...about Evolution James May's Things You Need to Know


...about Evolution

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For some, life is like a beautiful, endless symphony.

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For others, it's more like the music

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of an inebriated street busker just moments before he's arrested -

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nasty, brutal and short.

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Well, I'm here to tell you that it's actually both,

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and through a series of fundamental biological questions, such as...

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How am I related to a mouse?

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War, what is it good for?

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And am I hot or not?

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Just some of the things you need to know about evolution.

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We'll begin with biology's grand maestro - Charles Darwin.

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And what's always bothered me is this.

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Unless you live under a rock,

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you'll have heard of Charles Darwin.

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But before developing his revolutionary theory of evolution,

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Darwin's life was somewhat non-biological.

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First, he quit medical school

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because it was always making him sick.

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And then he very nearly entered the priesthood.

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CHEERING

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So, given that he was on course to become a servant of God,

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it's perhaps not surprising that Darwin wasn't the first person

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to suggest the notion of evolution.

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The idea that evolution has occurred was not new.

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Er, for example, Charles Darwin's own grandfather,

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he had written about that evolution has occurred, organisms have changed,

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and he talks about millions of ages, means the world is very old.

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Carolus Linnaeus, a Swedish botanist,

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in 1735 put humans and apes into the same group,

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sort of into an organised taxonomy.

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The person that's probably most important is Charles Lyell,

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because Lyell was a geologist and he was interested in how

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the surface of the earth changes and the fact that it's not static

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but that mountains sort of arise and lakes and rivers move around

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and the idea that these are very gradual slow changes

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over a long period of time.

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I think Darwin was really influenced by that, because he figured,

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you know, this could be applied to organisms too.

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Darwin really got into naturism...

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sorry, I mean naturalism, at university,

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but had to find his sea legs to make a career of it.

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In 1835, he visited the Galapagos Islands.

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Here, it was the unique nature of nature

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that rocked Darwin's world.

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It began with Galapagos finches,

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whose beaks all looked different across the island chain.

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Each beak seemed to have adapted to whatever food was on offer,

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be it seed, cactus,

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or grub. Ugh.

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Darwin saw this as no coincidence,

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and began to investigate other adaptations.

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His study took another 20 years to complete.

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But his conclusions went against everything

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the prevailing God-based theory said about life's origins.

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Darwin's take was that useful adaptations existed in all living species

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and were inherited through a process he called natural selection,

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and that nature alone was the driving force

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behind millions of years of evolutionary change.

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With that, Darwin became the daddy of modern biology.

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Not bad for a squeamish wannabe priest.

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Uggghh!

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Darwin's theory is now considered to be fact by most serious scientists.

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But even he couldn't really explain how these adaptations came about.

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These days, however, we know

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that they are the work of ugly, hideous little things

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that are normally the preserve of science fiction,

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ie, mutations.

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But this begs a rather difficult question.

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Are we all mutants?

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Think mutant, and you might think Godzilla.

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But evolution's mutants are minute compared with him.

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Our story begins in the 1850s,

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when the Austrian monk Gregor Mendel discovered

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how genetic traits were inherited, by breeding giant peas.

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But this only scratched the surface.

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He was breeding giant peas and dwarf peas

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and instead of the offspring being sort of a blend of the parents,

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they turned out to either be identical to the one parent

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or the other parent.

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But he didn't quite understand how it worked, the mechanism behind it,

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because he didn't really know about things at the molecular level,

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what was happening inside organisms, inside cells.

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Then, in the 20th century, we discovered the hideous truth.

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Molecular mutation.

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Not caused by experimentation,

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but microscopic errors in the genetic code

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hidden within each species.

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Mutations are entirely random events, and most of the time

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they're agents of evil.

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But occasionally they're forces for good, offering mini upgrades

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like better vision,

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faster flight, or, in the case of this monster, more bite.

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Meet obtusacanthus, an extinct 400-million-year-old fish,

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with a freaky face.

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In 2011, scientists found teeth outside its mouth.

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The theory is that the first teeth started out as fish scales

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that randomly mutated.

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But the randomness ends with natural selection or death.

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If the mutation offers any kind of edge,

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it gets passed on to the next generation.

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Those without the mutation, well...

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And, while mutations are random events,

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the process of evolution through natural selection isn't,

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because it's the ones with the beneficial mutations

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that go on to survive and then reproduce.

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Obtusacanthus' freaky face helped to hook its lunch.

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But it took millions of years for teeth to become a total mouthful,

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as seen in all the toothy mutants alive today.

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And, yes, that includes you.

