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02:54The yellow threads are male, the green ones female.
02:58The writhing segments disintegrate as they reach the light, releasing their contents.
03:11Milky sperm oozes out and meets the green eggs spilling through the ruptured body walls.
03:18Fertilization is achieved and on an astronomic scale.
03:27So, this simple animal, by a feat of timing which we still don't understand, manages to solve
03:34the problem that face all animals if there to be a biological success. How to pass on
03:38their genes to the next generation. But though the problem is always the same, the solutions
03:45are amazingly varied.
03:48Barnacles, stuck to the rocks groping for food face a particular difficulty when it comes
03:55to mating. They can't move. They can't move. Their solution is a male organ that proportionately
04:02is the longest possessed by any animal.
04:06The solution is a male organ that is the longest possessed by any animal.
04:12And they have another aid to mating.
04:40Each barnacle possesses both male and female organs. So every neighbour is a potential mate.
04:50Eggs are only produced once a year. And as soon as a barnacle has them ready, it advertises
04:55the fact by releasing a chemical. And all its neighbours reach across to try and fertilize
05:00it.
05:04Unlike eggs, which require a lot of energy to make, a sperm can be produced quickly and
05:09in great quantity. So, as a male, a barnacle can fertilize many others. They all compete
05:16to do so. And the egg bearer, as a consequence, is likely to be given far more sperm than necessary,
05:21and ejects most of it as a white blob.
05:24So a barnacle manages to get the best of both the male and the female world.
05:34These fish, blue-headed wrasse on the reefs of the Bahamas, are also bisexual, but not simultaneously.
05:41The big, blue-headed one is a male, the smaller one a female.
05:50A number of females visit a spawning site controlled by an individual male. As each lays her eggs,
05:56he fertilizes them. So he passes on his genes to far more young than an individual female does.
06:03In the competition to continue the line, it's better for a wrasse to be a big male than a female.
06:11And when a male dies, the biggest female claims his throne. Within two weeks, she develops a blue head,
06:18produces sperm, and becomes a parent of more babies than if she had remained a she.
06:29But most animals don't have this option. They're stuck with the sex they're born with.
06:36A male octopus is always male, and if he is to pass on his genes, he is the one who has to take action.
06:48Once he's grabbed the female, he strokes her to calm her, and he has eight arms with which to do so.
07:06His third right arm has a particularly sensitive tip, and while he caresses her with the other seven,
07:12he uses it to feel for her genital opening.
07:19He has found it.
07:21And now, with muscular waves, he pumps packets of sperm into her.
07:25The male dumpling squid, having mated in a similar way, separates.
07:43The male dumpling squid, having mated in a similar way, separates.
07:47Some of his sperm packets still trail from his special arm.
07:57But the majority have successfully released their contents.
08:07A female doesn't always have to accept the first male to grab her.
08:11A female tortoise in Madagascar proclaims her readiness to mate by releasing a perfume.
08:20But when a male turns up, she plays hard to get.
08:23A female tortoise in Madagascar.
08:33He, however, is armed.
08:39He has a spike on his shell that is so big that it gives the species its name, the plowshare tortoise.
08:45tortoise.
08:55He may not be able to force her to mate, but he can use his spike to demonstrate his strength
09:00in a very convincing way.
09:14Her perfume has attracted another male.
09:37Now the rivals must fight it out.
10:09With his opponent overturned, the victor can claim his prize.
10:26The female, having righted herself, seems to be sufficiently impressed by his strength
10:31to accept him as the most powerful male around.
10:41And the vanquished can only lie by helplessly.
10:48Female elephants have a similar way of sorting out the men from the boys.
10:57Producing a calf takes a female a long time.
11:0022 months of pregnancy and then a further four years of feeding it on milk.
11:05So she wants to make sure that her calf has the best father around.
11:09She becomes sexually receptive for just a few days every four years or so.
11:14Mature bulls spend most of their time away from the herd, wandering in special bull areas.
11:20So it's usually a teenage hanger-on who is the first to notice her availability.
11:27So there's a familyé–“ and a family, just one.
11:28She is a superstar.
11:30She has a casual woman.
11:31She has a bigücken уровень.
11:32She is a woman.
11:33She always wants to make sure that this is something that she is completely different.
