0:00:04 > 0:00:07Of all the questions that science can ask,
0:00:07 > 0:00:13I'm fascinated by one that goes to the very heart of who we are.
0:00:13 > 0:00:18It's a question about what's happening to us, as a species,
0:00:18 > 0:00:20right now.
0:00:20 > 0:00:25The question is, are we still evolving?
0:00:29 > 0:00:32We've learned an enormous amount about how we evolved in the past
0:00:32 > 0:00:34and became human.
0:00:34 > 0:00:40But has the process that made us now stopped?
0:00:40 > 0:00:43Or are we still changing?
0:00:46 > 0:00:49Across the world, scientists are looking for clues.
0:00:49 > 0:00:52And I'm going to join them.
0:00:52 > 0:00:54I want to find out what we can learn
0:00:54 > 0:00:58from breakthroughs in human genetics...
0:00:58 > 0:01:01It's very exciting because we are starting to piece together bits of
0:01:01 > 0:01:04information to get this sort of coherent picture of human evolution.
0:01:06 > 0:01:10I want to see if extreme environments might have forced us to change.
0:01:12 > 0:01:16And I want to find out about a technology that
0:01:16 > 0:01:20might change our species forever.
0:01:22 > 0:01:25- Do you think this is a good idea? - I'm not sure if it's a good idea.
0:01:25 > 0:01:28But I think trying to remove it as part of
0:01:28 > 0:01:32our future evolution is just a task that's not going to be accomplished.
0:01:32 > 0:01:34It's here, it's not going away.
0:01:34 > 0:01:39We know that evolution made us who we are.
0:01:39 > 0:01:42But are we still evolving?
0:02:00 > 0:02:02I'm Alice Roberts.
0:02:02 > 0:02:05I've studied how we've evolved in the past but now, I want to
0:02:05 > 0:02:09know if we're still changing.
0:02:14 > 0:02:19To find out, we need to understand how we got here in the first place.
0:02:23 > 0:02:27Our story, and the story of all life on earth,
0:02:27 > 0:02:30began an unimaginably long time ago.
0:02:36 > 0:02:40We can draw this as a massive tree of life, starting around 3.5
0:02:40 > 0:02:47billion years ago, and branching and branching and branching.
0:02:47 > 0:02:52Now, the vast majority of these branches are going to be
0:02:52 > 0:02:57single-celled organisms, many of them bacteria,
0:02:57 > 0:03:01and 600 million years ago, animals appear.
0:03:01 > 0:03:06So on this tiny bit of this tree of life we're going to have to fit
0:03:06 > 0:03:12all of the species of animals that have ever existed on this planet.
0:03:12 > 0:03:16And then seven million years ago, our own little part of this tree,
0:03:16 > 0:03:19hominins, us and our ancestors, appears.
0:03:19 > 0:03:24Our species, appearing about 200,000 years ago,
0:03:24 > 0:03:28is the only remaining twig.
0:03:30 > 0:03:36On an evolutionary timescale, humans have only just emerged.
0:03:36 > 0:03:39So is it possible that we've continued to evolve
0:03:39 > 0:03:42since our species first appeared?
0:03:49 > 0:03:55Given that it took 3.5 billion years for our species to evolve,
0:03:55 > 0:03:58200,000 years is just the blink of an eye.
0:04:00 > 0:04:04To find out if we've changed in that time, I want to understand
0:04:04 > 0:04:08how quickly evolution can happen.
0:04:11 > 0:04:16Evolution is an amazing phenomenon, it explains the huge diversity of
0:04:16 > 0:04:20life on this planet, past and present, and without
0:04:20 > 0:04:21it none of us would be here.
0:04:21 > 0:04:27No humans, no living things, none of this that's around me right now,
0:04:27 > 0:04:29apart from the rocks.
0:04:29 > 0:04:33And I'm going to see evolution in action.
0:04:37 > 0:04:41Tucked away in the rolling, green hills of the Devon countryside
0:04:41 > 0:04:43lies a derelict mine.
0:04:43 > 0:04:46The surrounding earth has been poisoned.
0:04:48 > 0:04:51But the mine has left a surprising legacy,
0:04:51 > 0:04:54and Professor Mark Hodson has discovered something that would've
0:04:54 > 0:04:57got Charles Darwin very excited.
0:04:57 > 0:05:00So, Mark, what is so special about this place?
0:05:00 > 0:05:02Well, this is Devon Great Consols.
0:05:02 > 0:05:06It used to be a copper mine and then evolved to become an arsenic mine.
0:05:06 > 0:05:09And at its peak, they produced so much that when it was stored on
0:05:09 > 0:05:12the docks, they used to say that there was enough arsenic
0:05:12 > 0:05:14to poison the planet.
0:05:14 > 0:05:16So, is it still poisonous today?
0:05:16 > 0:05:18In this area and all around we've
0:05:18 > 0:05:20measured the arsenic levels and we're talking three orders
0:05:20 > 0:05:23of magnitude more arsenic than would be considered safe.
0:05:23 > 0:05:25So that's a massive amount of arsenic in the soil.
0:05:25 > 0:05:27Oh, yeah, the soil's ooching with it.
0:05:27 > 0:05:33And yet despite that apparently lethal level of arsenic, Mark has
0:05:33 > 0:05:35found earthworms living in the soil.
0:05:35 > 0:05:38But they're not ordinary earthworms.
0:05:38 > 0:05:42If you take an earthworm from your garden and put it in this soil,
0:05:42 > 0:05:44that earthworm would die very rapidly.
0:05:46 > 0:05:52But the worms here have evolved to cope with the poisonous soil.
0:05:52 > 0:05:54And we're going to hunt for one.
0:05:55 > 0:05:58And you reckon this is a good spot to start?
0:05:58 > 0:06:01Yeah, it's moist, there's organic matter,
0:06:01 > 0:06:05- there's definitely some soil there so have a spade. - Thank you very much.
0:06:06 > 0:06:08It's not rocket science, this bit.
0:06:14 > 0:06:17- Ooh, ooh, ooh, I think I've found one.- Yeah.- Look.
0:06:17 > 0:06:19- Look, look, look.- Oh, yeah.
0:06:19 > 0:06:20You see if you can get him out.
0:06:20 > 0:06:24Quite small, he's a bit anaemic looking.
0:06:24 > 0:06:26Yeah, he's quite pale down this end.
0:06:26 > 0:06:28Yeah, yeah, almost yellowish.
0:06:28 > 0:06:32And that's characteristic of a lot of the worms we find in this area.
0:06:32 > 0:06:35But it's not just their colour that's changed.
0:06:35 > 0:06:39Mark believes these worms have evolved into a new species.
0:06:39 > 0:06:42And it's all thanks to natural selection,
0:06:42 > 0:06:48the process that drives evolution, and the process that made us who we are.
0:06:48 > 0:06:50So this isn't just
0:06:50 > 0:06:54a bog standard earthworm that's managing to survive in this soil?
0:06:54 > 0:06:57Well, we've done the genetics on these earthworms
0:06:57 > 0:07:01and what we've found is there's a distinct genetic difference.
