0:00:02 > 0:00:04For some, life is like a beautiful, endless symphony.
0:00:04 > 0:00:07For others, it's more like the music
0:00:07 > 0:00:11of an inebriated street busker just moments before he's arrested -
0:00:11 > 0:00:14nasty, brutal and short.
0:00:14 > 0:00:17Well, I'm here to tell you that it's actually both,
0:00:17 > 0:00:21and through a series of fundamental biological questions, such as...
0:00:21 > 0:00:25How am I related to a mouse?
0:00:25 > 0:00:28War, what is it good for?
0:00:28 > 0:00:31And am I hot or not?
0:00:31 > 0:00:35Just some of the things you need to know about evolution.
0:00:36 > 0:00:41We'll begin with biology's grand maestro - Charles Darwin.
0:00:41 > 0:00:44And what's always bothered me is this.
0:00:47 > 0:00:49Unless you live under a rock,
0:00:49 > 0:00:52you'll have heard of Charles Darwin.
0:00:53 > 0:00:57But before developing his revolutionary theory of evolution,
0:00:57 > 0:01:00Darwin's life was somewhat non-biological.
0:01:00 > 0:01:03First, he quit medical school
0:01:03 > 0:01:05because it was always making him sick.
0:01:05 > 0:01:09And then he very nearly entered the priesthood.
0:01:09 > 0:01:11CHEERING
0:01:11 > 0:01:15So, given that he was on course to become a servant of God,
0:01:15 > 0:01:18it's perhaps not surprising that Darwin wasn't the first person
0:01:18 > 0:01:22to suggest the notion of evolution.
0:01:22 > 0:01:26The idea that evolution has occurred was not new.
0:01:26 > 0:01:30Er, for example, Charles Darwin's own grandfather,
0:01:30 > 0:01:34he had written about that evolution has occurred, organisms have changed,
0:01:34 > 0:01:38and he talks about millions of ages, means the world is very old.
0:01:38 > 0:01:41Carolus Linnaeus, a Swedish botanist,
0:01:41 > 0:01:44in 1735 put humans and apes into the same group,
0:01:44 > 0:01:47sort of into an organised taxonomy.
0:01:47 > 0:01:50The person that's probably most important is Charles Lyell,
0:01:50 > 0:01:53because Lyell was a geologist and he was interested in how
0:01:53 > 0:01:57the surface of the earth changes and the fact that it's not static
0:01:57 > 0:02:01but that mountains sort of arise and lakes and rivers move around
0:02:01 > 0:02:04and the idea that these are very gradual slow changes
0:02:04 > 0:02:06over a long period of time.
0:02:06 > 0:02:10I think Darwin was really influenced by that, because he figured,
0:02:10 > 0:02:13you know, this could be applied to organisms too.
0:02:13 > 0:02:16Darwin really got into naturism...
0:02:16 > 0:02:19sorry, I mean naturalism, at university,
0:02:19 > 0:02:23but had to find his sea legs to make a career of it.
0:02:23 > 0:02:28In 1835, he visited the Galapagos Islands.
0:02:28 > 0:02:30Here, it was the unique nature of nature
0:02:30 > 0:02:33that rocked Darwin's world.
0:02:33 > 0:02:36It began with Galapagos finches,
0:02:36 > 0:02:40whose beaks all looked different across the island chain.
0:02:41 > 0:02:45Each beak seemed to have adapted to whatever food was on offer,
0:02:45 > 0:02:48be it seed, cactus,
0:02:48 > 0:02:50or grub. Ugh.
0:02:50 > 0:02:53Darwin saw this as no coincidence,
0:02:53 > 0:02:56and began to investigate other adaptations.
0:02:56 > 0:03:00His study took another 20 years to complete.
0:03:00 > 0:03:03But his conclusions went against everything
0:03:03 > 0:03:08the prevailing God-based theory said about life's origins.
0:03:08 > 0:03:14Darwin's take was that useful adaptations existed in all living species
0:03:14 > 0:03:19and were inherited through a process he called natural selection,
0:03:19 > 0:03:21and that nature alone was the driving force
0:03:21 > 0:03:25behind millions of years of evolutionary change.
0:03:25 > 0:03:29With that, Darwin became the daddy of modern biology.
0:03:29 > 0:03:32Not bad for a squeamish wannabe priest.
