Life - The race against time

Imagine if you could halt the constant march of time ... if you could slow it down ... and speed it up. Imagine if you could stop time ... or even reverse it. The world about us would look quite different. Imagine no longer ... come with us as we go on a journey through time.
Life is a race against the clock. For all of us, every second of every day the pressure is on to find food  ... meet a mate and have a family... all before our time is up.
By speeding through days, months and years we're going to see how plants and animals manipulate time to stay in the running. Why is it that a mouse lives for two years ... while a whale can live for 200? Why do these crabs have their own little alarm clocks that must be reset every day? What drives these caribou to run thousands of kilometres, through some of the harshest conditions on earth? And what has turned this hummingbird into the Pinocchio of the bird world?
It's all down to time. By crushing centuries into seconds we'll see life change beyond recognition and meet some real time travellers. But can anything truly cheat time and live forever?
Different animals have different life spans. Take a man and his dog. They both look like they could run and run... but one of them is already past his prime. The dog may look full of beans but it's six years old, and in dog-years that means well into middle age. Why do we have these hugely different life spans? Even with these creature comforts, a house mouse will be lucky if it survives till it's two. Could life span be all down to size?Of course, a mouse only has to grow a tiny body... ...but that's not the whole story. Its short time on earth is also about staying one step ahead of danger. A mouse's life is so likely to come to a swift end that it pays to live life in the fast lane.A newborn mouse grows up at break-neck speed. Within a matter of days the first hair erupts... Next their body lengthens... The whiskers grow... ...and the ears pop out. A baby mouse turns into an adult in just FIVE weeks. Right away it can start having babies of its own. In its short lifetime, a mouse can have several litters. You don't have to do the sums to see how mice can quickly take over the place. Individuals may not live very long, but their fast and furious way of life is a winning one, if you're constantly dicing with death. A wild owl lives up to eight years. So what gives them the extra-long lease? It's not just that they're bigger than mice. It takes a lot longer to bring up their brood takes the owls a whole year. By zooming through the months we can see that an infant owl has to develop some pretty complicated kit to become a successful hunter. It needs a beak that can rip into prey ... Special wing feathers that will help it glide silently through the night ... talons that can pincer a rodent... and discs of specialized feathers around each eye. Like satellite dishes these focus the tiniest rustlings directly to its pin-sharp ears. Even when it's fully fledged, our young owl still needs time to learn the tricks of its hunting trade. Only then can it hope to find a mate and have a family of its own. It's a more demanding way of life so they have to take things step by step.That's why barn owls live a lot longer than mice. But one animal has stretch edits lifetime to an absolute extreme. Primitive harpoon heads have recently been found in a few bowhead whales -this proves that these whales can live Size matters, but living in the Arctic Ocean it might take decades to fatten up and reach breeding age. But that's not the only delay. Over these frozen wastes, it can take ages to even find a partner. There is no speed dating here.In these tough waters bowheads need very, very long lives to make sure there is a next generation. So what about us? Going by size, And in fact most people have found partners and had a family by their thirties. But our lives don't stop there. Even though we might have done our bit to prolong the human race,we then expect to live way past our child-rearing years. Sociable animals apes, dolphins and humans, get an extension on life. We've earned this extra time by becoming helpful in old age. Grandparents and other members of extended families offer wisdom, wealth and, of course, baby-sitting. Mouse, owl, whale or man - We've all got different life spans which best suit how and where we live. But no matter how long or short our time on earth, We're all under the thumb of one great clock. As dawn breaks over Hong Kong, millions of people begin their journey to work.This mad rush hour may seem as far removed from nature as you can get. But in fact we're not the only animal. Trapped in a nine to five routine. Off a remote island in the Pacific, golden jellyfish crowd a marine lake. By speeding up the clock we can see that they too have a rush hour. Every day they rise at the same time and set off on the same commute across the lake. So why have they joined the rat race? The clue lies in their golden glow,a colour caused by millions of tiny algae that live within the jellyfish. The algae produce sugars which they share with their jellyfish partners. But to keep their golden complexion the algae need a secret ingredient sunlight. That's where their mobile homes come in.The jellyfish transport the algae up towards the sun each morning. The water glistens as the jellies break the surface, but their job isn't over. All day they have to work the area of the lake -shifting position to follow the arc-ing sun. It's a long day, but it's the only way that both algae and jellies get enough to eat. The relationship is so successful that jellyfish numbers have boomed today there are over ten million of them. Unlike our jobs,there are no breaks. This is round the