0:07:01 > 0:07:06These earthworms are more distinct from the earthworms in your garden than we are, compared to mice.
0:07:06 > 0:07:07That's wonderful.
0:07:07 > 0:07:12And what's really surprising is that it only took 170 years for
0:07:12 > 0:07:14the worms to change so much.
0:07:14 > 0:07:16Well, if you're looking for
0:07:16 > 0:07:21evolutionarily advantageous traits, here being able to deal with arsenic
0:07:21 > 0:07:23has got to put you at a distinct advantage.
0:07:23 > 0:07:26I think so, it doesn't get more clear cut than that.
0:07:26 > 0:07:30It is amazing to see an example of evolution happening.
0:07:30 > 0:07:32Right, after you...
0:07:40 > 0:07:45It's a classic illustration of natural selection in action.
0:07:46 > 0:07:51As the levels of arsenic rose in the soil around here,
0:07:51 > 0:07:56any worm that was lucky enough to have what was originally a chance mutation
0:07:56 > 0:07:57that allowed them to survive,
0:07:57 > 0:08:02would do so, and worms without that new adaptation would die.
0:08:02 > 0:08:06It's simple, brutal, and effective.
0:08:07 > 0:08:12It's also exactly the same process that made us.
0:08:12 > 0:08:16And if natural selection can change these worms so quickly,
0:08:16 > 0:08:20perhaps it's changed us, since our species first appeared.
0:08:23 > 0:08:26But there is something that makes us
0:08:26 > 0:08:29very different from any other animals.
0:08:39 > 0:08:43Our species emerged some 200,000 years ago.
0:08:45 > 0:08:50About 60,000 years ago, we spread out from Africa.
0:08:50 > 0:08:54And since then, we've moved to every corner of the planet.
0:08:57 > 0:09:03But on the course of that journey, something incredible happened,
0:09:03 > 0:09:06something that means the normal rules of evolution
0:09:06 > 0:09:10may no longer apply to us.
0:09:13 > 0:09:15Tens of thousands of years ago,
0:09:15 > 0:09:19our ancestors began to protect themselves from the environment
0:09:19 > 0:09:22in a way that no other creatures have managed to do.
0:09:22 > 0:09:25They invented things to make life easier...
0:09:25 > 0:09:29shelters, tools and other simple technologies that didn't exist
0:09:29 > 0:09:32anywhere else in the natural world.
0:09:32 > 0:09:35- May I have a hot chocolate, please? - Certainly, madam.- Thank you.
0:09:35 > 0:09:39So while polar bears evolved thick coats of blubber to cope with
0:09:39 > 0:09:45the cold, our ancestors made fires, and wrapped themselves in clothes.
0:09:45 > 0:09:48By helping us adapt to new environments,
0:09:48 > 0:09:53did our inventions stop us evolving?
0:09:54 > 0:09:56Humans are clearly
0:09:56 > 0:10:00a product of natural selection, but thousands of years ago
0:10:00 > 0:10:05we began to place barriers and buffers between ourselves and the elements
0:10:05 > 0:10:10to protect ourselves from the slings and arrows of the natural world.
0:10:10 > 0:10:16And that does beg a question: has all our technology sheltered us
0:10:16 > 0:10:18not only from nature,
0:10:18 > 0:10:22but from natural selection itself?
0:10:25 > 0:10:28It's a question that scientists have wondered about
0:10:28 > 0:10:30ever since Darwin's time.
0:10:30 > 0:10:34Has our culture, our technology, stopped us evolving?
0:10:38 > 0:10:43Are we the same as the people that emerged in Africa 200,000 years ago?
0:10:46 > 0:10:49It's an incredibly difficult question to answer.
0:10:49 > 0:10:54The trouble is, how do we find out if we've changed?
0:10:56 > 0:10:58I've come to Oxford,
0:10:58 > 0:11:03where there's an ancient clue that might help to unravel the mystery.
0:11:05 > 0:11:07Tucked away in the university's Natural History Museum
0:11:07 > 0:11:12are the oldest bones of a modern human ever found in the UK.
0:11:16 > 0:11:22They were discovered by the Reverend William Buckland, 180 years ago.
0:11:22 > 0:11:24It seems that Buckland thought that
0:11:24 > 0:11:29these could be the bones of a witch from Roman times
0:11:29 > 0:11:32and they're stained with ochre, they have this reddish appearance,
0:11:32 > 0:11:39so she became known as the Red Lady of Paviland and the name has stuck.
0:11:39 > 0:11:44But we now know that these are not the bones of a 2,000-year-old woman
0:11:44 > 0:11:48and I can see very clearly that this pelvis is male.
0:11:48 > 0:11:55These are the bones of a man who lived 33,000 years ago.
0:12:01 > 0:12:0633,000 years ago was before the peak of the last Ice Age.
0:12:06 > 0:12:11When he was alive, the Red Lady of Paviland shared
0:12:11 > 0:12:15the planet with Neanderthals, and woolly mammoths still roamed the earth.
0:12:17 > 0:12:20So are these bones the same as mine?
0:12:20 > 0:12:24Because if they are, perhaps we have stopped evolving.
0:12:26 > 0:12:30Now, I'm a physical anthropologist, I've looked at hundreds of skeletons,
0:12:30 > 0:12:34but if I didn't know how old these bones were, that they'd been radio
0:12:34 > 0:12:38carbon dated to 33,000 years ago,
0:12:38 > 0:12:42I'd believe you if you told me they were a few hundred years old.
0:12:42 > 0:12:45Of course, there's variation in skeletons, there's variation in
0:12:45 > 0:12:50our bodies, each of us will have a different skeleton,
0:12:50 > 0:12:56but these bones fit within that modern range of variation.
0:12:58 > 0:13:02There's nothing in this skeleton to suggest we've changed
0:13:02 > 0:13:04over millennia.
0:13:06 > 0:13:08So perhaps our use of technology
0:13:08 > 0:13:13and culture really has put us out of reach of natural selection
0:13:13 > 0:13:16and halted our evolution.
0:13:23 > 0:13:26But if we haven't evolved in thousands of years,
0:13:26 > 0:13:31then that would mean that we're all fundamentally the same.
0:13:33 > 0:13:35But it's clearly not as simple as that.
0:13:35 > 0:13:40You don't need to look around for long to realise that we have all
0:13:40 > 0:13:44changed and in a very obvious way.
0:13:48 > 0:13:51In the past, we were all dark-skinned.
0:13:51 > 0:13:54Now, we're not.
0:13:54 > 0:13:56It's a way in which we've evolved apart from each other
0:13:56 > 0:13:59since our species emerged.
0:14:01 > 0:14:05But it's also long been dismissed as a superficial difference,
0:14:05 > 0:14:07no more than skin deep.
0:14:10 > 0:14:15The key question is whether we've evolved in more fundamental ways,
0:14:15 > 0:14:17beneath the surface.
0:14:35 > 0:14:40To find out if we've changed, we need to look in extreme
0:14:40 > 0:14:45environments, at people who might have faced natural selection
0:14:45 > 0:14:47at its most brutal.
