DEMON ROAR
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A beautiful little island off the eastern coast of Puerto Rico.
The perfect spot for a luxurious Caribbean resort.
But there are no hotels, no condominiums, no people.
And yet, the island of Cayo Santiago is inhabited by monkeys.
The island is a beautiful island.
And yet, the island of Cayo Santiago is inhabited by monkeys.
These rhesus macaques are descendants of a group of 400 brought here from India in 1938
by scientists from Columbia University in New York.
Their original purpose was to establish a breeding colony
to provide monkeys for scientific research
and as a field site for the study of primate behavior.
Today, primate behavior is the main focus of the scientific work being done here.
In fact, these monkeys on this tiny island are some of the most important monkeys in the world.
Because it's from them that we human primates are learning
remarkable and exciting new things about primate behavior.
The more we learn about them, the more we learn about ourselves.
Music
Rhesus macaques, ground-dwelling monkeys from Asia, have been living free on Cayo Santiago for half a century,
teaching us what it means to be a primate.
First, you have to understand their silent body language.
The affection between mother and offspring needs no translation.
But the subtle shifts in position that show the macaques' relationships to one another are not so obvious.
Each macaque is acutely aware of its social ranking.
Theirs is a highly ordered, highly stratified society.
But they need to know more than who is dominant over whom.
They must also know each character as an individual.
Macaques of low status keep a sharp eye out for their betters, and especially for those known to be aggressive.
This dominant male is a bully. He goes out of his way to threaten and terrorize his subordinates.
They cut him a wide berth. Not all dominant males are this belligerent.
He seems to be looking for trouble, just waiting to catch someone too close.
John Berard is the latest in a series of innovative researchers captivated by the riddles of the rhesus.
Scientists at the Caribbean Primate Center have been deciphering the nuances of macaque behavior for 50 years.
But always there seem to be new and deeper puzzles to solve.
I came to Cayo, Santiago six years ago, thinking I would stay for only a few months.
Shortly after I arrived, I was both captivated and mystified by the behavior of one particular male.
He was both dominant and aggressive, being ranked fifth out of 50 monkeys in his group.
He was undoubtedly the most aggressive male in the group.
Other monkeys, both male and female, would jump away and grimace at his approach.
It seemed to me that his position in the male dominance hierarchy was firmly established.
Then suddenly he disappeared. He was found no place on the island.
Two weeks later, I saw him again with his social group.
But instead of being the dominant aggressive male I had known, his behavior changed.
He was now submissive, grimacing and cowering as if he were a submissive animal.
I remember seeing him coming back to the group after his disappearance.
As he approached, instead of chasing animals and of animals fleeing from him,
he sat meekly and passively on the outside of the group.
His main activity was now looking around nervously, being alert for the presence of other males.
Instead of boldly being aggressive, he was now fearful of being attacked.
I then realized that after being gone for only two weeks, he had dropped in rank from being a very dominant monkey
to being at the very bottom of the adult male hierarchy.
A baby macaque is born into a complicated world,
but at first it seems to contain only one other important being, mother.
Ever vigilant, loving and patient, she coaxes the infant to take its first steps.
Less than a week old, it has already begun the journey that will lead it into a complex society.
Soon its world expands to include its mother's family.
This is its matriline, grandmother, aunts, sisters and their young.
The social status of this all-important female clan influences a macaque's entire life.
But mother remains at the center of the infant's universe.
Not only does she supply food and affection,
she backs up her offspring in its every interaction with the larger macaque society.
With its mother's support, the infant begins the gradual process of learning about an unfamiliar world.
A calm and secure mother will instill these qualities in her offspring,
providing it with the necessary courage to venture away on voyages of discovery,
often in search of something good to eat.
There are far more difficult things to learn about this wondrous world than what to eat,
and knowledge does not come without some risk.
A macaque will spend a lifetime learning the rules that govern proper rhesus behavior.
Number one is simple, never wander too far from mother's protective embrace.
Macaques are seasonal breeders, and each winter a crop of newborns enters the extended family.
At first, they socialize with only their closest relatives.
These two are the offspring of a mother and her daughter, who keep a close watch.
Already differences in their personalities are beginning to show.
One baby is timid and reserved, the other bold and adventurous.
Being in the bosom of an extended family of adoring females can be a mixed blessing.
Seeing the little one unattended, a young female cousin cannot resist smothering it with affection.
It's all the baby can do to make it back to mother's comforting breast,
leaving only a foot and a cautious look for its ardent cousin.