11:34To their child should beMusic, she always wants to make no more sense of the adult.
11:38I just want to be a male child.
11:39That's she's a young woman.
11:40She has a child in the middle.
11:41She's a female voice, she was a daughter in the middle.
11:42She's a child, she takes a male child.
11:43She has a child in the middle.
11:45She says, she can't make no more sense of the child.
11:46And then she's a child in a family.
11:47And she's like, she has a child in the middle.
11:49She can kick theней on the hospital, she's a child in the middle.
11:50but he's not yet very good at mating and he's not the strong and a proven partner that she wants
12:06so she leaves him the male she seeks is a mature bull like this 50 year old male elephants are only in
12:26full sexual condition for three months of the year but this one is a gland behind his eye is discharging
12:32and his genitals are dripping he is in must during this time he devotes his energy to seeking out
12:42receptive females he assesses their condition by smell
13:02if a female smell is promising he tastes her urine to test it it's as important for her as it is for
13:21him to make clear her reproductive state this female isn't quite ready but there is one nearby who is
13:45the deep rumble is being made by a female who's just mated she's declaring that she's still
13:57receptive and her partner defers to the big male by walking away
14:01the big male starts to follow her
14:10she encourages him with a special coy swinging walk
14:37she's still a good one
14:40she's still a good one
14:42she's still a good one
14:44she's still a good one
14:45she's still a good one
14:46she's still a good one
14:47she's still a good one
14:48she's still a good one
14:49she's still a good one
14:50she's still a good one
14:51she's still a good one
14:52she's still a good one
14:53she's still a good one
14:54she's still a good one
14:55she's still a good one
14:56she's still a good one
14:57she's still a good one
14:58she's still a good one
14:59she's still a good one
15:00she's still a good one
15:01she's still a good one
15:02she's still a good one
15:03she's still a good one
15:04she's still a good one
15:05she's still a good one
15:06Each time she's mated, she calls again, just in case there's a bigger must-male around.
15:36By the end of her receptive period, when her egg is released into her womb, she will be partnered and guarded by the biggest male in the neighbourhood, and he will be the father of her calf.
15:47Chinchilla females are not so welcoming. If a male presses his suit when she's not ready for him, there's trouble.
16:10A quick squirt of urine in the face makes her feelings clear.
16:22He won't pester her again until he's cleaned himself.
16:26Things can be even more tricky for a male if his mate is well-armed, as spiders are.
16:36The female tarantula has fearsome poison fangs.
16:40The male is much smaller than she is and approaches her with obvious trepidation.
16:45His life at this moment depends on being able to hold her poison fangs out of the way.
17:00Only now dare he reach forward with his palps.
17:12At the end of these, there's a suction bulb, which is loaded with sperm.
17:16He must now thrust his palps into a pair of genital paws on her underside, just beyond her head, and that's a very dangerous proceeding.
17:30He's done it.
17:33Male spiders are by no means always so skilful.
17:36These few legs are all that remains of a male nephalospider who failed,
17:41but another male is on the same web now, preparing to chance his luck.
17:45And his task is indeed formidable, for his mate is gigantic, six inches across and several hundred times his weight.
18:00She's virtually blind, and she relies on vibrations of her web to tell her what's going on.
18:06If he sends the wrong vibes along the threads, she could easily get the idea that he's a meal.
18:11He's now within range of her strike.
18:22He retreated just in time.
18:25This indeed is a meal, a fly, a welcome diversion, as far as the male is concerned.
18:32While she's occupied with trussing it up in bonds of silk, he has his chance.
18:51He clambers over her mountainous underside and delivers his packet.
19:14He's so small it's hard to see him on her body,
19:16and it seems doubtful if she notices him at all.
19:26A male cockroach from Cuba positively encourages his mate to nibble him, or at any rate bits of him.
19:33He lifts his wings to offer her a potion produced from special glands,
19:37which not only smells good, but tastes good.
19:40While she licks them, he must couple, and do so before her nibble becomes a bite.
20:00He has achieved a connection and escaped injury.
20:03Now he must hang on until he has transferred his sperm.
20:33The mountain dusky salamander has an even more extreme way of persuading a female to mate with him.
20:43It involves biting her neck, a habit that has given him the nickname of vampire salamander.