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Let's just think about that for a second.

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If we are all simply mutations of earlier species,

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then we must all be connected -

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humans, dogs,

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cats, mice.

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So, how am I related to a mouse?

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At least 95% of the recipe book for Homo sapiens, that's you,

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is the same for chimpanzee.

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With mice, the figure is about 85%.

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And cabbage, roughly 40%.

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That doesn't mean we're 40% cabbage -

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nobody could stomach that much green.

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It means that some of the genetic instructions used during the cooking process

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are shared across species of both meat and veg.

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I laugh when I read in the newspaper

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and somebody says, you know, "Mr Smith, no relation to Bob Smith,"

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and I always say, "Of course we're related.

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"I'm related to a mouse, I'm related to a bacterium." We're all related.

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We may have different genes and different sequences,

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but the basic biochemical machinery hasn't changed.

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What has changed is how we make the body.

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You can see that a group of different species might be closely related

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because they share 90% of the genes with each other.

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And so that would suggest that they've diverged from each other relatively recently.

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This information can be found in a vital chapter

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of the evolutionary cookbook.

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It's called Common Ancestry.

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The living world is like a very large 3.8-billion-year-old tree,

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with today's organisms at the top.

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Go back in time, and you'd see where each species branches off.

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The earliest known human recipe is possibly Homo gautengensis,

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which is about two million years old.

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There's evidence that those guys may actually have used fire,

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which would make them amongst the world's first chefs.

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Go back 160 million years

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and you'll find the recipe for Juramaia sinensis.

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Found in China in 2011,

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it's believed to be the oldest common ancestor of mice and humans,

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because they're the first known placental mammals,

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that gave birth to live young.

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We're not really sure what the first ever recipe consisted of,

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but we've named it LUCA.

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The Last Universal Common Ancestor.

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But I wouldn't try it if I were you - it's 3.8 billion years old.

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Bleeeuurgh!

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Of course, when we talk about things that are millions of years old,

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we are talking primarily about fossils.

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And it is, unfortunately, quite difficult to get them to talk.

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There is however, a more dynamic way of making the connection

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between the living and the dead,

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using an age-old biological conundrum.

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Which came first, the dinosaur or the egg?

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There will always be a big market for fossils, but their value

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in trying to understand evolution does have a limit.

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If you really want to see evolution at work,

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you can't just rely on fossilised dinosaurs.

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But you might find eggs very useful.

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Or rather, what's inside them -

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embryos.

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Embryos possess all the biological knowhow

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that species need to develop.

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And we've found they also contain information that can connect

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creatures alive today to their distant ancestors.

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Scientists in the division of evolutionary developmental biology,

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or evo-devo, have been tinkering with

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certain genes in chicken embryos, exposing un-chicken-like traits,

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like teeth, and tails.

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These traits are evidence that chickens contain dinosaur DNA

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that's no longer needed.

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In fact, redundant DNA is pretty common.

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In humans, for example, only about 5% has confirmed employment.

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We're now trying to figure out what jobs, if any, the rest have.

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Because a lot of it no longer appears to be doing anything.

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One idea is that a lot of genes have become silent.

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So the information is there embedded, but it's not used,

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it's switched off or partly destroyed.

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And that, in a way, is evidence that organisms are related

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and evolution has occurred.

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But the jobless workforce doesn't just disappear.

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What scientists have discovered is that there is

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a sort of genetic hierarchy, with a senior management

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that can re-employ, or switch back on, dormant genes.

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And this can have some quite unusual consequences.

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Inactive DNA can sometimes return to work, which can lead to atavisms,

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evolutionary throwbacks like whales with tiny legs.

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The evo-devo scientists did a similar thing, deliberately,

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but whether they'll actually put dinosaurs back in business,

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full time, is largely speculation at the moment.

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So the bottom line

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is that within every living thing is proof of its own evolution.

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Which makes you feel sort of warm, really.

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Well, unless you're cold-blooded.

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And actually, speaking of things that are cold-blooded,

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it does seem that, despite everything we have in common,

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we can't help fighting each other.

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Planet Earth has been a war zone for millions of years.

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It's an arms race between predators and prey.

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Predators developed lethal weaponry like semi-automatic teeth.

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So prey evolved evasion strategies, like mimicry.

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Predators returned fire with protractile claws,

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only for prey to hit to back with hi-tech camouflage.

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But some species have gone further - chemical warfare.

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Pit vipers are cutting-edge killers.

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Their venom is haemotoxic, preventing blood from clotting,

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and evolves very quickly.

