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Eagles lead lonely lives.

2
00:01:24,867 --> 00:01:28,860
This one, flying over
the gaunt mountains of northern Scotland,

3
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may spend days
without seeing another of its own kind.

4
00:01:42,787 --> 00:01:47,224
In spring, when a pair are raising
one or, at the most, two chicks,

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young rabbits and birds are not difficult to find.

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But now, late in the year, food is scarce,

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and there's barely enough
on this bleak hillside to support a pair.

8
00:01:58,227 --> 00:02:02,425
The chicks had to leave
to find hillsides of their own.

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So an eagle doesn't have to deal
with the problems that face

10
00:02:16,307 --> 00:02:20,664
and can even dominate
the lives of more sociable animals.

11
00:02:43,267 --> 00:02:48,466
Unlike the lonely eagle,
many animals live in groups.

12
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But that inevitably causes problems.

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How do you get on with your friends and,

14
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more particularly, your rivals,
without continual squabbles?

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00:02:57,827 --> 00:03:03,106
There's another big bird in these Scottish skies,
bigger even than the golden eagle.

16
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It comes here in the autumn
and then it forms large flocks.

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Hooper swans, coming in to land
after a 1,000-mile journey from Iceland.

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There the winter will be dark and bitterly cold,

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and the birds have flown down
to spend the winter here

20
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in the milder conditions of Scotland.

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Suitable stretches of water, secluded, with
plenty of vegetation around to eat, are few,

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and this loch will soon be crowded.

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Some of the arrivals
are young birds travelling by themselves

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who have yet to find a mate.

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The next few months will be their opportunity
to form partnerships that will last a lifetime.

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Most are families, pairs with their
six-month-old cygnets hatched in Iceland.

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They will stay together until the next spring.

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They proclaim their arrival
with a clear challenge to those already here.

29
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They, too, intend to claim a place on the lake.

30
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The male fights most of the necessary battles.

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But his mate always backs him up,

32
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and the pair celebrates a successful skirmish
with an ecstatic triumph ceremony.

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There's a clear pattern to these encounters.

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Pairs consistently win against singletons.

35
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But the most dominant and successful of all
are the families: mother, father and cygnets.

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This is a particularly powerful one.
It has four young.

37
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Singletons or even pairs
who come too close are quickly seen off.

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The cygnets enthusiastically join
in the triumph ceremonies.

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As long as they stay close to their parents,
they will be treated with respect by other birds.

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But if they stray, they will be shown no mercy.

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The parents will fight others
on behalf of their young.

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The cygnets will stay with their parents
until the spring

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when they'll be strong enough
to fight their own battles.

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In the meantime, other members of the flock

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come to recognise and respect
the most powerful families

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and avoid confrontations where they can.

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An apparent peace breaks out on the lake.

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0ther swans give the family a wide berth.

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The cygnets can now swim and feed
without arguments.

50
00:07:19,427 --> 00:07:23,943
But not all seniorities are settled
in such a straightforward way,

51
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particularly within groups.

52
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Chickens, when allowed to range
freely in a farmyard, as these are,

53
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form themselves into small, tightly organised

54
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and remarkably stable groups.

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Usually there's a cockerel
and then a number of hens around him,

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and maybe one or two
other cockerels on the sidelines.

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0ne of the first studies ever made

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to find out how animals organise
themselves in groups

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was done with a group of chickens like this.

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If there are ten or less in the group,
then every bird knows every other individually.

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They move in a flock,
scratching around for whatever they can get,

62
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apparently harmoniously.

63
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But if I give them something they really like,
then they reveal their true competitive nature.

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Watch this.

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This pale hen is particularly aggressive.

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If she doesn't get to the food first,

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she'll peck those who do so
until they give way to her.

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This dark hen behaves in the same way

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and pecks everyone
except the fierce pale hen, whom she avoids.

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The result of these skirmishes is a peck order,

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a line of seniority
in which each bird knows its place.

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Should the lowliest hen at the bottom
of the peck order find a coveted morsel first,

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she'll be chased and harried
by all the others until she gives it up.

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Clearly, all hens are not equal.

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Dominant ones hand out the punishment,
junior ones get henpecked.

76
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But for most of the time, the relationships
between them seem very friendly,

77
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and the flock leads a quiet and productive life.

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It's the same with the cockerels.
They, too, avoid confrontation.

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But every now and again, the senior cockerel
has to remind the junior who is boss,

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just in case they get it into their heads
that they want to steal his crown.

