Un Mondo Di Vita S01e02 Il Ritmo Della Vita
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00:00A hungry hunter, with his eyes on the prize.
00:29But whatever he tries, he's just not fast enough.
00:56It's as if the dragonfly can see him coming in slow motion.
01:20And maybe he can.
01:27Dragonfly's food is tiny and quick.
01:35But unlike the frog, nine strikes out of ten, he gets a meal.
01:45Because his visual processes work five times faster than ours, and effectively slow down
01:55time.
02:07The frog won't stop trying.
02:14Close, but no cigar.
02:26The dragonfly isn't just keeping an eye on his slow motion stalker.
02:34He also has to defend his territory from rivals.
02:51With his eyes on the skies, he's less likely to spy someone hiding below.
03:08The frog may not have the dragonfly's lightning moves, but this time, he's right on cue.
03:38A sense of timing is crucial to survival throughout our webs of life.
04:00Nature works best when it's in sync with the planet's rhythms.
04:09To make the most of them, life must time its opportunities to perfection.
04:20Sometimes in milliseconds.
04:25Sometimes across millennia.
04:44Late afternoon in the Kalahari.
04:54A lioness has hungry mouths to feed.
05:01Her growing cubs need fresh meat every two days.
05:19There's food everywhere.
05:29But most of her targets are faster than she is.
05:35Chase them around under the blazing sun, and she'll quickly overheat.
05:45She needs to get close enough for an ambush.
05:56Tricky in broad daylight.
06:04Her prey a prime to spot movement.
06:19And once her cover is blown, she's much less of a threat.
06:29But she's not fully committed yet.
06:37Because she knows the tables are about to turn.
06:49As the sun sets, the odds shift in her favor.
07:00She's harder to spot.
07:07Less likely to overheat.
07:15And her night vision comes into its own.
07:31A herd of buffalo.
07:39Five times her weight, these armored giants are a dangerous target.
07:52But if they haven't seen her, then she has the edge.
08:04She targets a calf. Weaker. Less risky.
08:33In the twilight, she makes it look effortless.
08:45She has already cashed in on the advantage that dusk brings.
08:51And her cubs will feast tonight.
09:02The sun is always setting somewhere on Earth,
09:07creating an endless beat of changing fortunes.
09:15But our ever-spinning planet gives us more than just day and night.
09:23Because the sun's power isn't the only force that holds sway over life on Earth.
09:32The moon carves its own path through the night sky,
09:37pulling our oceans into a watery wasp.
09:42And sea creatures must dance to its tune.
09:51In northern Australia, the tide recedes.
10:00Beneath the mangroves, a new world appears.
10:09Home to a banana fiddler crab.
10:16He lives his life in the windows between the high tides.
10:21So he's on a tight schedule.
10:26Time to feed as fast as he can.
10:33While his female neighbors go double time.
10:42His banana claw might be slowing him down now.
10:47But when the moon is right, his time will come.
10:58The tide turns, and it's back to his burrow.
11:08The cycle repeats.
11:22But as the month moves on, the moon's pull on the ocean weakens.
11:29Each high tide covers less of the beach.
11:34Until eventually, for a few days, his burrow won't get covered at all.
11:50Now he's got one of the best spots on the beach.
11:59And another male wants in.
12:08Bananas at the ready.
12:14In a shoving contest, there's not much between them.
12:21But when it comes to the grapple, our champ's got the upper claw.
12:31Go find your own burrow.
12:36But time and tide wait for no crab.
12:41He's gotta find a mate.
12:48A quick preen, and he's ready to show off his winning claw.
12:56But in which direction?
13:01The beach is covered in crabs.
13:07And he's not great at sizing them up.
13:12How about her?
13:17He's not her type of crab.
13:24Ah.
13:27Time to claw back some dignity.
13:33She's more like it.
13:38But now he's got competition from all sides.
13:46He tries to tempt her with a wave.
13:52But they all know that trick.
13:56What if he goes a bit higher?
14:02They do too.
14:08Another.
14:10And another.
14:13It's turning into quite the beach party.
14:26How's a girl to choose?
14:32Finally, she selects the best banana on the beach.
14:43And only just in time.
14:49He seals her in his burrow before the tide returns.
14:56She'll release her larvae on the next full moon.
15:01When the strongest ebb will carry them far out to sea.
15:09A lucky few will survive.
15:12The rest provide a pulse of food to the ocean.
15:16Connecting whole webs of life to the never-ending rhythms of the moon.
15:29But our planet has another cycle that shapes nature's networks in a slower, but perhaps more profound way.
15:41The procession of the seasons.
15:47A yearly pulse that life must adapt to.
15:58With Earth's longer timescales, the stakes get higher.
16:06Because when opportunities only come around once a year, you've got to grab them while you can.
16:21In the Norwegian tundra, an old warrior watches over the herd.
16:39The females will be in season for just a few weeks.
