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01:00The mighty kangaroo, there's no animal like it in the world, so strange that the first
01:06Europeans were tempted to believe it arose from a separate creation.
01:28Separate and different, the first white explorers found a land where almost nothing seemed to
01:34match their previous experience.
01:44Terra Astralis, the great south land, nearly 4,000 kilometers across, stretching from the
01:51tropics to the edge of the Antarctic seas.
02:09The very texture of the land seemed alien, ancient, worn, scoured to its very bones.
02:24Craters, gouged by exploding meteorites, deepened the sense of a harsher world.
02:29The endless parched plains seemed hostile to Europeans from a green and gentle land.
02:44They searched in vain for familiar plants, and even animals they might recognize took strange
02:50and startling forms.
03:13Here, the inland rivers run mostly with sand.
03:16Water is precious, and a little has to go a long way.
03:21Yet it sustains an assortment of life, much of it unique to this greatest of islands.
03:42A land often parched and ungiving, but also a place of the most startling abundance.
03:59In the far north, tropical monsoons flood the heat-baked plains every year, transforming them
04:06into rich and productive wetlands, vibrant with life.
04:37In the far north, tropical monsoons flood the heat-baked plains.
04:39Eucalypts dominate the landscape.
04:42The unique trees of Australia, masters of drought and fire.
04:48Their wispy green crowns shelter colourful parrots.
04:57And an even more remarkable creature.
05:01The koala and kangaroo truly symbolized the special nature of Australia, and led Europeans
05:08to question how this island continent came to be so different from the rest of the world.
05:13The answer lies in its different origins.
05:16Both koala and kangaroo arose from a separate line of evolution.
05:21The marsupials, mammals which raise their young in pouches.
05:35The story of how the marsupials, and especially their most majestic form, the kangaroos, came to dominate Australia,
05:43traces the making of the continent itself, and all the extraordinary life it carries.
06:03The sea plays a crucial role.
06:06Australia is the way it is, because it is an island.
06:09For millions of years, the encircling sea isolated the great southland from the rest of the world, and kept outside
06:17influences at bay.
06:21But Australia wasn't always an island.
06:24Once it belonged to a primeval lost world.
06:28The evidence is exposed by the waves.
06:31Embedded in the rock lie fossilized remains of trees that formed part of a worldwide forest 250 million years ago.
06:40The trunks and leaves are of primeval trees called glossopteris.
06:47They and their world have long vanished.
06:54Identical fossil trees have turned up in Antarctica, South America, Africa and India.
07:00They support other evidence, such as the matching shapes of these continents,
07:04that they once joined Australia, forming a great supercontinent, Gondwana.
07:12This is the shape of Gondwana 150 million years ago, with Australia 3,000 kilometres further south than it is
07:20now.
07:24Even though it was close to the South Pole, there was no ice, because the world was much warmer.
07:30Gondwana in Australia was a place of plentiful rain and luxuriant vegetation.
07:44There are still places in Australia which recall that lost world.
07:49In these mountain streams live remarkable relics.
07:52Other, even stranger mammals than marsupials.
08:04The platypus is one of only three members of an ancient order to live into the present day.
08:11It's a creature so bizarre that zoologists thought the first specimen to reach Europe was a hoax,
08:17sewn together from bits of other animals.
08:21But oddity is in the eye of the beholder.
08:24The platypus is very well designed for its life in the water.
08:43It has warm blood, fur and feet webbed for swimming.
08:48But the most intriguing feature is that duck-like bill.
08:52With eyes, ears and nostrils closed under water, the bill has become an amazingly sophisticated sense organ.
09:00An acutely sensitive shovel that homes in on the minute electric currents emanating from the muscles of worms and grubs
09:08hiding in the gravel.
09:15The catch is stored in cheek pouches and taken to the surface to be ground up by horny plates and
09:21swallowed.
09:32The oily, waterproof fur traps a layer of air to insulate the platypus in water that drops close to freezing
09:39in winter.
09:55Platypuses normally live alone, though several may forage along the same stretch of river.
10:00They keep out of each other's way.