0:03:32 > 0:03:34Uggghh!
0:03:34 > 0:03:40Darwin's theory is now considered to be fact by most serious scientists.
0:03:40 > 0:03:45But even he couldn't really explain how these adaptations came about.
0:03:45 > 0:03:47These days, however, we know
0:03:47 > 0:03:51that they are the work of ugly, hideous little things
0:03:51 > 0:03:53that are normally the preserve of science fiction,
0:03:53 > 0:03:56ie, mutations.
0:03:56 > 0:03:59But this begs a rather difficult question.
0:03:59 > 0:04:02Are we all mutants?
0:04:02 > 0:04:05Think mutant, and you might think Godzilla.
0:04:05 > 0:04:10But evolution's mutants are minute compared with him.
0:04:10 > 0:04:12Our story begins in the 1850s,
0:04:12 > 0:04:15when the Austrian monk Gregor Mendel discovered
0:04:15 > 0:04:18how genetic traits were inherited, by breeding giant peas.
0:04:18 > 0:04:21But this only scratched the surface.
0:04:21 > 0:04:23He was breeding giant peas and dwarf peas
0:04:23 > 0:04:27and instead of the offspring being sort of a blend of the parents,
0:04:27 > 0:04:31they turned out to either be identical to the one parent
0:04:31 > 0:04:32or the other parent.
0:04:32 > 0:04:36But he didn't quite understand how it worked, the mechanism behind it,
0:04:36 > 0:04:40because he didn't really know about things at the molecular level,
0:04:40 > 0:04:43what was happening inside organisms, inside cells.
0:04:43 > 0:04:48Then, in the 20th century, we discovered the hideous truth.
0:04:48 > 0:04:50Molecular mutation.
0:04:50 > 0:04:53Not caused by experimentation,
0:04:53 > 0:04:56but microscopic errors in the genetic code
0:04:56 > 0:04:58hidden within each species.
0:04:58 > 0:05:02Mutations are entirely random events, and most of the time
0:05:02 > 0:05:04they're agents of evil.
0:05:04 > 0:05:09But occasionally they're forces for good, offering mini upgrades
0:05:09 > 0:05:10like better vision,
0:05:10 > 0:05:15faster flight, or, in the case of this monster, more bite.
0:05:15 > 0:05:20Meet obtusacanthus, an extinct 400-million-year-old fish,
0:05:20 > 0:05:23with a freaky face.
0:05:23 > 0:05:29In 2011, scientists found teeth outside its mouth.
0:05:29 > 0:05:32The theory is that the first teeth started out as fish scales
0:05:32 > 0:05:34that randomly mutated.
0:05:34 > 0:05:39But the randomness ends with natural selection or death.
0:05:39 > 0:05:42If the mutation offers any kind of edge,
0:05:42 > 0:05:45it gets passed on to the next generation.
0:05:45 > 0:05:48Those without the mutation, well...
0:05:48 > 0:05:51And, while mutations are random events,
0:05:51 > 0:05:55the process of evolution through natural selection isn't,
0:05:55 > 0:05:59because it's the ones with the beneficial mutations
0:05:59 > 0:06:02that go on to survive and then reproduce.
0:06:02 > 0:06:07Obtusacanthus' freaky face helped to hook its lunch.
0:06:07 > 0:06:12But it took millions of years for teeth to become a total mouthful,
0:06:12 > 0:06:15as seen in all the toothy mutants alive today.
0:06:15 > 0:06:19And, yes, that includes you.
0:06:19 > 0:06:22Let's just think about that for a second.
0:06:22 > 0:06:26If we are all simply mutations of earlier species,
0:06:26 > 0:06:28then we must all be connected -
0:06:28 > 0:06:31humans, dogs,
0:06:31 > 0:06:33cats, mice.
0:06:33 > 0:06:36So, how am I related to a mouse?
0:06:39 > 0:06:43At least 95% of the recipe book for Homo sapiens, that's you,
0:06:43 > 0:06:47is the same for chimpanzee.
0:06:47 > 0:06:50With mice, the figure is about 85%.
0:06:50 > 0:06:54And cabbage, roughly 40%.
0:06:54 > 0:06:56That doesn't mean we're 40% cabbage -
0:06:56 > 0:06:59nobody could stomach that much green.
