Natural World (1983) s28e03 Episode Script
Clever Monkeys
Even before we knew we were related, we'd always known there was part of them in us, and part of us in them.
We can see ourselves in their faces.
We share a long family history.
A sense of adventure.
Courage.
A society and its battles.
There is an understanding of life and death here.
What makes us human may not be uniquely human after all.
There are wild monkeys all around the world, yet only recently have we discovered just how extraordinary they are.
Jodhpur in India, and the monkey gods are awake.
Monkeys were here first.
We have a handful of other closer cousins, rare forest apes.
But monkeys represent the blueprints on which we are all based.
Some monkeys live with us, and perhaps live more like us than any other animal.
We have no idea what they think and feel.
We can, however, guess.
And there are lots of different scientific theories.
We do know they want to find out about everything, whatever the risks.
Toque macaques will try anything new, imagining rewards behind every closed drawer, tasting every new food.
DOG BARKS SMASH! 40 million years ago, in the ancient tropical forests, there were monkeys.
Our monkey ancestors may have looked a little like this.
Tiny.
In the tropical forests of Ecuador lives the pygmy marmoset, the smallest monkey in the world.
It's the size of a hamster, and it hunts like a cat.
Yet this monkey is closer to us than to cat or hamster.
The eyes face forward and see in 3D and colour, and have a powerful brain behind them.
Hands have fingerprints, and claws are long fingernails.
Being able to grasp physical objects also helps your understanding.
You learn things are there even if you can't see them.
Navigating around a tree is more complicated than flat ground.
Marmosets hold places and objects in their minds.
Once you can picture things, you can perhaps imagine improvements.
The marmoset family seem to.
They "farm" sap from trees.
Taking bites out of the bark has no immediate benefit.
The bark is spat out.
The family makes ordered holes like planting a field of cabbages.
A few days later, a harvest of sugary gum has emerged.
Planning ahead is clever, but so are your neighbours, waiting for you to do all the work.
The family next door launches raids every few days.
The owners are chased off.
And the invaders gobble up as much sap as they can.
The owners scent mark, which seems to give them new confidence.
They rally their forces, charge and chase off the neighbours.
A long time ago, the monkey mind turned to improving their world, and farming and warfare took root.
Monkeys lived together to defend food and watch for predators, and numerous little societies sprang up.
Each species made its own discoveries and customs.
Marmosets and tamarins will often share childcare.
The female emperor tamarin nearly always has twins, and she persuades two males to help look after them.
Their mother carries them, with the two fathers, neither certain of paternity, obediently in tow.
When mum wants to offload the kids, she signals to her mates with her tongue.
An obsession with their young, we now realise, is one of the things that is basic to all monkeys.
The infants have a father each to look after them, so mum goes to feed on nectar.
There's something curious about monkey babies.
The silver leaf monkey, for example, has orange young.
It's risky with predators around, it advertises defencelessness.
But to the family, it says, "Help me, look after me.
" Adults respond by worrying more, and devoting more time than if the baby wasn't so obviously vulnerable.
So young monkeys can stay being babies longer.
Childhood in monkeys is not primarily about a growing body, but a growing mind.
A young brain searches for understanding in slow stages, hands reaching out, working out what things are, and how they work.
A baby monkey slowly builds its understanding of the world and of others around them.
As physical growing slows down, so monkeys have time to wise up.
Awareness dawns in infancy.
Intelligence awakes and takes control.
These white-faced capuchins in Central America are very clever.
In fact, capuchin monkeys have a larger brain for their size than any of our closer ape cousins.
One group near the coast is able to track the tides.
When the water retreats, clams are exposed, and easy to collect.
But not so easy to open.
The trick is to roll and bang the clams hard, and often for a long time.
The thought of what's inside is what keeps them going.
It's hardly fast food.
Monkeys, like us, imagine food they can't yet see, and it drives them on.
After ten minutes, the clams start to weaken and the capuchins can pull open the shells.
If you're disappointed, it can only be because you've imagined more.
Opening clams is just the beginning.
Some troops have discovered how to get the best out of termite mounds, or reach water by using their tail as a sponge.
The young learn from their parents.
They have what scientists call a culture.
Monkey culture.
But the most important things for monkeys to understand are their fellow monkeys.