10:11But come breeding time in early spring, platypuses go courting, and it's the females that take the initiative.
10:28The two circle one another, stroking and nuzzling with that most sensitive of organs, the bill.
10:35The female has to be careful not to provoke the male, for he has a poisonous spur on each hind
10:41leg, though it's a weapon more likely to be wielded against other males.
10:48In courtship, touching and petting lead to mutual trust and allow the pair to mate.
11:10They'll mate often in the next few weeks, each encounter accompanied by its ritual of play and caresses.
11:43Once she's pregnant, the female retires to a change.
11:46The female retires to a chamber at the end of a burrow that winds into the river bank for anything
11:50up to 30 metres.
11:57Here, in a nest of damp leaves, she awaits the arrival of her young.
12:07It's the way they reproduce even more than their unusual lives, which makes platypuses and their only surviving relatives, the
12:15echidnas, such extraordinary mammals.
12:19The echidnas' ancestry also goes back to the forest of Gondwana.
12:25Two kinds survive.
12:26This long-beaked one snuffles for worms in the forest litter, sucking them up through its long snout.
12:41Its shorter-nosed and even spinier relative has strong claws to break open rotting wood and a long tongue to
12:49lick up termites and ants.
12:57Females need to stock up on food when the time nears to have their young.
13:02Like platypuses, they retire to a burrow.
13:06Remarkably, these animals don't give birth to babies like other mammals, but lay eggs.
13:20The echidna lays her single egg into a pouch.
13:24The embryo is already well-developed and hatches in only ten days.
13:44The baby echidna's first move is to find milk, the essential food for all young mammals.
13:53But these egg-laying mammals have no nipples.
13:57Instead, the baby prods a small patch of skin inside the pouch, stimulating the milk to ooze out through special
14:05pores.
14:25It might seem a rather messy way to suckle, but the tiny snout sucks up the liquid quite effectively,
14:31and the infant increases its weight a hundredfold in the first three weeks.
14:44The shapeless bundle soon grows into the likeness of its parent, though still naked.
14:55When the spines do grow, the youngster, understandably, is ejected from the pouch.
15:01But mother continues to suckle it for another five months.
15:05Only then does the young echidna leave the burrow for good.
15:11The echidna and platypus are part of Australia's Gondwanan heritage.
15:16The rest of their lines vanished, but around a hundred million years ago,
15:20other mammals appeared whose descendants would come to dominate Australia.
15:28Those ancestral mammals looked much like the brush-tailed Phascogale,
15:33small beasts with fur and warm blood that enabled them to be active in the cool of the night.
15:47The daylight hours belonged to the reptiles, which needed the sun's warmth to function.
15:53Most spectacular were the dinosaurs.
15:56They ruled Australia for a hundred million years.
16:03Most were plant eaters, feeding on ferns and other primitive vegetation.
16:14But great change was about to overtake this primordial world,
16:18and set the stage for the decline of the reptiles and the rise of the mammals.
16:35Gondwana was breaking up.
16:37Immense forces shifted continents, reshaped the seas, created new environments.
16:45The world's climate changed.
16:48There was a gradual cooling around the globe.
16:56The ancient forests gave way to a fundamentally different vegetation, the flowering plants.
17:02And it led to a fundamental shift in animal life too.
17:07By 65 million years ago, the dinosaurs had all but vanished, and the mammals were on the march.
17:14Flowers offer nectar to attract pollinators, most frequently insects.
17:20And they in turn make rich fare for small mammals.
17:40As the flowering plants spread, insect life burgeoned, and the mammals that fed on them prospered.
17:53Some no longer produced eggs, like echidnas and platypuses, but gave birth to babies.
18:02One group adopted very short pregnancies.
18:06Babies were born only partly formed, and completed their development on their mother's nipples.
18:11These were the marsupials.
18:15From small primitive beasts like these, arose a remarkable range of marsupials, with diverse ways of feeding and breeding.
18:28One feature evolved separately among several marsupials.
18:32A pouch to enclose and protect the young, growing on their nipples.