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(C0CKEREL CR0WS)

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Such peck orders occur in the wild as well.

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A group of caciques
has established a colony high in a tree

84
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overlooking the Manu River in Peru.

85
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The males established who was senior to whom
early in the breeding season

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with a series of disputes that none has forgotten.

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And those now determine
who will get the pick of any food around

88
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and, more importantly, who will consort
with a female when she's ready to mate.

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The males compete for the right to display
beside the clustered nests

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which were built and are occupied
by individual females alone.

91
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A subordinate male
will always give way to a dominant one,

92
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just as chickens do in a farmyard.

93
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It's a waste of energy to go on fighting
the same battles when the outcome is the same.

94
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The juniors snatch a mating if they can,

95
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but they may not succeed
unless they move up in the rankings.

96
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So why do caciques put up with the tensions
of social living, rather than going it alone?

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The reason becomes clear
when the colony is threatened.

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A toucan, an avid eater of eggs and chicks.

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A single cacique is unlikely to deter a toucan.

100
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But all the members of the colony together,
with their differences forgotten,

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can mount a highly effective defence.

102
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This nest is empty.

103
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But this one isn't.

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A capuchin monkey,
another most determined raider.

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So even subordinates in this community have
a better chance of producing surviving chicks

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than if they were to nest in isolation
with no effective defence against raiders.

107
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Lions, too, live in groups.

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The lionesses form the core of the pride.
There may be a dozen or so,

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all of them closely related,
mothers and daughters, sisters and aunts.

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And it's the lionesses
that do most of the hunting.

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The two or three males,
often brothers, fought as a team

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to drive off their predecessors
and join the pride.

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They will fight again
if newcomers try to displace them.

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But, most of the time, they have a peaceful life.

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Living in groups, for the lions,
brings several advantages.

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For one thing, they can tackle large,
powerful prey, such as buffalo.

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These huge animals
are three times the weight of a lion.

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A single hunter would be very unlikely
to tackle a healthy adult buffalo.

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It simply wouldn't have the weight
and strength to bring one down,

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and it might well get injured in the attempt.

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But a pride, working together, has a chance.

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A preliminary chase serves to get the measure
of the quarry and to isolate an individual.

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If one seems weaker than the rest,
it will become the target.

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The lions attack.

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Despite the numbers pinning it down,
the buffalo is still dangerous.

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It's finally killed and the feasting begins.

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What about seniority and rank in this group?
There's little squabbling or fighting.

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This kill has produced
such a huge quantity of meat

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that there is more than enough for everyone.

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So those who haven't got a place
at the carcass amiably await their turn.

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And that is just as well.

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Such lethally armed hunters
as these brothers and sisters

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could easily kill one another
if a dispute became violent.

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0nly in very hard times,
when the pride is extremely hungry,

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will issues of priority be settled by fighting.

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Lions, cooperating in prides,

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dominate the harsh and ruthless world
of the African plains.

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And the secret of that success
is their cooperation.

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When they work together,
no other hunters can match them.

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This cooperation extends
into other parts of their lives as well.

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00:16:29,947 --> 00:16:32,541
The lionesses nurture their cubs as a team,

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taking turns to guard them and even,
on occasion, suckling one another's infants.

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Baboons live in even bigger groups,
up to 150 or so.

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This gives their young,
who are defenceless for several years,

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the protection that comes from such numbers.

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This troop in Kenya is waking up,

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having spent the night in the relative safety
of its regular sleeping cliff.

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00:17:09,347 --> 00:17:14,137
Within a baboon troop, there's a fine balance
between friendship and rivalry.

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Like lions, their societies consist largely
of closely related mothers and their young,

150
00:17:20,307 --> 00:17:24,937
and it's the adult females
who largely control affairs.

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00:17:31,347 --> 00:17:33,907
The powerful males are all outsiders

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who only gained acceptance to the troop
by making friends with one or more females.

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Grooming is one way
that they established such bonds.

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Taking charge of a female's baby is another.

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A ferocious male can treat an infant
with great tenderness,

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which is the more remarkable when
you consider he may not even be the father.

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In baboon society, a social favour like this
will be remembered by the mother

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and may improve the male's friendship with her

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and the likelihood of him fathering her next baby.

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00:18:16,307 --> 00:18:20,095
Males consolidate such relationships
by encouraging females

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to join them for a careful grooming.

162
00:18:26,667 --> 00:18:30,455
Encounters with rival males,
however, must be handled carefully.