Outsmarting each other can make the difference between life and death.
Most animals are wary of outsiders, and defend their territory.
In monkeys, this has become a battle of wits.
The capuchins move around like chess pieces, testing their defences, trying to trap unwary scouts.
Previous battles and old grudges fuel the aggression.
In monkey society, everyone is an individual, and different rules can apply.
Friends fight for each other.
Rivals and foreigners can be killed if you can catch them.
Our feelings for friends and enemies are chillingly similar.
This is part of our nature too.
More capuchins are killed by each other than by any predator.
The invaders retreat, with nothing gained from the battle except injuries.
If murder and morality have roots in our past, then so too does compassion.
The fighters return, and are soothed and nursed.
Hands that when they were tiny explored the world and opened a mind, now demonstrate a gentle understanding of others.
Grooming does more than clean wounds and remove parasites.
It shows respect and affection.
Monkeys' attention to their health goes even further.
Some monkeys have discovered a few simple medicines.
The leaves of the Piper plant are antiseptic, and used by people here in Costa Rica as an insect repellent.
When a capuchin finds a Piper plant, they all become very excited, sharing, rubbing, disinfecting, and turning it into a party.
Self-medication becomes a social event.
We do the same.
Think of tea and alcohol.
A need to try everything is an extraordinary way to survive in the jungle.
Here are leaves that can cure disease or repel insects, feed you or poison you.
Knowledge, technology and culture are rooted here in the forest, in the hands of monkeys.
In Sri Lanka, toque macaques fish for caterpillars.
The caterpillars hang from the end of silk threads, but monkey hands can reel them in.
Local knowledge and their unique culture are what they live by.
They know a nearby lake is guarded by a six-foot monkey-eating monitor lizard.
Trust monkeys to find a way to reach the delicious lily flowers, safe from the monitor lizard.
Only the high born, the dominant in the monkey society are allowed to use these overhanging branches.
Those at the bottom of the social scale have to take bigger risks.
They take turns to watch for the monitor lizard.
While the guards are alert, it's pretty safe.
These lower ranking toque macaques will actually dive for lily roots and bulbs.
Little of this amazing behaviour is instinctive.
It was discovered, learned, and passed down the generations.
Keeping an eye out for your family and friends is an important part of their culture too.
Instincts in animals generally are automatic, restrictive but reliable.
But learning can be forgotten, and concentration can lapse.
What must a monkey guard feel when a youngster is lost on their watch? We can't know what they are thinking, but they behave in a way that we imagine we recognise.
Another of the troop has been killed in a fight.
He was the leader.
It was a battle for control of the group.
They are unusually silent as they gather around.
The victorious new leader watches from the side, his injuries ignored.
He does not interfere.
Some who brought about the old leader's downfall are now tender and respectful.
For many years he had been an ally, or a mate.
He'd been a caring father to a whole generation of young.
As scientists trace human qualities and feelings further back in time, so modern monkeys seem less "animal", more like rediscovered relatives.
Many are very rare, like the golden lion tamarin.
There's so much to discover.
Why does the white uakari in the Amazon think a red face a good sign? Or the golden snub-nosed monkey in China have blue eye shadow? Why does the emperor tamarin have a moustache? The weirdest may be the proboscis monkey in Borneo, with a 9" nose, and a fermenting stomach like a cow.
Perhaps the most beautiful is the Douc monkey of Cambodia.
Every monkey has its own different character and story.
Howler monkeys call to declare territory.
Lions roar and nightingales sing for the same reason.
Howlers have a silent duet too.
It's a love song, though in us it would be considered a little rude.
All animals instinctively pair together.
But if monkeys are at all sensitive, if they can guess what another monkey may be thinking, if they have memories and make plans for the future, it must be surprisingly close to how we feel.
We give words to thoughts and feelings.
Without words, is thinking even possible? The jungle to us may seem a cacophony of meaningless sounds.
Each animal listens to its own calls, and usually tunes out the rest.
But some monkeys are multilingual.
Guenons live here and there are several species of them.
Each has its own calls for communicating with other members of its troop.
These Diana monkeys have joined an army of other guenons - a United Nation of monkeys, and that requires them to understand each other.
On the forest floor live sooty mangabeys.