clock, day in, day out. The setting sun triggers a return commute -back down to the depths of the lake. Just as we need rest and recuperation the algae passengers must re-stock on vital nutrients that have sunk to the bottom. The algae get there on the jelly-train. Tomorrow the whole thing will start again. The sun is boss. We, and many other creatures, clock on while the sun floods the world with heat and light,and clock off when it sinks from view. Its daily rhythm is our daily grind. It may feel relentless, but the big clock in the sky sets the pace at which our bodies work best. But it's not the only timepiece controlling life on earth...Even though it is nearly the moon also has a profound influence on many animals. As it spins around the earth it drags a great bulge of oceanic water in its wake the rising tide. It ebbs and flows twice a day but that's not all. Each day the timing of the new tide shifts forwards by nearly an hour.It's a highly complicated schedule so how can anything live by it? It's two in the afternoon and the incoming tide is driving waves towards the beach to a surfer's paradise in Australia. The best surf is at the turn of the tide, but predicting when this is requires some precise astronomical calculations. Luckily, someone else has done the maths. All surfers need to do is check out the tide timetable... and then just watch the clock. That's it - surf's up! Being able to calculate these moments, means you can make the most of moon-power. But for other creatures this complicated shift in the tide times could make life very risky indeed.The receding tide is like a cloth being pulled back from over a hidden feast. The tiny creatures aren't exactly on a plate, but they are there for the taking. While the tide's out it's dinner time,not just for this one soldier crab, but a huge army of them. They're on a regimented march to the water's edge. With so many crabs to choose from, predators find it hard to single out their prey. Soldier crabs can only sieve out food along the shoreline while the sand is damp. So they haven't got long. Something extraordinary happens, just before the tide turns. It's as if a sergeant major has barked out the order to retreat. As one, the crabs scuttle back up the beach. Just as well. If they were to stay out a moment too long they would risk certain death. The incoming tide brings crab-hungry fish.
Even though the tide times are constantly shifting,soldier crabs - amazingly -never get caught out.How do they get the timing right?Are they sensing movement under the sand? Is it down to remarkable eyesight? Or is something else going on? If we isolate crabs from the outside world we can reveal the secret of their precision timing. Just watch what happens to these crabs as the tide rises and falls. When it's out they run around, as if it's time to feed. But when it re-floods, they mysteriously stop moving, as they would if they were in their burrows. It's all down to an internal alarm clock that's tied,not to the sun,but to the moon. What's more,it is incredibly sophisticated. It's self-adjusting. We wake up at more or less the same time each day. The crabs' wake-up call shifts by almost an hour with each tide. This is how the soldiers get their timing right. But it's not just animals that need to keep an eye on the clock. Many flowers open during daylight hours, but they don't all open at the same time. Take the morning glory.It opens soon after dawn,but the South African mesemb waits until noon. The evening primrose, as its name suggests, saves itself for the twilight hours. So what on earth is going on? Can plants really tell the time? When it comes to setting seed,flowers have a big problem. They must exchange pollen with each other a bit tricky when you're rooted to the spot. Flowers need go-betweens insects that can carry fertilizing pollen from one flower to another.To attract the attention of passing insects flowers have to flirt. And they do this with a dazzling array of colours and scents. But of course insects are being courted by every hot-blossomed flower in the bed. So some flowers have found a really cunning way of standing out in the crowd.And it's all down to timing.At sunrise the morning glory is already on the pull -opening its petals before any other flower. This might seem risky as few insects are up and about during these chilly hours. But the morning glory is counting on another early riser. Bumble bees are so big that they can warm up independently of the sun. They vibrate their wing muscles to generate their own internal heat -and can get airborne as early as five a.m. Morning glories are ready and waiting. In return for spreading pollen, the bees are rewarded with a drink of nectar. The Mexican poppy takes a different approach. It's less fussy about who it flirts with,so it waits 'til after breakfast before giving its all. Its bright orange outfit is critical to its future. If rain or wind threatens, the poppy folds its petals away. By late morning the flower bed is a riot of colour -a scramble of flowers trying to win the attentions of winged helpers. But the South African Mesembis only just opening. How can it afford this lazy start to the day? Its long lie-in matches that of its chosen pollen courier an insect that needs a little more time to get going. Monkey beetles cannot take off until their body temperature reaches 27 degrees. So they're only out and about during the very hottest part of the day. On cue, the eye-catching mesembs are ready. But time is limited. As soon as the temperature starts to drop,monkey beetles run out of steam. So the mesembs turn off the charm too. One flower saves itself until after sundown,when most others have gone to bed. Only then does the evening primrose waft its seductive