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00:18:30,627 --> 00:18:34,336
Lip smacking here is a gesture of appeasement.

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00:18:35,027 --> 00:18:41,375
Males pull other strange faces to act
as clear come-on signals to passing females.

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00:18:57,307 --> 00:18:59,775
Meetings can serve several functions.

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Seniorities and friendships are reaffirmed.

167
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Babies begin to learn the complex language
of smells, gestures

168
00:19:07,347 --> 00:19:10,225
and the importance of social relationships.

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00:19:10,987 --> 00:19:15,663
By caring for an infant, a male demonstrates
his commitment to its mother.

170
00:19:15,827 --> 00:19:19,217
And the babies, playing together,
learn about making friends,

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as they must if they're to achieve
a good social position later in life.

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00:19:33,867 --> 00:19:37,985
This babysitter misses the chance
of making friends with a passing female

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because he's surrounded by jealous males.

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00:19:40,827 --> 00:19:44,137
If he had abandoned the baby,
there might have been a squabble.

175
00:19:44,307 --> 00:19:48,300
As long as he holds onto it,
he will be left alone by his rivals.

176
00:19:48,467 --> 00:19:50,935
But he has plenty of other opportunities.

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00:19:51,107 --> 00:19:55,578
Being a good father figure makes a male
a great favourite with the females.

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00:20:16,667 --> 00:20:19,181
A young female passes the time of day,

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00:20:19,347 --> 00:20:22,783
but she's not sexually receptive and he's busy.

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00:20:27,067 --> 00:20:32,505
In this complex society,
social tensions can easily lead to conflict.

181
00:20:33,987 --> 00:20:37,457
When a female is threatened
and pursued by one male,

182
00:20:37,627 --> 00:20:42,542
she'll seek out another who is
a regular ally and cling to him for support.

183
00:20:46,707 --> 00:20:49,619
With a friend to help her, she's now safe,

184
00:20:49,787 --> 00:20:54,861
and, between them, some hard staring
is enough to see off the aggressor.

185
00:21:13,627 --> 00:21:19,224
For baboons, it's not how big you are
but who you know that counts.

186
00:21:29,947 --> 00:21:33,303
Arguments and squabbles
between adult animals

187
00:21:33,467 --> 00:21:38,097
striving to maintain their position
within their community are common enough.

188
00:21:38,267 --> 00:21:42,897
But acts of assistance, in which one
adult animal goes to the aid of another

189
00:21:43,067 --> 00:21:47,140
that's got itself into difficulties,
these are much rarer.

190
00:21:47,307 --> 00:21:52,461
But this sort of behaviour does seem
to occur regularly in one species of animal,

191
00:21:52,627 --> 00:21:56,700
a colony of which is living in this hollow tree.

192
00:21:57,307 --> 00:22:00,538
It's not an animal
that might immediately come to mind

193
00:22:00,707 --> 00:22:06,145
as an example of a caring, unselfish creature,
but that, apparently, is what it is.

194
00:22:14,547 --> 00:22:18,745
0n this pile of droppings
there are flecks of congealed blood,

195
00:22:19,507 --> 00:22:22,897
a characteristic sign of vampire bats.

196
00:22:23,947 --> 00:22:27,144
And the colony itself is roosting above me.

197
00:22:28,347 --> 00:22:32,704
These bats, all females,
habitually roost as a group.

198
00:22:32,867 --> 00:22:37,418
If they move elsewhere, they will stick together
and hang in the same arrangement.

199
00:22:37,587 --> 00:22:40,181
Most are related, although by no means all.

200
00:22:40,347 --> 00:22:43,817
But every bat knows
her regular companions well.

201
00:22:44,587 --> 00:22:47,181
At night, they fly off to look for blood.

202
00:22:50,787 --> 00:22:53,938
A donkey is a favourite target.

203
00:22:54,107 --> 00:22:59,625
0ne lands on its shoulder and shaves
a slice of skin without the donkey even noticing.

204
00:23:00,467 --> 00:23:02,856
Another goes for its ear.

205
00:23:04,387 --> 00:23:08,938
The bat's saliva contains an ingredient
that prevents blood from clotting,

206
00:23:09,107 --> 00:23:12,019
and it flows freely from the wound they make.

207
00:23:15,707 --> 00:23:18,505
A third bat tries a different point of attack.

