Keeping the Peace
Monkey See, Monkey Do
The Mating Game
ALAN ALDA We've come to a Caribbean island whose only inhabitants
are monkeys, to ask the question, what can they teach us about
ALAN ALDA (NARRATION) Can we find the roots of human morality in
how chimpanzees share? Do chimps use tools...
ALAN ALDA You want a stick?
ALAN ALDA (NARRATION) ...the same way we do? What's the link between
this odd primate and a special human skill?
ALAN ALDA It makes her smile.
ALAN ALDA (NARRATION) And we'll find out how to behave in polite
ALAN ALDA I'm Alan Alda. Join me and my new friends for Prime Time
ALAN ALDA This island off the coast of Puerto Rico is an exclusive
preserve for macaque monkeys, whose original home was in India.
Monkeys here live pretty much as they would if we weren't
ALAN ALDA (NARRATION) It's a great place for monkey watching.
ALAN ALDA Monkey watching is fascinating for two reasons. How like
us they are. And how not like us they are. The big difference,
of course, is in our heads. People are capable of language,
mathematics, culture, complex social structures - wonders
that seem to us to be so far above the abilities of monkeys
that they must be uniquely human. But are they? That's the
question we'll be asking for the next hour. How much of us
is in them? And how much of them is in us?
ALAN ALDA (NARRATION) Our first story is about what these days
is a very hot topic. Aggression. Macaques - rhesus monkeys
- spend much of their time hanging out in large groups. Mostly
they get along just fine, and arguments only rarely turn violent
enough for someone to get hurt. And when things do get a little
too stressful, the monkeys have plenty of room on the island
to get away from it all.
ALAN ALDA But what if they lived in more crowded conditions? These
monkeys aren't on an island. They're in a large enclosure
at the Yerkes Primate Center in Atlanta. And how they cope
with crowding here may help us understand how their fellow
primates, people, cope with the stress of living in the crowded
artificial conditions of cities.
ALAN ALDA (NARRATION) It may look as though the monkeys here have
plenty of room, but they're 500 times more crowded than they
are on the island. They are part of a long-term experiment
on crowding in monkeys inspired by the ideas of Yerkes primatologist
Frans de Waal.
ALAN ALDA How long have people been studying crowding in animals?
DE WAAL Well, probably very long, but the most influential
study came out in the 60s, where someone did a study on rats.
Rats lived in a small room and it got more and more crowded
the more they multiplied, and they became very aggressive.
They even started killing and eating each other.
ALAN ALDA (NARRATION) It's unusual here at Yerkes for the monkeys
to get packed together the way the rats were, but every now
and then they have to be rounded up for routine medical care.
They're used to the operation, and they head for their indoor
cage as soon as their keepers appear. Once inside, they're
anything but aggressive. In fact, their behavior reminded
me of the way we humans cope with being tightly packed together.
ALAN ALDA When you crowd people together in an elevator you don't
tend to get more aggression, you tend to get very ritualized
polite behavior. People don't even look at one another.
DE WAAL Yes, they avoid looking at each other, they avoid
interaction and so they avoid anything that may cause some
problems there because it's a very crowded space. And if you
do with rhesus monkeys an acute crowding experiment - which
is sort of the elevator effect - you get similar behavior.
They may stay next to each other but they don't move and they
don't interact very much.
ALAN ALDA (NARRATION) So when we're really packed together, people
and monkeys seem to cope the same way - by being very careful.
But what about everyday life? Monkey society is based on a
strict hierarchy, in which everyone knows his or her place.
In this moderately crowded enclosure, one important way to
avoid conflict is by grinning a lot - more scientifically
called the bared teeth response.
DE WAAL That's a behavior that goes up dramatically under
more crowded conditions, as if the subordinates are constantly
telling the dominants," I'm subordinate, don't worry about
me, I'm still at the same place in the hierarchy so you don't
need to attack me."
ALAN ALDA Are there some monkeys where baring the teeth is a sign
of aggression? I mean showing your teeth...
DE WAAL Well you can show your teeth in two ways. If a rhesus
monkey opens the mouth and stares at someone, that's a threat.
But the baring of the teeth in a sort of smile type of way
is a submissive gesture. In the apes such as chimpanzees and
in humans, it has got an affiliative and friendly component,
but still nervousness is often involved, and if someone smiles
too much we say that's a nervous person.
ALAN ALDA I'm a little nervous about getting scratched and bitten
ALAN ALDA (NARRATION) Peter Judge is in charge of the crowding
studies. Here's a typical incident in the long hours he spends
monkey watching. This baby is just a few weeks old, and a
popular playmate for the other monkeys. The mother, named
Allie, is constantly fending off unwanted invitations. Suddenly
a young monkey called DJ gets too rough.
PETER JUDGE Allie
ALAN ALDA (NARRATION) But moments later, DJ approaches Allie, and
the two monkeys make up.