They specialize in gathering fallen nuts.
Above are red colobus, spot-nosed and putty-nosed guenons, black and white colobus, Campbell's guenon, and the Diana monkey which live mainly in the upper canopy.
These monkeys all behave as though they're one troop, moving through the forest together, resting together, and all looking out for predators.
On the forest floor the sooty mangabey can rely on the eyes and ears above and relax, thanks to the alliance.
If a red colobus spots something like a snake, it gives the red colobus alarm call for, "Snake".
A spot-nosed guenon reacts immediately.
If a Diana monkey high in the tree sees an eagle, the alarm goes up, "Eagle" and all the monkeys look up.
Each species has a different alarm call, but they all understand each other.
With 8 different monkeys, and about 15 calls each, that's 120 different sounds.
The Mangabeys see a leopard.
All the other monkeys call, "Leopard", in their own way, but there are other calls in there too.
Diana monkeys have been the most studied.
Their ability to understand other species gives scientists a running translation of other monkey calls.
If Diana monkeys hear a string of calls by a Campbell's guenon, say, they behave as if they were hearing a sentence.
Some calls add detail - "Maybe," or "Not urgent.
" With another guenon, if the sounds are in a different order, it means something else.
Grammar, the basis of true language, was once thought of as uniquely human.
Chimps have not yet been shown to have this ability in the wild - only monkeys and people.
Diana monkeys also have a voice box more like ours, so alarm calls may be only a small part of their vocabulary.
If talking is an ancient monkey ability, we should find something similar in other monkeys around the world.
In forests from Africa to South America scientists have found monkeys whose calls refer to predators.
But do they ever use sounds for things when they can't see them, when they are just thinking about them? The white faced capuchins in Costa Rica live by streams full of danger.
They are nervous, maybe imagining death lurking under every log or pile of leaves.
They too have put sounds to some of their fears, and have different calls for different predators.
A call goes up, "Snake!" The whole troop leaps out of the water and up into the trees.
They soon calm down.
Once noticed, most predators are of little danger.
The warning system is built on trust and honesty.
Yet, very occasionally, some monkeys deliberately shout an alarm call when there is no snake there.
The reason for this deception lies in the fact that monkey society is very competitive.
The leaders often take food from subordinates.
The problem for a low-status monkey is not just finding food, it's hanging on to it, and sometimes they have to be a little crafty.
Suppose a subordinate is acting a little strangely, watching the others closely.
He then could, without any obvious panic, call, "Snake," and everybody leaps out of the water.
While the others are looking for snakes, he could sneak down and recover a fallen bird's egg he could have been hiding.
The leaders slowly return to the pool.
It seems that lying may be as old as language itself.
If our little manipulator is spotted with his egg, he's in big trouble.
This sort of deception has been noticed in several species.
It shows they imagine things when they're not visible, and it implies they are beginning to think about what each other may be thinking about.
Millions of years ago some monkeys reached this point, and then took another huge leap into the unknown.
They left the forest.
Open grassland is a hard place in which to survive.
Fruits and flowers are scarce.
There's nowhere to escape, and some very dangerous predators.
Baboons have grown larger than forest monkeys and 80 or so baboons stick together for defence.
They are wary and aggressive.
The big males will often go on the attack.
The young are helpless.
Most animals here run from birth.
Gazelles and baboons feed together, both watching for predators.
The baboons make do with tough plants, insects and grass mainly.
The fawns assume the baboons are allies, and don't realise that monkeys also eat meat.
When our ancestors left the trees, we changed too, and became more predatory and dangerous than the apes and monkeys we left behind in the forest.
There's more to learn in larger and more volatile societies.
All monkeys can be murderous, but baboons seem closer to violence, as though anger and frustration were just under the surface.
The lower ranking males find failing ambition very stressful, and become neurotic, with high blood pressure and ulcers.
High ranking males are dictatorial bullies while their power lasts, but when deposed become ill and have symptoms of depression.
Baboon society shares many of our problems.
We're psychologically similar.
Of course there are huge differences, but if you want to imagine your early ancestor on a hunt, think baboon.
A clever political mind is essential in large groups.
So the cleverest monkeys should be found in the biggest troops, equivalent to our towns or cities.
In the Simien Mountains of Ethiopia live huge herds of geladas.