18:37While pregnancy is only short, a mere 12 days among these bandicoots,
18:42the young need to be suckled for a relatively long time.
18:45It'll be 70 days before they're weaned.
18:52Pouches evolved in many different shapes and sizes.
18:55Some open forwards, some back.
18:59In hunters like this quoll, it's no more than a fold of skin.
19:04But the youngsters are firmly clamped to the teats.
19:07Their very existence depends on hanging on.
19:12They're already lucky to be alive.
19:15Their mother gave birth to nearly 30 young, but she has only six nipples,
19:19and the others lost out in the race to secure a teat.
19:29Later, when they're nearly full grown, the young quolls still cling to mother.
19:37They hitch a ride as best they can while she goes hunting through the undergrowth at night.
19:55It's a good way of picking up lessons in technique.
19:58And there's a meal at the end.
20:13The quolls evolved from tiny insect eaters.
20:16Their forebears were among the many pouched mammals,
20:19which spread out to exploit the changing environment of Gondwana.
20:28The marsupials reached Australia through the forests that stretched across the supercontinent.
20:35Their ancestors probably first emerged somewhere in the Americas.
20:41By 50 million years ago, only Australia, Antarctica and South America still clung together.
20:49And it's South America that provides important clues to why Australia's marsupials evolved the way they did.
21:05The Andes rose long after Gondwana split up.
21:09But in their shadow, traces of the ancient supercontinent still linger.
21:16The great mountains are flanked by forests of Southern Beach, among the earliest flowering plants,
21:22and almost identical to those that survive in Australia.
21:28And when night falls, an even more significant link with the past emerges.
21:35Dromysiops astralis is the closest living relative to the ancestor of all Australian marsupials.
21:42It's the size of a mouse and feeds on insects, like all that early stock.
21:54While Dromysiops's ancestors made their way to the Australian end of Gondwana,
21:58other marsupials diversified in the South American section.
22:04Among the most successful were the opossums.
22:08Around 80 species live on today.
22:11Some forage on the ground.
22:13Others, like this mouse opossum, roam up in the trees.
22:19They're mostly solitary beasts, though a glut of food may bring them together.
22:29The opossums are skilled at catching insects, and they also relish easily digested plant foods,
22:35especially nectar.
22:49While the woolly opossum and its relatives harvested a range of foods,
22:53they're young, safe in the pouch,
22:56other South American marsupials went on to become specialised flesh eaters.
23:08One opossum even took to the water in search of prey.
23:21The yapok is the only marsupial ever to adopt an amphibious way of life,
23:26the marsupial equivalent of the platypus.
23:36The yapok's well equipped for its special existence.
23:40The hind feet are webbed to generate swimming power,
23:45and the tips of the forepaws are enlarged into sensitive pads to feel for prey.
23:53One disadvantage might be the pouch.
23:56Water might get in and drown the babies, but that's taken care of too.
24:01Fatty secretions around the lip seal it into a watertight chamber.
24:09Underwater, those sensitive fingers do their work.
24:12The eyes are closed, and the yapok finds its food entirely by touch.
24:38The yapok returns to the surface to devour its catch of fish and crustaceans.
24:46Why none of Australia's marsupials ever adopted this way of life is a mystery.
24:51Perhaps the platypus was already too well established.
24:58Remarkable as the yapok is, fossil remains reveal that even more extraordinary marsupials once lived here.
25:05Large ferocious hunters and killers.
25:09Some resembled giant otters with large slashing teeth.
25:14Others were dog-like hunters, some the size of bears.
25:19The sabre-tooth Thylacosmylus and its relatives, perhaps the fiercest of all.
25:25Their prey wasn't other marsupials, but another kind of mammal altogether.
25:30These exotic marsupial hunters are extinct, but relics of their prey live on.
25:38The sloth belongs to that other group of mammals, the so-called Eutherians,
25:43which nurture their young, not in pouches, but inside the mother's body, in wombs.
25:52These mammals without pouches, the line to which we ourselves belong, were evolving at the same time as marsupials.
26:02While some, like the anteaters, fed on insects, most of the Eutherian mammals were plant-eaters,
26:08and it was their flesh which fed the marsupials.
