1
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(DRUMMING)

2
00:01:12,767 --> 00:01:16,760
(PE0PLE SINGING IN SAM0AN)

3
00:01:16,927 --> 00:01:19,521
(HAND-CLAPPING)

4
00:01:45,327 --> 00:01:48,717
This is Samoa, in the middle of the Pacific.

5
00:01:48,887 --> 00:01:52,880
It's 0ctober, the moon has just
entered its third quarter,

6
00:01:53,047 --> 00:01:58,963
and the villagers have come out onto the reef,
because this is an extraordinary moment.

7
00:01:59,127 --> 00:02:03,439
0n this one day of the year,
just around dawn for about an hour,

8
00:02:03,607 --> 00:02:08,806
the sea produces the most delicious food
that the people ever get from it.

9
00:02:08,967 --> 00:02:14,166
The water becomes alive
with millions upon millions of worms -

10
00:02:14,327 --> 00:02:16,522
palolo.

11
00:02:27,287 --> 00:02:32,441
To be accurate, each of these wriggling threads
is only half a worm - the back half.

12
00:02:32,607 --> 00:02:37,806
The head ends are still safe within burrows
in the stony walls of the coral reef.

13
00:02:37,967 --> 00:02:42,483
But these tail ends
contain the all-important sex cells.

14
00:02:54,527 --> 00:02:58,805
The yellow threads are male,
the green ones, female.

15
00:03:06,207 --> 00:03:11,600
The writhing segments disintegrate
as they reach the light, releasing their contents.

16
00:03:11,767 --> 00:03:13,962
Milky sperm oozes out

17
00:03:14,127 --> 00:03:18,962
and meets the green eggs
spilling through the ruptured body walls.

18
00:03:26,207 --> 00:03:28,721
Fertilisation is achieved

19
00:03:28,887 --> 00:03:31,447
and on an astronomic scale.

20
00:03:40,207 --> 00:03:45,520
So this simple animal, by a feat of timing
which we still don't understand,

21
00:03:45,687 --> 00:03:50,886
manages to solve the problem that faces
all animals if they're to be a biological success -

22
00:03:51,047 --> 00:03:54,835
how to pass on their genes to the next generation.

23
00:03:55,007 --> 00:03:57,805
But though the problem is always the same,

24
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the solutions are amazingly varied.

25
00:04:08,607 --> 00:04:11,599
Barnacles, stuck to the rocks, groping for food,

26
00:04:11,767 --> 00:04:16,761
face a particular difficulty
when it comes to mating - they can't move.

27
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Their solution is a male organ
that, proportionately,

28
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is the longest possessed by any animal.

29
00:04:39,207 --> 00:04:41,926
And they have another aid to mating.

30
00:04:42,087 --> 00:04:46,365
Each barnacle possesses
both male and female organs,

31
00:04:46,527 --> 00:04:49,519
so every neighbour is a potential mate.

32
00:04:49,687 --> 00:04:52,406
Eggs are only produced once a year.

33
00:04:52,567 --> 00:04:58,085
As soon as a barnacle has them ready,
it advertises the fact by releasing a chemical,

34
00:04:58,247 --> 00:05:02,445
and all its neighbours
reach across to try and fertilise it.

35
00:05:04,287 --> 00:05:08,075
Unlike eggs, which require
a lot of energy to make,

36
00:05:08,247 --> 00:05:11,239
sperm can be produced quickly
and in great quantity.

37
00:05:11,407 --> 00:05:17,482
So, as a male, a barnacle can fertilise
many others. They all compete to do so.

38
00:05:17,647 --> 00:05:22,641
The egg bearer, as a consequence,
is given far more sperm than necessary

39
00:05:22,807 --> 00:05:25,765
and ejects most of it as a white blob.

40
00:05:25,927 --> 00:05:31,718
So a barnacle manages to get the best
of both the male and the female world.

41
00:05:33,687 --> 00:05:37,680
These fish, blue-headed wrasse
on the reefs of the Bahamas,

42
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are also bisexual, but not simultaneously.

43
00:05:43,727 --> 00:05:48,039
The big, blue-headed one is a male,
the smaller one, a female.

44
00:05:50,127 --> 00:05:55,121
A number of females visit a spawning site
controlled by an individual male.