0:15:05 > 0:15:10Dr Cynthia Beall believes she's found the perfect place to look
0:15:10 > 0:15:13for signs of human evolution -
0:15:13 > 0:15:20high in the Himalayan mountains, home of the Nepalese Sherpas.
0:15:20 > 0:15:23She's spent much of her life trying to work out
0:15:23 > 0:15:28whether they're fundamentally different to the rest of us.
0:15:28 > 0:15:34Every time we do a research project here in Nepal or in Tibet, scientists
0:15:34 > 0:15:38get excited because we find unusual features of their biology, and that
0:15:38 > 0:15:44suggests there is something very interesting and exciting going on.
0:15:50 > 0:15:52There's something about this environment
0:15:52 > 0:15:57that's potentially lethal, and that's the thin mountain air.
0:16:02 > 0:16:07At this altitude it contains dangerously low levels of oxygen.
0:16:12 > 0:16:15What makes altitude harder is that every breath full of air has only
0:16:15 > 0:16:19about 60% of the oxygen molecules than at sea level.
0:16:19 > 0:16:21Now that is an enormous
0:16:21 > 0:16:28stress physiologically because every cell in our body needs to get oxygen
0:16:28 > 0:16:32regularly in order to generate the energy it needs to sustain life.
0:16:38 > 0:16:44So when the Sherpas moved to the moutains thousands of years ago,
0:16:44 > 0:16:47did they begin to evolve apart from the rest of us?
0:16:52 > 0:16:57Cynthia has come to Namche Bazaar, a small village in Nepal.
0:16:57 > 0:17:01At an altitude of 3,500 metres,
0:17:01 > 0:17:04it's known as the Last Town Before Everest.
0:17:06 > 0:17:09In just the past two days, two foreigners have died nearby
0:17:09 > 0:17:12due to altitude sickness.
0:17:16 > 0:17:21But the Sherpas, who have been living up here for 10,000 years,
0:17:21 > 0:17:23don't struggle with the low oxygen levels.
0:17:26 > 0:17:31After decades of research, Cynthia has been the first person in
0:17:31 > 0:17:37the world to work out why no locals die from the effects of high altitude.
0:17:39 > 0:17:44The first thing she wanted to look at was their blood, because the way
0:17:44 > 0:17:48that most of us cope with low oxygen is to raise the numbers of red blood
0:17:48 > 0:17:50cells and therefore the haemoglobin
0:17:50 > 0:17:55level in our blood, to help draw more oxygen from the thin air.
0:17:55 > 0:17:59But those extra cells aren't the perfect solution
0:17:59 > 0:18:00to a lack of oxygen.
0:18:00 > 0:18:07By thickening our blood they can cause blood clots and even death.
0:18:07 > 0:18:10So did the Sherpas' ability to survive at high altitude
0:18:10 > 0:18:15have something to do with their haemoglobin?
0:18:15 > 0:18:19Someone from low altitude, let's say a young man who had been trekking for
0:18:19 > 0:18:23a month out here, would probably have
0:18:23 > 0:18:2917.8, 18.5 grams of haemoglobin.
0:18:30 > 0:18:35OK, now let's see what Pembola's haemoglobin concentration is.
0:18:35 > 0:18:38And he's 16.4.
0:18:40 > 0:18:42With these haemoglobin levels, the Sherpas don't suffer
0:18:42 > 0:18:47the problems that many of us face when we come to high altitude.
0:18:47 > 0:18:51But how could they be getting enough oxygen without
0:18:51 > 0:18:54raising their haemoglobin levels?
0:18:54 > 0:18:58Once we had established that Tibetans and Sherpas don't have
0:18:58 > 0:19:02very high haemoglobin levels, that led us to think about what
0:19:02 > 0:19:09are they doing in order to get enough oxygen to their cells,
0:19:09 > 0:19:13and we decided that it was time that we took a good look at blood flow.
0:19:13 > 0:19:18Using a video microscope, Cynthia was able to look inside the Sherpas'
0:19:18 > 0:19:21upper lip to investigate their network of capillaries.
0:19:21 > 0:19:23Oh, it looks gorgeous.
0:19:23 > 0:19:25Big thick,
0:19:25 > 0:19:30it's like a meandering river with lots and lots of little tributaries.
0:19:34 > 0:19:38There's a big density that we would not see
0:19:38 > 0:19:41if we tested my blood vessels, however.
0:19:41 > 0:19:45We wouldn't see so much twisting and turning,
0:19:45 > 0:19:48we wouldn't see such wide blood vessels.
0:19:50 > 0:19:53Cynthia had made a breakthrough.
0:19:54 > 0:19:58The Sherpas have evolved to be different from the rest of us.
0:20:01 > 0:20:04Their unique blood circulation delivers them the oxygen they need
0:20:04 > 0:20:09without the potentially fatal risks of high haemoglobin levels.
0:20:15 > 0:20:20There have been hints for a couple of decades now that something
0:20:20 > 0:20:24exciting was happening among high-altitude Tibetans and Sherpas.
0:20:26 > 0:20:30The work that we've done gives evidence of evolution by natural selection,
0:20:30 > 0:20:34and it has been very satisfying to be able to finally say that.
0:20:39 > 0:20:44The Sherpas of Nepal provide clear evidence that some of us, at least,
0:20:44 > 0:20:48are different from our ancestors.
0:20:48 > 0:20:53There have been changes to the structure and function of our bodies
0:20:53 > 0:20:55that are much more than just skin deep.
0:20:56 > 0:21:01Although we may have sheltered ourselves from the natural world,
0:21:01 > 0:21:04in some extreme environments at least,
0:21:04 > 0:21:06humans didn't stop evolving.
0:21:12 > 0:21:16And that begs the question, what about the rest of us?
0:21:16 > 0:21:18Have we all continued to evolve?
0:21:20 > 0:21:24It's a question that technological developments have been able
0:21:24 > 0:21:27to shed extraordinary new light on.
0:21:31 > 0:21:35I've come to The Broad Institute in Massachusetts,
0:21:35 > 0:21:38one of the world's leading genome research centres.
0:21:39 > 0:21:44I've studied the effects of evolution in a really traditional way,
0:21:44 > 0:21:48by looking at the differences in structure of the human body.
0:21:48 > 0:21:52But I don't think it's going too far to say that this place
0:21:52 > 0:21:57has totally revolutionised research into human evolution.
0:21:59 > 0:22:03Unravelling the human genome was a scientific breakthrough
0:22:03 > 0:22:07that many hope will change the future of medicine.
0:22:07 > 0:22:11But for Pardis Sabeti, it's done something very different.
0:22:11 > 0:22:14It's opened up a window onto our past.
0:22:17 > 0:22:20Our genomes contain a wealth of information
0:22:20 > 0:22:24about the genetic changes that have happened in our history.
0:22:24 > 0:22:30That means Pardis can scan the genome to look for signs of recent evolution,
0:22:30 > 0:22:34like the Sherpas' ability to survive at high altitude.