PETER JUDGE DJ sits in proximity
Allie. DJ groom Allie
ALAN ALDA (NARRATION) Grooming each other is the monkey's main
way of relaxing and having a good time together. What Peter
Judge found is that in the potentially explosive conditions
of crowding, monkeys do a lot more to keep the peace between
each other than they do when they have room to spare.
PETER JUDGE If you look at aggressive behavior, some of the aggression
goes up and some of it doesn't. If you look at friendly behavior,
almost every category of friendly behavior increases. We think
that in a condition like that where you're always close to
your potential aggressor, it's worth your while to restore
the relationship and resolve the conflict.
ALAN ALDA (NARRATION) Rhesus monkeys have been off on their own
evolutionary pathway, separate from the one that led to humans,
for something like 30 million years. More closely related
to us - separated by only 6 million years of evolution - are
chimpanzees. It was watching chimps that first convinced Frans
De Waal 20 years ago that the higher primates all share a
deeply-rooted instinct for making peace. This group of 19
chimpanzees, living below Frans' office at Yerkes, includes
Jimoh the alpha male or group leader; and Peony, the dominant
female, here with her daughter. The adolescent males in the
group often act like adolescents. But the fights rarely get
serious, and as with the rhesus monkeys they usually end in
friendly reconciliations - this one involving tickling and
DE WAAL Now we will throw them in...
ALAN ALDA (NARRATION) Frans recently began some experiments with
his chimps that are convincing him that not only peacemaking,
but even such supposedly human traits as morality, have biological
roots which that we share with chimpanzees. These bundles
of leaves are a treat for the chimps, an addition to their
DE WAAL Thats a juvenile who took it and the alpha male takes
it over from him..
ALAN ALDA (NARRATION) Most of the chimps gather around one of the
bundles, and peacefully share the leaves. But the bundle right
below us was taken by a young female called Georgia, who is
much less willing to share.
ALAN ALDA You think Georgia is stingy because she hasn't learned
to share yet or is she just naturally stingy?
DE WAAL Well, in human terms you would almost say that she
doesn't have the confidence yet and the position yet to be
generous with others. She still very much in a sort of competitive
mode like, "How much can I get myself?"
ALAN ALDA (NARRATION) Georgia sat with her back to us, her new
baby's hand just visible at her elbow, firmly monopolizing
DE WAAL In a year we collect thousands of food transfers between
individuals. We see that among adults, it's reciprocal- if
I share a lot with you, you will share a lot with me. Juveniles
are totally out of this. Juveniles work on a stealing operation.
ALAN ALDA (NARRATION) Georgia's tactic of stealing backfires as
another juvenile steals the whole bundle from her.
DE WAAL That's a typical juvenile way of doing it.
ALAN ALDA (NARRATION) Georgia's selfishness has other consequences,
DE WAAL Individuals such as Georgia, who are not very generous.
When they are in need of food, they're the first one to be
rejected by other individuals. And so it is as if the other
individuals are saying "Well, you're never sharing with me,
why should I share with you?". And this is also how young
females such as Georgia are gradually learning. Its much better
to cooperate with a system like that. We actually get more
out of it by cooperating and contributing to it.
ALAN ALDA (NARRATION) Frans and his research assistant Mike Seres
have kept track in the thousands of trials they have run of
just who shares with whom. What's remarkable is that the chimps
keep track too. So if one chimp shares food with another in
the morning... the generosity is returned by a spell of grooming
in the afternoon. The very young are allowed to get away with
behavior that the females in this group don't tolerate from
an adolescent male. He picks up a stick and tries intimidation,
but the group isn't impressed. Here's Georgia, again causing
trouble. Jimoh ambles over, nudges her gently, and she holds
out her hand in apology. Again, Jimoh breaks up a squabble.
So while as in human society there's conflict and aggression,
chimps have many strategies for keeping the peace. Frans sees
in these behaviors the root of what in humans we call morality.
DE WAAL They have many of the emotions and elements of human
morality such as empathy and sympathy probably. Generosity.
Certain forms of altruism. Rules and regulations. Conflict
resolution, which is one of my main interests, is how to resolve
conflict among themselves. And basically you can look at human
morality as a system that resolves conflicts among parties
that live in one society.
ALAN ALDA Does that lead you to think in a different way about
the origins of human morality than you did before?
DE WAAL Human morality must have some deep evolutionary roots.
It must come from somewhere. And probably in other animals
we can find not the whole system, but we can find certain
elements of human morality. And that is what I am seeing when
I look at chimpanzees.
ALAN ALDA (NARRATION) Chimpanzees are our closest non-human relatives.
But they're not the only primates with a code of ethics. Even
though they branched off from us 40 million years ago, there's
a species of monkey that also trades tit-for-tat - Capuchins.
Capuchins are being studied by one of Frans de Waal's research
students, Lisa Parr.
PARR Capuchins are well known for being very manipulative
in their food. So you can that their ..oops
ALAN ALDA Wasn't too good about that manipulation.