20:49But he doesn't do it to drink her blood.
20:51Special glands on his chin produce an aphrodisiac,
21:00and he anoints her with it by rubbing her neck.
21:03But he must do more than this to really get it under her skin.
21:13A quick scratch with his teeth, and he's vaccinated her.
21:17Now she'll follow him wherever he goes.
21:21But he has a particular problem.
21:25Salamanders are amphibians, and unlike all other four-legged land animals,
21:29the male amphibian doesn't have a special apparatus with which to inject sperm into a female's body.
21:35So he has to use another method.
21:44He begins to walk away, and the female, excited by her vaccination, follows him.
21:51As she continues to walk after him, he leads her across it so that her underside presses against it.
22:12When it's level with her genital opening, she draws it in.
22:22But some females, no matter what the male does, are physically inaccessible for most of their lives.
22:28Crabs wear suits of armor, which makes mating impossible.
22:37But this big male has detected a faint taste in the water
22:41that tells him that the little female is about to shed hers.
22:45As soon as she slips out of her shell, while her new one is still pliable,
23:04she and he can become intimate.
23:06And he's going to hold on to her so that no other male will get the chance to claim her at that crucial moment.
23:12Her molt has begun.
23:16Her shell has split along the underside, and he is helping her to disrobe.
23:22The empty suit of armor lying in front of her makes it seem as if he has two females in his embrace.
23:28The fact that one is merely the ghost of her former self is revealed only by its vacant eye sockets
23:40and the way the current blows it about.
23:45Now the female, with her new shell still soft and leathery, crawls beneath him.
23:51He fertilizes her swiftly before her shell hardens.
24:05She won't be able to mate again until her next moat.
24:08Soon he will abandon her, but he's already ensured that the eggs she will nurture for the next few weeks
24:21will carry his genes.
24:27A male butterfly has to be just as alert as a crab if he's to secure a mate.
24:32And this forest in Costa Rica is full of competitors for the females
24:36who are appearing from pupae hanging in the bushes.
24:41This is a male heliconius butterfly,
24:44and he's settled on a pupa which he knows contains a female.
24:50He's waiting for that moment when the female will emerge, a virgin,
24:55and then in the first few seconds of her adult life, he'll mate with her.
25:00And so intent is he on achieving that,
25:04that he won't move even if I touch him with my fingers.
25:09But watch what happens if I take this,
25:12which is an adult female which is newly mated.
25:15What happens if I brush him lightly with her?
25:18The reason he left is because this female, when she was mated,
25:28was given a particular smell, which even I can detect.
25:33A smell that all other males find very repugnant.
25:36So if I let her fly away, that male may return to complete its business.
25:41And even before the newly emerged female's wings have expanded,
25:46he mates with her, dabbing her with his smell,
25:49which will repel other males for weeks.
25:52No rival will displace his sperm.
25:54A female wolf, who's just become sexually receptive,
26:23joins her howling pack in the Canadian north.
26:29All the males are interested in her,
26:32but there's a ranking system in the pack,
26:34and the senior male has priority in mating.
26:37Others who try their luck have to be reminded who's boss.
26:41And he claims his rights.
26:55But he does not now leave her.
27:17Indeed, he couldn't even if he wanted to.
27:19His genitals have swollen so greatly inside her
27:23that the pair are locked together.
27:28This is no unfortunate accident.
27:31It's an important part of the male's breeding strategy.
27:35Remaining tied for so long gives his sperm time to reach her eggs
27:39before a competitor can displace him.
27:41It may be half an hour or so before they're able to pull apart.
27:51The aftermath of such a genital lock may be slightly painful,
27:56but the process has virtually guaranteed him his paternity.
28:00And animals that don't take such precautions
28:03can't be nearly so certain.
28:05A male bluegill sunfish swimming in a lake in North America
28:11seems big, strong, and confident enough to take on any rivals.
28:17He's eight years old, and he too is ready to breed.
28:20He hollows out a shallow nest by fanning his tail.
28:26Then he sets about persuading one of the females
28:29in the shoals swimming nearby to come down and join him.
28:32He's offering both a nest and his parental services.
28:44One arrives.
28:46Although she's considerably smaller than he is,
28:48she is full-grown, and he chibbers her into his nest to lay.
28:54She catches his mood from his distended fins and circling dance.