0:22:36 > 0:22:40So you're analysing the DNA of people living today,
0:22:40 > 0:22:45but you're actually able to detect when changes in their DNA occurred,
0:22:45 > 0:22:47going back tens of thousands of years?
0:22:47 > 0:22:49Yeah, that's the thing that sometimes
0:22:49 > 0:22:51is hard to kind of understand,
0:22:51 > 0:22:54but it's essentially that we are living records of our past,
0:22:54 > 0:22:57and so we can look at DNA of individuals from today
0:22:57 > 0:23:00and get a sense of how they all came to be this way.
0:23:01 > 0:23:05By comparing the DNA of thousands of people, Pardis is able to find
0:23:05 > 0:23:09examples of genetic mutations that have become common
0:23:09 > 0:23:12in just the last few thousand years.
0:23:12 > 0:23:17Ultimately we're looking for that rare mutation that somehow is
0:23:17 > 0:23:21so beneficial it didn't get lost, and not only did it not get lost,
0:23:21 > 0:23:25it started spreading very quickly through the population.
0:23:25 > 0:23:29And she's found much more evidence of natural selection than scientists expected.
0:23:29 > 0:23:32Now we basically have scanned the genome
0:23:32 > 0:23:35and found a lot of places where interesting things are going on.
0:23:35 > 0:23:37In this recent study that we did, we had 250 new
0:23:37 > 0:23:41regions of the genome that we've identified to be under selection.
0:23:41 > 0:23:45And we can start looking at what those parts of the genome are
0:23:45 > 0:23:48and what they do, and really get a global view of human evolution.
0:23:52 > 0:23:57With 250 areas of our genomes that have undergone recent natural selection,
0:23:57 > 0:24:01it's clear that we've evolved away from our ancestors
0:24:01 > 0:24:04far more than anyone had ever anticipated.
0:24:06 > 0:24:09And the changes to the way our bodies work
0:24:09 > 0:24:14tell the story of how our world has changed since our species appeared.
0:24:16 > 0:24:18Is there any evidence of adaptation
0:24:18 > 0:24:22to different environments as people spread throughout the world?
0:24:22 > 0:24:27Yeah, absolutely. So as these populations migrate outside of Africa and went north,
0:24:27 > 0:24:31in Europe and Asia you see lots of mutations for pigmentation,
0:24:31 > 0:24:34changing your skin colour as you go to climates that have less light.
0:24:34 > 0:24:38What's interesting is you see all these different pigmentation mutations
0:24:38 > 0:24:41but they're different ones that occurred in Europe and Asia,
0:24:41 > 0:24:45and all different populations trying to drive to that.
0:24:45 > 0:24:49- And presumably there are lots more? - Yeah, you see lots of metabolisms,
0:24:49 > 0:24:53so changing to diets in all populations.
0:24:53 > 0:24:56You see them all over the place. Then we have all sorts of new ones
0:24:56 > 0:25:00that we're interested in. In Asia you see hair and sweat,
0:25:00 > 0:25:05so something to do with maybe thermoregulation.
0:25:05 > 0:25:08And you can see that in very, very recent time,
0:25:08 > 0:25:11there's been mutations to high altitude.
0:25:11 > 0:25:15And Pardis has found that one of the greatest drivers of our evolution
0:25:15 > 0:25:17has been disease.
0:25:17 > 0:25:21One of the classic examples is the sickle cell mutation
0:25:21 > 0:25:24that protects from malaria
0:25:24 > 0:25:28that emerged in Africa sometime within the last 10,000 years.
0:25:28 > 0:25:34What is the impact of genetic research like this on our understanding of human evolution?
0:25:34 > 0:25:36It's absolutely revolutionised it.
0:25:36 > 0:25:39The ability to mine these large data sets and start looking at
0:25:39 > 0:25:42many, many people throughout their genomes -
0:25:42 > 0:25:45we're at a place now where we can create so many different
0:25:45 > 0:25:48hypotheses as to what's driving evolution and get down to
0:25:48 > 0:25:52the single unit that changed and then be able to explore that.
0:25:54 > 0:25:58Our genomes have given us a phenomenal new source of information
0:25:58 > 0:26:02about how the world has changed us.
0:26:02 > 0:26:07The major events of our past are written into our genes.
0:26:07 > 0:26:11But our genetic history contains a lot of surprises.
0:26:27 > 0:26:32There's one development in our history that fascinates me more than almost any other,
0:26:32 > 0:26:37and it set us on course for the modern world.
0:26:39 > 0:26:47There are few more pivotal moments in our past than when we started farming some 10,000 years ago.
0:26:47 > 0:26:51It was to be a defining point in our history.
0:26:51 > 0:26:54It would transform our diets, our cultures,
0:26:54 > 0:26:58and provide the foundations of our civilisations.
0:26:58 > 0:27:02But did its impact run even deeper than that?
0:27:03 > 0:27:11We used to believe that our cultural and technological developments like farming would stop us evolving.
0:27:11 > 0:27:17By giving us a stable food supply that could keep even the weakest members of society fed
0:27:17 > 0:27:22throughout the year, it would distance us from natural selection.
0:27:22 > 0:27:28But did farming stop us evolving, or did it just change how we evolved?
0:27:33 > 0:27:35To answer that we need to understand
0:27:35 > 0:27:40how farming might have affected us 10,000 years ago.
0:27:41 > 0:27:48Mark Thomas is a geneticist who's trying to do exactly that.
0:27:48 > 0:27:53To do it he's got some volunteers and several pints of milk.
0:27:54 > 0:27:58Right, so what we're going to be doing is we're going to be testing
0:27:58 > 0:28:04your ability to digest the sugar in milk. The sugar's called lactose.
0:28:04 > 0:28:07All babies produce an enzyme in their gut
0:28:07 > 0:28:09called lactase which breaks it down.
0:28:09 > 0:28:11But about 65% of people in the world,
0:28:11 > 0:28:16after the weaning period is over, they can't digest the sugar in milk.
0:28:16 > 0:28:19It may give you a bit of diarrhoea, it may give you, sort of,
0:28:19 > 0:28:21a lot of flatulence, a lot of farts.
0:28:21 > 0:28:27So if you're happy with this and you're happy to go ahead, then, gentlemen, just drink your milk.
0:28:30 > 0:28:36If milk can't be digested properly, a lot of hydrogen is produced...
0:28:36 > 0:28:39OK, so, deep breath then breathe out nice and slowly.
0:28:39 > 0:28:43..allowing Mark to test someone's lactose tolerance
0:28:43 > 0:28:46by measuring the amount of hydrogen in their breath.
0:28:49 > 0:28:52We've got 31 parts per million.
0:28:52 > 0:28:57The higher the reading, the more hydrogen and the less lactose tolerant they are.
0:28:57 > 0:29:00Right, so how are you feeling?
0:29:02 > 0:29:06There's like a battle going on between God knows who down there.
0:29:06 > 0:29:08Other than that...
0:29:08 > 0:29:12All right. Do you feel any need to visit the gents?
0:29:12 > 0:29:16- If I was to make a guess, I'd say midnight.- That's good going.
0:29:16 > 0:29:19Before we started farming,
0:29:19 > 0:29:23every adult on the planet would have had the same reaction.