PARR I think he wants the whole bunch. He doesn't want just
a piece. They also have extremely large brains for their body
size. It's the largest among the new world monkeys.
ALAN ALDA And they all have crewcuts- too.
ALAN ALDA (NARRATION) Today 's experiment will involve Bias, a
female capuchin. And Vincent, a male colleague.
ALAN ALDA (NARRATION) Vincent is given a bucket of apples. Then
it's time for us to discreetly withdraw.
PARR These two individuals are very tolerant of one another.
The are sitting very close together. And they are doing what
we've term passive food sharing
ALAN ALDA What does that mean passive food sharing?
PARR It means the food possessor is sitting close enough so
that discarded pieces and broken bits of pieces are within
reach of the passive food partner.
ALAN ALDA So because he is not preventing her from taking the food,
that's considered sharing .
ALAN ALDA Now is there any indication that he is leaving these
pieces deliberately in some way or are they just falling out
his mouth. I mean is he just a sloppy eater who doesn't care
who grabs his food.
PARR Well, we have control studies that we do where there
is only one animal in the cage and under those circumstances,
the animal usually doesn't sit close to the mesh so the pieces
aren't left within reach.
ALAN ALDA (NARRATION) So Capuchins too share and share alike. It
seem that no matter what primate species he looks at, Frans
de Waal finds evidence of cooperation and peacemaking.
ALAN ALDA It seems kind a reassuring idea that this drive for holding
down violence comes naturally to our cousins and probably
DE WAAL I'm glad you use the word naturally. Because usually
people use animals only for the bad side of human nature like
what people do in Rwanda or Bosnia. They say they are acting
like animals. So as soon as we do something bad its sort of
beastly behavior. If we do something good, its our noble human
nature that causes it. And I think we have both sides in us
and we can see both sides in the primates. We have aggressive
tendencies, violent tendencies, there is no denying that.
At the same time we have mechanisms to deal with these issues
ALAN ALDA (NARRATION) Like human babies, chimp babies are completely
dependent on their mothers when they're born and for a long
time afterwards, as they learn to become good chimps.
ALAN ALDA But when chimps are born in captivity a lot of mothers
don't seem able to teach their babies the proper rules of
chimp society. So at Yerkes , a lot of babies are brought
here to the chimp nursery. Where its up to humans to teach
them how to become good chimps.
ALAN ALDA (NARRATION) Abandoned at birth, 3-week old Julie is now
being raised by Kim Bard - who tries to be as chimp-like as
BARD We nurture them as babies chimpanzee style. We don't
want them to be humans, we want them to be good chimpanzees.
So, human babies you would feed lying down. Chimp babies eat
like this. What are you smiling at?
ALAN ALDA Is that a smile?
BARD Yes, that's a smile.
ALAN ALDA She smiles with her bottom teeth, a little like Bob Hope.
BARD They smile with the bottom gums, in her case showing.
If you see the top teeth, its by definition not a smile in
ALAN ALDA (NARRATION) Like human babies, chimp babies are magnets
ALAN ALDA Funny, I must be a least as programmed as she is, because
I got a lot more interested as soon as she grabbed my fingers.
Do you find that happening in a mother chimp if the baby grabs
on to her.
BARD She has the baby grabbing on to her all the time. And
what she does is do these kinds of things.. what does it do
if I move her leg? What does it do when I move the other leg?
ALAN ALDA (NARRATION) And soon I was playing mother chimp.
ALAN ALDA So what happens if I do this? It makes her smile. If
I do this? If I do this. And a one and a two and three and
four and a five... Look at this the beginning of aerobics.
You want to do pull ups? Oh good.. and two and three. One
more. You can do it! You can do it! And four- she is smiling,
she loves it!
ALAN ALDA (NARRATION) In their own social groups, young chimps
interact with relatives of all ages - brothers, sisters, cousins,
aunts and uncles. They learn essential chimp manners - the
dos and don'ts of chimp society. Most important, young females
- soon to be mothers themselves - learn how to handle babies.
So in the nursery, young female chimps are encouraged to play
with younger animals. Today Evelyne, age 3, is there to help
look after Andie, who's 18 months. Until the nursery program
began, many female chimps raised in captivity were unprepared
There are mothers who have just been around infants and they
go "I don't know what to do with them?". When they cry, should
I pick them up or should I toss them somewhere? I don't know
what this thing is. With this experience, this is something
that occurs in the wild- a lot of juveniles get experience
with younger siblings, they know, they learn how to react.
ALAN ALDA (NARRATION) Evelyne got a little worried by our camera.
Andy was displaying at you all. And Evelyne wants her to keep
her distance a little bit, so she kind of grabbed her back.
Evelyne is being very protective towards Andy.
ALAN ALDA (NARRATION) While Evelyne was the perfect older sister
with Andie, 7-month old Lindsay was a bit more puzzling. Curiosity
took over from caring - until finally a toe was just too tempting...
Then it was my turn. I'd been cautioned to expect anything.