0:06:59 > 0:07:04It means that some of the genetic instructions used during the cooking process
0:07:04 > 0:07:07are shared across species of both meat and veg.
0:07:07 > 0:07:10I laugh when I read in the newspaper
0:07:10 > 0:07:13and somebody says, you know, "Mr Smith, no relation to Bob Smith,"
0:07:13 > 0:07:15and I always say, "Of course we're related.
0:07:15 > 0:07:19"I'm related to a mouse, I'm related to a bacterium." We're all related.
0:07:19 > 0:07:23We may have different genes and different sequences,
0:07:23 > 0:07:26but the basic biochemical machinery hasn't changed.
0:07:26 > 0:07:30What has changed is how we make the body.
0:07:30 > 0:07:34You can see that a group of different species might be closely related
0:07:34 > 0:07:37because they share 90% of the genes with each other.
0:07:37 > 0:07:42And so that would suggest that they've diverged from each other relatively recently.
0:07:42 > 0:07:45This information can be found in a vital chapter
0:07:45 > 0:07:47of the evolutionary cookbook.
0:07:47 > 0:07:50It's called Common Ancestry.
0:07:50 > 0:07:55The living world is like a very large 3.8-billion-year-old tree,
0:07:55 > 0:07:58with today's organisms at the top.
0:07:58 > 0:08:02Go back in time, and you'd see where each species branches off.
0:08:02 > 0:08:08The earliest known human recipe is possibly Homo gautengensis,
0:08:08 > 0:08:11which is about two million years old.
0:08:13 > 0:08:17There's evidence that those guys may actually have used fire,
0:08:17 > 0:08:21which would make them amongst the world's first chefs.
0:08:22 > 0:08:25Go back 160 million years
0:08:25 > 0:08:30and you'll find the recipe for Juramaia sinensis.
0:08:30 > 0:08:33Found in China in 2011,
0:08:33 > 0:08:37it's believed to be the oldest common ancestor of mice and humans,
0:08:37 > 0:08:42because they're the first known placental mammals,
0:08:42 > 0:08:44that gave birth to live young.
0:08:45 > 0:08:48We're not really sure what the first ever recipe consisted of,
0:08:48 > 0:08:51but we've named it LUCA.
0:08:51 > 0:08:54The Last Universal Common Ancestor.
0:08:55 > 0:09:00But I wouldn't try it if I were you - it's 3.8 billion years old.
0:09:00 > 0:09:02Bleeeuurgh!
0:09:04 > 0:09:07Of course, when we talk about things that are millions of years old,
0:09:07 > 0:09:10we are talking primarily about fossils.
0:09:10 > 0:09:15And it is, unfortunately, quite difficult to get them to talk.
0:09:15 > 0:09:18There is however, a more dynamic way of making the connection
0:09:18 > 0:09:20between the living and the dead,
0:09:20 > 0:09:24using an age-old biological conundrum.
0:09:24 > 0:09:28Which came first, the dinosaur or the egg?
0:09:29 > 0:09:32There will always be a big market for fossils, but their value
0:09:32 > 0:09:36in trying to understand evolution does have a limit.
0:09:36 > 0:09:39If you really want to see evolution at work,
0:09:39 > 0:09:42you can't just rely on fossilised dinosaurs.
0:09:42 > 0:09:46But you might find eggs very useful.
0:09:46 > 0:09:49Or rather, what's inside them -
0:09:49 > 0:09:50embryos.
0:09:50 > 0:09:54Embryos possess all the biological knowhow
0:09:54 > 0:09:56that species need to develop.
0:09:56 > 0:10:00And we've found they also contain information that can connect
0:10:00 > 0:10:04creatures alive today to their distant ancestors.
0:10:04 > 0:10:08Scientists in the division of evolutionary developmental biology,
0:10:08 > 0:10:11or evo-devo, have been tinkering with
0:10:11 > 0:10:15certain genes in chicken embryos, exposing un-chicken-like traits,
0:10:15 > 0:10:18like teeth, and tails.
0:10:18 > 0:10:22These traits are evidence that chickens contain dinosaur DNA
0:10:22 > 0:10:24that's no longer needed.
0:10:24 > 0:10:27In fact, redundant DNA is pretty common.