0:29:23 > 0:29:30Ok, so Prav is 200. That's pretty impressive, that is pretty impressive,
0:29:30 > 0:29:32those are classic results.
0:29:32 > 0:29:34Beautiful results.
0:29:34 > 0:29:36Are you sure you don't want to...?
0:29:36 > 0:29:38No, I stand by my word about midnight.
0:29:38 > 0:29:42I wouldn't make those kind of promises if I was you.
0:29:45 > 0:29:48Most of them, they're more or less at the same level as their baseline
0:29:48 > 0:29:53before they drunk the milk and they stay at that baseline throughout the whole experiment.
0:29:53 > 0:29:56Prav, however, has just sky rocketed, so he's gone from
0:29:56 > 0:29:59a relatively low baseline, to something really, really high.
0:29:59 > 0:30:04These are absolutely clear cut and typical results for somebody who's a non digester.
0:30:05 > 0:30:11For someone healthy, like Prav, lactose intolerance is a discomfort, rather than a serious problem.
0:30:13 > 0:30:16But Mark's research shows that for our ancestors,
0:30:16 > 0:30:22whether or not you could digest milk into adulthood could be a matter of life and death.
0:30:22 > 0:30:26And the lucky few who could, were the evolutionary winners.
0:30:27 > 0:30:31It's probably the most advantageous characteristic
0:30:31 > 0:30:34that Europeans have evolved in the last 30,000 years.
0:30:34 > 0:30:38But milk is only ever going to be a component of somebody's diet,
0:30:38 > 0:30:42so why would drinking milk into adulthood be so strongly selected for?
0:30:42 > 0:30:47Milk has got lots of energy in it, it's very nutrient-dense, it's got lots of other goodies
0:30:47 > 0:30:50like you know, various vitamins and calcium, and so on and so on.
0:30:50 > 0:30:54Also it's a relatively clean fluid, so it's much better than drinking
0:30:54 > 0:30:58stream water or river water or well water or something like that.
0:30:58 > 0:31:02Another advantage is that if you're growing crops
0:31:02 > 0:31:05you have a boom and bust in terms of the food supply,
0:31:05 > 0:31:08so you have one growth season a year and you have lots, then nothing.
0:31:08 > 0:31:11So if you're looking at a population under pressure
0:31:11 > 0:31:14where people are struggling to get adequate nutrition,
0:31:14 > 0:31:18anybody who CAN drink milk into adulthood will be better off.
0:31:18 > 0:31:22Right. The advantage that's been measured is just incredible,
0:31:22 > 0:31:26absolutely incredible, how big an advantage it was
0:31:26 > 0:31:29for these early farmers in Europe.
0:31:29 > 0:31:33The core of Mark's research has been trying to understand
0:31:33 > 0:31:35how what happened thousands of years ago,
0:31:35 > 0:31:39has determined the genes of people alive today.
0:31:39 > 0:31:42And how does the origin of lactase persistence
0:31:42 > 0:31:45and its spread throughout these populations relate to farming?
0:31:45 > 0:31:47Incredibly well.
0:31:47 > 0:31:51Where wee see it we see the people have a tradition of dairying.
0:31:51 > 0:31:55It's very common in Europe and particularly in North Western Europe,
0:31:55 > 0:31:58so especially in places like Southern Scandinavia, Britain
0:31:58 > 0:32:01and probably most, most dramatically in Ireland
0:32:01 > 0:32:04where virtually everybody is lactase persistent.
0:32:04 > 0:32:08You can see it's very, very low, almost absent in South East Asia.
0:32:08 > 0:32:14I think research like this is incredibly elegant and gives us such an insight into our past.
0:32:14 > 0:32:17Absolutely. It's basically a hidden world of information.
0:32:17 > 0:32:22And that hidden world of information has revealed that rather than
0:32:22 > 0:32:26sheltering us from the effects of natural selection,
0:32:26 > 0:32:30farming actually drove our evolution.
0:32:30 > 0:32:36It appears that changes that we made to our world had as much power
0:32:36 > 0:32:42to transform our genes as anything that nature itself could throw at us.
0:32:47 > 0:32:53But something fundamental has changed in the last 200 years,
0:32:53 > 0:32:59something that might have finally allowed us to escape the pressure of natural selection.
0:32:59 > 0:33:05Today, in the developed world, our way of life has changed completely.
0:33:05 > 0:33:10If you can't digest milk, you just drink something else.
0:33:10 > 0:33:13With our plentiful supplies of food,
0:33:13 > 0:33:17our medicine and sanitation, almost everyone,
0:33:17 > 0:33:24irrespective of their genetic make-up, can survive long enough to pass on their genes.
0:33:24 > 0:33:28So can we really still be evolving today?
0:33:46 > 0:33:51I've come to a place where there are clues about our current evolution.
0:33:54 > 0:33:59And I'm going to meet someone who believes that on these tombstones,
0:33:59 > 0:34:04there's evidence that natural selection itself might be dead.
0:34:07 > 0:34:11This is a good place to remind ourselves, the patterns of life and death,
0:34:11 > 0:34:15which are the raw material for Darwin's great engine of evolution,
0:34:15 > 0:34:19natural selection, they've changed dramatically in the 21st century
0:34:19 > 0:34:24compared to the 20th and in the 20th century compared to the last
0:34:24 > 0:34:2810,000 years and to me, that says that natural selection at least,
0:34:28 > 0:34:30if it hasn't stopped, has at least slowed down.
0:34:38 > 0:34:42Most of these graves are 19th century, a bit before,
0:34:42 > 0:34:45and here's one, it's an absolute classic from the 1870s.
0:34:45 > 0:34:48Somebody died in their 40s, then if you go down,
0:34:48 > 0:34:54- there's young Robert died aged three months, then another one. - And another one, yeah.
0:34:54 > 0:34:59So lots and lots of childhood death. And that's true on nearly all these graves.
0:34:59 > 0:35:03As you come through, you see dead babies under these gravestones.
0:35:03 > 0:35:05Steve there's another one here,
0:35:05 > 0:35:09this is another tiny baby died five months, four years and five months.
0:35:09 > 0:35:12Four years and five months. These are individual tragedies
0:35:12 > 0:35:17but they also tell us something important about biology and the figures are quite amazing.
0:35:17 > 0:35:22In Shakespeare's time, about one English baby in three made it to be 21.
0:35:22 > 0:35:26In the year of Darwin's birth, about one English baby in two
0:35:26 > 0:35:28- made it to be 21. - It's a real lottery.
0:35:28 > 0:35:31But now, about 99% of the English babies born make it to be 21.
0:35:31 > 0:35:35It's a nasty thing to say, maybe, but these dead children,
0:35:35 > 0:35:38these were the fuel, the raw material of natural selection,
0:35:38 > 0:35:42many of those kids died because of the genes they carried.
0:35:42 > 0:35:45Well, certainly just personally, I'm asthmatic and
0:35:45 > 0:35:48I would've probably died as a child,
0:35:48 > 0:35:51so I wouldn't have been able to pass my genes on
0:35:51 > 0:35:55had it not been for the modern drugs which got me through.