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This should make them unrivalled assassins.

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But some viper species have a sworn enemy -

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the possum.

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In 2011, a blood-clotting gene from the Virginia possum

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was found to be evolving incredibly quickly,

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strengthening its resistance to the viper's bite,

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which explains why it can make such a dangerous opponent its prey.

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Both creatures are now locked in mortal combat,

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because without the possum,

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the viper would not have evolved as it did, and vice-versa.

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Strategists call this co-evolution,

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which sees sworn enemies evolving together.

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The prey is getting better at escaping,

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and the predator responds in a sort of complementary way

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to become better at catching the prey.

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So co-evolution is this sort of tit-for-tat

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where evolutionary changes in one organism

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are going to create evolutionary changes in another.

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So, no cheetahs, no gazelles.

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No foxes, no hares.

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At least, not as they appear today.

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War is hell, but good luck trying to evolve as a pacifist.

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So, you're born a mutant,

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you grow into adulthood,

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and you stave off death, at least temporarily,

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through natural selection.

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Whatever can be next?

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Well, you're probably ready to achieve your evolutionary climax -

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reproduction.

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And, as you go through the world seeking a suitable mate,

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the question you'll be asking yourself is this.

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Hotness is in the eye of the beholder.

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But looks aren't part of the package for all species.

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Some creatures measure hotness intra-sexually,

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like those who fight for the right to procreate.

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Others compete inter-sexually,

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attempting to dance... sing...

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or buy their way into the arms of the opposite sex.

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Mating calls are a very popular approach.

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In 2011, a species of water boatman called Micronecta scholtzi

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was found to have, pound for pound, the loudest mating call on Earth.

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Despite being just 2mm long, it can hit 99 decibels,

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proving that size isn't everything.

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That's loud enough for humans to hear,

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and it illustrates just how dedicated life is to reproduction.

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It's how the genes are passed on from one generation to the next,

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it's how the gene pool deepens,

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and it's how natural history programmes

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are able to get away with showing those sex scenes.

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You'd think the boatman's vocals would be a dead giveaway to predators,

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but he could be what's called a Fisherian runaway.

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Named after the biologist RA Fisher, the theory is that his call,

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or other traits like the peacock's plumage,

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don't seem to help with survival and might even get them killed.

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But it's exactly what their partners are looking for.

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This leads to a positive feedback loop,

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whereby the more pronounced the trait,

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the more it's favoured by the opposite sex in each new generation.

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A vicious evolutionary circle, with the occasional happy ending.

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But you don't have to have sex to reproduce. Yeah.

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You could be a simple organism that just...divides.

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I can't do that myself, but bacteria can do that, and it's asexual.

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Similarly, there are certain organisms like earthworms.

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You can chop an earthworm and produce different earthworms.

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So we have asexual reproduction, which happens in many organisms,

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and in fact in large parts of the tree of life,

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they're the rule rather than the exception.

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Whatever your strategy, though,

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the ultimate evolutionary measure of hotness isn't looks,

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or charm, or bruises.

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It's if you've got one of these.

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BABY SUCKS DUMMY

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That of course explains why there are so many of us,

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but it doesn't explain why there is such a great variety of organisms.

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The world had a lot to do with that, or rather its geography did.

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Next question.

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What has geography got to do with evolution?

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Animals first made landfall hundreds of millions of years ago, sort of.

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We now cover the face of the planet.

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But this wasn't just the result of our love of travel.

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Land masses divide, mountains rise, rivers become lakes,

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and when geography gets in the way, it interrupts the gene flow.

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Fold in other factors, like an erratic climate,

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and you get speciation - new species.

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Geographical isolation is the basic and minimum necessity

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for a speciation to occur.

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The environment here's not going to be identical to here,

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so the best traits for surviving here aren't necessarily the best traits for surviving here.

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Eventually those changes are significant enough

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for us to say those are two different species.

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Some creatures disappeared underground.

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Many became tree-dwellers. Others went airborne.

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A handful returned to the life aquatic,

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with some becoming dolphins and whales.

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Millions of years of geographical change

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has led to a diverse population

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that today includes over 5,000 mammals,

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10,000 birds and a million-plus insects.

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That's out of an estimated 8.7 million species,

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and we've only recorded about 1.7 million of those.

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And those figures don't take into account all the countless

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microscopic bacteria and viruses littered all over the place.

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The world truly is a zoo.

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But Earth's geography also brought some species back together,

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sort of, through convergent evolution.

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Sometimes, different creatures can face similar conditions, even in

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different parts of the world, and as a result can evolve similar traits.