26:16One group, the primates, became especially adept at harvesting fruit and leaves.
26:28They're very social animals, roaming in troops founded on females and their young, and led by strong males.
26:46With the strong bonds between mothers and infants, and their great agility,
26:51South America's primates were very efficient exploiters of their treetop world.
27:00But neither their ancestors, nor any of the other early Eutherian mammals,
27:05ever managed to reach the Australian end of Gondwana.
27:12That feat was achieved only by the marsupials, and they were well entrenched by the time a major event
27:18ensured that the pouched mammals would inherit Australia.
27:26Fifty million years ago, Australia broke away from Gondwana,
27:30and drifted north with its founding company of ancestral marsupials.
27:42With no Eutherian mammals competing for living space,
27:46the Australian marsupials evolved into an astounding range of creatures,
27:51including a great variety of plant-eaters.
28:01There were bulky beasts, the size of oxen, that browsed on shrubs and low trees,
28:07the largest marsupials that ever lived.
28:13Others had long pendulous trunks to reach higher branches.
28:19And with such an abundance of bulky flesh, there were flesh-eaters.
28:24The largest and most ferocious was Thylacaleo, a killer possum the size of a panther.
28:36Other pouched hunters were more wolf-like.
28:38The last thylacines were still marauding through the forests of Tasmania until fifty years ago.
28:46Unlike the marsupial lions with their swift pounce, the thylacines wore their quarry down in dogged pursuit.
29:00Once there was a whole range of these marsupial wolves, as there was of this fearsome-looking creature.
29:14The Tasmanian devil is the sole relic of a large company of beasts that fed almost exclusively on carrion.
29:31The devils hark back to Australia's golden age of marsupials.
29:49Fifteen million years ago, their ancestors feasted on a vast array of marsupial flesh,
29:55from bandicoots to the many animals which evolved to feed on plants.
30:02The earliest plant-eaters lived up in the trees.
30:06The ancestors of possums and this spotted Cuscus, which still inhabits the northern forests.
30:13The Cuscuses remain aloft, but some of their distant forebears ventured to the ground.
30:20And from those primitive possums emerged the most distinctive marsupial of all, the kangaroo.
30:30How the first move out of the trees might have happened is revealed by the brush-tailed possum.
30:38It feeds in the canopy, but it also browses on the forest floor.
30:45To keep its balance on the branches, it moves with a bounding gait.
30:50And here may well be the genesis of the kangaroo hop.
31:21Some of those early venturers stayed on the ground, where bounding proved an effective way.
31:29The musky rat kangaroo represents those first ground-dwellers.
31:35A living portrait of the founder of the entire kangaroo family.
31:42With locomotion delegated largely to the hind legs, the front paws became hands to manipulate plants, fallen fruits and seeds.
32:02This tiny kangaroo lives alone.
32:05Such nutritious foods are fairly scattered and best collected away from competition.
32:11It often buries left-overs, squirrelling them away for times when food might run short.
32:24But while there were new opportunities on the ground, there were also new dangers.
32:29And the early kangaroos like this rufous betong learnt to build nests to hide from their enemies.
32:35That prehensile tail, so useful for hanging onto branches up in the trees, now made a handy carrier for nesting
32:44material.
32:55That tail also came to serve as a counterbalance.
32:59With stronger hind legs and longer feet, bounding became true hopping.
33:08Though betongs are solitary animals, they do need to get together to breed, and they do so very cautiously.
33:16Males and females are equal in size and strength, and his attempts to woo her are extremely tentative.
33:29His hind leg shields him while he gets his nose close enough to check by her smell whether she's ready
33:36to mate.
33:43Among these tree kangaroos, males have to compete with each other for mating rights, and grow much more powerful than
33:50females.
34:00The large bucks smear their scent liberally around the terrain.
34:10Glans on the chest secrete a forceful chemical message that spells out his size and power.
34:15A message that tells other males he's around, and not to be tampered with.
34:35Males are thrown into conflict more often because these kangaroos live in loose groups, and over time competition tends to
34:43lead to greater size.