0:35:55 > 0:35:58I think the real reason that evolution has come to an end
0:35:58 > 0:36:03is partly modern medicine but more important perhaps, modern engineering.
0:36:03 > 0:36:07It's worth remembering that even in the year of The Origin of Species
0:36:07 > 0:36:11that the House of Commons had to put rags in its windows, soaked in bleach
0:36:11 > 0:36:14because of the stench of the filthy water in the Thames.
0:36:14 > 0:36:17People died of cholera in their millions, that's all gone.
0:36:17 > 0:36:20Do you think there's a danger that we're being a little arrogant
0:36:20 > 0:36:24and short sighted in thinking that we have removed ourselves from natural selection,
0:36:24 > 0:36:28because when the next really big disaster comes along, it'll be back.
0:36:28 > 0:36:31That's probably true. We don't know what that disaster will be,
0:36:31 > 0:36:35but there are all kinds of horrible things just lurking around the corner.
0:36:35 > 0:36:38The one which is really worrying is epidemic disease.
0:36:38 > 0:36:41There are so many people who travel around so much,
0:36:41 > 0:36:46that it's certainly possible that something like the black death or cholera could come back.
0:36:55 > 0:37:01It's clear that our lives have been transformed in the last couple of centuries,
0:37:01 > 0:37:05that medicine and engineering now mean that we are much safer,
0:37:05 > 0:37:10that an individual is much more likely to survive to adulthood
0:37:10 > 0:37:13and at least get the chance to pass their genes on.
0:37:15 > 0:37:19So this really could be as far as we'll go...
0:37:19 > 0:37:22the technological developments of the last century
0:37:22 > 0:37:27might have brought us to the end of the evolutionary line.
0:37:27 > 0:37:29But for that to be the case,
0:37:29 > 0:37:34we'd need to keep in control of disease, forever.
0:37:46 > 0:37:51All it would take for natural selection to make a comeback in the developed world
0:37:51 > 0:37:55would be a lethal, contagious disease.
0:37:55 > 0:37:58We may be in control for the time being,
0:37:58 > 0:38:02but viruses and bacteria don't stay the same,
0:38:02 > 0:38:04they evolve too.
0:38:07 > 0:38:13So our future is inextricably linked to what happens to them.
0:38:14 > 0:38:19Professor Andrew Read has been studying a deadly virus.
0:38:19 > 0:38:22It affects chickens, not humans,
0:38:22 > 0:38:25but it has worrying implications for our future.
0:38:30 > 0:38:35So with this virus now, every time a bird gets infected, it's fatal?
0:38:35 > 0:38:38As far as we know, yes. This is on a liver,
0:38:38 > 0:38:41this is the liver of a chicken here and you can see these are tumours,
0:38:41 > 0:38:45cancer tumours that have been caused by the virus and obviously
0:38:45 > 0:38:49four or five gross tumours on a liver like that...
0:38:49 > 0:38:51It's just shocking.
0:38:51 > 0:38:55The virus is of particular concern because it wasn't always this virulent.
0:38:55 > 0:39:02Something that humans have done has caused it to evolve.
0:39:02 > 0:39:06The original virus did not cause anything like this.
0:39:06 > 0:39:08The strains that we now have
0:39:08 > 0:39:11circulating in farms today, they do this sort of damage.
0:39:11 > 0:39:13The virus itself has changed
0:39:13 > 0:39:16and become much more damaging to the birds.
0:39:16 > 0:39:20What did we do to make it go from something that was just
0:39:20 > 0:39:24a minor irritant to something that kills all chickens in ten days?
0:39:29 > 0:39:33Unless we can work out what we've done to cause the virus to evolve
0:39:33 > 0:39:36in such a lethal direction,
0:39:36 > 0:39:41we could be at risk of doing the same thing to pathogens that affect humans.
0:39:48 > 0:39:51So I suppose the thing to realise is that we're not alone.
0:39:53 > 0:39:58We tend to imagine that evolution is us against the environment,
0:39:58 > 0:40:00but there's a lot of ongoing arms races between
0:40:00 > 0:40:05different species as they evolve and change the world and each other.
0:40:05 > 0:40:10In their laboratories, Andrew and his team are trying to understand
0:40:10 > 0:40:13what made the virus evolve,
0:40:13 > 0:40:17to see what it can tell us about our own future.
0:40:28 > 0:40:33What can these chickens tell us about diseases in human populations?
0:40:33 > 0:40:37I think one of the lessons of the poultry industry has been that
0:40:37 > 0:40:40when you change things radically, the diseases that are in them
0:40:40 > 0:40:42often change radically as well.
0:40:42 > 0:40:46It's very hard to imagine that the cause of this evolution
0:40:46 > 0:40:49was not something to do with the intensification and
0:40:49 > 0:40:51the commercialisation of the chicken industry.
0:40:51 > 0:40:55And Andrew has a surprising theory about why the virus
0:40:55 > 0:40:56evolved in such a dangerous way.
0:40:56 > 0:40:59The most popular hypothesis, and the one that most of
0:40:59 > 0:41:02the work is going on and what we're interested in, is the possibility
0:41:02 > 0:41:06that vaccinating the chickens against the virus has done this.
0:41:06 > 0:41:10That vaccinating the chickens has actually caused the virus to change?
0:41:10 > 0:41:12Yes. If you keep the birds alive with vaccines, that allows
0:41:12 > 0:41:16a much longer transmission period, it keeps the birds going much longer,
0:41:16 > 0:41:18so the virus, although it's very hot,
0:41:18 > 0:41:21is not killing the bird any more because the vaccine's stopping that.
0:41:21 > 0:41:23So, that allows it to transmit
0:41:23 > 0:41:26in a way that it wouldn't have done in a pre-vaccine era.
0:41:26 > 0:41:29I think this is really interesting, cos it shows quite clearly
0:41:29 > 0:41:31that we can assume that
0:41:31 > 0:41:36we're somehow removing ourselves from natural selection by using medicine
0:41:36 > 0:41:38to deal with disease, but actually what we're doing
0:41:38 > 0:41:42is just changing the, kind of... the selective landscape out there.
0:41:42 > 0:41:45Yeah, as a disease evolutionary biologist,
0:41:45 > 0:41:47I don't feel like I'm about to go out of work.
0:41:47 > 0:41:48Things are always changing.
0:41:48 > 0:41:50Just take drug resistance.
0:41:50 > 0:41:53Bacteria that we thought we had under control, lots of them now
0:41:53 > 0:41:56are becoming multi drug resistant. There are some bacteria now that
0:41:56 > 0:41:59can't be killed by drugs, known drugs, that wouldn't also kill us.
0:41:59 > 0:42:05But the virus' evolution might also be due to modern factory farming,
0:42:05 > 0:42:08with vast numbers of chickens packed in closely together.
0:42:08 > 0:42:11It's a change in the chickens' habitats
0:42:11 > 0:42:15that mirrors our own increasingly urbanised world.