Speeded up, they move like an army.
Groups of mothers and their young, a harem, gather together to form troops of up to 800 monkeys.
Geladas' hands are usually busy plucking grass instead of grooming, so to keep in touch, geladas have become the chattiest of all monkeys.
The gossipy banter can sound to scientists like sentences with words or even names for each other.
Most agree it's often used to defuse tension.
In geladas, there's a lot to be tense about.
There are gangs of young males trying to steal away the women from the family harems.
Each handful of females is guarded by a single male, the harem master.
The spare boys try and tempt the girls away, hoping the resident father figure doesn't notice.
The males flash teeth at each other.
They may fight, but it's usually just showing off, in case the girls are watching.
There's a lot of flirting on both sides.
And then if an innocent looking female is tempted to wander off past her guardian, he has to decide what to do.
Girls mostly sneak off secretly for affairs.
This is a blatant challenge to his authority.
The illicit couple just sit.
The suitor seems to be using his hand to hide his grimace.
He probably doesn't want trouble.
Chimps, baboons and macaques may also try to look innocent when they break the rules.
This is a complicated social problem.
Using your brain to control societies is called Machiavellian Intelligence, after a sixteenth century courtier who wrote on manipulating political power.
Instead of launching into an attack, the politician here tries to grab a baby.
Monkey etiquette dictates nobody attacks anyone holding a baby, so they are like living flak jackets.
The mothers are worried, and quickly scoop up the youngest.
Here, the two males face each other.
The family man backs towards one of his more loyal wives, calling for support.
One of the youngsters suddenly switches from mother to father.
This should calm things down.
With the youngster attached, the father is protected, and the harem should unite.
But it can go wrong.
The youngster is slipping off.
The family are frantic.
The harem master has no protection from attack.
The bachelor is finally driven off, with a little help from the mothers.
But the fathers are meant to guard the precious young.
He knows he's in all sorts of trouble.
If the infant dies, the mothers may not support him again.
Our brain too, wrestles with our own similar problems.
We are as social and as competitive.
Intelligence sweeps in through monkey evolution, to apes and us, and leaves a chilling legacy.
Becoming clever can mean being controlling, stressed, perhaps unhappy.
The females are plotting, worrying for their young.
He worries about other males stealing his girls.
All of them are thinking about whom they can trust.
Is this the pinnacle of monkey brainpower? Monkeys also set us on a path towards co-operation, planning, tool-making and technology.
The cleverest monkey perhaps took that path too.
Stone slabs have been found in the forests of Brazil that have been worn into hollows, apparently by prehistoric people, using stone hammers.
It turns out they were not made by humans at all.
A bearded capuchin monkey starts the processing of palm nuts by tapping them to see if they are ripe.
There are only 20 or 30 monkeys in a group, with fewer social pressures.
They are thinkers and doers, not chatterers.
The ripest palm nuts are stripped of their outer case ready to be dropped on to the ground to dry out, which will take about three days.
Each stage seems very well co-ordinated, a routine in a monkey culture, choreographed to perfection.
Tapping again tells the monkeys which ones are ready.
The next stage may take place at the other end of the valley, the nut-cracking site.
The hammers are of a harder stone, brought up from the river beds by the monkeys.
They are heavy - some as heavy as the monkey itself.
Palm nuts are extremely hard and difficult to crack open.
It only works if you get it exactly right.
Somehow these clever monkeys get amazingly good at it.
Collecting a ripe nut has taken days of harvesting, testing, ripening, transportation, collecting tools and choosing sites, not forgetting years of learning in the nut-cracking school.
The Year Two class is still wrestling with the basics.
The sounds echo through the forest.
Jaguars know it's monkeys at work.
The capuchins always select their sites carefully, preferably below the edge of the escarpment.
But it's more than just an escape route.
We are increasingly realising we are not the only intelligent life on the planet.
40 million years ago, it seems, there were creatures with hands and eyes who took great care of their babies because they took a long time to grow up.
The story has ended up with us, seeing ourselves in their faces.
We can be proud of the fact that what makes us human isn't just human after all.
Next week, Natural World reports on a mysterious die-off of India's endangered gharial crocodiles.
For the second time Rom Whittaker is battling to bring this ancient species back from the brink.