0:10:27 > 0:10:33In humans, for example, only about 5% has confirmed employment.
0:10:33 > 0:10:37We're now trying to figure out what jobs, if any, the rest have.
0:10:37 > 0:10:40Because a lot of it no longer appears to be doing anything.
0:10:40 > 0:10:46One idea is that a lot of genes have become silent.
0:10:46 > 0:10:50So the information is there embedded, but it's not used,
0:10:50 > 0:10:53it's switched off or partly destroyed.
0:10:53 > 0:10:57And that, in a way, is evidence that organisms are related
0:10:57 > 0:11:00and evolution has occurred.
0:11:00 > 0:11:05But the jobless workforce doesn't just disappear.
0:11:05 > 0:11:08What scientists have discovered is that there is
0:11:08 > 0:11:12a sort of genetic hierarchy, with a senior management
0:11:12 > 0:11:16that can re-employ, or switch back on, dormant genes.
0:11:16 > 0:11:21And this can have some quite unusual consequences.
0:11:21 > 0:11:27Inactive DNA can sometimes return to work, which can lead to atavisms,
0:11:27 > 0:11:31evolutionary throwbacks like whales with tiny legs.
0:11:33 > 0:11:37The evo-devo scientists did a similar thing, deliberately,
0:11:37 > 0:11:40but whether they'll actually put dinosaurs back in business,
0:11:40 > 0:11:44full time, is largely speculation at the moment.
0:11:44 > 0:11:46So the bottom line
0:11:46 > 0:11:51is that within every living thing is proof of its own evolution.
0:11:51 > 0:11:53Which makes you feel sort of warm, really.
0:11:53 > 0:11:56Well, unless you're cold-blooded.
0:11:57 > 0:12:00And actually, speaking of things that are cold-blooded,
0:12:00 > 0:12:04it does seem that, despite everything we have in common,
0:12:04 > 0:12:07we can't help fighting each other.
0:12:12 > 0:12:16Planet Earth has been a war zone for millions of years.
0:12:17 > 0:12:21It's an arms race between predators and prey.
0:12:21 > 0:12:26Predators developed lethal weaponry like semi-automatic teeth.
0:12:26 > 0:12:32So prey evolved evasion strategies, like mimicry.
0:12:32 > 0:12:36Predators returned fire with protractile claws,
0:12:36 > 0:12:41only for prey to hit to back with hi-tech camouflage.
0:12:42 > 0:12:47But some species have gone further - chemical warfare.
0:12:47 > 0:12:50Pit vipers are cutting-edge killers.
0:12:50 > 0:12:55Their venom is haemotoxic, preventing blood from clotting,
0:12:55 > 0:12:58and evolves very quickly.
0:12:58 > 0:13:01This should make them unrivalled assassins.
0:13:01 > 0:13:04But some viper species have a sworn enemy -
0:13:04 > 0:13:05the possum.
0:13:05 > 0:13:11In 2011, a blood-clotting gene from the Virginia possum
0:13:11 > 0:13:14was found to be evolving incredibly quickly,
0:13:14 > 0:13:16strengthening its resistance to the viper's bite,
0:13:16 > 0:13:23which explains why it can make such a dangerous opponent its prey.
0:13:23 > 0:13:25Both creatures are now locked in mortal combat,
0:13:25 > 0:13:28because without the possum,
0:13:28 > 0:13:33the viper would not have evolved as it did, and vice-versa.
0:13:33 > 0:13:36Strategists call this co-evolution,
0:13:36 > 0:13:39which sees sworn enemies evolving together.
0:13:39 > 0:13:41The prey is getting better at escaping,
0:13:41 > 0:13:44and the predator responds in a sort of complementary way
0:13:44 > 0:13:47to become better at catching the prey.
0:13:47 > 0:13:49So co-evolution is this sort of tit-for-tat
0:13:49 > 0:13:52where evolutionary changes in one organism
0:13:52 > 0:13:55are going to create evolutionary changes in another.
0:13:55 > 0:13:58So, no cheetahs, no gazelles.
0:13:58 > 0:14:00No foxes, no hares.
0:14:00 > 0:14:03At least, not as they appear today.
0:14:03 > 0:14:07War is hell, but good luck trying to evolve as a pacifist.