0:42:15 > 0:42:20So do you think that pathogens like viruses and bacteria
0:42:20 > 0:42:24will always be there in our environment, shaping our evolution?
0:42:24 > 0:42:27They're always going to be there. How they shape human evolution
0:42:27 > 0:42:29is going to be very interesting.
0:42:29 > 0:42:32There's not going to be a day when we declare the war
0:42:32 > 0:42:35on infectious disease over. That is not going to happen.
0:42:38 > 0:42:40With the work of people like Andrew,
0:42:40 > 0:42:45we may be able to at least keep on top of infectious disease for a while.
0:42:45 > 0:42:50But it's hard to imagine that we'll always be in control.
0:42:53 > 0:42:58It seems that some diseases are evolving just as rapidly
0:42:58 > 0:43:01as we're devising weapons to combat them.
0:43:01 > 0:43:05And that means that there is a possibility that at some point in the future,
0:43:05 > 0:43:09a particularly nasty infection could take hold and
0:43:09 > 0:43:14even turn into a worldwide pandemic that decimated populations
0:43:14 > 0:43:19not just in the developing world, but in the developed world as well.
0:43:19 > 0:43:24And that would put natural selection back into the driving seat.
0:43:42 > 0:43:46But perhaps it isn't just about death and disease.
0:43:46 > 0:43:51Perhaps what matters more, is birth.
0:43:51 > 0:43:54After all, even if these days almost all of us survive
0:43:54 > 0:43:58long enough to have children, some people have none,
0:43:58 > 0:44:01some people have three or four.
0:44:01 > 0:44:06And that difference must drive evolution, in the same way as if
0:44:06 > 0:44:09some people died before being able to pass on their genes.
0:44:11 > 0:44:16So, if we can work out who's having the children in our societies,
0:44:16 > 0:44:19perhaps we can guess what future generations will look like.
0:44:26 > 0:44:31I've come to a small town in Massachusetts, called Framingham.
0:44:31 > 0:44:36On the surface, there's nothing unusual about its inhabitants.
0:44:36 > 0:44:41But actually, it's the first town in the world where the future evolution
0:44:41 > 0:44:46of the people living here hasn't just been guessed at,
0:44:46 > 0:44:48it's been calculated.
0:44:53 > 0:44:57And Stephen Stearns is the man who's calculated it.
0:44:57 > 0:45:03- So this is Framingham - this is where you've been doing your research? - This is Framingham. Yes.
0:45:03 > 0:45:07Your work is ground breaking because you're looking at human evolution
0:45:07 > 0:45:11from the perspective of investigating fertility patterns.
0:45:11 > 0:45:16That's right, and we've been able to discover some really fascinating things with it
0:45:16 > 0:45:21and I think the key thing here is that we've been able to use these fertility patterns
0:45:21 > 0:45:26to see that evolution is still going on in this town of Framingham and
0:45:26 > 0:45:33that it is changing, er, traits such as height and weight, age at first birth,
0:45:33 > 0:45:38age at menopause, and this was unexpected. This was quite exciting.
0:45:38 > 0:45:42Steve chose Framingham for his study because he had access
0:45:42 > 0:45:46to unprecedented levels of data about local residents,
0:45:46 > 0:45:48spanning 60 years.
0:45:48 > 0:45:52And by examining how many children tall people have,
0:45:52 > 0:45:55or blonde people have, or brown-eyed people have,
0:45:55 > 0:46:00Steve has been able to work out what the next generation might look like.
0:46:00 > 0:46:05It's an entirely new approach to the study of evolution.
0:46:05 > 0:46:11Well, it's interesting, if one goes back and looks at the way that
0:46:11 > 0:46:14Darwin formulated natural selection.
0:46:15 > 0:46:18Darwin thought mostly about mortality,
0:46:18 > 0:46:25and it wasn't until some time in the mid to late 20th century
0:46:25 > 0:46:28that people really realised that it's not really mortality,
0:46:28 > 0:46:32it's reproductive success that is what's changing gene frequencies.
0:46:32 > 0:46:35So given what you've already measured, can you be specific about
0:46:35 > 0:46:38the changes in height and weight that you might expect to see in the future?
0:46:38 > 0:46:43What we have found with height and weight, basically, is that natural selection
0:46:43 > 0:46:47appears to be operating to reduce the height
0:46:47 > 0:46:50and to slightly increase their weight.
0:46:50 > 0:46:53So people are getting shorter and fatter?
0:46:53 > 0:46:56They're becoming more pleasingly plump.
0:46:58 > 0:47:01And do you think this is something which is...
0:47:01 > 0:47:03Is this a real biological change?
0:47:03 > 0:47:06Is it a genetic change, or are we just looking
0:47:06 > 0:47:08at a cultural influence?
0:47:08 > 0:47:10Are people just eating more?
0:47:10 > 0:47:14Well, there's no doubt that there are big cultural effects on things
0:47:14 > 0:47:16like weight.
0:47:16 > 0:47:23But we can estimate what the genetic component is of the variation in height or the variation in weight.
0:47:23 > 0:47:27So we're pulling out a small genetic signal,
0:47:27 > 0:47:31and a fairly small selection pressure.
0:47:31 > 0:47:36And if this were to act consistently, it would add up to major change.
0:47:36 > 0:47:41It isn't the evolutionary future that many of us would've expected.
0:47:41 > 0:47:42But there it is.
0:47:42 > 0:47:45Shorter and fatter.
0:47:45 > 0:47:48But perhaps we won't be heading in that direction forever.
0:47:48 > 0:47:52I think what's very probably going on is that selection is
0:47:52 > 0:47:57moving a population up and down all the time. It goes off in a certain direction for a while
0:47:57 > 0:48:00and then it goes back in the other direction.
0:48:00 > 0:48:03It's only if you get a significant change in the environment
0:48:03 > 0:48:06that it will then continuously go in a new direction.
0:48:06 > 0:48:10Can you predict anything else about how we might evolve in the future?
0:48:10 > 0:48:13Are there any other traits that we might see coming to the fore?
0:48:13 > 0:48:17In the long term, I think that where we are going at this point
0:48:17 > 0:48:20is actually absolutely unknown.
0:48:20 > 0:48:23We see rapid evolution when there's rapid environmental change
0:48:23 > 0:48:27and the biggest part of our environment is culture and culture is exploding.
0:48:27 > 0:48:32That's, I really think, the take-home message of the Framingham study,
0:48:32 > 0:48:36that we are continuing to evolve, that biology is going to change
0:48:36 > 0:48:41with the culture and it's just a matter of not being able to see it
0:48:41 > 0:48:45because we're stuck right in the middle of the process right now.
0:48:49 > 0:48:54It seems that far from being over, our evolution is impossible to stop,
0:48:54 > 0:48:58and the enormous changes in the way we live over the last century
0:48:58 > 0:49:01may be driving it even faster than ever.
0:49:15 > 0:49:18And now, human evolution
0:49:18 > 0:49:20is on the brink of taking an entirely new turn.
0:49:20 > 0:49:26We could be about to rewrite the very rules of natural selection.
