NARRATOR: Strangely beautiful... As endangered as the giant panda... Elusive... until now.

This is the first time these rare snub-nosed monkeys have been so thoroughly documented.

We begin in spring in a remote valley of the Chinese Himalayas.

And one family has two new babies.

One has an ideal childhood and is nurtured, the other struggles after his mother abandons him.

For two years, the crew follows the brothers... MAN: I've been here for a couple of hours now, just waiting for the monkeys.

NARRATOR: Enduring impossible terrain and extreme weather... MAN: Now, we're up on the top of the mountain, 4,200 meters up.

NARRATOR: To find out how the families push apart and then pull together in one of the highest forests in the world in the 'Mystery Monkeys of Shangri-La.'

NARRATOR: Hidden in the Himalayas in China are the Snow Mountains.

Behind peaks of up to 22,000 feet are inaccessible canyons miles deep.

For centuries here, there have been stories of lost cities and woodland elves.

The northeast corner of Yunnan Province is cut off from the world by its formidable geography.

Here, the eastern end of the Himalayas is sliced through by huge rivers.

The Nujiang, the Mekong, and the Yangtze form 1,000 square miles of isolated mountains and forests.

[ Bird cries ] Chinese scientists arrived by mule train in 1960 looking for an animal known only from skins, and thought perhaps extinct.

They returned with news of a large mountain monkey, a living yeti.

Xi Zhinong, a Chinese photographer, became obsessed.

Starting in the 1980s, he dedicated himself to finding the monkeys.

He became the first to film them in the wild.

[ Monkeys chattering ] There are only a few thousand Yunnan snub-nosed monkeys.

They are gentle, with odd-looking noses and prominent forelocks.

The young have ears like Yoda.

The adults, with pink lips and almond eyes, are hauntingly beautiful.

Though sometimes they do seem like old movie stars with too much plastic surgery.

They live at a higher elevation than any other monkey.

It's 30 years later, and Xi Zhinong has hired a new team.

The expedition has two young cameramen, six porters, three rangers, and a scientist.

They cross mountain passes at 14,000 feet.

The oxygen level is almost half.

Cameraman Jacky Poon finds it tough.

POON: Now we're up on the top of the mountain, 4,200 meters up.

And it's snowing and it's hailing.

Trying to get a breath and see the screen is not easy.

Aah.

NARRATOR: Behind the passes are valleys.

As the team descends, the temperature rises.

They find an enchanted garden behind mile-high walls.

Jacky Poon can hardly believe it.

POON: It's like you're going into a different world.

You start to hear birds and see flowers.

It's magical.

All of a sudden, in the trees, are the monkeys.

It's a huge thrill to see them.

NARRATOR: Jacky Poon and Wuyuan Qi are amazed.

The monkeys seem unafraid of them.

These monkeys are unique, 'cause they're not too bothered by people.

But they're still wild animals, so you can't tell them what to do, can't control them.

So very, very privileged. Very privileged.

NARRATOR: Xi Zhinong's ambition is to make a film following individual monkeys for two years.

Park rangers and scientists will help track them with a team.

It has never been attempted before -- for some very good reasons.

Covering impossible terrain are the last remaining troops of Yunnan snub-nosed monkeys in the world.

They move miles between precipitous valleys to find food.

One smaller troop is easier to follow.

There are eight families in this troop, each with a male and several females and their young.

By March, after months of waiting, the team sees one of the eight families with a newborn.

[ Chattering ] Scientists have only once witnessed a birth.

The other mothers helped like midwives.

The new baby is not alone -- the family has two arrivals.

Two half-brothers.

The mothers have just one baby each every two or three years.

It's too harsh here to support more.

The other mothers and the father need to help.

In a family of six adults, these two half-brothers should both be well looked after.

But cameraman Jacky Poon notices one is neglected.

POON: Each mother treats her babies very differently.

One is great, and one is really hopeless.

She keeps leaving her baby behind.

Maybe she's inexperienced -- I don't know.

It's like she can't really believe that she's a mother now.

Luckily, the rest of the family helps her and looks after the baby as well.

NARRATOR: The other mothers even provide milk.

After a few weeks, his mother still isn't coping.

[ Screeches ] While the other baby is protected and indulged, he's raised haphazardly by the whole family.

POON: The baby is passed around so much from one aunt to another, to the children, we called it the 'Pass the Parcel' baby.

NARRATOR: Neglected babies usually suffer permanent psychological damage compared to those loved and cared for.

But scientific studies also show that a few of those that survive can become tougher and braver.

When everyone is tired of him, he's dumped on dad.