0:14:10 > 0:14:13So, you're born a mutant,
0:14:13 > 0:14:16you grow into adulthood,
0:14:16 > 0:14:20and you stave off death, at least temporarily,
0:14:20 > 0:14:22through natural selection.
0:14:22 > 0:14:24Whatever can be next?
0:14:24 > 0:14:29Well, you're probably ready to achieve your evolutionary climax -
0:14:29 > 0:14:30reproduction.
0:14:30 > 0:14:34And, as you go through the world seeking a suitable mate,
0:14:34 > 0:14:37the question you'll be asking yourself is this.
0:14:41 > 0:14:45Hotness is in the eye of the beholder.
0:14:45 > 0:14:49But looks aren't part of the package for all species.
0:14:49 > 0:14:52Some creatures measure hotness intra-sexually,
0:14:52 > 0:14:56like those who fight for the right to procreate.
0:14:56 > 0:14:58Others compete inter-sexually,
0:14:58 > 0:15:03attempting to dance... sing...
0:15:03 > 0:15:06or buy their way into the arms of the opposite sex.
0:15:06 > 0:15:10Mating calls are a very popular approach.
0:15:10 > 0:15:16In 2011, a species of water boatman called Micronecta scholtzi
0:15:16 > 0:15:21was found to have, pound for pound, the loudest mating call on Earth.
0:15:21 > 0:15:27Despite being just 2mm long, it can hit 99 decibels,
0:15:27 > 0:15:30proving that size isn't everything.
0:15:30 > 0:15:33That's loud enough for humans to hear,
0:15:33 > 0:15:38and it illustrates just how dedicated life is to reproduction.
0:15:38 > 0:15:41It's how the genes are passed on from one generation to the next,
0:15:41 > 0:15:43it's how the gene pool deepens,
0:15:43 > 0:15:46and it's how natural history programmes
0:15:46 > 0:15:49are able to get away with showing those sex scenes.
0:15:52 > 0:15:57You'd think the boatman's vocals would be a dead giveaway to predators,
0:15:57 > 0:16:00but he could be what's called a Fisherian runaway.
0:16:00 > 0:16:05Named after the biologist RA Fisher, the theory is that his call,
0:16:05 > 0:16:08or other traits like the peacock's plumage,
0:16:08 > 0:16:12don't seem to help with survival and might even get them killed.
0:16:12 > 0:16:16But it's exactly what their partners are looking for.
0:16:16 > 0:16:19This leads to a positive feedback loop,
0:16:19 > 0:16:22whereby the more pronounced the trait,
0:16:22 > 0:16:26the more it's favoured by the opposite sex in each new generation.
0:16:26 > 0:16:31A vicious evolutionary circle, with the occasional happy ending.
0:16:31 > 0:16:34But you don't have to have sex to reproduce. Yeah.
0:16:34 > 0:16:39You could be a simple organism that just...divides.
0:16:39 > 0:16:43I can't do that myself, but bacteria can do that, and it's asexual.
0:16:43 > 0:16:48Similarly, there are certain organisms like earthworms.
0:16:48 > 0:16:52You can chop an earthworm and produce different earthworms.
0:16:52 > 0:16:57So we have asexual reproduction, which happens in many organisms,
0:16:57 > 0:16:59and in fact in large parts of the tree of life,
0:16:59 > 0:17:02they're the rule rather than the exception.
0:17:02 > 0:17:04Whatever your strategy, though,
0:17:04 > 0:17:08the ultimate evolutionary measure of hotness isn't looks,
0:17:08 > 0:17:10or charm, or bruises.
0:17:10 > 0:17:13It's if you've got one of these.
0:17:13 > 0:17:16BABY SUCKS DUMMY
0:17:16 > 0:17:19That of course explains why there are so many of us,
0:17:19 > 0:17:23but it doesn't explain why there is such a great variety of organisms.
0:17:23 > 0:17:27The world had a lot to do with that, or rather its geography did.
0:17:29 > 0:17:30Next question.
0:17:30 > 0:17:35What has geography got to do with evolution?
0:17:35 > 0:17:40Animals first made landfall hundreds of millions of years ago, sort of.
0:17:40 > 0:17:43We now cover the face of the planet.
0:17:43 > 0:17:48But this wasn't just the result of our love of travel.