These wobbly, curious little creatures are irresistible to females too young to have babies of their own.
But this would-be babysitter belongs to a different, less dominant family,
and she's quickly displaced by the infant's real aunt.
This kind of anting behavior is vital to both the babysitter and her charge.
The young aunt needs to learn how to be a good mother,
and the baby needs to know the members of its family, with which it will share much of its life.
Occasionally, though, infants are accidentally injured or even killed by these inexperienced doting aunts.
The baby's mother, the aunt's older sister, decides this has gone far enough.
The aunt tries to pacify her sister by grooming her, a calming and bonding activity.
They're joined by the grandmother, who grooms her youngest daughter.
Mother macaques always favor their youngest daughters.
Secure in her own mother's presence, the young aunt tries again for the baby.
Tired of this struggle, the mother walks off.
But aunt and grandmother aren't far behind.
With her mother's backing, the aunt tries one more grab for the baby.
The grandmother rises in her defense and threatens the uncooperative mother.
As a female gets older, she tends to drop in rank.
When a female is born, she takes the rank immediately following her mother's in the dominance hierarchy.
In this way, each female birth causes all the females in the group lower than her mother to fall one step.
The only exception is the female at the very top of the hierarchy, the alpha female,
who enjoys her position for her entire life.
These female matrilines form the bedrock of macaque society and are peaceful and nurturing.
As many as four different matrilines combine to form the physical and social core of a macaque's natal group,
the larger troop into which it's born.
No female macaque is ever alone.
When a female gets into a fight with a female from another matriline,
she knows she can count on her family to come to her defense.
And just as females are ranked within the matriline, matrilines are ranked within the group.
These arguments rarely result in injury. Within the group, combat is mostly vocal and ritualized.
Macaques use facial expressions to threaten lower-ranking monkeys.
The infants mimic these, learning how to be dominant and where they stand within the group.
Once all disputes are settled, the wandering troop enjoys a very unmonkey-like diversion,
a cool swim on a hot day.
Of the primates, only humans and macaques seem to really love the water.
The more adventurous swim out beyond where they can touch bottom,
while mothers introduce their young ones to the pleasures of a cool dip.
After being pampered and coddled by its mother for a full year,
an event occurs that comes as a sudden blow to the young macaque, the birth of a new baby.
No longer welcome at its mother's breast, the youngster will never again be the center of her attention.
The pain of rejection must sting, but it's time for the young monkey to make its way in the larger macaque society.
It is at this age, as yearlings, that the lives of males and females begin to take two very different paths.
Females begin to strengthen their relationships within the matriline.
Males begin to look outside their immediate family for companionship.
They start to spend more time at the periphery of the group,
where they play freely not only with their kin, but with unrelated males as well.
Adult males are sometimes enticed to join in.
Mouting, which is used as a greeting and as a dominance display, causes this young macaque to react defensively.
Play enables the youngsters to form friendships with other males in their group,
and to get to know their individual personalities.
They have no need to sort out their position within the boys' club.
That is determined by their mother's rank within the group.
Mostly, they just have fun.
Woo!
It seems inevitable that adolescents everywhere eventually wear on their elders' nerves.
An aggressive male has had enough of these hijinks,
but the youngsters' new friendships prove stronger than their fear of reprisals.
Through the valiant efforts of his friends, the detainee escapes,
having learned to be more cautious around that male.
Hanging around at the fringe of the group, the young macaques meet many unfamiliar adult males.
This one is attempting to join the youngsters' group,
and actively cultivates a relationship with the shy adolescent.
While some adults are working their way into the group, the adolescent males are on their way out.
They spend more and more time at the periphery, observing the neighboring groups with great care.
They take stock of the internal dynamics of these groups, trying to determine where they might fit in best.
Only after months of close observation will they make the first hesitant attempts to socialize with these other monkeys.
Some males manage to maintain their boyhood friendships in these days of adolescent wandering.
Three or four of them will form a small band, which trails behind the new group they've chosen.
They grow to maturity in these all-male subgroups.
They would be at terrible risk if they tried to complete their transfer before reaching full size.
One quarter of all males die within a year of their first group transfer,
most from wounds inflicted by members of the new group.
When they reach sexual maturity at age five or six, they finally complete their transfer into the new group.
By leaving their natal group before they become sexually active, inbreeding is avoided.
But there's a privileged class of male macaques that doesn't undergo this male rite of passage.
This is the alpha female of this group. All of her offspring benefit from her status.
Her daughters rank high, and one of them will inherit her position.
The sons of the alpha female will lead radically different lives from other males.