It's unusual in monkeys for the father to be the helpful family type.

POON: They seem to have a very special bond.

He looks after him and grooms him most of the time while his mother is out looking for food.

After observing and filming, we really want to know what happens to these two half-brothers.

It's hard enough finding the monkey troop at all, let alone following one family.

But this is really worth it because of the potential story for each individual that no one has ever seen before.

NARRATOR: The monkeys' lives are part of the wider story of the mountains and the isolated people who live here.

The whole area has hardly been filmed.

[Birds cawing] Hidden from the outside world is an ancient city.

It's called Shangri-La, named after a famous mythical paradise.

Prayer flags and burnt offerings are made by Tibetan Buddhists.

They believe that all mountain life is like a family, and that people and animals need each other, even become each other after death.

In spring, monks from the nearby monastery lead the village yaks up toward the monkeys' forests.

It takes several days, and the calves face many hazards.

[Yak lowing] They are heading for mountain meadows.

The monks will live at 13,000 feet for a few months in some of the highest human homes on Earth.

It's May, and in the forest, the neglected baby is still being passed around the family, and is always hungry.

While his half-brother is cosseted like a prince, he struggles to cope.

Scientists call determination like this 'stress-inoculated resilience.'

One gets everything he needs except freedom.

For the other, neglect becomes a new adventure.

In May, the rhododendron forests welcome sunbirds arriving from miles below.

Scarlet minivets make lichen nests lined with monkey fur.

Alpine butterflies sip on buddleia.

The little adventurer ends up again with his Zen-like father.

These family monkeys are exceptional in the time that they give to each other.

By June, the team is confident that both babies will survive their first six months.

They have time to focus on the wider troop.

Snub-nosed monkeys can travel many miles a day for food.

They find fir trees dripping with lichen like cotton candy.

In winter, there is little else edible in the forest, so the monkeys depend on the lichen.

The Usnea lichen is also a powerful antibiotic and well-known to Chinese medicine.

[Monkeys chattering] The troop of about 100 monkeys is composed of eight self-contained families and about 30 surplus adult males.

They form an all-male group, a gang of bachelors.

A big male stands out.

He is inured in one eye, with a scar falling like a tear from the other.

Everyone seems just a little afraid of him.

He's the pirate king, and his crew act as lookouts.

One day, the team sees what they are watching for.

Over the mountains comes a massive, 500-strong troop, wilder, with no rangers and scientists with them.

Several have lost limbs, probably in snares set for deer.

[Monkeys chattering] When most monkey troops meet, it's very violent.

Outnumbered by five to one, our group hasn't a chance in a fight.

They move to the ground where they're faster.

A few males discreetly swap sides.

The younger females eye the neighbors with interest.

Despite the tension, this isn't a battle.

The troops mix, displaying.

This is more social, like a recruitment drive... with some speed dating.

When time's up, a quarter of the world's population parts peacefully.

Their gentleness is a scientific puzzle.

Lichen is everywhere, so maybe not worth fighting over.

Yet a wild bamboo grove is well worth defending.

Bamboo shoots grow a foot a day, and are full of energy for nursing mothers.

The monkeys look like little Buddhas sometimes.

But to the team, it is more their gentle generosity that links the monkeys and the local monks.

Yunnan snub-nosed monkeys are as rare as giant pandas, which may have once come up here in summer, but are now long gone from these mountains.

After a morning's foraging, the afternoon is for grooming and snoozing.

The little prince has had his milk.

His neglected half-brother is kept alive by the whole family, but he doesn't get as much to eat.

He often forages on his own.

The monkeys eat over 30 different plants, and he's learning them by himself, like a street kid teaching himself to survive.

While the mothers nod off, the cosseted prince makes a bid for freedom.

The two half-brothers play.

[Chattering] Their games include hide-and-seek and ambushing each other, and showing off their gymnastics, and making sure no one else gets any rest.

They are growing up fast.

Jacky Poon sees more new behavior all the time.

POON: Sometimes in the afternoon, after snoozing, the younger monkeys will go with a group of adults, particularly from the all-male group, to go and explore the forest.

It's like a school, really.

They watch each other and learn.

NARRATOR: This temperate forest is one of the botanically richest in the world, with thousands of species.

This is a U.N. World Heritage Site for biodiversity.

Young snub-nosed monkeys learn to hunt for unique beetles and spiders.

Childhood here is drawn out over five years.

Some of these pupils are in their third or fourth year.

In theory, none of this rich diversity should be here.

At 13,000 feet, this is well above the snow line in the Rockies or the Alps.