208
00:23:30,467 --> 00:23:32,935
(D0NKEY BRAYS)

209
00:23:42,667 --> 00:23:45,465
The bat on the ground still hasn't got a hold,

210
00:23:45,627 --> 00:23:48,903
but it's very hungry
and it makes one last attempt.

211
00:23:50,267 --> 00:23:53,020
But, no, she won't feed tonight.

212
00:23:54,907 --> 00:23:58,900
0n returning to the roost,
she hangs up beside an old friend.

213
00:24:01,427 --> 00:24:05,943
She turns to her neighbour and licks
her face repeatedly, begging for food.

214
00:24:06,107 --> 00:24:10,498
If she goes hungry
for more than a day or two, she will die.

215
00:24:11,267 --> 00:24:14,782
But her friend regurgitates
enough life-giving blood

216
00:24:14,947 --> 00:24:17,461
to keep her going until the following day.

217
00:24:23,027 --> 00:24:26,099
0n another night, the situation may be reversed,

218
00:24:26,267 --> 00:24:30,818
and the bat that is receiving now
will repay the gift if it's needed.

219
00:24:30,987 --> 00:24:35,503
But cheats, bats that refuse to give
to a neighbour who once helped them,

220
00:24:35,667 --> 00:24:39,660
will quickly be detected and, in consequence,
may never be helped again.

221
00:24:39,827 --> 00:24:44,821
So, for a vampire, it pays to help your neighbours,
whether they're related or not.

222
00:24:44,987 --> 00:24:47,501
Look after them and they will look after you.

223
00:24:48,867 --> 00:24:51,586
Such mutual assistance is much more common

224
00:24:51,747 --> 00:24:54,944
among communities
whose members are closely related.

225
00:24:55,107 --> 00:24:58,099
Dwarf mongooses live in groups of a dozen or so

226
00:24:58,267 --> 00:25:00,861
in the tunnels of old overgrown termite hills,

227
00:25:01,027 --> 00:25:05,020
and most of them
are the children of one breeding pair.

228
00:25:17,147 --> 00:25:22,585
This is the old female. While she is alive,
no other female here will breed.

229
00:25:22,747 --> 00:25:25,261
And this is her mate, the old male.

230
00:25:40,787 --> 00:25:43,255
They feed almost entirely on insects

231
00:25:43,427 --> 00:25:46,897
which they scratch out of the ground
and from rotten logs.

232
00:25:47,067 --> 00:25:52,061
Every day the troop goes out to collect them.
It's a very time-consuming business.

233
00:26:08,467 --> 00:26:10,935
A nice, big, crunchy beetle.

234
00:26:25,027 --> 00:26:27,541
But digging like this has its perils.

235
00:26:27,707 --> 00:26:31,700
With your head in a hole,
you can't see if an enemy approaches,

236
00:26:31,867 --> 00:26:35,701
and with your rump in the air,
you're dangerously exposed.

237
00:26:37,507 --> 00:26:42,262
So while some hunt, other members
of the colony are on guard duty.

238
00:26:43,547 --> 00:26:47,017
These sentinels,
usually males, but sometimes females,

239
00:26:47,187 --> 00:26:49,462
will get their turn to feed in due course.

240
00:26:51,627 --> 00:26:54,141
The youngest babies are now coming out.

241
00:27:05,507 --> 00:27:10,103
Their mother can't always be with them.
She has to spend much of her time feeding.

242
00:27:10,267 --> 00:27:14,260
Junior members of the colony
take turns to babysit.

243
00:27:24,387 --> 00:27:28,096
0ne or two of these babysitters
may replace the old breeders one day,

244
00:27:28,267 --> 00:27:31,703
but, for now, the best
they can do is to serve the colony.

245
00:27:31,867 --> 00:27:34,904
In doing so,
they may promote their own genetic line,

246
00:27:35,067 --> 00:27:37,786
for the nurses are often
the older sisters of the babies

247
00:27:37,947 --> 00:27:43,146
who carry as many of their genes
as their own young would.

248
00:27:51,147 --> 00:27:54,822
A martial eagle, a most dangerous enemy.

249
00:27:59,187 --> 00:28:02,816
The sentinels keep a close eye on it
to see if it's coming their way.

250
00:28:02,987 --> 00:28:05,581
If it does, they will whistle an alarm signal.

251
00:28:06,507 --> 00:28:08,498
(WHISTLING)

252
00:28:37,587 --> 00:28:42,422
The nurses groom their charges,
play with them and catch insects for them.