0:17:48 > 0:17:53Land masses divide, mountains rise, rivers become lakes,
0:17:53 > 0:17:57and when geography gets in the way, it interrupts the gene flow.
0:17:57 > 0:18:00Fold in other factors, like an erratic climate,
0:18:00 > 0:18:04and you get speciation - new species.
0:18:04 > 0:18:09Geographical isolation is the basic and minimum necessity
0:18:09 > 0:18:11for a speciation to occur.
0:18:11 > 0:18:14The environment here's not going to be identical to here,
0:18:14 > 0:18:19so the best traits for surviving here aren't necessarily the best traits for surviving here.
0:18:19 > 0:18:22Eventually those changes are significant enough
0:18:22 > 0:18:24for us to say those are two different species.
0:18:24 > 0:18:28Some creatures disappeared underground.
0:18:28 > 0:18:32Many became tree-dwellers. Others went airborne.
0:18:32 > 0:18:34A handful returned to the life aquatic,
0:18:34 > 0:18:37with some becoming dolphins and whales.
0:18:37 > 0:18:40Millions of years of geographical change
0:18:40 > 0:18:42has led to a diverse population
0:18:42 > 0:18:45that today includes over 5,000 mammals,
0:18:45 > 0:18:5010,000 birds and a million-plus insects.
0:18:52 > 0:18:56That's out of an estimated 8.7 million species,
0:18:56 > 0:19:00and we've only recorded about 1.7 million of those.
0:19:00 > 0:19:03And those figures don't take into account all the countless
0:19:03 > 0:19:08microscopic bacteria and viruses littered all over the place.
0:19:08 > 0:19:11The world truly is a zoo.
0:19:11 > 0:19:16But Earth's geography also brought some species back together,
0:19:16 > 0:19:19sort of, through convergent evolution.
0:19:19 > 0:19:23Sometimes, different creatures can face similar conditions, even in
0:19:23 > 0:19:28different parts of the world, and as a result can evolve similar traits.
0:19:28 > 0:19:32Insect, bird and bat wings evolved over millions of years,
0:19:32 > 0:19:35and at different points in geological time.
0:19:35 > 0:19:38But it isn't always that obvious.
0:19:38 > 0:19:40Humpback whales and pelicans
0:19:40 > 0:19:43both feed by gulping masses of water into their mouths.
0:19:43 > 0:19:46This behaviour evolved independently,
0:19:46 > 0:19:50but led to a structurally similar expandable lower jaw.
0:19:50 > 0:19:53Incredible, for two creatures that are worlds apart...
0:19:55 > 0:19:57..sort of.
0:19:57 > 0:20:00So that's 8.7 million species,
0:20:00 > 0:20:04and of those we know about 1.7.
0:20:04 > 0:20:06I mean, obviously it would take
0:20:06 > 0:20:09a very, very long time to count them all,
0:20:09 > 0:20:16although I wonder, how long did it take for life to become that diverse?
0:20:16 > 0:20:20In other words, is life a marathon or a sprint?
0:20:20 > 0:20:24According to Darwin, evolution runs at a steady pace,
0:20:24 > 0:20:26known as gradualism.
0:20:26 > 0:20:28And the track is inclined,
0:20:28 > 0:20:31with species evolving over marathon periods.
0:20:31 > 0:20:35But anyone trying to use the fossil record to prove this
0:20:35 > 0:20:38would find there were obstacles in the way.
0:20:40 > 0:20:44One of the main obstacles is the record itself.
0:20:44 > 0:20:47Because so much of it is missing, it's very difficult
0:20:47 > 0:20:51to determine the speed over a particular period of history.
0:20:51 > 0:20:55There is even evidence that, on the face of it at least,
0:20:55 > 0:20:57seems to contradict the marathon theory.
0:21:00 > 0:21:03Take, for example, the Cambrian Explosion,
0:21:03 > 0:21:08a sub-aqua event held about 550 million years ago.
0:21:08 > 0:21:11Before this, ocean creatures were primarily soft-bodied,
0:21:11 > 0:21:15like sponges, and barely set any records at all.
0:21:17 > 0:21:20Then came the explosion, in which all manner of competitors
0:21:20 > 0:21:23seemed to burst forth in record time,
0:21:23 > 0:21:26perhaps less than 20 million years,
0:21:26 > 0:21:29with hardened skeletons and bi-lateral physiques.