ALAN ALDA Hello. What do say? How are You? So far, so good- and
now it was time for me to learn a few chimp manners.
BARD It's okay.
ALAN ALDA Now that scared me. Does he mind if I get scared?
BARD Yes. He is telling you that he scared.
ALAN ALDA He is coming up to my face like that. Is he trying to
BARD No, he is scared himself.
ALAN ALDA This one is poking me in the ear
BARD He is grooming. He is trying to tell you he's is a little
nervous. And the way to calm chimpanzees when they are nervous
both to make you a little calmer and to make him calmer is
to groom. We try to - don't look at their face, but you look
at the part you are grooming. And immediately you are going
to find that they relax. And not move and get into this very
still posture. We make chimpanzee grooming sounds. Either
a ........ or the kind Kathy makes is ----- . But its a very
ALAN ALDA That's got his attention a lot!
BARD And what Lucas likes- he just calms immediately. Is he
ALAN ALDA I think he is trying to eat my chin
BARD If you have a freckle or something- that might be particularly
ALAN ALDA A freckle? What do they like them for dessert?
BARD This is a way to ask for play.
ALAN ALDA When they put their hand on the head like that?
BARD They are like- tickle me right there.
ALAN ALDA Oh I see. If I was to ask for a little tickling. He is
not really watching.
BARD What you need to do is to get really loose. So you get
ALAN ALDA I'm going to get really loose now..
BARD And when ever they touch you, even if they don't mean
it as tickling, you laugh.
ALAN ALDA (NARRATION) Unfortunately, my chimp laugh didn't seem
too convincing - especially to Merlin.
ALAN ALDA Ouch.
BARD That's not nice- but now he is saying I'm sorry .
ALAN ALDA (NARRATION) Merlin and I made up, as all good chimps
ALAN ALDA That's okay. That's okay.
ALAN ALDA (NARRATION) And here in the Yerkes nursery, that's the
goal - rearing chimps to be the best chimps they can be.
SEE, MONKEY DO?
TOMASELLO We'll put some honey in here...
ALAN ALDA (NARRATION) Every once in a while, Mike Tomasello gives
the chimps at Yerkes some honey.
TOMASELLO They poke sticks into holes and beehives..
ALAN ALDA (NARRATION) In the wild, chimps often use simple tools
to get at food. They crack open nuts with rocks, and poke
sticks into beehives for honey.
ALAN ALDA You want a stick? This use of tools seems very human-like
- yet another example of a behavior apes share with humans.
It's even led to speculation that apes learn skills and pass
them on to others just as we do. But is that really what's
ALAN ALDA How do did they learn to do this? Do they learn the same
way we do?
TOMASELLO Well there are a couple of different theories about
how they might go about learning this. On the one hand I would
say they do go about learning it in very much the same way
a child would. They are exposed to the tool, they have a problem
in front of them and they either some combination of trial
and error or insightful problem solving. And in many cases,
I believe they do employ insightful problem solving in the
sense that they don't have to try out every possible solution.
They can look at the problem and see which one might work
ALAN ALDA (NARRATION) That chimps can figure out for themselves
how to use a stick to get honey is impressive enough. But
can they pick up the skill by watching others, as we can?
To help answer that question, Mike Tomasello has recruited
another primate species, a close relative of both chimpanzees
and gorillas - the orang-utan. Orangs are more placid and
so easier to work with than chimps - though they have their
ALAN ALDA Is it okay to look them in the eye?
TOMASELLO Oh yeah they are fine. He might spit at you, but
other than that they are fine.
ALAN ALDA (NARRATION) This is Iney. My job was to try teaching
her how to use a rake to get a piece of fruit.
ALAN ALDA Look at this. Look at this
ALAN ALDA (NARRATION) I made a show of turning the rake over, making
it easier to pull in the apple.
ALAN ALDA Umm. Good. Iney ignored my advice. Tiram looked uncooperative
from the start. This time my rake was already turned over,
so I simply pulled it in. Tiram also ignored my action and
experimented on his own.
TOMASELLO Good job. Good job, Tiram. What I did with the rake
didn't seem to matter.
ALAN ALDA I didn't turn it over. But Tiram did turn the rake over.
TOMASELLO Because Tiram is going to do what ever he is going
to do regardless of what you are doing. He is figuring out
how to do it on his own.
ALAN ALDA I think the reason that they don't do exactly what I
do is that I don't grab it with my feet. I'm just using my
ALAN ALDA (NARRATION) Tomasello believes that what apes learn from
others is the general idea that a tool can be useful - not
the exact details of how to use it.
ALAN ALDA So, they benefit from seeing it used. And they come over
to the place where its being used. And they will pick it up
and use it. But they won't exactly imitate the use. Its not
like a carpenter teaching his daughter how to use a plane.
ALAN ALDA (NARRATION) This difference between how apes learn and
how children learn is Mike Tomasello's main interest.
TOMASELLO This is Matthew. This is Alan.