E- mail subtitling@bbc.
co.
uk
We can see ourselves in their faces.
We share a long family history.
A sense of adventure.
Courage.
A society and its battles.
There is an understanding of life and death here.
What makes us human may not be uniquely human after all.
There are wild monkeys all around the world, yet only recently have we discovered just how extraordinary they are.
Jodhpur in India, and the monkey gods are awake.
Monkeys were here first.
We have a handful of other closer cousins, rare forest apes.
But monkeys represent the blueprints on which we are all based.
Some monkeys live with us, and perhaps live more like us than any other animal.
We have no idea what they think and feel.
We can, however, guess.
And there are lots of different scientific theories.
We do know they want to find out about everything, whatever the risks.
Toque macaques will try anything new, imagining rewards behind every closed drawer, tasting every new food.
DOG BARKS SMASH! 40 million years ago, in the ancient tropical forests, there were monkeys.
Our monkey ancestors may have looked a little like this.
Tiny.
In the tropical forests of Ecuador lives the pygmy marmoset, the smallest monkey in the world.
It's the size of a hamster, and it hunts like a cat.
Yet this monkey is closer to us than to cat or hamster.
The eyes face forward and see in 3D and colour, and have a powerful brain behind them.
Hands have fingerprints, and claws are long fingernails.
Being able to grasp physical objects also helps your understanding.
You learn things are there even if you can't see them.
Navigating around a tree is more complicated than flat ground.
Marmosets hold places and objects in their minds.
Once you can picture things, you can perhaps imagine improvements.
The marmoset family seem to.
They "farm" sap from trees.
Taking bites out of the bark has no immediate benefit.
The bark is spat out.
The family makes ordered holes like planting a field of cabbages.
A few days later, a harvest of sugary gum has emerged.
Planning ahead is clever, but so are your neighbours, waiting for you to do all the work.
The family next door launches raids every few days.
The owners are chased off.
And the invaders gobble up as much sap as they can.
The owners scent mark, which seems to give them new confidence.
They rally their forces, charge and chase off the neighbours.
A long time ago, the monkey mind turned to improving their world, and farming and warfare took root.
Monkeys lived together to defend food and watch for predators, and numerous little societies sprang up.
Each species made its own discoveries and customs.
Marmosets and tamarins will often share childcare.
The female emperor tamarin nearly always has twins, and she persuades two males to help look after them.
Their mother carries them, with the two fathers, neither certain of paternity, obediently in tow.
When mum wants to offload the kids, she signals to her mates with her tongue.
An obsession with their young, we now realise, is one of the things that is basic to all monkeys.
The infants have a father each to look after them, so mum goes to feed on nectar.
There's something curious about monkey babies.
The silver leaf monkey, for example, has orange young.
It's risky with predators around, it advertises defencelessness.
But to the family, it says, "Help me, look after me.
" Adults respond by worrying more, and devoting more time than if the baby wasn't so obviously vulnerable.
So young monkeys can stay being babies longer.
Childhood in monkeys is not primarily about a growing body, but a growing mind.
A young brain searches for understanding in slow stages, hands reaching out, working out what things are, and how they work.
A baby monkey slowly builds its understanding of the world and of others around them.
As physical growing slows down, so monkeys have time to wise up.
Awareness dawns in infancy.
Intelligence awakes and takes control.
These white-faced capuchins in Central America are very clever.
In fact, capuchin monkeys have a larger brain for their size than any of our closer ape cousins.
One group near the coast is able to track the tides.
When the water retreats, clams are exposed, and easy to collect.
But not so easy to open.
The trick is to roll and bang the clams hard, and often for a long time.
The thought of what's inside is what keeps them going.
It's hardly fast food.
Monkeys, like us, imagine food they can't yet see, and it drives them on.
After ten minutes, the clams start to weaken and the capuchins can pull open the shells.
If you're disappointed, it can only be because you've imagined more.
Opening clams is just the beginning.
Some troops have discovered how to get the best out of termite mounds, or reach water by using their tail as a sponge.
The young learn from their parents.
They have what scientists call a culture.
Monkey culture.
But the most important things for monkeys to understand are their fellow monkeys.
Outsmarting each other can make the difference between life and death.