253
00:28:42,587 --> 00:28:47,581
Though they have never been pregnant,
they may even come into milk and suckle them.

254
00:28:51,667 --> 00:28:56,536
By the middle of the day, it's very hot
and many of the group need a snooze.

255
00:28:56,707 --> 00:28:59,221
And it's safe for them to drop off

256
00:28:59,387 --> 00:29:02,777
because some members of the family
are still on guard.

257
00:29:08,187 --> 00:29:12,703
So, by taking turns to help out
and waiting for a chance to breed,

258
00:29:12,867 --> 00:29:16,860
the mongooses are able to survive
and continue their family line

259
00:29:17,027 --> 00:29:19,621
where as pairs they would surely fail.

260
00:29:23,667 --> 00:29:28,741
0ne mammal has taken this specialisation
within the community to an extreme.

261
00:29:29,547 --> 00:29:33,745
Just how extreme hasn't been
appreciated until quite recently.

262
00:29:33,907 --> 00:29:37,502
That's hardly surprising,
because the most anyone normally sees

263
00:29:37,667 --> 00:29:40,465
of this amazing creature is no more than this.

264
00:29:58,587 --> 00:30:04,503
It's a powerful and industrious digger
that spends its entire life underground.

265
00:30:04,667 --> 00:30:06,942
A naked mole rat.

266
00:30:07,587 --> 00:30:10,943
These creatures live
in highly inbred groups of 80 or more

267
00:30:11,107 --> 00:30:15,817
and feed on the gigantic underground tubers
developed by some desert plants

268
00:30:15,987 --> 00:30:18,547
as a way of storing food and water.

269
00:30:18,707 --> 00:30:22,222
But they have no way
of knowing where these tubers are.

270
00:30:22,387 --> 00:30:26,778
All they can do is dig away and hope
they will eventually bump into one.

271
00:30:26,947 --> 00:30:29,541
So the colony is perpetually tunnelling.

272
00:30:35,667 --> 00:30:38,704
Digging in this hard ground requires teamwork.

273
00:30:38,867 --> 00:30:44,100
Some workers, at the front end of the tunnel,
gnaw into the baked earth.

274
00:30:44,267 --> 00:30:48,101
A mole rat's lips close
behind the long, curved front teeth,

275
00:30:48,267 --> 00:30:51,862
so that it doesn't get
any of the earth into its mouth.

276
00:30:57,627 --> 00:31:01,540
0ther team members, behind,
kick the soil back along the tunnel

277
00:31:01,707 --> 00:31:05,382
until it reaches one of the surface exits.

278
00:31:06,587 --> 00:31:10,705
It's so unvaryingly hot here
that the mole rats need no fur.

279
00:31:10,867 --> 00:31:14,542
Because they're hardly ever
in the light, eyes are of little use,

280
00:31:14,707 --> 00:31:20,418
and they're virtually blind, so they run
backwards and forwards like tube trains.

281
00:31:27,227 --> 00:31:30,025
Not all the mole rats dig.

282
00:31:30,187 --> 00:31:35,307
A few, a little bigger than the tunnellers,
spend most of their time lazing about

283
00:31:35,467 --> 00:31:38,106
in a large central chamber.

284
00:31:43,867 --> 00:31:45,858
These are soldiers.

285
00:31:46,027 --> 00:31:51,021
Some are male, some female. And they're
saving their energies for an emergency.

286
00:31:51,187 --> 00:31:53,178
And here comes one.

287
00:32:01,707 --> 00:32:05,336
A snake has found its way
down one of those exit holes.

288
00:32:06,987 --> 00:32:12,698
The workers flee in front of it,
squeaking with alarm to rouse the soldiers.

289
00:32:22,707 --> 00:32:24,698
With those formidable teeth,

290
00:32:24,867 --> 00:32:28,177
the soldiers are capable
of stabbing the snake to death,

291
00:32:28,347 --> 00:32:30,815
and they block the tunnel.

292
00:32:38,107 --> 00:32:40,302
(SQUEAKING)

293
00:32:47,867 --> 00:32:50,017
Reinforcements arrive.

294
00:32:57,747 --> 00:33:00,784
The snake thinks better of it.

295
00:33:03,267 --> 00:33:07,658
The mother of the colony, the queen,
is the only breeding female.

296
00:33:07,827 --> 00:33:10,864
She gives birth to a dozen or so young at a time

297
00:33:11,027 --> 00:33:14,144
and produces a new litter every 13 weeks.