0:21:29 > 0:21:33The Cambrian Explosion was a period of time when we see
0:21:33 > 0:21:38incredibly rapid diversification of animal bodies in particular.
0:21:38 > 0:21:43A lot of new species emerged very rapidly in a short period of time.
0:21:43 > 0:21:45And there appear to be sudden big changes
0:21:45 > 0:21:49in characteristics that the organisms possess.
0:21:49 > 0:21:54Suddenly creatures have eyes where they didn't have any eyes at all,
0:21:54 > 0:21:59or, you know, some major structure that wasn't seen before suddenly emerges.
0:21:59 > 0:22:05We don't fully understand how life became so diverse so quickly.
0:22:05 > 0:22:08It could have been the result of an evolutionary arms race,
0:22:08 > 0:22:10or an environmental change
0:22:10 > 0:22:13that led some species to develop bony skeletons,
0:22:13 > 0:22:17which might explain why their records were so well kept.
0:22:17 > 0:22:19It was evidence like this, though,
0:22:19 > 0:22:23that led scientists to suggest a different pace -
0:22:23 > 0:22:25punctuated equilibrium,
0:22:25 > 0:22:28in which evolution combines huge leaps forward
0:22:28 > 0:22:31together with long periods of rest.
0:22:31 > 0:22:33So, which is it?
0:22:33 > 0:22:36Well, there might not be an outright winner.
0:22:36 > 0:22:40It could have been long steady runs for some,
0:22:40 > 0:22:44a faster rate for others and a variety of speeds in-between.
0:22:44 > 0:22:49The ultimate fitness workout. Sounds exhausting.
0:22:49 > 0:22:53But no matter how fast you live life,
0:22:53 > 0:22:55sooner or later, death is going to catch up with you.
0:22:55 > 0:22:58And I don't mean on an individual basis.
0:22:58 > 0:23:02I'm talking now about species extinction.
0:23:04 > 0:23:07Why do species go extinct?
0:23:07 > 0:23:10Statistically speaking, you're lucky to be here,
0:23:10 > 0:23:17because 99% of all species that have ever lived are extinct.
0:23:17 > 0:23:20The dinosaurs folded 65 million years ago,
0:23:20 > 0:23:23the last of five mass extinctions,
0:23:23 > 0:23:28killing off 75% of life each time.
0:23:28 > 0:23:31Man eliminated the dodo,
0:23:31 > 0:23:34one of almost 900 recorded species
0:23:34 > 0:23:37who've lost big since the year 1,500.
0:23:37 > 0:23:40Invasive species are another serious problem,
0:23:40 > 0:23:44like the pet Burmese pythons we've let loose in Florida,
0:23:44 > 0:23:48who are now threatening several endangered populations.
0:23:48 > 0:23:53But however deadly we've become, in terms of geological time
0:23:53 > 0:23:57the biggest killer is evolution itself.
0:23:57 > 0:24:01It's nothing personal, neither is it in any way pre-meditated.
0:24:01 > 0:24:07It's a simple matter of the hand you're dealt, or, if you like,
0:24:07 > 0:24:12the inability of species to adapt to the world around them.
0:24:14 > 0:24:16One of the worst hands a species can be dealt
0:24:16 > 0:24:18is a change in environment.
0:24:18 > 0:24:23When that happens, the large, slow-breeding ones are normally the first to go.
0:24:23 > 0:24:27Lack of genetic diversity can also be an issue,
0:24:27 > 0:24:30especially for small populations.
0:24:30 > 0:24:33The smaller the population gets, just from a purely statistical
0:24:33 > 0:24:37point of view, the less likely they are to be different form each other.
0:24:37 > 0:24:39For example, if you're on an island, you can only mate
0:24:39 > 0:24:42with other members of the population on the island
0:24:42 > 0:24:44and they may all have similar characteristics,
0:24:44 > 0:24:47so your offspring are all going to have similar characteristics.
0:24:47 > 0:24:51There's little raw material for natural selection to work with,
0:24:51 > 0:24:53and so this can lead to extinction.
0:24:53 > 0:24:59These natural causes have generated an estimated background extinction rate
0:24:59 > 0:25:01of roughly one species per million,
0:25:01 > 0:25:05per year, for the last 3.5 billion years.
