybe the recording is the wrong part of her song, or perhaps because she is singing to someone else, he doesn't reply.

(dramatic music) ♪ The team notices that he has some reaction.

(indistinct remarks) (gibbon singing) He listens, but in silence.

♪ Preparations are made for the next stage.

The distance is a few hours at skywalking speed.

The problem is navigation.

There are ways around villages and there are cell towers most of the way.

The route is planned.

♪ She seems ready.

She's waited long enough.

More volunteers, new microphones, and old hands are ready with the family and along the way.

Dr. Fei and Lee are with the male.

In other gibbons, males migrate further than females, so the plan is to lead him to her.

The cell phones connect, but neither gibbon starts singing.

After the failure of the relationship with the zoo male, no one assumes anything.

The chat room goes live.

At a crucial moment, a few random app subscribers log in by mistake.

(laughing) Four lonely human hearts have joined the chat room.

The newcomers have unwittingly stepped into the weirdest attempt at matchmaking on Earth.

(suspenseful music) ♪ Slowly, the female starts.

♪ She's tentative, singing a phrase or two.

♪ (gibbon singing) ♪ Everything is in place.

♪ For the first time, he replies.

(gibbon singing) ♪ Almost immediately, the male begins to move around his territory.

Lee and Fei have planned for this and move up to the ridges, trying to draw him in the right direction.

♪ The hope is that he's starting to venture beyond his territory.

♪ The teams keep in touch on another cell phone.

♪ (gibbons singing) Even to our ears, the audible range of the calls reaches across the valleys.

If he's interested, he should be following.

(gibbons singing) The duet sounds different compared to the simple enthusiasm with the zoo male.

It's a good sign.

(orchestral music) ♪ The territory of the family at Nankang lies ahead.

(indistinct conversations) ♪ (gibbons singing) ♪ Each ridge will get him closer to her.

♪ (speaking Chinese) (narrator) Thousands of hours of effort with these few gibbons may just be beginning to pay off.

The male continues calling.

He's moving towards the sound of the female coming from the megaphone.

♪ He's coming, close enough to see now.

♪ (leaves rustling) (gibbons singing) (opera singer vocalizing) (tender music) ♪ (singing in foreign language) ♪ (narrator) At the edge of her family's territory, he will have to stop and sing from there.

The agitated family is territorial.

He'd risk attack.

♪ (gibbons singing) (opera singers vocalizing) ♪ A duet for a gibbon is as intimate as meeting.

♪ If she chooses, she'll leave the family to establish a new territory.

♪ No matchmaker can hang around and follow them into the bedroom.

There's a point that you must just melt away.

♪ The feasibility is demonstrated.

♪ The rest will be up to them.

♪ (gibbons chittering) ♪ (leaves rustling) ♪ The technology has research implications far beyond these forests.

Humpback whales could sing together.

Nightingales find each other, and even frogs could connect with our help.

(soft music) ♪ Linlin may get another chance.

Zoos and marine parks are full of animals that could be put in touch with each other or the wild.

(gibbons crying) ♪ Almost as a postscript, a miracle did happen, but not quite as anyone expected.

When the team was searching for single males, they found one western family with an adult daughter.

They return to see how they are doing.

The mother and father are still there, and the daughter too.

But there is now a brand new member of the family.

It's not with the daughter.

It's with the mother.

Gibbons often wait more than five years between pregnancies.

So a birth is a rare event.

The baby is about a week old.

Babies are born white but turn dark after a few months.

Skywalker newborns have been glimpsed once or twice in the wild, but like everything about Skywalker gibbons, never filmed before.

Of course, his nickname from the team is Luke.

Luke Skywalker Gibbon.

(peaceful music) ♪ There are only about 150 Skywalker gibbons in the wild.

Now there's one more.

♪ The daughter has a little brother.

If she's to start her own family, she may need some help.

♪ After all, we all need a little help finding the right person.

Cell phone coverage, a dating app, and a team of dedicated scientists seem as natural a place to start as any.

♪ (opera singer vocalizing) ♪ (bright music)