298
00:33:14,307 --> 00:33:17,504
And she may live for 12 or 13 years.

299
00:33:28,307 --> 00:33:32,095
The father of the brood is one or other
of the two oldest soldiers.

300
00:33:32,267 --> 00:33:34,906
But he's not as long-lived as the queen.

301
00:33:35,067 --> 00:33:39,106
A year or two of sexual activity
seems to exhaust him and he dies.

302
00:33:39,267 --> 00:33:43,226
His place will be taken
by another senior soldier.

303
00:33:48,467 --> 00:33:50,856
All these babies will become tunnellers.

304
00:33:51,027 --> 00:33:53,860
Some will later graduate to being soldiers,

305
00:33:54,027 --> 00:33:58,862
but none of the females, while the queen lives,
will become sexually mature.

306
00:33:59,027 --> 00:34:01,018
Why?

307
00:34:02,067 --> 00:34:07,505
The colony has a communal latrine,
used by all, including the queen.

308
00:34:07,667 --> 00:34:13,264
The workers, when they visit it, deliberately
anoint their naked skin with its contents.

309
00:34:13,427 --> 00:34:18,501
This gives them the colony's odour,
so they are recognised and accepted by all.

310
00:34:18,667 --> 00:34:23,297
But in doing that, they may commit
themselves to a life of sterility,

311
00:34:23,467 --> 00:34:25,856
for the queen's urine contains a substance

312
00:34:26,027 --> 00:34:30,305
that helps to suppress
the development of ovaries in others.

313
00:34:34,467 --> 00:34:40,019
The supply of the fertility suppressant
will continue as long as the queen lives.

314
00:34:40,187 --> 00:34:44,180
0nly when she dies will one
of the female soldiers mature sexually

315
00:34:44,347 --> 00:34:46,736
and succeed to the throne.

316
00:34:49,107 --> 00:34:53,737
The queen spends most of her life
in the chamber surrounded by her soldiers.

317
00:34:53,907 --> 00:34:56,421
She doesn't dig. She doesn't fight.

318
00:34:56,587 --> 00:35:00,626
She concentrates her physical strength
on producing within her belly

319
00:35:00,787 --> 00:35:03,301
huge broods of babies.

320
00:35:08,987 --> 00:35:11,660
So the ranks of the short-lived tunnellers

321
00:35:11,827 --> 00:35:14,899
are maintained to continue
the digging that's essential

322
00:35:15,067 --> 00:35:20,187
to find food for themselves,
their brothers and sisters and their queen.

323
00:35:32,867 --> 00:35:37,418
These hard-working porters
are also members of a society,

324
00:35:37,587 --> 00:35:41,978
but one which numbers
not a few dozen but several million.

325
00:35:42,147 --> 00:35:45,298
Nor are they just gathering straightforward food.

326
00:35:45,467 --> 00:35:50,063
They're taking part in a much more
complex agricultural system.

327
00:35:57,067 --> 00:36:02,266
Leaf-cutting ants demolish plants
morning, noon and night.

328
00:36:02,427 --> 00:36:07,023
Heavy rain and direct sunshine
are the only conditions that stop them.

329
00:36:09,347 --> 00:36:11,815
Every one of these workers is a female.

330
00:36:11,987 --> 00:36:15,775
They're all sisters,
working together in one of the most organised

331
00:36:15,947 --> 00:36:18,666
and tightly knit communities of all.

332
00:36:32,547 --> 00:36:35,015
They use their legs as callipers,

333
00:36:35,187 --> 00:36:38,577
guiding their jaws
so that they cut a segment of a size

334
00:36:38,747 --> 00:36:42,820
that is the most economical to cut
and most practical to carry.

335
00:36:45,987 --> 00:36:48,820
But they can't eat these leaf segments.

336
00:36:48,987 --> 00:36:54,141
Cellulose, the main constituent of leaves
apart from water, is very indigestible.

337
00:36:54,307 --> 00:36:59,301
They have to take all these pieces back
to their underground nest for treatment.

338
00:36:59,987 --> 00:37:03,900
The journey may be down
a tree trunk for 50 feet or more.

339
00:37:29,627 --> 00:37:33,984
And once on the ground,
there may still be 100 yards to go.

340
00:37:47,227 --> 00:37:49,821
0nce inside the entrance of the nest,

341
00:37:49,987 --> 00:37:54,299
the leaves are carried down long corridors
deep below ground.