ALAN ALDA Hi Matthew. This is fun. And I finally got to work with
a primate species I'm a bit more used to.
ALAN ALDA Can you say what this is?
Its an airplane.
ALAN ALDA (NARRATION) Tomasello has set up an experiment with children
that's similar to the one with orangs.
ALAN ALDA Watch me, Matthew
ALAN ALDA (NARRATION) With the rake already on its back, I pull
in the toy. The key point is that I didn't turn the rake over;
it was already the way I wanted it. And Matthew also doesn't
turn over the rake - even though it would obviously work better
if he did.
TOMASELLO It's Alan's turn. Next time, I make a show of flipping
the rake. And that's all Matthew needs. MOTHER Good job, Matthew.
ALAN ALDA Okay, Mike's going to drop it here.
TOMASELLO Rachel, watch, I'm going to drop it in. With Rachel,
I again make a big deal of flipping the rake.
ALAN ALDA And I take it out. Mike's going to drop it in now , it's
your turn. You try it. Rachel gets it at once - but like the
orangs, she puts her own spin on the solution.
ALAN ALDA That's very good. You're pretty good with that bear.
But after again watching what I do with the rake, Rachel imitates
my actions precisely.
TOMASELLO Rachel's turn. And it's this ability to exactly
imitate that Mike Tomasello believes is the key difference
in how humans learn when compared to apes. It gives kids like
Anna a short cut to learning that apes don't have. And it
maybe what enables us to pass on from generation to generation
everything that's been learned before. The way chimps use
sticks to get honey is a reminder of both how like us they
are - and how not like us they are. And it gives us another
insight into what makes humans so different.
ALAN ALDA You think there is any thing we can learn about the way
we learn by studying this more basic way the chimps learn.
TOMASELLO Many times with humans the problem is that we are
so immersed in something we can't get out of it to see it.
So, we all have had the experience of going to another culture
and seeing them do something differently. And we didn't realize
what we did until we saw that it could be done differently.
And I think that is a lot of the value of studying non-human
primates is to see how something is done differently.
back to top
ALAN ALDA Even though the way apes learn is different from the
way humans learn, when apes are reared and taught by humans
they can learn some surprisingly human skills. The best known
of these is when chimps and some gorillas have been taught
a simple language. But what's not so well known is that some
chimps have been taught elementary math skills.
ALAN ALDA (NARRATION) This is the playground of a unique elementary
school housed at Ohio State University, where Sally Boysen
is teaching chimpanzees to count.
BOYSEN One. Two. See that. One, two. Where's the two? That's
ALAN ALDA (NARRATION) Bob, 4 years old, is one of her youngest
BOYSEN One. Two. Good work, that was good. We're not done
yet. Try a cookie.
ALAN ALDA (NARRATION) Like most 4-year olds, Bob's attention sometimes
BOYSEN He's learning just those first two numbers and once
- I knew he was going to do that. His attention span is a
lot shorter than a child's, and we end up investing a lot
more time in playing and social interaction than in actual
training. That's kind of the opposite of what we see in children.
Where they spend a couple hours at school and 15 minutes in
recess, we spend 15 minutes in school and two hours of recess.
ALAN ALDA (NARRATION) While Bob is still in kindergarten, 10-year
Sheba is already a first-grader.
BOYSEN Seven. That was the right answer. OK, you can...
ALAN ALDA (NARRATION) She is learning her numbers from 1 through
BOYSEN How many is that? How many is it? Five is the right
answer. Ok, you get 'em all. Ok, good work.
ALAN ALDA (NARRATION) Sheba also understands zero.
BOYSEN Okay. Look, Sheba. How many things do we have here?
None. There are no candies.
ALAN ALDA (NARRATION) And sometimes runs the class herself.
BOYSEN Oh, you think you should get reinforced anyway. How
many is that? You can do your own trials. It was one. That
was good. Well, gee, I don't even have to be here. That's
ALAN ALDA (NARRATION) Now that Sheba knows her numbers, Sally plans
a new challenge. She puts 3 peaches in one box. And 3 peaches
in another. This is the first time a chimp has ever been given
an addition problem.
BOYSEN Okay. How many peaches? How many? Show me. Yes! Six
is the right answer. Good girl, there's six peaches out there.
ALAN ALDA (NARRATION) The task involves Sheba's counting the first
set of peaches, holding that number in her head, then continuing
the count with the second set.
BOYSEN Get the right answer. Five. Good.
ALAN ALDA (NARRATION) Without ever being trained to add, Sheba
gets it right the first time. Then Sally makes the task even
harder, by replacing the peaches with plastic numbers.
BOYSEN There we go. Okay. How many was that. Can you pick?
Show me. Four. Perfect.
ALAN ALDA (NARRATION) Astonishing though Sheba's performance would
seem to most people, Sally isn't surprised.
BOYSEN To find capabilities in the range that we have with
numerical concepts is not surprising to me. It means we have
to rethink our ideas about what humanness is all about, and
also what champanzeeness is all about.