28:58Things are going well.
29:00But lurking in the weeds is a tiny, two-year-old male.
29:05He will never build a nest or woo a female,
29:08but he's a serious rival nonetheless.
29:12As soon as the female lays,
29:14he darts in and delivers a jet of sperm.
29:19Back he comes and adds another squirt
29:21before he's finally chased off.
29:23The owner of the nest continues his dance.
29:39The more eggs that are laid in it, the better.
29:47The little sneak retires to the weeds.
29:50Now the big male seems to have been joined by a second female.
29:55Not so.
29:56The new one, in the middle,
29:58is an older, sneaking male,
30:00who dances so like a female
30:01that the big male doesn't notice the difference.
30:05The nest owner continues to chase away other males,
30:09leaving the female impersonator with the real female,
30:12unhurriedly fertilising her eggs.
30:14Eventually, the big male is left in sole charge of the nursery.
30:30He labours away,
30:32fanning the eggs to keep a current of oxygen-rich water flowing over them.
30:36And he is a devoted father,
30:38steadfastly standing guard over the fry when they hatch.
30:41With him hovering above them,
30:46they're safe from most predators.
30:48But the fact is that two-thirds of them are probably not his.
30:55Baby lily trotters, jacanas,
30:57are also left in the charge of their father.
31:00Unusually for a bird,
31:02the female defends the territory
31:04and mates with three or four males
31:06who build the nests and look after the broods.
31:09A strange female is trespassing on this breeding territory.
31:34There are eggs here,
31:36so the male should be nearby.
31:37The intruder lurks in the weeds,
31:51watching him with interest.
31:53Finding a male alone
31:54probably means that his mate has been killed
31:56and her territory and all her males
31:59could be up for grabs.
32:00He displays aggressively towards her,
32:06trying to drive her away.
32:08But female jacanas are bigger than the males
32:10and she is not to be deterred.
32:19He is of no use to her
32:21while he broods another female's eggs.
32:23She starts to smash them
32:27and he is unable to prevent her.
32:29They work, she stands for another living.
32:44Does anyone need to escape?
32:46That's amazing.
32:47plays in bright rhythm
32:47and ну� outros
32:47parts of the body
32:54once we get out of the body
32:56They were on the verge of hatching.
33:06Having destroyed his brood, she now offers herself to him.
33:11And the bereaved male mates with the murderer of his chicks.
33:28Again and again, she displays and induces him to mate with her.
33:33So she succeeds in getting rid of all the chicks that do not carry her genes
33:45and replaces them with those that do.
33:55One female with many mates is unusual.
33:58In most polygamous relationships,
34:00it's the male who has a harem of several females.
34:04And that is the arrangement here.
34:10A male sea louse is recruiting.
34:23He puffs out silt from his burrow,
34:26lacing it with a chemical taste that a female sea louse finds irresistible.
34:39She is bloated with the blood of a fish which she parasitised.
34:43But she will never feed again,
34:45and now she's looking for a mate.
34:47She is bloated with a man.
34:52She is like a meal in her mother.
34:52Short face, the old lady.
35:05She is responsible for anyone's work.
35:06It wants no comentari.
35:07She is his Researchин's life.
35:09She is looking for a friend.
35:14One by one, he assembles his harem.
35:44Inside his tunnel, he parks his females in a long line.
36:08For three months, he continues to collect them until eventually he may have two dozen
36:13or so.
36:15As each molts, she, like the female crab, becomes sexually available, so he monitors their progress
36:22with great care.
36:32When the critical time arrives, he mates with each of them.
36:38Polygamy gives a great advantage to the individual who controls the harem.
36:42The more wives a male has, the more children will carry his genes, and it can develop wherever
36:47a female is able to raise her young with little or no help from her mate.
36:52So not surprisingly, polygamy has appeared in many very different parts of the animal kingdom.
36:59Each of these dark clusters, hanging from the many-domed roof of a cave in Trinidad, is a harem
37:05of a dozen or more greater spear-nosed bats.
37:08The male, who controls the harem, suspends himself in a prominent position, keeping a sharp lookout
37:27for young males who might try to take over.
37:30If he's not up to the job, his reign will be brief.
37:38A young intruder hangs around nearby.