Most animals are wary of outsiders, and defend their territory.
In monkeys, this has become a battle of wits.
The capuchins move around like chess pieces, testing their defences, trying to trap unwary scouts.
Previous battles and old grudges fuel the aggression.
In monkey society, everyone is an individual, and different rules can apply.
Friends fight for each other.
Rivals and foreigners can be killed if you can catch them.
Our feelings for friends and enemies are chillingly similar.
This is part of our nature too.
More capuchins are killed by each other than by any predator.
The invaders retreat, with nothing gained from the battle except injuries.
If murder and morality have roots in our past, then so too does compassion.
The fighters return, and are soothed and nursed.
Hands that when they were tiny explored the world and opened a mind, now demonstrate a gentle understanding of others.
Grooming does more than clean wounds and remove parasites.
It shows respect and affection.
Monkeys' attention to their health goes even further.
Some monkeys have discovered a few simple medicines.
The leaves of the Piper plant are antiseptic, and used by people here in Costa Rica as an insect repellent.
When a capuchin finds a Piper plant, they all become very excited, sharing, rubbing, disinfecting, and turning it into a party.
Self-medication becomes a social event.
We do the same.
Think of tea and alcohol.
A need to try everything is an extraordinary way to survive in the jungle.
Here are leaves that can cure disease or repel insects, feed you or poison you.
Knowledge, technology and culture are rooted here in the forest, in the hands of monkeys.
In Sri Lanka, toque macaques fish for caterpillars.
The caterpillars hang from the end of silk threads, but monkey hands can reel them in.
Local knowledge and their unique culture are what they live by.
They know a nearby lake is guarded by a six-foot monkey-eating monitor lizard.
Trust monkeys to find a way to reach the delicious lily flowers, safe from the monitor lizard.
Only the high born, the dominant in the monkey society are allowed to use these overhanging branches.
Those at the bottom of the social scale have to take bigger risks.
They take turns to watch for the monitor lizard.
While the guards are alert, it's pretty safe.
These lower ranking toque macaques will actually dive for lily roots and bulbs.
Little of this amazing behaviour is instinctive.
It was discovered, learned, and passed down the generations.
Keeping an eye out for your family and friends is an important part of their culture too.
Instincts in animals generally are automatic, restrictive but reliable.
But learning can be forgotten, and concentration can lapse.
What must a monkey guard feel when a youngster is lost on their watch? We can't know what they are thinking, but they behave in a way that we imagine we recognise.
Another of the troop has been killed in a fight.
He was the leader.
It was a battle for control of the group.
They are unusually silent as they gather around.
The victorious new leader watches from the side, his injuries ignored.
He does not interfere.
Some who brought about the old leader's downfall are now tender and respectful.
For many years he had been an ally, or a mate.
He'd been a caring father to a whole generation of young.
As scientists trace human qualities and feelings further back in time, so modern monkeys seem less "animal", more like rediscovered relatives.
Many are very rare, like the golden lion tamarin.
There's so much to discover.
Why does the white uakari in the Amazon think a red face a good sign? Or the golden snub-nosed monkey in China have blue eye shadow? Why does the emperor tamarin have a moustache? The weirdest may be the proboscis monkey in Borneo, with a 9" nose, and a fermenting stomach like a cow.
Perhaps the most beautiful is the Douc monkey of Cambodia.
Every monkey has its own different character and story.
Howler monkeys call to declare territory.
Lions roar and nightingales sing for the same reason.
Howlers have a silent duet too.
It's a love song, though in us it would be considered a little rude.
All animals instinctively pair together.
But if monkeys are at all sensitive, if they can guess what another monkey may be thinking, if they have memories and make plans for the future, it must be surprisingly close to how we feel.
We give words to thoughts and feelings.
Without words, is thinking even possible? The jungle to us may seem a cacophony of meaningless sounds.
Each animal listens to its own calls, and usually tunes out the rest.
But some monkeys are multilingual.
Guenons live here and there are several species of them.
Each has its own calls for communicating with other members of its troop.
These Diana monkeys have joined an army of other guenons - a United Nation of monkeys, and that requires them to understand each other.
On the forest floor live sooty mangabeys.
They specialize in gathering fallen nuts.