342
00:37:58,427 --> 00:38:04,059
Here, in special chambers, they're taken over
by a slightly smaller caste of worker

343
00:38:04,227 --> 00:38:07,378
who cut the leaves into smaller segments still.

344
00:38:07,547 --> 00:38:12,496
These chambers are gardens
where the colony cultivates a special fungus.

345
00:38:12,667 --> 00:38:17,183
The leaf segments are the raw material
on which the fungus will grow.

346
00:38:17,347 --> 00:38:20,100
But, first, the segments must be processed.

347
00:38:20,267 --> 00:38:24,624
It could be very damaging
if bacteria or spores of an alien fungus

348
00:38:24,787 --> 00:38:28,302
got into the nest
and started to germinate like a weed.

349
00:38:28,467 --> 00:38:33,257
So the workers meticulously clean
the surface of each piece by licking it.

350
00:38:40,107 --> 00:38:43,144
The edge of every segment is then chewed.

351
00:38:43,307 --> 00:38:46,538
This yields some food
for the worker doing the job,

352
00:38:46,707 --> 00:38:49,221
for leaf sap is digestible.

353
00:38:49,907 --> 00:38:53,297
And it also prepares the leaf for the next stage.

354
00:38:53,987 --> 00:38:57,980
The garden chambers vary in size
from an orange to a melon,

355
00:38:58,147 --> 00:39:02,265
but they're all filled with a honeycomb
of grey, spongy material.

356
00:39:21,027 --> 00:39:24,463
And now these smallest workers of all take over.

357
00:39:24,627 --> 00:39:29,143
They're a mere two millimetres long,
the size of a grain of sand.

358
00:39:29,307 --> 00:39:33,937
0nly these tiny dwarfs can enter
the minute spaces within the gardens.

359
00:39:34,107 --> 00:39:37,179
They push the leaf fragments into the matrix

360
00:39:37,347 --> 00:39:41,135
and then plant tufts of fungus
all over their pulped surface.

361
00:39:43,147 --> 00:39:47,743
Within 24 hours, the green of the leaf
has almost completely disappeared

362
00:39:47,907 --> 00:39:50,375
beneath a tissue of white threads.

363
00:40:01,147 --> 00:40:06,858
A day or so later and the threads of fungus
begin to develop tiny knobs at their ends.

364
00:40:07,027 --> 00:40:10,622
This, at last, is the crop
that the ants can eat.

365
00:40:13,027 --> 00:40:15,860
Some of the workers consume it there and then.

366
00:40:16,027 --> 00:40:19,064
Most is carried away to feed to developing grubs

367
00:40:19,227 --> 00:40:24,779
and the other workers who laboured so hard
gathering the leaf segments in the first place.

368
00:40:40,427 --> 00:40:45,865
0ne by one, these swollen ends of the threads
are torn from the tangled mass.

369
00:40:56,667 --> 00:41:00,262
Sap, sucked from the edges of the leaves
during their processing,

370
00:41:00,427 --> 00:41:05,217
is fed by a gardener to another worker
who has duties elsewhere in the colony.

371
00:41:10,987 --> 00:41:14,980
Slowly, the swarms of workers
complete the harvest.

372
00:41:20,227 --> 00:41:22,422
Now the fungus is spent.

373
00:41:22,587 --> 00:41:28,059
Its remains and the mulch of leaves on which
it grew has to be cleared out of the garden.

374
00:41:28,227 --> 00:41:32,505
The workers swarm all over
the grey honeycomb, breaking it up.

375
00:41:46,107 --> 00:41:50,783
Every particle is carried up the corridors
and taken out of the nest.

376
00:41:59,907 --> 00:42:03,980
Long processions of workers set off for the exits.

377
00:42:08,307 --> 00:42:13,142
Here, out in the open, by the side of the nest,
they have their refuse tip.

378
00:42:41,347 --> 00:42:45,784
So one cycle of fungus cultivation is completed.

379
00:42:47,387 --> 00:42:51,175
And the scale of their operations is enormous.

380
00:42:51,347 --> 00:42:55,659
They can strip an entire tree
of its leaves in a single night.

381
00:42:55,827 --> 00:42:59,661
Their pathways extend
for 100 yards in all directions.

382
00:42:59,827 --> 00:43:05,220
The nest is 20 feet across
and it goes down for as much as 18 feet.

383
00:43:05,387 --> 00:43:08,060
Inside, there are a thousand or so chambers

384
00:43:08,227 --> 00:43:11,663
where the ants have their gardens
and where they live.