35:05Tree kangaroos are something of an evolutionary oddity.
35:08They used to live on the ground, but somewhere in the past they returned to the canopy to take advantage
35:14of the abundant leaves there.
35:23They've become re-adapted to life in the treetops, with short, broad feet padded to prevent slipping, and powerful arms
35:32with long, sharp claws to grip trunks and branches.
35:41Tree kangaroos range throughout the rainforests that once covered Australia.
35:46Now they're only found in a few patches in the far north, and New Guinea.
36:02While these odd creatures remain out on an evolutionary limb of their own, the main stem of the kangaroo family
36:09was sent branching in new directions,
36:11by a dramatic change which overtook Australia 10 to 15 million years ago.
36:21The climate became drier, and much of the rainforest gave way to open woods and grasslands.
36:28The changes prepared the ground for the rapid expansion of the kangaroos.
36:33As well as browsing on the leaves of trees and shrubs, some wallabies began eating the coarser grasses.
36:44As they moved into the grasslands, they carried with them the miracle of marsupial birth.
36:51That most extraordinary process is signalled by a Tamar wallaby licking her pouch.
37:11The birth is only the start of an arduous journey.
37:15Before it's even clawed its way free of the membrane, the young responds to gravity and starts heading upwards towards
37:22the pouch.
37:23Pretty much of the
37:24you
37:24The
37:52The
37:56The licking's not so much to clean a path as to keep the way moist and prevent this
38:01tiny creature drying out.
38:04That's all the help it gets from its mother.
38:16It's only fingertip size, but its forearms and claws are well developed and strong enough
38:21to haul its way up through the jungle of its mother's fur.
38:25The chest and lungs, too, are already quite large to gulp in vital air on the long climb.
38:46Once it reaches the lip of the pouch, it's probably scent that guides the little creature
38:51deep inside to one of the four teeths.
39:11Its tiny jaws clamp onto the nipple, which then expands inside the mouth, so locking the young
39:18firmly onto the teat.
39:24Even the composition of the milk changes to match the baby's growing needs, becoming steadily
39:30richer in fats and proteins.
39:33But there's a grimmer option, too.
39:35If conditions turn bad, the flow of milk stops and the baby dies, so saving the mother's resources.
39:50If it goes the full term, this period in the pouch lasts nearly six months.
39:55Then the young has its second birth into the world outside.
40:12These first excursions are quite brief, and the pouch remains home for some months yet.
40:22Pouches are put to good advantage in Australia's unpredictable environment.
40:26They're convenient baby carriers, while parents search for better pastures.
40:35With a flexible means of reproduction and an efficient means of travel, the kangaroos were
40:40set to advance with the spreading grasslands.
41:04Pouches are put to good advantage in Australia's
41:15The powerful hind legs work rather like efficient springs, and the innards flop up and down,
41:22pumping air in and out of the lungs, so saving on muscle effort.
41:45With the move from forest browsing to grazing in the open, kangaroos like these eastern greys became more social.
41:52Such quantities of easy food take away the need to keep out of each other's way, and there are more
41:59eyes to spot danger.
42:05As the Australian climate grew drier, grass became more abundant, but it's also hard on the teeth and digestion.
42:14Kangaroo teeth grew stronger to grind the tough fibres, and their large stomach acquired special microbes to break them down
42:22into easily absorbed nutrients.
42:27Many species even developed a kind of cud chewing to help the digestion.
42:32They cough up partly chewed food and send it through the stomach once more.
42:44Living on the grasslands also led to greater care of the young.
42:49The open plain leaves Joey exposed to predatory eyes, especially those of wedge-tailed eagles,
42:55and mother holds it back until she's checked that there's no danger.
43:09Only when she's sure that it's safe does she relax the pouch muscles to let her baby out.
43:33It keeps returning to the pouch, but mother won't let it back in yet.
43:38She's teaching Joey to come when she calls.
43:54When it obeys she opens her arms and leans forward so her pouch flops open.
44:06Gradually the spells inside shorten.