scent over the garden. It lures in night-flyers,such as moths. By waiting this late,the evening primrose has the pick of the insect night shift. So it seems plants really can tell the time. Right through the day they keep appointments with their insect go-betweens. It's a highly efficient way of getting fertilized. So, importantly, it guarantees the next generation of floral timekeepers. Judging time over a day is one thing, but how about over months and years? Sometimes this is essential. Especially when it comes to keeping the whole family line on track. And for one North American animal it's turned into a truly desperate struggle against the clock.It's high summer in northern Quebec and a huge herd of caribou covers the tundra. This is the richest pasture around. It's a perfect place to raise their young. But these caribou can't stay here. They are about to be driven away. But what's giving them the push? They live so far north that their world flips between seasonal extremes. It's June, and these warm summer meadows are about to become howling snow scapes. As the autumn weather closes in,the caribou are forced to run south.It's the start of an incredible marathon. But there's a deadline. They need to get back to the summer meadows by June next year to give birth to their young.The further they go south,the more time it will take to get back.So they've got to keep one eye on the advancing weather and one on the clock. All the while their hormones are working to schedule.They flood through the males which kick-starts the rut. Antlers develop and harden in unison,allowing the males to battle for females. The shorter day-length has got female hormones racing too. It's no accident that males and female shave their minds on the same thing. It's all part of the master plan to ensure that all the females get pregnant at the same time.Once that's done,they're desperate to head back north,back to their meadows. But now the bad weather is blocking their way. For now, they have to bide their time down here not a soft option. So they scratch a living from lichens under the snow.It's a relentless search for the right diet. Lichens aren't enough for expectant mothers. Sometimes time just runs out.The females are now living close to the wire. The June deadline is getting closer. They're heavily pregnant but they're still four thousand kilometers away from the rich summer meadows where they want to give birth. Even though the ground is still frozen,alarm bells are ringing,telling the females to head north again. They've been on their feet for months. They've clocked up nine thousand kilometres, all to make it back to the calving meadows in time. They arrive back, just as these rich meadows come to their peak. And that's the clever bit. Thousands of calves are born within days of each other and it's all been precision-timed. That's because there's just a short window when the grass is at its best and when the calves can grow up quickly on their mothers' fortified milk. They've met the deadline,but time doesn't stand still. Within an hour of birth a calf is able to keep up with its mother,and will soon be ready to join the caribou herd's annual marathon race against time.The natural rhythms of the earth hold animals in a vice-like grip. To survive, they've simply got to keep up. But some remarkable creatures have managed to step off this time-treadmill. They've set their own agenda. and the town of Elkin, North Carolina,has been overwhelmed by a swarm of cicadas. Normally bird and mammal predators would be having a field day picking off these tasty morsels. But strangely enough,no-one's eating them.It's as if the cicadas aren't really there. What's going on?These are periodic cicadas, so called because they've come up with an ingenious strategy to outwit their enemies but to see it in action we have to go back in time half a century of Elkin looks very different.The only familiar things are the cicadas.The residents of Elkin might have time on their hands,but the adult cicadas have no time to lose.They only have three more weeks to complete their life cycle. First they must find a partner,which they do with their own chirpy little number.Once they've mated, the females lay all their eggs in the branches of trees. After they've hatched the larvae fall to the ground and bury themselves. This in itself isn't unusual. But what happens next is.If we whizz through to the same time the fashions have moved on,but the cicadas are nowhere to be seen. In fact, we have to fast forward before there is any sign of them again.While Neil Armstrong takes his first steps on the moon,back on earth people are celebrating the summer of love. The cicadas have also emerged for their own summer loving.The world has moved on,


but the cicadas go through the same old routine. Once again the nymphs bury themselves and disappear from view. But for how long will it be this time?they re-appear. How on earth can the next generation, buried deep underground, measure the passing of time so accurately? It's now thought that the cicadas pick up cues from the yearly rise and fall of sap in plant roots. Yep, these guys are actually counting. It's only when they've counted that these little time travellers appear again. But what's the reason for taking time out for so long? Well, since they show up so rarely,no animal can rely on themas a source of food. In fact most animals wouldn't even recognize them as food -they might have seen this sight only once in a lifetime. With little to threaten them,the nymphs move into position for the last stage of their development. Here they can time-travel and emerge into adulthood in peace. By morning the whole town of Elkinis littered with their discarded nymphal shells. As long as they can accurately and emerge altogether,they will outwit any potential predators. It's not just mathematically brilliant,it's biologically clever. Periodic cicadas have, quite literally,calculated how to stay out of other creature's mouths and in the race against time. By time travelling through three generations of cicadas we've unlocked the secret of their success. But just imagine if we could travel back through thousands of generations. What stories would unfold in front of our eyes? Flying around with a beak this big is no joke. How did this poor hummingbird