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Insect, bird and bat wings evolved over millions of years,

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and at different points in geological time.

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But it isn't always that obvious.

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Humpback whales and pelicans

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both feed by gulping masses of water into their mouths.

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This behaviour evolved independently,

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but led to a structurally similar expandable lower jaw.

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Incredible, for two creatures that are worlds apart...

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..sort of.

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So that's 8.7 million species,

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and of those we know about 1.7.

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I mean, obviously it would take

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a very, very long time to count them all,

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although I wonder, how long did it take for life to become that diverse?

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In other words, is life a marathon or a sprint?

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According to Darwin, evolution runs at a steady pace,

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known as gradualism.

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And the track is inclined,

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with species evolving over marathon periods.

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But anyone trying to use the fossil record to prove this

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would find there were obstacles in the way.

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One of the main obstacles is the record itself.

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Because so much of it is missing, it's very difficult

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to determine the speed over a particular period of history.

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There is even evidence that, on the face of it at least,

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seems to contradict the marathon theory.

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Take, for example, the Cambrian Explosion,

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a sub-aqua event held about 550 million years ago.

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Before this, ocean creatures were primarily soft-bodied,

0:21:080:21:11

like sponges, and barely set any records at all.

0:21:110:21:15

Then came the explosion, in which all manner of competitors

0:21:170:21:20

seemed to burst forth in record time,

0:21:200:21:23

perhaps less than 20 million years,

0:21:230:21:26

with hardened skeletons and bi-lateral physiques.

0:21:260:21:29

The Cambrian Explosion was a period of time when we see

0:21:290:21:33

incredibly rapid diversification of animal bodies in particular.

0:21:330:21:38

A lot of new species emerged very rapidly in a short period of time.

0:21:380:21:43

And there appear to be sudden big changes

0:21:430:21:45

in characteristics that the organisms possess.

0:21:450:21:49

Suddenly creatures have eyes where they didn't have any eyes at all,

0:21:490:21:54

or, you know, some major structure that wasn't seen before suddenly emerges.

0:21:540:21:59

We don't fully understand how life became so diverse so quickly.

0:21:590:22:05

It could have been the result of an evolutionary arms race,

0:22:050:22:08

or an environmental change

0:22:080:22:10

that led some species to develop bony skeletons,

0:22:100:22:13

which might explain why their records were so well kept.

0:22:130:22:17

It was evidence like this, though,

0:22:170:22:19

that led scientists to suggest a different pace -

0:22:190:22:23

punctuated equilibrium,

0:22:230:22:25

in which evolution combines huge leaps forward

0:22:250:22:28

together with long periods of rest.

0:22:280:22:31

So, which is it?

0:22:310:22:33

Well, there might not be an outright winner.

0:22:330:22:36

It could have been long steady runs for some,

0:22:360:22:40

a faster rate for others and a variety of speeds in-between.

0:22:400:22:44

The ultimate fitness workout. Sounds exhausting.

0:22:440:22:49

But no matter how fast you live life,

0:22:490:22:53

sooner or later, death is going to catch up with you.

0:22:530:22:55

And I don't mean on an individual basis.

0:22:550:22:58

I'm talking now about species extinction.

0:22:580:23:02

Why do species go extinct?

0:23:040:23:07

Statistically speaking, you're lucky to be here,

0:23:070:23:10

because 99% of all species that have ever lived are extinct.

0:23:100:23:17

The dinosaurs folded 65 million years ago,

0:23:170:23:20

the last of five mass extinctions,

0:23:200:23:23

killing off 75% of life each time.

0:23:230:23:28

Man eliminated the dodo,

0:23:280:23:31

one of almost 900 recorded species

0:23:310:23:34

who've lost big since the year 1,500.

0:23:340:23:37

Invasive species are another serious problem,

0:23:370:23:40

like the pet Burmese pythons we've let loose in Florida,

0:23:400:23:44

who are now threatening several endangered populations.

0:23:440:23:48

But however deadly we've become, in terms of geological time

0:23:480:23:53

the biggest killer is evolution itself.

0:23:530:23:57

It's nothing personal, neither is it in any way pre-meditated.

0:23:570:24:01

It's a simple matter of the hand you're dealt, or, if you like,

0:24:010:24:07

the inability of species to adapt to the world around them.

0:24:070:24:12

One of the worst hands a species can be dealt

0:24:140:24:16

is a change in environment.

0:24:160:24:18

When that happens, the large, slow-breeding ones are normally the first to go.