45
00:05:55,287 --> 00:05:58,006
As each lays her eggs, he fertilises them.

46
00:05:58,167 --> 00:06:03,685
So he passes on his genes to far more young
than an individual female does.

47
00:06:03,847 --> 00:06:06,361
In the competition to continue the line,

48
00:06:06,527 --> 00:06:10,839
it's better for a wrasse
to be a big male than a female.

49
00:06:11,007 --> 00:06:15,717
And when a male dies,
the biggest female claims his throne.

50
00:06:15,887 --> 00:06:20,278
Within two weeks, she develops a blue head,
produces sperm,

51
00:06:20,447 --> 00:06:25,237
and becomes a parent of more babies
than if she had remained a ''she''.

52
00:06:28,967 --> 00:06:34,564
But most animals don't have this option.
They're stuck with the sex they're born with.

53
00:06:36,567 --> 00:06:39,035
A male octopus is always male,

54
00:06:39,207 --> 00:06:43,997
and if he is to pass on his genes,
he is the one who has to take action.

55
00:06:47,847 --> 00:06:51,681
0nce he's grabbed the female,
he strokes her to calm her.

56
00:06:51,847 --> 00:06:54,566
He has eight arms with which to do so.

57
00:07:05,727 --> 00:07:09,720
His third right arm
has a particularly sensitive tip.

58
00:07:09,887 --> 00:07:15,678
While he caresses her with the other seven,
he uses it to feel for her genital opening.

59
00:07:18,687 --> 00:07:20,882
He has found it.

60
00:07:21,047 --> 00:07:26,041
Now, with muscular waves,
he pumps packets of sperm into her.

61
00:07:38,647 --> 00:07:43,641
The male dumpling squid,
having mated in a similar way, separates.

62
00:07:52,527 --> 00:07:57,043
Some of his sperm packets
still trail from his special arm.

63
00:07:58,487 --> 00:08:03,197
But the majority
have successfully released their contents.

64
00:08:07,647 --> 00:08:11,526
A female doesn't always have to accept
the first male to grab her.

65
00:08:13,807 --> 00:08:19,803
A female tortoise in Madagascar proclaims
her readiness to mate by releasing a perfume.

66
00:08:19,967 --> 00:08:23,357
But when a male turns up, she plays hard to get.

67
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He, however, is armed.

68
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He has a spike on his shell that is so big
that it gives the species its name,

69
00:08:44,647 --> 00:08:47,036
the ploughshare tortoise.

70
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He may not be able to force her to mate,

71
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but he can use his spike to demonstrate
his strength in a very convincing way.

72
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Her perfume has attracted another male.

73
00:09:37,207 --> 00:09:40,324
Now the rivals must fight it out.

74
00:10:16,687 --> 00:10:21,397
With his opponent overturned,
the victor can claim his prize.

75
00:10:26,567 --> 00:10:31,561
The female, having righted herself, seems
to be sufficiently impressed by his strength

76
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to accept him as the most powerful male around.

77
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(GRUNTING)

78
00:10:41,367 --> 00:10:44,962
And the vanquished can only lie by helplessly.

79
00:10:53,727 --> 00:10:58,118
Female elephants have a similar way
of sorting out the men from the boys.

80
00:10:58,287 --> 00:11:01,006
Producing a calf takes a female a long time,

81
00:11:01,167 --> 00:11:05,763
22 months of pregnancy and then
a further four years of feeding it on milk.

82
00:11:05,927 --> 00:11:10,318
So she wants to make sure
that her calf has the best father around.

83
00:11:10,487 --> 00:11:15,083
She becomes sexually receptive
for just a few days every four years or so.

84
00:11:15,247 --> 00:11:21,038
Mature bulls spend most of their time away
from the herd, wandering in special bull areas.

85
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So it's usually a teenage hanger-on
who is the first to notice her availability.

86
00:12:00,407 --> 00:12:03,080
But he's not yet very good at mating,

87
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and he's not the strong and proven partner
that she wants, so she leaves him.

88
00:12:18,367 --> 00:12:23,157
The male she seeks is a mature bull
like this 50-year-old.

89
00:12:24,287 --> 00:12:28,997
Male elephants are only in full sexual condition
for three months of the year.

90
00:12:29,167 --> 00:12:35,163
But this one is. A gland behind his eye
is discharging and his genitals are dripping.