385
00:43:11,827 --> 00:43:14,421
And it's virtually impregnable.

386
00:43:14,587 --> 00:43:19,058
Even the vibrations of my footsteps
are enough to bring out the defenders.

387
00:43:24,747 --> 00:43:30,743
These soldiers are 300 times heavier
than the little dwarfs working in the gardens.

388
00:43:30,907 --> 00:43:34,695
They bite any alien thing -
shoes, socks, anything.

389
00:43:35,867 --> 00:43:38,825
As long as they only bite my clothing,
they're no problem.

390
00:43:38,987 --> 00:43:41,945
If they got onto my flesh,
they would have me hopping about,

391
00:43:42,107 --> 00:43:45,179
for they can slice a very painful slit in your skin.

392
00:43:45,347 --> 00:43:49,465
They seldom let go. 0nce they've fastened
their jaws, they stay fastened,

393
00:43:49,627 --> 00:43:52,095
even if the rest of their body gets torn off.

394
00:43:52,267 --> 00:43:54,303
Soldiers are expendable.

395
00:43:54,467 --> 00:43:59,939
Their task is to protect the one single individual
in the colony who is indispensable.

396
00:44:01,187 --> 00:44:04,941
The queen,
mother of all the members of the colony.

397
00:44:05,107 --> 00:44:07,496
She is as big as a newborn mouse.

398
00:44:07,667 --> 00:44:12,183
0n her nuptial flight, she was impregnated
by three or four males.

399
00:44:12,347 --> 00:44:17,341
The sperm they gave her then lasts her
for the rest of her long and productive life.

400
00:44:27,627 --> 00:44:32,337
The workers continually groom and clean
every part of her great body.

401
00:44:40,947 --> 00:44:45,975
Some attend her rear, waiting to collect
the eggs she produces in bursts.

402
00:44:46,147 --> 00:44:48,661
She may lay a million a year.

403
00:44:48,827 --> 00:44:54,584
Some are fertilised from her sperm store,
others are not. But they, too, will hatch.

404
00:44:55,947 --> 00:44:58,905
0ne appears, a tiny white bead.

405
00:44:59,067 --> 00:45:04,061
A worker waits for it to emerge completely,
feeling it delicately with its jaws.

406
00:45:05,307 --> 00:45:09,585
It picks it off
and takes it away to the nursery chambers.

407
00:45:10,947 --> 00:45:13,461
The grubs that develop from fertilised eggs

408
00:45:13,627 --> 00:45:17,859
mostly become members
of the exclusively female workforce.

409
00:45:18,027 --> 00:45:20,541
The way they are fed by the workers

410
00:45:20,707 --> 00:45:24,302
determines which
of the six different castes they will be.

411
00:45:24,467 --> 00:45:26,935
Unfertilised eggs develop into males,

412
00:45:27,107 --> 00:45:32,340
who fly out of the nest to mate with young
winged queens and establish new colonies.

413
00:45:32,507 --> 00:45:35,305
0nce these ants start on adult life,

414
00:45:35,467 --> 00:45:40,018
they will not be able to change roles,
as mole rats or dwarf mongooses can.

415
00:45:40,187 --> 00:45:42,747
Their destiny is fixed.

416
00:45:48,667 --> 00:45:52,023
The first ants, back in the evolutionary past,

417
00:45:52,187 --> 00:45:55,224
almost certainly operated as single individuals,

418
00:45:55,387 --> 00:45:59,141
as many species of their wasp
and bee relatives still do today.

419
00:45:59,307 --> 00:46:02,299
0ver millions of years,
they came to live in communities

420
00:46:02,467 --> 00:46:04,935
of increasing size and complexity.

421
00:46:05,107 --> 00:46:07,780
Now that process has come full circle.

422
00:46:07,947 --> 00:46:12,782
By producing individuals specialised
to do particular jobs in their society,

423
00:46:12,947 --> 00:46:16,735
five million insects have become effectively one.

424
00:46:16,907 --> 00:46:19,375
But what a superbly efficient one.

425
00:46:20,227 --> 00:46:25,301
It's not the monkeys or the rodents or, indeed,
the human beings who dominate the forest.

426
00:46:26,107 --> 00:46:29,816
It's the tiny ant that, by multiplying itself,

427
00:46:29,987 --> 00:46:33,343
has turned itself into a super-organism,

428
00:46:33,507 --> 00:46:36,385
a complex, highly disciplined society.