Something special heats this high paradise.

In August, the secret becomes visible.

[Bird caws] Warmth flows up from the jungles below thanks to a quirk of geography.

Rivers, including the Yangtze and the Mekong, have cut valleys deeper than the Grand Canyon.

Air funnels from Borneo and India as through central-heating pipes.

Below the Himalayas, a few hundred Asian elephants live in Yunnan's river valleys.

These Chinese survivors drink snowmelt from the forested peaks above.

Up in the mountains, two vertical miles higher, the jungle monsoon arrives.

[Thunder rumbles] High on the slopes, it drenches the monkeys and the filming crew.

POON: It feels good coming out here, even when it's raining, pouring down rain, right?

QI: Yeah.

POON: We'll film, but after about an hour, we'll have to take our clothes off and start putting them on the camera just in case the camera gets wet.

Long-term out there, it does get you -- make you a bit crazy, I guess.

NARRATOR: Fruit, like Himalayan dogwood, and cousins of lychees and kiwi fruit, and countless berries, all ripen.

It's the last chance to fill up before the leaves turn.

The two brothers, now six months old, are best friends.

But their world is changing fast.

It's soon time for the monks to leave the alpine meadows.

With help from their neighbors, they are making yak butter -- churning and cooking.

[Singing] NARRATOR: It's used to add to tea, and enjoyed by the filming crew.

POON: They kind of turn it into this frothy tea.

It almost tastes like the English tea, but salty, with more fat.

It warms you up very quickly, and after a while, it even tastes amazing.

NARRATOR: After it's churned and cooked, yak butter is set and shaped.

A summer's milk fat will be carried down to the villages, with some left for the team to keep them going through the winter.

In the thin air, the temperature drops alarmingly fast.

The filming expedition will follow the family despite the increasing cold.

The rangers and scientists camp wherever the monkeys lead them.

Finding a monk's hut is a rare luxury.

POON: Quite a long like today.

It's been -- how long has it been?

-QI: Seven hours? -POON: Seven hours, I think.

We've had about eight people, and four rangers on top, just to carry probably half a ton of equipment.

So, tomorrow we're gonna send out the rangers to check out the monkeys, to track the monkeys down.

QI: It was quite a hard day today.

The weather is not good, and we didn't find the monkeys.

NARRATOR: At dawn, they set off to continue the search.

The rangers use ridges to look for the troop.

POON: Just this morning, I'm coming up, I was in the front with the rangers.

They spotted something.

So, we come up here to an open area to check out this area, and we found some movement, and we're thinking it's monkeys.

So, we pretty much ran over here.

You know, it couldn't be anything else rustling around the trees.

So, quite lucky. It is cold and windy up here.

These monkeys are certainly more tough than us.

NARRATOR: By mid-September, autumn's chill has reached the forest.

The two half-brothers will face their first winter together in the warm arms of the family.

Just behind the peaks is the Tibetan Plateau -- high, flat, and freezing.

Wild yaks eke out an existence.

Chiru, an antelope, live higher than any other.

Alongside are kiang, a wild ass, cousin of the ancestral horse.

This freezing plain now controls the monkeys' lives, as the monsoon did from below only a month before.

Maybe once they could head down to the tropics, but rivers and cities have cut them off, and now they depend on lichen that only grows above 10,000 feet.

They are trapped.

And when they are thirsty, there is only snow.

Each family remains distinct within the troop, nestling close together.

The prince and his half-brother are at the heart of the huddle.

There are dangers here much worse than the cold.

The all-male group is restless.

The leaders would like to have wives and children to keep them warm, and plan a midwinter rebellion.

The violence, when it comes over two nights in January, is all the more shocking from these gentle monkeys.

[Screeches] The battle-scarred bachelor king leads a rare attack on our family in order to steal the females.

[Screeching] Our family dad is thrown out of the tree... and unfortunately killed by the fall.

POON: The scientists found his body a few days later.

He was a great father that looked after the baby very well.

It was such a sad moment for us, for the whole team filming the monkeys.

NARRATOR: The team finds the half-brother alone.

The other mothers are with a new male, a sidekick of the pirate king.

The little prince is in there being comforted.

But mother has probably gone off with another male, leaving her baby behind.

He's truly an orphan now, and the new male wants no part of him.

The troop has other families, and it's possible they could adopt him -- but it's never been seen before.

POON: I really thought he would die.

We all did.

All we can do is hope.

NARRATOR: When things seem at their worst, life sometimes surprises you.

He rallies and follows some birds to collect berries.

The monkeys are not the only ones influenced by hardship.