91
00:12:35,327 --> 00:12:37,557
He is in musth.

92
00:12:39,287 --> 00:12:44,486
During this time, he devotes his energy
to seeking out receptive females.

93
00:12:51,927 --> 00:12:54,725
He assesses their condition by smell.

94
00:13:14,647 --> 00:13:19,437
If a female's smell is promising,
he tastes her urine to test it.

95
00:13:19,607 --> 00:13:25,398
It's as important for her as it is for him
to make clear her reproductive state.

96
00:13:40,487 --> 00:13:45,356
This female isn't quite ready,
but there is one nearby who is.

97
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(RUMBLING)

98
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The deep rumble is being made
by a female who's just mated.

99
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She's declaring that she's still receptive,

100
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and her partner defers to the big male
by walking away.

101
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The big male starts to follow her.

102
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She encourages him
with a special, coy, swinging walk.

103
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Each time she is mated, she calls again,
just in case there's a bigger musth male around.

104
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By the end of her receptive period
when her egg is released into her womb,

105
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she will be partnered and guarded
by the biggest male in the neighbourhood,

106
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and he will be the father of her calf.

107
00:16:03,967 --> 00:16:07,164
Chinchilla females are not so welcoming.

108
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If a male presses his suit
when she's not ready for him, there's trouble.

109
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A quick squirt of urine in the face
makes her feelings clear.

110
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He won't pester her again
until he has cleaned himself.

111
00:16:30,447 --> 00:16:36,443
Things can be even more tricky for a male
if his mate is well armed, as spiders are.

112
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The female tarantula has fearsome poison fangs.

113
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The male is much smaller than she is
and approaches her with obvious trepidation.

114
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His life at this moment depends on being able
to hold her poison fangs out of the way.

115
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0nly now dare he reach forward with his palps.

116
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At the end of these there's a suction bulb
which he's loaded with sperm.

117
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He must thrust his palps into a pair of genital
pores on her underside, just beyond her head.

118
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That's a very dangerous proceeding.

119
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He's done it.

120
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Male spiders are by no means always so skilful.

121
00:17:36,167 --> 00:17:41,366
These few legs are all that remains
of a male Nephila spider who failed.

122
00:17:41,527 --> 00:17:46,521
But another male is on the same web now,
preparing to chance his luck.

123
00:17:48,847 --> 00:17:51,361
And his task is indeed formidable,

124
00:17:51,527 --> 00:17:57,124
for his mate is gigantic, six inches across
and several hundred times his weight.

125
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She's virtually blind and relies on vibrations
of her web to tell her what's going on.

126
00:18:06,207 --> 00:18:12,203
If he sends the wrong vibes along the threads,
she could easily get the idea that he's a meal.

127
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He's now within range of her strike.

128
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He retreated just in time.

129
00:18:27,167 --> 00:18:33,163
This, indeed, is a meal. A fly, a welcome
diversion as far as the male is concerned.

130
00:18:46,407 --> 00:18:52,004
While she's occupied with trussing it up
in bonds of silk, he has his chance.

131
00:19:09,527 --> 00:19:14,237
He clambers over her mountainous underside
and delivers his packet.

132
00:19:14,407 --> 00:19:17,399
He's so small, it's hard to see him on her body,

133
00:19:17,567 --> 00:19:20,877
and it seems doubtful if she notices him at all.

134
00:19:26,607 --> 00:19:33,001
A male cockroach from Cuba encourages
his mate to nibble him - or bits of him.

135
00:19:33,167 --> 00:19:37,285
He lifts his wings to offer her a potion
produced from special glands

136
00:19:37,447 --> 00:19:41,042
which not only smells good but tastes good.

137
00:19:41,207 --> 00:19:47,237
While she licks them, he must couple,
and do so before her nibble becomes a bite.

138
00:20:00,127 --> 00:20:03,278
He has achieved a connection
and escaped injury.

139
00:20:03,447 --> 00:20:08,475
Now he must hang on
until he has transferred his sperm.

140
00:20:37,727 --> 00:20:43,723
The mountain dusky salamander has an extreme
way of persuading a female to mate with him.

141
00:20:43,887 --> 00:20:49,883
It involves biting her neck, a habit that has
given him the nickname of vampire salamander.