44:09Grass increasingly replaces milk, and the Joey learns to groom and clean itself as it grows to independence.
44:24The bond between the young kangaroo and its mother remains strong for a time yet,
44:29but she's already given birth again, and the new baby is growing on a teat inside the pouch,
44:35even while she's still suckling the young at foot.
44:44Males are always on the lookout for does that may be in season, ever ready to follow the sexual trail.
45:02The bucks try to mate with as many females as they can.
45:06But the most powerful male, the King Grey, claims exclusive mating rights,
45:12and he's ever alert for a challenge.
45:19By scratching her tail, this male interloper finds out if she's receptive.
45:24But it's also a very provocative act, not one that the dominant male can afford to ignore.
45:45The big bucks approach is enough to deter the interloper.
45:49If he's working up courage for a challenge, the time isn't right just yet.
45:54He moves away when the King Grey arrives to assert his rights.
46:14The smell of the doe's urine tells him she's almost ready to mate.
46:28But she'll only remain receptive for a few hours,
46:31and he covers her with a scent from his chest gland to warn off other males.
46:45Again, that inquisitive tail scratching, a kind of foreplay.
46:50This time, she remains still, a sign that she's ready for him to mount.
46:59Remarkably, the fertilised egg doesn't grow to full term immediately,
47:03but stops at the 100-cell stage.
47:06It won't resume growing until the present young's about to leave the pouch.
47:15Right now, there's a different kind of interruption.
47:19The interloper decides that this is the time to launch his challenge.
47:35The female makes off.
47:38The challenger goes after her.
47:44With the king in hot pursuit to reclaim his authority.
47:59The king grey paws and rubs at a clump of grass as a warning.
48:03A ritualised deployment of scent.
48:07Then, a show of power.
48:10Rearing two metres high, mighty arms tipped with sharp claws.
48:14An intimidating sight.
48:16And normally enough to make rivals turn tail.
48:22But this challenger is of equal size.
48:25And not about to be faced down.
48:35Life at the top is precarious and short.
48:38King greys are under constant challenge.
48:40And defending their status, eventually wears them out.
48:58The dominant buck looks away.
49:01A last attempt to avoid battle.
49:04It fails.
49:15The aim is to overpower.
49:18By whatever means it takes.
49:20Paws and legs swing into action.
49:45The hind claws are sharp enough to disembowel.
49:48But in defence, the belly skin's tough like a shield.
50:01To minimise injury, the testicles are retracted.
50:04And the head's thrown back to protect the eyes.
50:25A year of fending off rivals has taken the edge off the King Grey's stamina.
50:30A year of fending off rivals has taken the edge off the King Grey's stamina.
50:46The raking nails on the hind feet send the fur flying.
51:11Each takes the advantage of higher ground.
51:14Finally, it's the challenger who positions himself for the decisive blow.
51:19And that's it.
51:37The battle's won.
51:38The challenger is king.
51:40But for the loser, there's no mercy.
51:42He's banished to the poorer feeding grounds.
51:46Worn out by the stress of battle, he may well die.
51:58Win or lose, such a fight takes a terrible toll.
52:02But for the victor, the rewards are great.
52:06It's taken him ten years to reach the top.
52:08And although he may reign for only a year,
52:11he'll have nearly all the matings and the legacy of numerous young
52:15to inherit his winning strength.
52:20These titanic battles arose out of the way the lives of kangaroos changed
52:25with the nature of Australia.
52:27Part of the new pattern that saw these majestic marsupials extend their dominion
52:33right into the arid interior.
52:48This parched and scoured country is the realm of the largest living marsupials,
52:53the red kangaroos.
52:59These splendid animals became superbly tuned to the swings between long drought
53:04and brief plenty.
53:05The triumphant climax of a line that began with a tiny animal chasing insects
53:11around the forests of Gondwana a hundred million years ago.
53:37The forces that created these unique symbols of Australia also shaped the life of the seas
53:43that fringe the continent, the seas under the tropic of Capricorn.
54:05OFTEN
54:16고속
54:39ORGAN PLAYS
55:00ORGAN PLAYS
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