become the Pinocchio of the bird world? It's the humbling story of what happens when a bird is driven to drink. All hummingbirds' tipple of choice is sugar-rich nectar. But they have to work to get it - hovering in mid-air while shooting their long tongue down a flower. Just doing this uses up huge quantities of energy, so the more they drink,the more they need.They're addicted to the stuff. But it's the flowers that control the shots, because they need the birds to distribute their pollen. As the birds are given a good drink of nectar,pollen rubs off onto the bird's forehead. As time moved on certain flowers got increasingly picky about who came for a drink. Their flowers changed shape so that not all hummers could get in. It's like having a lock and key on the drinks cabinet. Only the birds with the right-shaped bill can get access. One bird tried to cheat the system. Thousands of years ago, swordbills with slightly longer beaks got an extra shot of nectar from the Datura flower. But their heads were no longer in contact with the pollen,so the flower grew longer in response. Over generations, flower and beak tried to outsmart each other. Both became longer and longer, increasingly dependent on each other. No other bird can reach the nectar from this outlandish flower and the swordbills are stuck in a rut too. And that could be their undoing. For them,the future is now a one-way street, one that's more likely to be a dead end. By speeding through days,months and years we've seen how life adapts to an ever-changing world, but is it possible for anything to truly cheat time and live forever? We humans have done our best to extend our lifetimes. With family support, and better health we've added decades to our life span. But there is something that's taken almost magical control of its time on earth. To discover the secrets of its eternal life we must remain in this English churchyard, but imagine travelling back one thousand, six hundred years... to a funeral in the Dark Ages. It was a simple ceremony but these early Christians were known to mark the grave by planting the sapling of a yew tree. Maybe our ancestors already had a hunch about the enduring nature of this tree. If we watch this yew sapling grow at speed,will its secrets be revealed? In its first two hundred years it witnesses the felling of most of the wild wood around. Perhaps because it marks a grave, our yew tree is spared. It's when it creeps into its third century that it starts to unveil mysterious powers. Only the flesh of its berries is safe to eat.The leaves and bark are highly poisonous and are left well alone. The needles are like a curse. As they fall their toxic juices leach out into the earth. It wipes out the competition so that the yew has all the goodness of the soil to itself.This is how it gives itself a head start.It might have stood out as monks were spreading the Christian faith across England, because our four hundred year old yew had become a favoured burial site. A church is built on this sacred ground. As the centuries pass the church increases in stature. Meanwhile the yew-tree seems master of its own destiny. It doesn't just grow slowly. It appears to be able to stop itself growing altogether. These are tricks which our tree will need, because as we roll into the Middle Ages there's trouble in store.

The weather is at its worst. The winters are long and cold and it rains cats and dogs. Many of its neighbours are toppled by strong gales. But the yew stands firm. During its slow, slow growth it's laid down hard, close-grained wood.And that gives its trunk and branches immense strength and flexibility. It weathers the middle ages,but at twelve hundred years old disaster is about to strike big time. While Cavaliers and Roundheads are tearing the country apart the yew tree has its own battle to fight. The dense wood, which served it so well,has trapped pools of water between the branches. The very heart of the tree is beginning to rot. Surely this is the end? But at what seems like its final hour, it conjures up its most remarkable trick of all. The tree throws itself a lifeline. A young branch from the canopy does a U-turn and grows downwards ... right down into the rotting wood. There it feeds off its own compost. It has turned itself into a new root. It digs down through the heartwood into the ground, replanting itself. This is a tree that has the power to be born again, and again. Rejuvenated, the tree marches steadily on... into the twenty-first century. It's now sixteen hundred years old and still going strong. These days it often stands over a wedding. This yew has already outlived but who knows how much further through time it might travel? This ancient tree seems to know nothing of old age or death. It appears to have found life's holy grail the ultimate time-busting strategy the ability to live forever. But the yew tree is not the only winner. Over time individuals may come and go, entire species may adapt or die. But life itself -in all its different forms -has been steadily marching through time - so far for an incredible three and a half billion years! That's staying power. And that's what matters most in life's race against time.