142
00:20:50,047 --> 00:20:53,278
But he doesn't do it to drink her blood.

143
00:20:56,807 --> 00:21:00,959
Special glands on his chin
produce an aphrodisiac,

144
00:21:01,127 --> 00:21:04,119
and he anoints her with it by rubbing her neck.

145
00:21:04,287 --> 00:21:08,883
But he must do more than this
to really get it under her skin.

146
00:21:13,727 --> 00:21:17,197
A quick scratch with his teeth
and he's vaccinated her.

147
00:21:17,367 --> 00:21:20,882
Now she'll follow him wherever he goes.

148
00:21:22,687 --> 00:21:27,078
But he has a particular problem.
Salamanders are amphibians.

149
00:21:27,247 --> 00:21:29,841
Unlike all other four-legged land animals,

150
00:21:30,007 --> 00:21:36,003
the male amphibian doesn't have an apparatus
with which to inject sperm into a female's body.

151
00:21:36,167 --> 00:21:38,681
So he has to use another method.

152
00:21:44,967 --> 00:21:51,315
He begins to walk away, and the female,
excited by her vaccination, follows him.

153
00:21:58,687 --> 00:22:02,077
He deposits a blob of sperm on the ground.

154
00:22:06,487 --> 00:22:08,876
As she continues to walk after him,

155
00:22:09,047 --> 00:22:13,837
he leads her across it
so that her underside presses against it.

156
00:22:14,007 --> 00:22:18,603
When it's level with her genital opening,
she draws it in.

157
00:22:22,647 --> 00:22:29,086
Some females, no matter what the male does,
are physically inaccessible for most of their lives.

158
00:22:33,687 --> 00:22:37,680
Crabs wear suits of armour,
which makes mating impossible.

159
00:22:37,847 --> 00:22:41,635
But this big male has detected
a faint taste in the water

160
00:22:41,807 --> 00:22:46,198
that tells him that the little female
is about to shed hers.

161
00:22:59,967 --> 00:23:04,563
As soon as she slips out of her shell,
while her new one is still pliable,

162
00:23:04,727 --> 00:23:07,195
she and he can become intimate.

163
00:23:07,367 --> 00:23:13,124
He's going to hold onto her so that no other male
can claim her at that crucial moment.

164
00:23:14,607 --> 00:23:21,206
Her moult has begun. Her shell has split along
the underside and he is helping her to disrobe.

165
00:23:23,247 --> 00:23:29,436
The empty suit of armour makes it seem
as if he has two females in his embrace.

166
00:23:34,207 --> 00:23:40,203
The fact that one is the ghost of her former self
is revealed only by its vacant eye sockets

167
00:23:40,367 --> 00:23:43,564
and the way the current blows it about.

168
00:23:45,967 --> 00:23:51,758
Now the female, with her new shell
still soft and leathery, crawls beneath him.

169
00:24:01,127 --> 00:24:05,200
He fertilises her swiftly,
before her shell hardens.

170
00:24:05,367 --> 00:24:09,838
She won't be able to mate again
until her next moult.

171
00:24:15,447 --> 00:24:17,836
Soon he will abandon her,

172
00:24:18,007 --> 00:24:24,196
but he's ensured that the eggs she will nurture
for the next few weeks will carry his genes.

173
00:24:27,767 --> 00:24:32,761
A male butterfly has to be just as alert
as a crab if he is to secure a mate.

174
00:24:32,927 --> 00:24:37,318
This forest in Costa Rica
is full of competitors for the females

175
00:24:37,487 --> 00:24:41,685
who are appearing from pupae
hanging in the bushes.

176
00:24:41,847 --> 00:24:45,044
This is a male Heliconius butterfly,

177
00:24:45,207 --> 00:24:50,406
and he's settled on a pupa
which he knows contains a female.

178
00:24:50,567 --> 00:24:55,766
He's waiting for that moment
when the female will emerge, a virgin,

179
00:24:55,927 --> 00:25:00,717
and then in the first few seconds
of her adult life, he'll mate with her.

180
00:25:00,887 --> 00:25:04,004
And so intent is he on achieving that

181
00:25:04,167 --> 00:25:08,638
that he won't move
even if I touch him with my fingers.