Buddhism was founded across the Himalayas under the shadow of the harsh mountains.

The monks believe that life is delicate, interconnected, and we should care for it all.

On the edge of the forest, the monks are helping a rare pheasant.

It's in decline, poached for food.

They have bred a small flock, and today they release them with ceremony and prayers.

[Ringing] [Squawks] Tea is poured over a statue that looks a little like a baby monkey.

Buddhists believe that many animals can be kind.

But scientists say that altruism -- kindness -- is rarely, if ever, seen in animals.

These monkeys may be exceptional.

POON: I would say if any animal shows compassion, it's these snub-nosed monkeys.

NARRATOR: The orphan's life is in the hands of the seven other families and a gang of 30 males.

Then the team loses him in the snow.

POON: Finding the orphan was really hard, even with four rangers who knew most of the monkeys by sight.

They're using their incredible eyesight to look for any movement in the distant mountains.

And there's also another ranger up on top also spotting for the monkeys, too.

And for us, we've just got to be quiet, and hopefully we'll get to see the monkeys soon.

But you can see over there, through the distance, just a lot of snow.

So, tracking through these snows really isn't easy.

NARRATOR: Jacky Poon and Wuyuan Qi try to hide in the path of the troop to learn what has happened to the orphaned baby.

POON: I've been here for a couple of hours now, and just waiting for the monkeys that could well be coming across the mountain right in front of me.

I'm spotting for any movements in the trees, and my colleague Wu is down in the gully, and he's looking for movement as well.

We've been told by rangers this morning that the monkeys gonna come across this way.

If they come into this valley, I'm pretty sure we'll get them, either one of us.

So, just trying to be patient.

I'm so happy when the monkeys come by, and I find the orphan on his own.

He's still alive.

NARRATOR: He seems to be searching -- for food, or his half-brother, or his mother.

The team sees him approach other families, ones they've never seen him with before.

The families seem willing to adopt him.

In most monkeys, adoptions are by blood relatives, and infants beg to join them.

These families seem to accept him already.

Maybe he spends the colder nights with them.

Yet he soon leaves.

His independence is extraordinary.

He finds himself in the bachelor group.

Young males all join this gang when they are much older and reaching adulthood.

The bachelors can be dangerous, particularly the battle-scarred king.

Scientists know he led the fatal midwinter attack.

Yet the baby monkey gets closer to his father's killer.

The warrior looks up, but ignores him.

Through March and April, the team are able to stay with the solitary juvenile more easily.

POON: I'm filming one day when the abandoned orphan spots his mother.

It's the first time, as far as I know.

[Chatters] He jumps over to her.

She hasn't got any milk for him.

They hug for ages.

Then her new family moves on and she has to follow.

He just sits there, abandoned all over again.

Then, suddenly, the big male, and probably one of his father's killer, come over and sit next to him.

It's like the big bachelor is being thoughtful.

He offers comfort and friendship.

That was the moment I thought, 'Whoa, these monkey are not like animals at all.'

NARRATOR: To the team, it's a turning point.

The abandoned baby has some surprising friends.

They're unlikely to be close relatives, and there's not much a one-year-old can offer in return -- yet for the moment, the big bachelors seem protective.

Until one day the scar-faced leader chooses a tree that makes it impossible for the little one to follow.

The all-male group above pay no attention.

Maybe they've had enough of their little mascot.

[Crying] The pirate king guards the trunk.

Then a hand reaches down.

The heart of a killer seems to melt.

For the crew and the scientists, it's a remarkable moment.

Spring finally returns again in May.

The monks and their yaks have returned to the high meadows.

It's a disappearing world of milking, churning, and cooking.

Neighbors discuss how the monks and monkeys can be part of a modern China while drinking tea enriched with yak butter.

Above the monks' meadow and the monkeys' forest are peaks famous for their plants and animals.

There are Himalayan blue poppies and snow lotuses -- a plant with fur that's visited by hairy mountain bees.

There's even a Parnassius butterfly that walks between flowers to stay out of the wind.

In June, increasing numbers of people make a long trek here searching for a caterpillar infected by a fungus called cordyceps.

It's been discovered to be a remedy for cancer.

The trade in medicinal plants is lucrative, and the mountains are picked clean.

Little seems sacred to the visitors from the cities below.

Traditionally, the gifts of the mountain gods were respected.

The Buddhist monks hold on to a belief that these mountains somehow contain the secret to understanding life.

[Bird screeches] [Insects buzzing] In a rhododendron glade at 13,000 feet, our lone youngster dines on flowers.