John Barard calls them poor little rich boys.
Strangely, this four-year-old male has shown no interest in watching or exploring other groups.
Instead, he prefers to spend most of his time close to his mother, the alpha female.
Backed by the most powerful matriline in his group, his rise through the male hierarchy has been quick.
He is groomed whenever he likes by whomever he chooses,
and he's used to having subordinate animals leap out of his way.
He begins mating at a younger age than other males.
Since he hasn't left home, incest does occur, though rarely.
Usually he mates with females from the other matrilines of his group.
But at about age 10, belatedly, he will decide to attempt to transfer to another group,
as this poor little rich boy is doing now.
It doesn't prove as easy as his charmed life has led him to expect.
The next day, he's licking his wounds.
As a privileged youngster, he didn't master the social skills he needs to enter a group as a subordinate,
and now he's paying the price.
Through years of careful observation, John Barard has discovered that a male macaque
leaves all the trappings of his former status behind once he changes groups.
In the new group, a male's rise in dominance is determined solely by the length of time
he's in that group.
When a male joins a new group, regardless of his previous rank,
he begins at the very bottom of the male hierarchy.
It's only as the males above him immigrate out of the group, or die,
that he's able to rise and achieve a higher rank.
Cayo Santiago is composed of two islets connected by a narrow isthmus.
The 1,200 macaques living here are divided into seven groups,
which range in size from 50 to 250 individuals.
The groups are also ranked in a hierarchy, with larger groups dominant over smaller ones.
None of the groups lay claim to any specific territory.
Instead, they take temporary control of whatever area they occupy.
When the largest and most dominant group moves, it sets up a chain reaction.
This low-ranking group has decided to move onto the small islet at the end of the isthmus.
Foraging high in the trees, they spot the most dominant group on the island approaching over the isthmus.
They try to leave before the dominant group blocks their only escape route.
They try everything they can to avoid a confrontation with this high-ranking group.
Too late, the fleeing group of 200 macaques dashes headlong down the strip of land,
on the left side by the sea, and on the right by a row of rival monkeys.
The dominant group glares menacingly.
With their subordinates already in flight before them, they need only feign a few half-hearted attacks,
more for effect than to inflict any harm.
Eager to get off the isthmus, they keep on running, but at the top of the cliff, they run into more serious trouble.
Here, emerging from the brush, another group of macaques, one that's almost their equal in size and rank.
Since it's unclear which group is dominant, neither gives way. Instead, they fight.
Battle lines are drawn up as in human warfare, but in this skirmish, there's no clear victor.
When dominance has been determined clearly, there's no need for violence between groups.
Low-ranked groups simply move out of the way of more dominant ones.
Whenever a group begins to move, there always seem to be a few adult males lurking about on its outskirts.
These males once belonged to other groups, where many had risen high in the male hierarchy.
Yet now, they act submissive, much like young males attempting a group transfer.
They follow the group at a distance and cautiously observe the other animals.
Even though these males are often in their physical prime, they back down from confrontations and glance about nervously.
They've abandoned their group and are trying to join a new one, even though it means losing their status and beginning again at the bottom of the social ladder.
John Berard found that every year about a third of all adult males change groups.
What advantage could they gain?
John focused his research on this question and discovered an answer as surprising as it was simple.
It turned out that males immigrated between groups in order to win the sexual favors of the females.
During the mating season, a female decides who she wants as a mate and actively pursues him.
This one has chosen a male who just recently transferred into her group.
She ranks low in the male hierarchy, but that doesn't seem to matter to her.
She follows him and invites him to mate, but something seems wrong.
The couple looks around nervously.
As a low-ranking male, he's hesitant to accept the females offer.
If a high-ranking male should see them, they would be chased.
Perhaps a little grooming will set the proper mood.
Grooming is a regular part of macaque courtship.
But this couple seems too distracted to enjoy it.
Finally, they both seem reassured that there are no dominant males lurking nearby,
and they immediately make good use of their privacy.
When no attack is forthcoming, they decide to try it one more time.
High-ranking males do try to exercise some control over the females during the mating season.
No low-ranking newcomer will attempt to mate in clear view of a more dominant male.
But with experience, a female becomes very adept at sneaking off to a liaison with one of the new boys in town.
Inevitably, some of the sneakers are found out.
Perhaps as a safety measure, the dominant male most often chases the female,
because fights between adult males can be dangerous.
Some females have no taste for forbidden fruit, and choose instead to mate with one of their group's dominant males.