182
00:25:09,847 --> 00:25:15,843
But watch what happens if I take this,
which is an adult female which has newly mated.

183
00:25:16,007 --> 00:25:19,317
What happens if I brush him lightly with her?

184
00:25:24,007 --> 00:25:28,603
The reason he left is because this female,
when she was mated,

185
00:25:28,767 --> 00:25:32,965
was given a particular smell
which even I can detect,

186
00:25:33,127 --> 00:25:37,120
a smell that all other males find very repugnant.

187
00:25:37,287 --> 00:25:42,122
If I let her fly away,
that male may return to complete his business.

188
00:25:42,287 --> 00:25:47,884
And even before the newly emerged female's
wings have expanded, he mates with her,

189
00:25:48,047 --> 00:25:52,438
dabbing her with his smell,
which will repel other males for weeks.

190
00:25:52,607 --> 00:25:55,519
No rival will displace his sperm.

191
00:25:55,687 --> 00:25:58,155
(H0WLING)

192
00:26:20,087 --> 00:26:23,875
A female wolf who's just become
sexually receptive

193
00:26:24,047 --> 00:26:27,244
joins her howling pack in the Canadian north.

194
00:26:29,487 --> 00:26:31,955
All the males are interested in her,

195
00:26:32,127 --> 00:26:37,724
but there's a ranking system in the pack
and the senior male has priority in mating.

196
00:26:37,887 --> 00:26:42,199
0thers who try their luck
have to be reminded who's boss.

197
00:26:53,767 --> 00:26:56,235
And he claims his rights.

198
00:27:15,807 --> 00:27:20,597
But he does not now leave her.
Indeed, he couldn't even if he wanted to.

199
00:27:20,767 --> 00:27:26,558
His genitals have swollen so greatly inside her
that the pair are locked together.

200
00:27:29,287 --> 00:27:34,759
This is no unfortunate accident. It's an important
part of the male's breeding strategy.

201
00:27:34,927 --> 00:27:39,637
Remaining tied for so long
gives his sperm time to reach her eggs

202
00:27:39,807 --> 00:27:42,401
before a competitor can displace him.

203
00:27:42,567 --> 00:27:46,879
It may be half an hour or so
before they're able to pull apart.

204
00:27:52,567 --> 00:27:56,879
The aftermath of such a genital lock
may be slightly painful,

205
00:27:57,047 --> 00:28:01,245
but the process has virtually
guaranteed him his paternity.

206
00:28:01,407 --> 00:28:07,004
Animals that don't take such precautions
can't be nearly so certain.

207
00:28:08,087 --> 00:28:11,921
A male bluegill sunfish
swimming in a lake in North America

208
00:28:12,127 --> 00:28:16,917
seems big, strong and confident enough
to take on any rivals.

209
00:28:17,087 --> 00:28:21,080
He's eight years old,
and he, too, is ready to breed.

210
00:28:21,247 --> 00:28:25,240
He hollows out a shallow nest by fanning his tail.

211
00:28:26,327 --> 00:28:31,321
Then he sets about persuading one of
the females in the shoals swimming nearby

212
00:28:31,487 --> 00:28:33,876
to come down and join him.

213
00:28:35,527 --> 00:28:39,725
He is offering both a nest
and his parental services.

214
00:28:44,607 --> 00:28:49,806
0ne arrives. Although she's considerably
smaller than he is, she is full-grown.

215
00:28:49,967 --> 00:28:53,164
He chivvies her into his nest to lay.

216
00:28:54,247 --> 00:29:00,686
She catches his mood from his distended fins
and circling dance. Things are going well.

217
00:29:00,847 --> 00:29:05,238
But lurking in the weeds
is a tiny two-year-old male.

218
00:29:05,407 --> 00:29:08,683
He will never build a nest or woo a female,

219
00:29:08,847 --> 00:29:11,964
but he's a serious rival nonetheless.

220
00:29:12,127 --> 00:29:16,917
As soon as the female lays,
he darts in and delivers a jet of sperm.

221
00:29:19,767 --> 00:29:24,761
Back he comes and adds another squirt
before he's finally chased off.

222
00:29:36,167 --> 00:29:39,364
The owner of the nest continues his dance.

223
00:29:39,527 --> 00:29:42,485
The more eggs that are laid in it, the better.