37:43The harem boss is not going to be caught unawares and threatens him.
37:55Repulsed from one, the young hopeful backs into another and gets the same reception.
38:02The harem boss is not going to be caught.
38:29Holding a harem by force has inevitable consequences.
38:34If it's always the strongest male in the community who fathers the great majority of babies, then
38:39over many generations, males will become bigger and bigger until their size and ferocity makes
38:45them very dangerous.
38:46A full-grown male sea lion comes ashore in Patagonia early in the season to claim a patch of beech
39:00and start assembling his harem.
39:03The females all arrive within a few days of one another.
39:08They're only a third his size and he tries to keep as many as he can close to him.
39:21Young males come true.
39:23They're not big enough yet to win battles for females.
39:30Within a day or so of arriving, the females give birth to the pups who were conceived a
39:34year ago, almost certainly on this very beach.
39:42Six days after the birth of her pup, a female becomes sexually receptive again and the beach
39:49master, who has taken her into his harem, mates with her.
39:54The best sites for a harem are well above high-water mark, but now the beach is very crowded indeed
40:00and even the less good positions are occupying.
40:10Around the edge of the central breeding area, males without a harem prowl around looking for
40:16a chance to mate.
40:17There's an atmosphere of suppressed violence in the colony.
40:24A young male rushes into the breeding area.
40:44As the harem holders are forced to fight, others see a chance of winning something from
40:49the confusion.
40:54The
41:01the
41:04the
41:07the
41:09the
41:11the
41:15An intruding male tries to abduct a female.
41:39He will rape her if he can.
41:45The violence spreads.
42:06A young male who is still not mated works off his frustration on a pup.
42:15A young male who is still not mated works on a pup.
42:25A young male who is still not mated works on a pup.
42:32So the number of different ways in which males and females can come together and raise their
42:46young is huge.
42:47I, because of the particular species to which I belong and the particular society in which
42:52I happen to have been reared, tend to think that the monogamous pair, one male, one female,
42:58husband and wife, staying together long enough to share responsibility of raising the young,
43:03is the norm.
43:04But actually, in the animal kingdom at large, it's very, very rare.
43:10And one of the few creatures that also does that is this beautiful bird, the royal albatross.
43:21These two birds first mated over 20 years ago, and they have been together ever since.
43:28They met as five-year-olds when they returned to these cliffs where they had hatched.
43:34While their elders nested, they joined with groups of others of their own age to dance.
43:39As the dance parties proceeded, the male and the female began to dance with one another
43:58habitually.
44:02After a few weeks of these courtship games, the young birds flew off back to sea.
44:08During the year that followed, they cruised the oceans separately, looking for fish.
44:13But the following year, they were both back.
44:29By now, they were regular companions during their time ashore.
44:33And then, the male claimed the nest site.
44:40The male claimed the nest site.
44:47The male claimed the 시간 list here was seven years later.
45:00And the female named a sequence of other times ashore.
45:04The man named Larkovia who always of the ONG MIKE on earth hid his horse.
45:13At last, after four years of courtship, their alliance was consolidated.
45:32The permanence of their partnership was essential, for an albatross chick takes nearly a year to grow big enough to be able to fend for itself at sea.
45:41Throughout that long time, each parent must make great voyages lasting several weeks to collect food,
45:48and be so faithful that it flies back hundreds of miles to feed its chick and relieve its near-starving partner, who has been its lonely guard.
46:03If you watch animals objectively for any length of time, you're driven to the conclusion that their main aim in life
46:10is to pass on their genes to the next generation.
46:14Most do so directly by breeding.
46:18In the few examples that don't do so by design, they do it indirectly,
46:23by helping a relative with whom they share a great number of their genes.
46:27And inasmuch as the legacy that human beings pass on to the next generation is not only genetic,
46:34but to a unique degree cultural, we do the same.
46:38So, animals and ourselves, to continue with the line, will endure all kinds of hardship,
46:45overcome all kinds of difficulties,
46:47and eventually, the next generation appears.
46:51This albatross is over 30 years old.
47:17She's already a grandmother, and this year, once again, she's produced a chick.
47:24She'll devote the next 10 months of her life looking after it.
47:30She has faced the trials of life and triumphed.
47:35For her little, two-day-old chick, the trials are just beginning.
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