16:43His only chance to father next year's calves.
16:56Other males will want to stake their claim.
17:05So, each year, this muskox must face a ritual tournament to retain his crown.
17:18Arrival.
17:28For the king, the gauntlet has been thrown down.
17:37He puts up a front.
17:47It's an old trick to psych out his opponent.
17:59But the challenger doesn't back down.
18:08They walk in parallel, hoping their size will scare the other off.
18:16Not this time.
18:28An airbag beneath their armored horns cushions them from an impact as violent as a car crash.
18:44The king is a veteran of many battles.
18:49He uses the slope to make the most of his weight.
19:07As he tries to gouge his opponent, he loses the upper ground.
19:23Not for long.
19:33This time, experience wins the day.
19:42There will be more jousts to come in this annual tournament.
19:48And only if he can win them all will he secure his position for another year.
20:00Now, all across the northern hemisphere, winter closes in.
20:12In this harshest of seasons, everyone must bide their time.
20:25Resources freeze.
20:29Temperatures plummet.
20:32And life is held in suspended animation.
20:44The only certainty of winter is that in time, it will draw to a close.
20:54The Earth's yearly journey around the sun brings the northern hemisphere back into more direct sunlight.
21:08Longer days return.
21:12And winter yields to spring.
21:20This is the season that life makes its own.
21:35All powered by the growing warmth of the sun.
21:44Seedlings race for their place in the strengthening light.
21:53Each with its own strategy to get ahead.
22:00Leaves sprout and unfurl.
22:08Each one a natural solar panel, harnessing the sun's energy.
22:16Drawing in carbon dioxide and converting it into food to grow.
22:27So many plants come to life that the planet seems to take a deep breath in.
22:35Carbon dioxide levels dip dramatically, helping bring balance to the atmosphere we all depend on.
22:46The changing season triggers countless creatures to move north as nature's networks spring back to life.
23:00Billions of birds flock towards distant breeding grounds.
23:11Ocean giants travel thousands of miles in search of food.
23:20While huge herds surge across the waking landscape.
23:30To succeed, all of these heroic journeys must be timed to perfection.
23:38Even those of the most miniature migrators.
23:47As the last snow melts deep in the forest, pools appear.
23:57In just a few weeks, they'll dry out in the heat.
24:04By the time one creature wakes from her winter sleep, a countdown has already begun.
24:17This salamander needs to reach her pool and complete her breeding cycle before the water disappears.
24:30The first spring rain is the starting gun for the race of her life.
24:46In salamander speed, she's sprinting.
24:56Her ancestors followed the same routes through the forest.
25:03But times have changed since they first walked the earth.
25:21In a few hours, she's almost at the finish line.
25:27The pool where her own life began.
25:32Now, she needs to find a mate as quickly as she can.
25:41Other salamanders have also raced to this pool.
25:48And they may just have a trick to help them with their speed dating.
25:55In the forest shadows, mostly blue light penetrates.
26:02Their vision is particularly sensitive in the twilight.
26:08And in this blue hue, their bodies begin to glow.
26:37Some scientists have only recently discovered this phenomenon.
26:44Could it be that it helps in their race to find a mate?
26:58Now, she can lay her fertilized eggs.
27:10But time is already working against the next generation.
27:19They need to hatch and finish developing before their pool disappears.
27:32And it's already started shrinking.
27:43Every spotted salamander's life is hurried by the ticking of the seasonal clock.
27:51So, too, are countless other creatures.
27:56Their lives tied to the rhythms of the earth, moon, and sun.
28:04But some mysterious beings dance to their own beat, keeping time not in seasons, but in decades.
28:19Inside a maple tree, sap flows for the first time since last fall.
28:30Kick-starting new growth.
28:39But deep below ground, one creature is using this pulse to count the passing of the seasons.
28:51A periodical cicada.
28:57She feeds on the tree's sweet sap.
29:01So, as it rises each spring, she can tell that another year has passed.
29:09She borrowed underground 17 years ago.
29:15Now, she's tunneled to the surface, ready for the moment she's been waiting for.
29:36As darkness cloaks this Indiana woodland, things are about to get strange.
29:51Above ground, she's vulnerable.
30:02She's timed her emergence to perfection.
30:07There's safety in numbers.
30:13Billions of cicadas have synchronized their 17-year life cycle.
30:22Like a zombie horde, they rise in unison.
30:31Safely off the ground, they begin the next stage of their resurrection.
30:43An eerie transformation into their adult form.
30:53For the first time in 17 years, dawn breaks to a chorus of cicadas, almost as loud as a chainsaw.
31:15The neighbors barely know what's hit them.
31:22The last time these insects appeared was long before they were born.
31:31It would be terrifying if they weren't so tasty.
31:40For the next few weeks, this banquet puts meat on everyone's menu.
31:51But with more than a million in a single acre, the diners barely make a dent in the buffet.
32:06So the risen can finally achieve their purpose.