Rhododendrons are generally poisonous, but he's discovered the flowers contain nectar.

Sitting by himself, he watches his old family nearby.

His half-brother, the prince -- his old playmate -- is there having a tantrum.

[Chattering] He's being weaned.

His mother wants to stop his milk.

He's furious.

It's a battle of wills, but his mother seems determined.

Eventually, the spoiled prince gives up and notices his half-brother.

Cameraman Jacky Poon holds his breath.

POON: It's the first time this year I've seen them playing together. It's amazing.

NARRATOR: As young males grow up, they are encouraged to nurture friendships.

It's the first stage of forming the alliances they'll need later in the bachelor group.

POON: It was fun at first, but sadly something went wrong.

The abandoned baby got something in his eye.

He was blinded temporarily, and his playmate ran straight back to his family.

I realized why the little prince was so keen to be with his family -- there was a new little baby just born.

[Whimpers] NARRATOR: With the new arrival, the prince instantly forgets his playmate and his missing milk.

All he wants to do is hold the baby.

Over the next few days, he pesters and waits for his chance.

[Whimpering] Then, one wet afternoon, he gets it.

He's not sure what to do with the baby, but he's not going to give it up.

The newborn's hard to manage -- more than he can handle.

Something's not right.

Panic seems to sweep over the mothers.

[Chattering] POON: Watching, we realized that something's terribly wrong.

The baby is dead.

He's probably just caught a chill or something, which happens quite a lot, but it's very tragic.

The mother carries the baby for three days.

She must know that it's dead, but it's like she can't bear to let go.

NARRATOR: She finally lays it in the leaves on the forest floor.

POON: After the baby's death, the prince goes back to his mother, and she lets him suckle again.

It was like she can't reject him after such a tragedy.

He seems very precious to her and to the family.

NARRATOR: The abandoned orphan is once again forgotten, and will return to the edge of this monkey society.

In autumn, many species of mushroom grow in the forest, and local families at the end of the Baimang Snow Mountain National Park come to collect them.

The head ranger and his family are among them.

Like many of the local Tibetan Buddhists, they are polyandrous.

The ranger's daughter has two husbands -- brothers.

It takes many adults working together to raise even a small family here.

The harsh mountain life creates unusual families among humans as well as monkeys.

[Singing in indigenous language ] NARRATOR: Traditional entertainment competes with television these days.

On TV are the hidden forests and monkeys famous in China, and Xi Zhinong's campaign to take on developers and create the reserve.

The commentary tells of the forest elves that are fearful and have nowhere to go.

[Boy continues singing] The ranger's grandson sings of their forest.

[Singing continues] In summer, the meadows are full of flowers.

For over 100 years, Western plant collectors have brought back azaleas and primroses, snow lotus and poppies, irises, orchids, and rhododendrons from the Himalayas for our gardens.

At the edge of the meadow, the outcast watches.

The cosseted prince grooms his step-father.

Unusually among primates, affection seems not to depend on bloodline.

The forgotten friend sees the little prince move to his mother for milk.

But she refuses.

Once more, he is furious.

[Screeching] His dance of frustration is ignored by all -- except the little orphan, his half-brother.

Everyone else just wants to snooze.

[Screeching continues] The spoiled baby gives up at last and finally comes over to play.

The two half-brothers tussle together, rediscovering a friendship.

Up here, the important things to these monkeys are family and friends.

They return to the trees to play there.

Later, the adults wake, and the little prince returns to his mother.

She still refuses him milk.

[Screeching] It's time to grow up.

From that moment, the two half-brothers are inseparable.

POON: I knew that was it, almost the end of the story.

Except one day, the scar-faced leader of the bachelors got angry at them.

He sits down beside them.

The bachelor king seems to accept them into the gang.

I'm so happy for them.

Some of the older males are brothers, here, too.

Their lives have finally come together.

After so much hardship, the rest of their lives must surely be easier.

They're still here, growing up.

Narrator: Like a chill, civilization is creeping around the mountains, pushing the monkeys higher and into a smaller area.

Xi Zhinong's life's work to save a rare monkey is not over.

But now, the monkeys are famous here as symbols of friendship and kindness.

[Bird caws] Everyone knows of China's rapid growth, but it's not the whole story.

POON: What I want to tell people internationally is to let them know that we're doing something here, you know?

We're doing good things here.

And, you know, we're trying to make a difference.

I think that's probably the most important for me.

NARRATOR: The local monks believe that life flows between us all like smoke.

Anyone who is lost, they say, needs help and kindness and a chance to find their way back -- even a little monkey.