224
00:29:47,607 --> 00:29:50,644
The little sneak retires to the weeds.

225
00:29:50,807 --> 00:29:55,597
Now the big male seems to have been joined
by a second female.

226
00:29:55,767 --> 00:30:00,283
Not so. The new one in the middle
is an older sneaking male

227
00:30:00,447 --> 00:30:05,965
who dances so like a female
that the big male doesn't notice the difference.

228
00:30:06,127 --> 00:30:09,119
The nest owner chases away other males,

229
00:30:09,287 --> 00:30:15,078
leaving the female impersonator with
the real female, unhurriedly fertilising her eggs.

230
00:30:20,487 --> 00:30:25,117
Eventually, the big male is left
in sole charge of the nursery.

231
00:30:30,927 --> 00:30:36,524
He labours away, fanning the eggs
to keep oxygen-rich water flowing over them.

232
00:30:36,687 --> 00:30:42,683
He's a devoted father, steadfastly
standing guard over the fry when they hatch.

233
00:30:44,807 --> 00:30:49,198
With him hovering above them,
they're safe from most predators.

234
00:30:49,367 --> 00:30:53,838
But the fact is that two thirds of them
are probably not his.

235
00:30:54,687 --> 00:31:00,080
Baby lily-trotters, jacanas,
are also left in the charge of their father.

236
00:31:00,247 --> 00:31:04,559
Unusually for a bird,
the female defends the territory

237
00:31:04,727 --> 00:31:09,926
and mates with three or four males
who build the nests and look after the broods.

238
00:31:22,727 --> 00:31:27,323
A strange female is trespassing
on this breeding territory.

239
00:31:35,047 --> 00:31:39,040
There are eggs here,
so the male should be nearby.

240
00:31:39,207 --> 00:31:43,519
He returns to protect them,
but he seems to be alone.

241
00:31:48,967 --> 00:31:53,199
The intruder lurks in the weeds,
watching him with interest.

242
00:31:53,367 --> 00:31:57,360
Finding a male alone probably means
that his mate has been killed,

243
00:31:57,527 --> 00:32:01,918
and her territory and all her males
could be up for grabs.

244
00:32:04,607 --> 00:32:08,282
He displays aggressively towards her,
trying to drive her away,

245
00:32:08,447 --> 00:32:13,840
but female jacanas are bigger than the males
and she is not to be deterred.

246
00:32:19,087 --> 00:32:23,877
He is of no use to her
while he broods another female's eggs.

247
00:32:25,287 --> 00:32:29,883
She starts to smash them,
and he is unable to prevent her.

248
00:32:58,967 --> 00:33:01,765
They were on the verge of hatching.

249
00:33:07,407 --> 00:33:12,083
Having destroyed his brood,
she now offers herself to him.

250
00:33:22,927 --> 00:33:27,717
And the bereaved male
mates with the murderer of his chicks.

251
00:33:28,607 --> 00:33:34,239
Again and again, she displays
and induces him to mate with her.

252
00:33:41,007 --> 00:33:46,001
So she succeeds in getting rid of all the chicks
that do not carry her genes

253
00:33:46,167 --> 00:33:48,965
and replaces them with those that do.

254
00:33:55,487 --> 00:33:58,957
0ne female with many mates is unusual.

255
00:33:59,127 --> 00:34:04,247
In most polygamous relationships, it's the male
who has a harem of several females,

256
00:34:04,407 --> 00:34:06,204
and that is the arrangement here.

257
00:34:11,127 --> 00:34:14,119
A male sea louse is recruiting.

258
00:34:23,887 --> 00:34:26,401
He puffs out silt from his burrow,

259
00:34:26,567 --> 00:34:32,164
lacing it with a chemical taste
that a female sea louse finds irresistible.

260
00:34:39,407 --> 00:34:43,400
She is bloated with the blood of a fish
which she parasitised,

261
00:34:43,567 --> 00:34:48,163
but she will never feed again,
and now she's looking for a mate.

262
00:35:28,687 --> 00:35:32,077
0ne by one, he assembles his harem.

263
00:35:55,207 --> 00:35:59,917
Inside his tunnel,
he parks his females in a long line.

264
00:36:08,247 --> 00:36:15,198
For three months he continues to collect them,
until eventually he may have two dozen or so.