Above are red colobus, spot-nosed and putty-nosed guenons, black and white colobus, Campbell's guenon, and the Diana monkey which live mainly in the upper canopy.
These monkeys all behave as though they're one troop, moving through the forest together, resting together, and all looking out for predators.
On the forest floor the sooty mangabey can rely on the eyes and ears above and relax, thanks to the alliance.
If a red colobus spots something like a snake, it gives the red colobus alarm call for, "Snake".
A spot-nosed guenon reacts immediately.
If a Diana monkey high in the tree sees an eagle, the alarm goes up, "Eagle" and all the monkeys look up.
Each species has a different alarm call, but they all understand each other.
With 8 different monkeys, and about 15 calls each, that's 120 different sounds.
The Mangabeys see a leopard.
All the other monkeys call, "Leopard", in their own way, but there are other calls in there too.
Diana monkeys have been the most studied.
Their ability to understand other species gives scientists a running translation of other monkey calls.
If Diana monkeys hear a string of calls by a Campbell's guenon, say, they behave as if they were hearing a sentence.
Some calls add detail - "Maybe," or "Not urgent.
" With another guenon, if the sounds are in a different order, it means something else.
Grammar, the basis of true language, was once thought of as uniquely human.
Chimps have not yet been shown to have this ability in the wild - only monkeys and people.
Diana monkeys also have a voice box more like ours, so alarm calls may be only a small part of their vocabulary.
If talking is an ancient monkey ability, we should find something similar in other monkeys around the world.
In forests from Africa to South America scientists have found monkeys whose calls refer to predators.
But do they ever use sounds for things when they can't see them, when they are just thinking about them? The white faced capuchins in Costa Rica live by streams full of danger.
They are nervous, maybe imagining death lurking under every log or pile of leaves.
They too have put sounds to some of their fears, and have different calls for different predators.
A call goes up, "Snake!" The whole troop leaps out of the water and up into the trees.
They soon calm down.
Once noticed, most predators are of little danger.
The warning system is built on trust and honesty.
Yet, very occasionally, some monkeys deliberately shout an alarm call when there is no snake there.
The reason for this deception lies in the fact that monkey society is very competitive.
The leaders often take food from subordinates.
The problem for a low-status monkey is not just finding food, it's hanging on to it, and sometimes they have to be a little crafty.
Suppose a subordinate is acting a little strangely, watching the others closely.
He then could, without any obvious panic, call, "Snake," and everybody leaps out of the water.
While the others are looking for snakes, he could sneak down and recover a fallen bird's egg he could have been hiding.
The leaders slowly return to the pool.
It seems that lying may be as old as language itself.
If our little manipulator is spotted with his egg, he's in big trouble.
This sort of deception has been noticed in several species.
It shows they imagine things when they're not visible, and it implies they are beginning to think about what each other may be thinking about.
Millions of years ago some monkeys reached this point, and then took another huge leap into the unknown.
They left the forest.
Open grassland is a hard place in which to survive.
Fruits and flowers are scarce.
There's nowhere to escape, and some very dangerous predators.
Baboons have grown larger than forest monkeys and 80 or so baboons stick together for defence.
They are wary and aggressive.
The big males will often go on the attack.
The young are helpless.
Most animals here run from birth.
Gazelles and baboons feed together, both watching for predators.
The baboons make do with tough plants, insects and grass mainly.
The fawns assume the baboons are allies, and don't realise that monkeys also eat meat.
When our ancestors left the trees, we changed too, and became more predatory and dangerous than the apes and monkeys we left behind in the forest.
There's more to learn in larger and more volatile societies.
All monkeys can be murderous, but baboons seem closer to violence, as though anger and frustration were just under the surface.
The lower ranking males find failing ambition very stressful, and become neurotic, with high blood pressure and ulcers.
High ranking males are dictatorial bullies while their power lasts, but when deposed become ill and have symptoms of depression.
Baboon society shares many of our problems.
We're psychologically similar.
Of course there are huge differences, but if you want to imagine your early ancestor on a hunt, think baboon.
A clever political mind is essential in large groups.
So the cleverest monkeys should be found in the biggest troops, equivalent to our towns or cities.
In the Simien Mountains of Ethiopia live huge herds of geladas.
Speeded up, they move like an army.