ALAN ALDA (NARRATION) There's one numbers game Sally has devised
that really demonnstrates Sheba's chimpanzeeness. One of the
players is Sarah. Her job is to eat candies. Sheba's job is
to choose how many candies Sarah gets.
BOYSEN One, two, three, four down here. Are you watching?
ALAN ALDA (NARRATION) Here's how the game works:
BOYSEN We're going to put two in here. Which shall we... Give
those to Sarah, OK.
ALAN ALDA (NARRATION) Whichever set of candies Sheba points to
first goes to Sarah.
BOYSEN And Sheba only gets two...
ALAN ALDA (NARRATION) Sheba gets what's left.
BOYSEN Too bad.
ALAN ALDA (NARRATION) So if Sheba understands the game, she should
pick the smaller amount first.
BOYSEN Five in that one and we'll put one in there. Now which
one do you want Sarah to have? Oh, you want Sarah to have
these. It's okay.
ALAN ALDA (NARRATION) But no matter how many times they try it,
Sheba always points to the larger amount first. It's a game
she just can't seem to figure out how to win. Sally has a
hunch that making the task more abstract might help.
BOYSEN Let me ask you a question. Which one do you want to
give - you want to give two to Sarah.
ALAN ALDA (NARRATION) And remarkably, Sheba now picks the smaller
BOYSEN Oh, you lucky girl. One, two, three, four, five, six.
ALAN ALDA (NARRATION) Sarah is not that impressed by Sheba's new
BOYSEN We have four - now wait, wait until I show you what
else we've got. Now what shall we give to Sarah? Two, we'll
give Sarah two.
ALAN ALDA (NARRATION) Sally Boysen suspects that because of Sheba's
natural greediness, she can't resist the candies themselves.
But while the numbers engage her reason, allowing her to play
the game intelligently. Unlike Sheba, the males in Sally's
group are too big and too aggressive to be let out of their
BOYSEN I've got your toe...
ALAN ALDA (NARRATION) Still Sally has found a way to play with
them...and to work with them.
BOYSEN How much of a peach is this? Half of a peach. Right.
ALAN ALDA (NARRATION) Darrell is working on fractions.
BOYSEN It's a half of a peach. That's right. What's that in
your mouth, a peach pit? Thank you. Yummy, yummy. How many
of these do I have? Two bananas. Right. There's two bananas
here. Now watch what I'm going to do. This. And one more time,
and now I have this little weensy piece. It's a fourth of
ALAN ALDA (NARRATION) When Sally cuts the fruit in front of him,
Darrell chooses correct fraction.
BOYSEN ( To Darrell) I've got some left, too. I have another
fourth. That's right. There it is.
BOYSEN Darrell has to understand that there are whole things
and there are parts of things; and that we can assign a name
for different parts of an apple, for example. So that there's
a special name for a half of an apple, a special name for
a fourth of an apple.
ALAN ALDA (NARRATION) The chimps aren't happy when Sally turns
her attention to the camera. But they figure out a way to
get revenge. Soon, they're calm enough to start work again.
Darrell's next challenge is to figure out what fraction of
a pear this represents, without actually seeing the fruit
BOYSEN (to Darrell) Not half. Oh, you're guessing all of them,
guessing all of them. I want to show you something. Look what
if I took a whole pear like this. Oops. This is one pear,
isn't it? And I'm going to cut it up for you.
BOYSEN Darrell's still not able to reliably pick the correct
fraction. It really helps him still at this phase of the understanding
of the concept to see a whole piece of fruit divided into
portions. But we're working towards that.
BOYSEN (to Darrell) Darrell, look how many pieces I cut this
into - one, two, three, four. That's right, this is only a
fourth. That's good, a fourth. Good, do you want it? You don't
want it? Okay. Would you rather have a piece of candy? Alright.
There you go. You can stay here. We're still working.
ALAN ALDA (NARRATION) Sally believes that chimps, like humans,
have an intuitive understanding of numbers. It isn't that
Sally is teaching them to count or add or do fractions. Instead,
she is simply giving her chimpanzees an opportunity to show
us what they can do.
ALAN ALDA (NARRATION) These are primates too - lemurs - the most
distant of our primate cousins. Lemurs branched off from the
family tree 70 million years ago. Common then, they live wild
today only on the island of Madagascar. But about 500 lemurs
also live here in North Carolina, in a forest owned by Duke
University. Some lemurs are nocturnal: They wake up only when
it gets dark. This lemur is an aye-aye. His name is Nosferatu.
In Madagascar, the aye-aye is considered an evil omen, and
often shot on sight. Aye-ayes are one of the most highly endangered
primates in the world. And one of the weirdest. To eat breakfast,
Nosferatu scoops out an egg using his extraordinary 6-inch
long middle finger. Breakfast over, Nosferatu goes foraging
much as he would in the forest, looking for worms and insect
larvae living inside tree branches. How he does it fascinates
Duke University psychologist Carl Erickson.