265
00:36:15,367 --> 00:36:20,202
As each moults, she, like the female crab,
becomes sexually available.

266
00:36:20,367 --> 00:36:23,564
So he monitors their progress with great care.

267
00:36:32,087 --> 00:36:36,558
When the critical time arrives,
he mates with each of them.

268
00:36:37,487 --> 00:36:42,481
Polygamy gives a great advantage
to the individual who controls the harem.

269
00:36:42,647 --> 00:36:46,640
The more wives a male has,
the more children will carry his genes.

270
00:36:46,807 --> 00:36:52,803
It can develop wherever a female is able to raise
her young with little or no help from her mate.

271
00:36:52,967 --> 00:36:58,963
So, not surprisingly, polygamy has appeared
in many different parts of the animal kingdom.

272
00:37:00,007 --> 00:37:05,400
Each of these dark clusters hanging from
the many domed roof of a cave in Trinidad

273
00:37:05,567 --> 00:37:10,163
is a harem of a dozen or more
greater spear-nosed bats.

274
00:37:21,407 --> 00:37:26,401
The male, who controls the harem,
suspends himself in a prominent position,

275
00:37:26,567 --> 00:37:31,163
keeping a sharp lookout for young males
who might try to take over.

276
00:37:31,327 --> 00:37:35,115
If he's not up to the job, his reign will be brief.

277
00:37:37,327 --> 00:37:41,240
A young intruder hangs around nearby.

278
00:37:43,167 --> 00:37:48,366
The harem boss is not going to be caught
unawares, and threatens him.

279
00:37:55,327 --> 00:37:59,923
Repulsed from one,
the young hopeful backs into another

280
00:38:00,087 --> 00:38:02,555
and gets the same reception.

281
00:38:29,047 --> 00:38:33,643
Controlling a harem by force
has inevitable consequences.

282
00:38:33,807 --> 00:38:39,279
If it's always the strongest male in the community
who fathers the great majority of babies,

283
00:38:39,447 --> 00:38:43,440
then over many generations
males will become bigger and bigger

284
00:38:43,607 --> 00:38:47,759
until their size and ferocity
makes them very dangerous.

285
00:38:54,767 --> 00:38:59,761
A full-grown male sea lion comes ashore
in Patagonia early in the season

286
00:38:59,927 --> 00:39:04,284
to claim a patch of beach
and start assembling his harem.

287
00:39:06,287 --> 00:39:09,404
The females arrive
within a few days of one another.

288
00:39:09,567 --> 00:39:15,563
They're only a third his size, and he tries
to keep as many as he can close to him.

289
00:39:22,087 --> 00:39:27,719
Young males come, too. They're not
big enough yet to win battles for females.

290
00:39:30,167 --> 00:39:35,764
Within a day or so of arriving, the females give
birth to the pups who were conceived a year ago,

291
00:39:35,927 --> 00:39:38,725
almost certainly on this very beach.

292
00:39:43,207 --> 00:39:48,486
Six days after the birth of her pup,
a female becomes sexually receptive again,

293
00:39:48,647 --> 00:39:54,119
and the beachmaster, who has taken her
into his harem, mates with her.

294
00:39:55,287 --> 00:39:58,597
The best sites for a harem
are well above high-water mark,

295
00:39:58,767 --> 00:40:05,445
but now the beach is very crowded indeed
and even the less good positions are occupied.

296
00:40:11,087 --> 00:40:13,681
Around the edge of the central breeding area,

297
00:40:13,847 --> 00:40:18,284
males without a harem prowl around
looking for a chance to mate.

298
00:40:18,447 --> 00:40:23,043
There's an atmosphere
of suppressed violence in the colony.

299
00:40:36,407 --> 00:40:39,797
A young male rushes into the breeding area.

300
00:40:45,287 --> 00:40:47,676
As the harem-holders are forced to fight,

301
00:40:47,847 --> 00:40:53,126
others see a chance of winning something
from the confusion.

302
00:41:36,287 --> 00:41:39,677
An intruding male tries to abduct a female.

303
00:41:39,847 --> 00:41:42,236
He will rape her if he can.

304
00:42:05,127 --> 00:42:11,726
The violence spreads. A young male who has
not mated works off his frustration on a pup.