0:24:180:24:23

Lack of genetic diversity can also be an issue,

0:24:230:24:27

especially for small populations.

0:24:270:24:30

The smaller the population gets, just from a purely statistical

0:24:300:24:33

point of view, the less likely they are to be different form each other.

0:24:330:24:37

For example, if you're on an island, you can only mate

0:24:370:24:39

with other members of the population on the island

0:24:390:24:42

and they may all have similar characteristics,

0:24:420:24:44

so your offspring are all going to have similar characteristics.

0:24:440:24:47

There's little raw material for natural selection to work with,

0:24:470:24:51

and so this can lead to extinction.

0:24:510:24:53

These natural causes have generated an estimated background extinction rate

0:24:530:24:59

of roughly one species per million,

0:24:590:25:01

per year, for the last 3.5 billion years.

0:25:010:25:05

Thanks to us, the rate may now be more than 1,000 times that.

0:25:050:25:11

But we'd do well to remember two things -

0:25:110:25:14

when it comes to extinction, luck has very little to do with it,

0:25:140:25:18

and the house always wins.

0:25:180:25:20

Extinctions, it seems,

0:25:200:25:23

are simply a fundamental part of the evolutionary process.

0:25:230:25:27

But modern science has gone beyond

0:25:270:25:30

just trying to understand that process.

0:25:300:25:33

And one area of research in particular

0:25:330:25:35

has thrown up something of a blockbuster question.

0:25:350:25:40

Can we create life?

0:25:400:25:43

In 2011, Japanese and Russian scientists

0:25:430:25:46

announced a plan to resurrect the woolly mammoth,

0:25:460:25:50

attempting to turn science fiction into science fact.

0:25:500:25:54

The plan, broadly speaking, is to inject DNA from a frozen mammoth

0:25:540:25:58

into the egg of its closest living relative, the elephant.

0:25:580:26:04

Then, they'll insert the egg into a female elephant's womb,

0:26:040:26:07

where, fingers crossed, it will develop as a baby mammoth.

0:26:070:26:12

Sounds complicated...because it is.

0:26:120:26:14

If the DNA isn't perfectly intact,

0:26:160:26:18

they'll be back to the drawing board.

0:26:180:26:20

But even if they get things right,

0:26:200:26:22

there's still no guarantee it will work.

0:26:220:26:25

Stay tuned, though,

0:26:250:26:27

because the scientists say mammoths could be returning to Earth by 2016.

0:26:270:26:32

Not all attempts to create life are quite so, well, mammoth.

0:26:320:26:37

In 2010, US scientists produced the world's first synthetic life form,

0:26:370:26:44

a copy of a bacterial species, using man-made DNA.

0:26:440:26:49

They essentially took an empty bacterial cell,

0:26:490:26:51

took the DNA that existed in it, flushed it out,

0:26:510:26:55

and replaced it with synthetic strands of DNA that essentially

0:26:550:26:58

have been sort of stitched together to produce a functional DNA molecule.

0:26:580:27:02

When they did that, what happened was that the cell acquired

0:27:020:27:05

all the characteristics that were coded for by the new DNA that had been put in,

0:27:050:27:10

which is pretty amazing.

0:27:100:27:11

OK, it doesn't look like much, and it wasn't really NEW life.

0:27:110:27:17

Like any copy, it was based on an original.

0:27:170:27:21

And, like the mammoth project,

0:27:210:27:23

the artificial element required an organic host.

0:27:230:27:26

In this case, an empty bacterial cell.

0:27:260:27:30

Producing something totally original,

0:27:300:27:33

self-replicating molecules, with a novel genetic code,

0:27:330:27:36

that doesn't require a host organism,

0:27:360:27:39

is still science fiction at the moment.

0:27:390:27:41

But if it ever becomes science fact, it'll be an instant classic.

0:27:410:27:47

Evolution 2.0.

0:27:470:27:49

Of course, the big difference is, in part two,

0:27:490:27:53

it'll be scientists wanting to create life.

0:27:530:27:56

And that brings us to the final thing you need to know -

0:27:560:28:00

evolution does not in itself have a goal, and it never has.

0:28:000:28:06

Animals, plants, even bacteria - they're not trying to be perfect,

0:28:060:28:11

they're just trying to make the best

0:28:110:28:13

of whatever the world throws at them.

0:28:130:28:15

And when you think of it like that,

0:28:150:28:17

it sort of takes the stress out of life, doesn't it?

0:28:170:28:20

So why not just sit back, relax...

0:28:200:28:24

..and try not to get eaten.

0:28:260:28:28

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