0:25:05 > 0:25:11Thanks to us, the rate may now be more than 1,000 times that.
0:25:11 > 0:25:14But we'd do well to remember two things -
0:25:14 > 0:25:18when it comes to extinction, luck has very little to do with it,
0:25:18 > 0:25:20and the house always wins.
0:25:20 > 0:25:23Extinctions, it seems,
0:25:23 > 0:25:27are simply a fundamental part of the evolutionary process.
0:25:27 > 0:25:30But modern science has gone beyond
0:25:30 > 0:25:33just trying to understand that process.
0:25:33 > 0:25:35And one area of research in particular
0:25:35 > 0:25:40has thrown up something of a blockbuster question.
0:25:40 > 0:25:43Can we create life?
0:25:43 > 0:25:46In 2011, Japanese and Russian scientists
0:25:46 > 0:25:50announced a plan to resurrect the woolly mammoth,
0:25:50 > 0:25:54attempting to turn science fiction into science fact.
0:25:54 > 0:25:58The plan, broadly speaking, is to inject DNA from a frozen mammoth
0:25:58 > 0:26:04into the egg of its closest living relative, the elephant.
0:26:04 > 0:26:07Then, they'll insert the egg into a female elephant's womb,
0:26:07 > 0:26:12where, fingers crossed, it will develop as a baby mammoth.
0:26:12 > 0:26:14Sounds complicated...because it is.
0:26:16 > 0:26:18If the DNA isn't perfectly intact,
0:26:18 > 0:26:20they'll be back to the drawing board.
0:26:20 > 0:26:22But even if they get things right,
0:26:22 > 0:26:25there's still no guarantee it will work.
0:26:25 > 0:26:27Stay tuned, though,
0:26:27 > 0:26:32because the scientists say mammoths could be returning to Earth by 2016.
0:26:32 > 0:26:37Not all attempts to create life are quite so, well, mammoth.
0:26:37 > 0:26:44In 2010, US scientists produced the world's first synthetic life form,
0:26:44 > 0:26:49a copy of a bacterial species, using man-made DNA.
0:26:49 > 0:26:51They essentially took an empty bacterial cell,
0:26:51 > 0:26:55took the DNA that existed in it, flushed it out,
0:26:55 > 0:26:58and replaced it with synthetic strands of DNA that essentially
0:26:58 > 0:27:02have been sort of stitched together to produce a functional DNA molecule.
0:27:02 > 0:27:05When they did that, what happened was that the cell acquired
0:27:05 > 0:27:10all the characteristics that were coded for by the new DNA that had been put in,
0:27:10 > 0:27:11which is pretty amazing.
0:27:11 > 0:27:17OK, it doesn't look like much, and it wasn't really NEW life.
0:27:17 > 0:27:21Like any copy, it was based on an original.
0:27:21 > 0:27:23And, like the mammoth project,
0:27:23 > 0:27:26the artificial element required an organic host.
0:27:26 > 0:27:30In this case, an empty bacterial cell.
0:27:30 > 0:27:33Producing something totally original,
0:27:33 > 0:27:36self-replicating molecules, with a novel genetic code,
0:27:36 > 0:27:39that doesn't require a host organism,
0:27:39 > 0:27:41is still science fiction at the moment.
0:27:41 > 0:27:47But if it ever becomes science fact, it'll be an instant classic.
0:27:47 > 0:27:49Evolution 2.0.
0:27:49 > 0:27:53Of course, the big difference is, in part two,
0:27:53 > 0:27:56it'll be scientists wanting to create life.
0:27:56 > 0:28:00And that brings us to the final thing you need to know -
0:28:00 > 0:28:06evolution does not in itself have a goal, and it never has.
0:28:06 > 0:28:11Animals, plants, even bacteria - they're not trying to be perfect,
0:28:11 > 0:28:13they're just trying to make the best
0:28:13 > 0:28:15of whatever the world throws at them.
0:28:15 > 0:28:17And when you think of it like that,
0:28:17 > 0:28:20it sort of takes the stress out of life, doesn't it?
0:28:20 > 0:28:24So why not just sit back, relax...
0:28:26 > 0:28:28..and try not to get eaten.
0:28:46 > 0:28:47Subtitles by Red Bee Media Ltd