305
00:42:41,527 --> 00:42:45,315
So the number of different ways
in which males and females

306
00:42:45,487 --> 00:42:48,479
can come together and raise their young is huge.

307
00:42:48,647 --> 00:42:54,643
I, because of the species to which I belong
and the society in which I have been reared,

308
00:42:54,807 --> 00:42:59,801
tend to think that the monogamous pair,
one male, one female, husband and wife,

309
00:42:59,967 --> 00:43:05,166
staying together long enough to share
responsibility of raising the young, is the norm.

310
00:43:05,327 --> 00:43:09,923
But actually, in the animal kingdom at large,
it's very, very rare.

311
00:43:10,087 --> 00:43:15,480
And one of the few creatures
that also does that is this beautiful bird...

312
00:43:16,647 --> 00:43:19,036
..the royal albatross.

313
00:43:21,327 --> 00:43:27,516
These two birds first mated over 20 years ago,
and they have been together ever since.

314
00:43:27,687 --> 00:43:33,398
They met as five-year-olds, when they returned
to these cliffs where they had hatched.

315
00:43:34,367 --> 00:43:39,919
While their elders nested, they joined with
groups of others of their own age to dance.

316
00:43:42,407 --> 00:43:45,604
(C0NSTANT CALLING)

317
00:43:53,367 --> 00:43:55,835
As the dance parties proceeded,

318
00:43:56,007 --> 00:44:00,523
the male and the female began
to dance with one another habitually.

319
00:44:02,487 --> 00:44:07,925
After a few weeks of these courtship games,
the young birds flew off back to sea.

320
00:44:08,087 --> 00:44:13,559
During the year that followed, they cruised
the oceans separately, looking for fish,

321
00:44:13,727 --> 00:44:16,924
but the following year they were both back.

322
00:44:29,727 --> 00:44:33,561
By now they were regular companions
during their time ashore.

323
00:44:40,087 --> 00:44:43,284
And then the male claimed a nest site.

324
00:45:22,087 --> 00:45:27,684
At last, after four years of courtship,
their alliance was consolidated.

325
00:45:32,807 --> 00:45:35,765
The permanence of their partnership
was essential,

326
00:45:35,927 --> 00:45:41,923
for an albatross chick takes nearly a year
to grow big enough to fend for itself at sea.

327
00:45:42,087 --> 00:45:48,276
Throughout that time, each parent must make
voyages lasting several weeks to collect food

328
00:45:48,447 --> 00:45:53,237
and be so faithful that it flies back
hundreds of miles to feed its chick

329
00:45:53,407 --> 00:45:58,197
and relieve its near-starving partner,
who has been its lonely guard.

330
00:46:04,247 --> 00:46:09,640
If you watch animals objectively for any
length of time, you're driven to the conclusion

331
00:46:09,807 --> 00:46:14,927
that their main aim in life is to pass on
their genes to the next generation.

332
00:46:15,087 --> 00:46:17,885
Most do so directly, by breeding.

333
00:46:18,047 --> 00:46:21,835
And the few examples that don't do so by design,

334
00:46:22,007 --> 00:46:28,321
they do it indirectly, by helping a relative
with whom they share a great number of genes.

335
00:46:28,487 --> 00:46:33,481
And inasmuch as the legacy that human beings
pass on to the next generation

336
00:46:33,647 --> 00:46:38,846
is not only genetic but to a unique degree
cultural, we do the same.

337
00:46:39,007 --> 00:46:43,000
So animals and ourselves, to continue the line,

338
00:46:43,167 --> 00:46:47,763
will endure all kinds of hardship,
overcome all kinds of difficulties,

339
00:46:47,927 --> 00:46:51,522
and eventually the next generation appears.

340
00:47:13,647 --> 00:47:17,435
This albatross is over 30 years old.

341
00:47:17,607 --> 00:47:20,201
She's already a grandmother,

342
00:47:20,367 --> 00:47:24,565
and this year, once again, she's produced a chick.

343
00:47:24,727 --> 00:47:30,245
She'll devote the next ten months
of her life looking after it.

344
00:47:30,407 --> 00:47:33,604
She has faced the trials of life

345
00:47:33,767 --> 00:47:35,962
and triumphed.

346
00:47:36,127 --> 00:47:41,121
For her little two-day-old chick,
the trials are just beginning.