ERICKSON How do you find food in a rainforest at night when
its rather rare and its hidden below the surface of the tree.
Its seems like a formidable problem and I would really like
to know what is in his head when he does that.
ALAN ALDA (NARRATION) To find our what's in Nosferatu's head, Carl
is making an artificial tree branch, complete with hiding
places for worms. He's going to test three different hypotheses
about how the aye-aye is finding its prey. The first hypothesis
is that Nosferatu's sharp ears can hear the worms even when
they're deep in the wood.
ERICKSON It's possible that when he taps, the prey gets excited
and that he hears that excitement and so he goes for the act
of prey. One way to make to make sure he can't hear them is
to have them dead.
ALAN ALDA (NARRATION) Chopped-up - and therefore silent - worms
test the second possibility: that Nosferatu smells his prey
rather than hearing it. The third option is that it's not
the worms but the holes the aye-aye finds , so one is left
empty. The cavities are two inches beneath the surface. Nosferatu
can't wait to begin the hunt.
ERICKSON He is very eager. And as you can see often times
I can't get the wood blocks in fast enough for him.
ALAN ALDA (NARRATION) Nosferatu has no trouble finding the first
cavity, with the live worms. After fishing them out he moves
on - and at once finds the hole with the dead worms. But worms,
live or dead, don't seem to be what he's locating - because
soon he finds the empty cavity as well. It's the cavities,
not the worms, he's searching for.
ERICKSON What we need to do then is find out what it is about
cavities that is so interesting to the aye-aye .
ALAN ALDA (NARRATION) One thing about cavities the aye-aye find
interesting is their shape. Carl makes a pair of X-shaped
cavities, and gives them to Nosferatu to check out . The aye-aye
taps around, apparently making a mental map of the shape -
then selects where to gnaw very precisely.
ERICKSON The aye-aye seems to have selected the area near
the intersection. And this suggests to us that it is not simply
detecting the configuration, but is going beyond that to find
a strategic location and reach all the arms of the X through
a single entry point.
ALAN ALDA (NARRATION) Carl has made a cut-away branch with tunnels
and a central hole, to see what's going on inside the tree.
Nosferatu, as usual, is an enthusiastic collaborator. The
extraordinary flexibility of Nosferatu's middle finger means
the worms have almost nowhere to hide. The aye-aye may be
only a very distant relative. But in its ability to create
mental maps, and in particular in its extraordinary dexterity,
there's a kinship with humans that shines through even 70
million years of evolution.
ALAN ALDA For our last story we are heading back to the place where
we began, the island of Cayo Santiago, about half mile off
the shore of Puerto Rico. We are going there because while
there are a lot of things you can learn about monkeys in captivity,
there are some things - like matters of sexual politics -
that can only be studied when you are looking at monkeys in
the wild. And monkeys on Cayo Santiago are about as wild as
monkeys can be.
ALAN ALDA (NARRATION) Nine hundred rhesus monkeys live on this
island today - the descendants of monkeys released here 60
years ago. Mothers are at the center of rhesus society - as
John Berard of the University of Puerto Rico has learned from
13 years of monkey watching.
BERARD The mother-infant bond in primates as in humans is
very strong The whole society revolves around mom.
ALAN ALDA (NARRATION) The Cayo Santiago monkeys have been watched
by generations of researchers. But probably no-one has got
to know them as well as John Berard. Wandering the island
with him is like being introduced to his extended family..
BERARD This is her son who is an adult
ALAN ALDA (NARRATION) ...And some of its squabbles.
ALAN ALDA What do you think happened?
BERARD Yeah, what happened here was... that a male went after
the infant. And then the mother of the infant came by and
scooped up her infant and then turned and screamed at the
ALAN ALDA (NARRATION) Who bosses whom is built into monkey society.
Females inherit their rank from mom and keep it all their
lives. This imperious blond monkey is group's dominant female.
And this is the dominant male, scattering all before him.
While the monkeys live freely here, they get some help from
those who watch them. This feeding corral provides much of
their food, and is a good place to see the dominance heirachy
ALAN ALDA What's most of their fighting about?
BERARD Most of their fighting actually is just little family
ALAN ALDA Like what? It's your turn to do the dishes..
BERARD Often its hard to tell..
ALAN ALDA What would it be? Food?
BERARD No, its simply...your in my spot.
ALAN ALDA Your in my spot? That's what they fight about? They have
this whole island?
ALAN ALDA (NARRATION) Unlike females, most males leave home at
puberty. When they join a new group, they enter at the bottom
of the social ladder. It's humiliating and stressful, and
John Berard's research has been aimed at finding out why they
do it. This young female is the key to the answer. Followed
by her baby, she leaves the feeding corral - and is in turn
followed by a high-ranking male. Most previous research on
monkeys would suggest he is the most likely to mate with her.
But tagging along is a low-ranking newcomer to the group.