Groups of mothers and their young, a harem, gather together to form troops of up to 800 monkeys.
Geladas' hands are usually busy plucking grass instead of grooming, so to keep in touch, geladas have become the chattiest of all monkeys.
The gossipy banter can sound to scientists like sentences with words or even names for each other.
Most agree it's often used to defuse tension.
In geladas, there's a lot to be tense about.
There are gangs of young males trying to steal away the women from the family harems.
Each handful of females is guarded by a single male, the harem master.
The spare boys try and tempt the girls away, hoping the resident father figure doesn't notice.
The males flash teeth at each other.
They may fight, but it's usually just showing off, in case the girls are watching.
There's a lot of flirting on both sides.
And then if an innocent looking female is tempted to wander off past her guardian, he has to decide what to do.
Girls mostly sneak off secretly for affairs.
This is a blatant challenge to his authority.
The illicit couple just sit.
The suitor seems to be using his hand to hide his grimace.
He probably doesn't want trouble.
Chimps, baboons and macaques may also try to look innocent when they break the rules.
This is a complicated social problem.
Using your brain to control societies is called Machiavellian Intelligence, after a sixteenth century courtier who wrote on manipulating political power.
Instead of launching into an attack, the politician here tries to grab a baby.
Monkey etiquette dictates nobody attacks anyone holding a baby, so they are like living flak jackets.
The mothers are worried, and quickly scoop up the youngest.
Here, the two males face each other.
The family man backs towards one of his more loyal wives, calling for support.
One of the youngsters suddenly switches from mother to father.
This should calm things down.
With the youngster attached, the father is protected, and the harem should unite.
But it can go wrong.
The youngster is slipping off.
The family are frantic.
The harem master has no protection from attack.
The bachelor is finally driven off, with a little help from the mothers.
But the fathers are meant to guard the precious young.
He knows he's in all sorts of trouble.
If the infant dies, the mothers may not support him again.
Our brain too, wrestles with our own similar problems.
We are as social and as competitive.
Intelligence sweeps in through monkey evolution, to apes and us, and leaves a chilling legacy.
Becoming clever can mean being controlling, stressed, perhaps unhappy.
The females are plotting, worrying for their young.
He worries about other males stealing his girls.
All of them are thinking about whom they can trust.
Is this the pinnacle of monkey brainpower? Monkeys also set us on a path towards co-operation, planning, tool-making and technology.
The cleverest monkey perhaps took that path too.
Stone slabs have been found in the forests of Brazil that have been worn into hollows, apparently by prehistoric people, using stone hammers.
It turns out they were not made by humans at all.
A bearded capuchin monkey starts the processing of palm nuts by tapping them to see if they are ripe.
There are only 20 or 30 monkeys in a group, with fewer social pressures.
They are thinkers and doers, not chatterers.
The ripest palm nuts are stripped of their outer case ready to be dropped on to the ground to dry out, which will take about three days.
Each stage seems very well co-ordinated, a routine in a monkey culture, choreographed to perfection.
Tapping again tells the monkeys which ones are ready.
The next stage may take place at the other end of the valley, the nut-cracking site.
The hammers are of a harder stone, brought up from the river beds by the monkeys.
They are heavy - some as heavy as the monkey itself.
Palm nuts are extremely hard and difficult to crack open.
It only works if you get it exactly right.
Somehow these clever monkeys get amazingly good at it.
Collecting a ripe nut has taken days of harvesting, testing, ripening, transportation, collecting tools and choosing sites, not forgetting years of learning in the nut-cracking school.
The Year Two class is still wrestling with the basics.
The sounds echo through the forest.
Jaguars know it's monkeys at work.
The capuchins always select their sites carefully, preferably below the edge of the escarpment.
But it's more than just an escape route.
We are increasingly realising we are not the only intelligent life on the planet.
40 million years ago, it seems, there were creatures with hands and eyes who took great care of their babies because they took a long time to grow up.
The story has ended up with us, seeing ourselves in their faces.
We can be proud of the fact that what makes us human isn't just human after all.
Next week, Natural World reports on a mysterious die-off of India's endangered gharial crocodiles.
For the second time Rom Whittaker is battling to bring this ancient species back from the brink.
E- mail subtitling@bbc.
co.
uk