32:13They mate, and the females lay their eggs.
32:22It's their final act.
32:28Within a matter of weeks, all that's left are husks.
32:35A massive dose of fertilizer, pulsing life back into nature's underground networks.
32:53Why 17 years?
32:56We still don't really know.
33:01But this pattern evolved deep in the past, when a long life cycle may have helped to survive more frequent cold snaps.
33:12Because our planet also has climatic rhythms that span tens of thousands of years.
33:22Far beyond any living creature's sense of timing.
33:30But the slowest changes can have the most profound effects on life.
33:38For better, and for worse.
33:47The Sahara Desert, as large as the United States, and one of the harshest environments on Earth.
33:58If you're not adapted to the heat, you won't survive.
34:09This light-footed agama lizard is small enough to find shelter.
34:22And his scaly skin keeps much-needed moisture locked in.
34:32But even he needs to drink sometimes.
34:39Fortunately for him, even in this barren wilderness, there is water.
34:53A miraculous oasis for weary desert travelers.
35:07But it might not be as welcoming as it seems.
35:23Incredibly, this pool is full of crocodiles.
35:35In the middle of the desert.
35:41A hundred miles from the nearest flowing water.
35:50While their far-flung relatives swim through lush swamps, these crocodiles are trapped here.
36:02For them, it's not an oasis. It's a prison.
36:11Where every inmate must fight for themselves.
36:24There's fierce competition for anything that moves.
36:33A migrating honey buzzard stops to drink.
36:45And wades in to cool off.
37:02It won't feed everyone.
37:11If they stay here, they could starve.
37:19But if they make a break for freedom, they'll be back.
37:33It's a desperate dilemma as their world shrinks around them.
37:47But the fact they're here at all is a sign of a rhythm measured in millennia.
37:56Because it wasn't always like this.
38:08Just a few thousand years ago, this desert was green and fertile.
38:16Crocodiles swam in flowing rivers.
38:23Because our spinning planet has a long-term wobble that repeats over millennia.
38:32Moving its hemispheres closer to and then further from the sun.
38:38And altering our climate as it goes.
38:44On its current path, the West African monsoon weakened.
38:51And rain stopped falling in the Sahara.
38:58Within just a few hundred years, the crocodile's lush swamps became one of the planet's largest deserts.
39:07But even in today's searing climate, there is still an echo of the long-lost past.
39:26Just a few precious days of rainfall each year.
39:33This briefest of wet seasons lets us travel back in time.
39:42To glimpse what life was like here 10,000 years ago.
39:49In a green Sahara.
39:56If the inmates can cling on, in another 10,000 years or so,
40:03we'll be able to see what life was like here 100 years ago.
40:10We'll be able to see what life was like here 100 years ago.
40:17We'll be able to see what life was like here 100 years ago.
40:23In another 10,000 years or so, the planetary wobble will run full circle.
40:31Water will flow again, freeing their distant descendants to reclaim long-lost rivers.
40:43The creeping pace of our planet's slowest rhythms makes them almost impossible to see.
40:52But if these rhythms are interrupted, even by the smallest increment,
40:59we can start to see things change before our eyes.
41:09Autumn, in Oregon's Cascade Mountains.
41:16This hare is trying to stay out of trouble.
41:24With good reason.
41:29Hares rarely die of old age.
41:36A hunting goshawk will spot anything that moves.
41:43So the skittish hare freezes,
41:50barely even breathing.
41:57Hidden in plain sight.
42:04The hawk moves on, and the hare can breathe a sigh of relief.
42:11But her home is about to transform beyond recognition.
42:26If your best bet for staying alive is camouflage,
42:32how do you cope when your world suddenly changes color?
42:41You change too.
42:50As the winter days shorten, she malts from brown to white.
42:59An incredible costume change.
43:06Once again, all she has to do is freeze.
43:13And, like magic, she vanishes.
43:24But now, a new threat.
43:30Man-made climate change means that some winter days are unseasonably warm,
43:37and snow cover can disappear overnight.
43:45Her color change is triggered not by temperature, but by day length.
43:52And these warmer days are still short.
44:01So now, she's desperately out of sync with her surroundings.
44:08And an easy target.
44:15Time for plan B.
44:22Speed.
44:33She's lost him.
44:39But when you're this conspicuous, staying hidden isn't an option.
45:10Next time, she may not be so lucky.
45:19Mismatched hares are more likely to be picked off.
45:26And now, they're out of step more often.
45:33Her kind could still have a future in this changing world.
45:42This snowshoe hare has adapted to stay brown all year round.
45:51So, his life is easier when snow is thin on the ground.
46:02The future of their species may depend on more guys like him.
46:16Nature works best when life keeps step with the planet's many rhythms.
46:33So, what happens when human activity disrupts the tempo?
46:45As the world changes suddenly all around us,
46:52can nature survive the coming storm?
47:02To be continued...
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