And now an elaborate game begins. The female is in control
here, sitting between the high ranking male on the left and
the newcomer on the right. The dominant male stays close,
but the newcomer strolls away - and the female follows. The
young male has found a secluded spot in the bushes. As the
female heads toward him, the older male spots her and chases
her away. But it was clearly a risk she was more than willing
ALAN ALDA Now what is this attraction to the new guy in the group.
I mean it sounds like all those Hollywood movies, where the
young guy comes in on a motorcycle and he is new to town and
all the women say wow ....what is that?
BERARD I think its the motorcycle thing. They use to have
motorcycles back here in the 40's. But then they got rid of
ALAN ALDA Little monkey motorcycles... What do you think is the
BERARD Its just novelty. I think .. it just pretty obvious
that they like new males. And we have been watching females
in this one group now for six years. And every year its the
same thing, its the new guys. Its forget about the guys that
they mated with last year. Forget about the guys who are long
term residents. It's just the novelty aspect..
ALAN ALDA (NARRATION) Back in the bushes, the novelty of the outsider
proves irresistible. Until again, the dominant male interrupts
- and again vents his anger against the female. John's research
suggests a male's high rank doesn't cut much ice with the
group's females. In fact, it may act against him.
ALAN ALDA Do monkeys develop a long term sexual relationship here
on this island?
BERARD No typically what happens is that, males join groups
and they are new to the group. And females go out of the way
to mate with the new guys in the group. So they mate the first
year in the group. Then they become friends after that. Once
they become friends rhesus females don't mate with their friends.
ALAN ALDA The mating stops after the friendship starts?
BERARD So it is like sex first, then friendship, then that's
ALAN ALDA And they never rekindle the old flame?
BERARD Once it's out, it's out , yes.
ALAN ALDA (NARRATION) What John wants to know now is, who is fathering
most of the offspring? The outsiders or the insiders? There's
only one way to find out - an island wide program of paternity
testing. The researchers are capturing the monkeys one by
one for blood testing. It's a tense time for people and monkeys
alike. John frees most of the monkeys - and the mother and
baby he's after obligingly run into a cage. Mother and baby
are lightly anesthetized so that blood samples can be easily
taken. Both will wake up in an hour or so and be released.
The results of the DNA fingerprints confirm what John suspected.
The newcomers to the group, despite their lowly social status,
are siring as many offspring as the dominant males. So the
island's babies have many different fathers - and therefore
many different genes - thanks to the females' taste for novelty.
ALAN ALDA What do you suppose is the evolutionary advantage to
having novelty being exciting? I mean I presume that's...
somewhere in there is why novelty is a factor in this. How
does it work?
BERARD The kids are being sired by different males every year.
And that must be adaptive in some way to rhesus macaques.
Rhesus live in a variety of habitats. They live from Pakistan
to China. From sea level to high in the mountains. So in order
to adapt to that many different kinds of environments, perhaps
its very important to have a genetically diverse stock.
ALAN ALDA (NARRATION) There's one more surprise from John's research
- another reason high social rank, for males, can be a curse
rather than a blessing. The sons of high ranking females inherit
their mom's rank, and are treated like princes by everyone
in the group. They don't even have to fight their own battles.
No sooner has this high-born son picked a quarrel, than a
female from the group rushes in to finish it. When these privileged
males finally do leave home, they have a much harder time
of it than more lowly monkeys. They are the victims of much
more aggression... And many never do successfully enter a
new group, living out their lives as solitary hermits on the
fringes of monkey society.
ALAN ALDA It kind of sounds like familiar behavior. The privileged
kid who can't necessarily take care of himself while he is
on his own.
BERARD They don't know how to buy corn flakes or anything.
They always had it provided for them. So they go to supermarket
and they can't choose what to buy.
ALAN ALDA (NARRATION) We began our exploration of the primate world
by asking how much of our non-human cousins is in us , and
how much of us is in them. What we've found can lead to a
new appreciation of both them and us: Of the things we share
through our common evolutionary origins; and of the things
that make each primate species unique since we've gone our
ALAN ALDA It's very easy to talk about these animals as if they
are human. A lot of their behavior seems like what we do.
So you think that their thinking process must like ours, but
maybe it is? How much is it?
BERARD Again, you always have to be careful. The questions
you're asking me is what's going on their minds. The real
answer is we really don't know. All I know is what they are
doing. And its obviously they are doing these things and its
obvious these rules exist in the laws because all the males
and all the females do the same sort of thing. They do it
in their own style but its how they do it...
ALAN ALDA (NARRATION) And after an hour of monkey watching, I began
to wonder just who was watching whom.
ALAN ALDA This guy is jumping around through the trees, he has
his eye on me.
BERARD That's because you are the new guy here. She knows
ALAN ALDA And she is doing this lip smacking thing at me. What
does that mean?
BERARD That's simply a sign of assurance. It's neither aggressive
nor submissive. It's simply that she wants to get friendly.
ALAN ALDA She's not blowing me kisses?
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