With no fear of reprisal, the couple gives themselves up to the pleasures of courtship.
For a few days, they will be inseparable, grooming each other and mating several times.
The baby playing nearby may be their offspring from the previous year.
But after a few years, even the alpha male falls from favor with the females.
This alpha male is like an elderly king, a truly self-made monarch.
He joined this group at five years of age, and invested 12 years to reach his dominant position.
Today, at 21, he's arthritic and weak, but not one of his subjects would dare challenge him.
This does not mean, though, that the females will accept his advances.
He approaches an adult male who is busily courting a female.
When the king begins to show that he, too, is interested in her, the unlucky suitor retreats without protest.
But he remains nearby, hopeful that the female really wants him and will follow him when she gets a chance.
This female, however, turned out to be one of the old king's favorite companions.
The disappointed suitor gives up.
The old king is lucky to have a special friend who continues to mate with him long after the other females in his group have lost interest.
It's likely that he'll continue to enjoy all the privileges of his rank until he dies, an unusually kind fate for this old gentleman.
This alpha male, the young emperor of the largest and most powerful group on the island, has a very different history from the old king's.
He's a poor little rich boy, a son of the alpha female.
With the help of his mother and entire female clan, he became the undisputed chief at only six years of age.
Unlike most young males, his high status meant that he enjoyed mating success as soon as he reached sexual maturity.
In previous years, he fathered several offspring, but this season he finds that things have changed.
He gives this female a hip push, an invitation to mate.
She totally ignores him.
This sudden indifference comes as a cruel blow.
Not easily discouraged, he follows her with a proudly raised tail, symbol of his dominance.
But right behind is another male, a low ranking newcomer who's noticed that the amorous emperor is having some difficulties.
And sure enough, when the newcomer is left alone, the female returns and begins courting this comparative stranger.
Despite his lack of status, she clearly prefers him over the young emperor.
The stranger wants no trouble with the young emperor and quickly withdraws when he strolls by.
But as soon as the danger is passed, the female returns to her clandestine courtship.
This female preference for newcomers probably has evolved as a way of ensuring genetic diversity among their offspring.
It strongly rewards males who change groups, even though they lose their dominance rank.
Throughout the mating season, the young emperor had no better success.
To find mating partners, he must change groups.
But this is especially difficult for poor little rich boys.
One of my subjects was the alpha male in his male group.
His mother had been the alpha female and he was the alpha male for about 11 years.
He was very secure in his position and in many ways he was what I consider to be the platonic ideal of an alpha male.
When he was 16 years old, he abdicated and went solitary.
When I checked on the other males for solitary, I found that the three oldest males also fit the same life history description.
They had also been alpha males in the male groups and had gone solitary.
Having enjoyed the advantages of high rank since birth, these poor little rich boys have neither the stomach nor the social skills for playing the subordinate.
These solitary males live a life apart, outcasts roaming the periphery of society.
Some become wanderers, joining a group for a month or so during the mating season, only to move on again afterwards.
As outsiders, their brushes with society are often dangerous and many eventually die from the wounds they receive during their attempts to rejoin a group.
But some solitary males become the zen masters of the colony.
This 27-year-old has learned to act with such discretion that he's accepted on the fringes of society.
He befriends young males and even enjoys some success during the mating season.
John Berard has discovered that like us, the life of every macaque is determined as much by their personalities as by their social standing.
The parallels between the society that he studies and the society to which he belongs gives a deeper meaning to his work.
One of the most wonderful things we share with macaques is the great joy of play.
The monkeys of Cayo Santiago have given us a rare insight into the social life of primates.
Males were once believed to govern primate societies, but now we know that it's the females who provide the backbone of the macaque community.
While males transfer from group to group in search of mates, females dedicate their entire lives to their groups.
There's a deep feeling of solidarity among the females. They're always willing to come to each other's aid.
A fight breaks out between two females of different groups.
Drawn by family ties, even females with clinging babies rush to back up their companions, and a long chain of alliances is formed on each side.
In no time at all, what began as a private scuffle between individuals becomes a major battle between the groups.
Approaching the edge of a cliff, it becomes a war of position.
It should not surprise us that the males have backed away from all the action. After all, their average stay within a group is only 17 months. In fact, it is almost exclusively the females who fight for their group.
Ties of blood and long years of companionship have forged their bonds of loyalty.
An intimate understanding of our primate relatives offers us a mirror, however imperfect, on our own humanity.
We can see some likeness in the reflection, but it may be beyond the realm of science to tell us just how deep the resemblance goes.
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