0:49:32 > 0:49:36We've reached a point now, where our technology could affect
0:49:36 > 0:49:41our evolution in a way that seemed unthinkable just a few decades ago.
0:49:41 > 0:49:45We're on the verge of being able to literally write
0:49:45 > 0:49:48our own genetic future.
0:49:52 > 0:49:54I've come to Los Angeles,
0:49:54 > 0:50:00a city whose inhabitants are determined to have the perfect body.
0:50:00 > 0:50:05Whether through exercise, surgery, or other means,
0:50:05 > 0:50:09the goal is nothing less than physical perfection.
0:50:09 > 0:50:13And with genetic engineering on the horizon,
0:50:13 > 0:50:16that goal could be one step closer.
0:50:16 > 0:50:20I'm about to meet somebody who's had more of a hand in shaping the future
0:50:20 > 0:50:23of humanity than almost anybody else. Just last year,
0:50:23 > 0:50:29he was instrumental in the creation of around 400 new babies.
0:50:34 > 0:50:40Dr Jeff Steinberg was involved in creating the world's first test-tube baby back in 1978.
0:50:40 > 0:50:47At his clinic in LA, he's still helping people to conceive.
0:50:47 > 0:50:50So are these all pictures of test-tube babies?
0:50:50 > 0:50:54They sure are. They sure are. Some of the thousands.
0:50:54 > 0:50:59But nowadays, he's helping couples create their very own designer babies.
0:50:59 > 0:51:04His clinic routinely screens embryos for genetic diseases,
0:51:04 > 0:51:08and more controversially, it was the first in the world to offer people
0:51:08 > 0:51:10the choice of cosmetic traits.
0:51:12 > 0:51:17Selecting offspring like this could change the course of our evolution.
0:51:17 > 0:51:21And it all starts with something that still utterly amazes me -
0:51:21 > 0:51:26the very beginnings of human life. A living embryo.
0:51:30 > 0:51:33So we'll come over here and this will give us a great chance
0:51:33 > 0:51:37to actually watch the biopsy of the embryo.
0:51:37 > 0:51:40So this is when you take the cell to look at the genetics.
0:51:40 > 0:51:44Yeah. So to do that, we've got to separate the one cell
0:51:44 > 0:51:46from the other eight cells inside the embryo.
0:51:46 > 0:51:48And you can do that? You can take a cell away
0:51:48 > 0:51:51and the embryo will still carry on developing normally?
0:51:51 > 0:51:54Totally normally. It's like it never happened.
0:51:56 > 0:51:58So you can see the multiple cells on the embryo.
0:51:58 > 0:52:01So at the moment, it's a ball of about eight cells?
0:52:01 > 0:52:06An eight cell embryo. We've applied the suction pipette to it so it'll hold it in place for us,
0:52:06 > 0:52:09and now we're going to pierce the zona pelluca -
0:52:09 > 0:52:12the outer shell that protects the embryos -
0:52:12 > 0:52:15and we're actually going to prepare to go in and remove
0:52:15 > 0:52:18one of the cells so that we can analyse it genetically.
0:52:18 > 0:52:22- That single cell, it's there. - It's out.
0:52:22 > 0:52:25And you can see the remainder of the embryo's not phased a bit by that.
0:52:25 > 0:52:29So then you're able to look at the genes contained within that cell,
0:52:29 > 0:52:32which are identical to all the other ones?
0:52:32 > 0:52:36- Yea, yeah.- And analyse it and look at the, look at the genes that you've got there
0:52:36 > 0:52:38- and screen it?- That's exactly right.
0:52:40 > 0:52:44By screening a cell from each embryo, Dr Steinberg can work out
0:52:44 > 0:52:48which embryos are free from genetic diseases.
0:52:48 > 0:52:52But he can also screen the embryo for other traits.
0:52:52 > 0:52:55- So you're also picking up the sex of the embryo.- Yes.
0:52:55 > 0:52:59Are you actually allowing people to choose whether they have a boy or a girl?
0:52:59 > 0:53:03Anyone can choose here. Yep. They can choose a boy, choose a girl,
0:53:03 > 0:53:06and we've done this close to 9,000 times now.
0:53:06 > 0:53:10It just seems so peculiar. It's such an odd thing to do,
0:53:10 > 0:53:13- to be able to determine the sex of your baby. - If a couple has five girls,
0:53:13 > 0:53:15they're going to walk in and say, "We want a boy."
0:53:15 > 0:53:17OK, so what about other traits?
0:53:17 > 0:53:23Not the sex of the embryo, not things which are potentially going to cause a disease,
0:53:23 > 0:53:26but other things, like eye colour or hair colour?
0:53:26 > 0:53:31We actually isolated the genes that allow us to choose eye colour and hair colour in the Scandinavians.
0:53:31 > 0:53:34Right? We announced it, and we started hearing from
0:53:34 > 0:53:38people that were interested in this, but we also heard from a lot of people on the outside,
0:53:38 > 0:53:40including the Catholic Church,
0:53:40 > 0:53:42that had some big problems with it.
0:53:42 > 0:53:44And they said, "No, not at this point."
0:53:44 > 0:53:47So we retracted it. Even though we can do it, we're not doing it.
0:53:47 > 0:53:52So the technology is available right now to basically have a designer baby, where you choose the sex,
0:53:52 > 0:53:55choose the eye colour, choose the hair colour,
0:53:55 > 0:53:58- choose how intelligent they are?- In our life times, I think we will see
0:53:58 > 0:54:03tremendous advances made in determining where intelligence comes from,
0:54:03 > 0:54:07identifying the genes that are associated with intelligence,
0:54:07 > 0:54:11and perhaps maybe not being able to guarantee an intelligent person,
0:54:11 > 0:54:15but certainly guarantee that we will contain the chromosomes
0:54:15 > 0:54:19that lead to the ability to develop better intelligence.
0:54:19 > 0:54:21Do you think this is a good idea?
0:54:21 > 0:54:26I'm not sure if it's a good idea and that's why we're not forcefully pursuing it right now,
0:54:26 > 0:54:28and we're going to need help from the outside world.
0:54:28 > 0:54:32We need help from the ethicists, we need help from the geneticists
0:54:32 > 0:54:33and we need help from society.
0:54:33 > 0:54:36However, if you want to know what the future holds,
0:54:36 > 0:54:38this is where the future is taking place right now.
0:54:38 > 0:54:41It seems to me that this really is a watershed moment
0:54:41 > 0:54:46in the future of humanity and in human evolution because we're just on
0:54:46 > 0:54:52the verge of actually being able to genetically engineer our own future.
0:54:52 > 0:54:56I mean, this is something which evolution on this planet
0:54:56 > 0:54:59has never experienced before -
0:54:59 > 0:55:01a species actually taking control like this.
0:55:01 > 0:55:05I think it will play a huge part in our evolution and I think rightfully so.
0:55:05 > 0:55:08We need to be cautious about it because it can go right and wrong.
0:55:08 > 0:55:11But I think it's going to get better, it's going to get more beneficial
0:55:11 > 0:55:13and it's going to help more people.
0:55:13 > 0:55:16But I think trying to remove it as part of our future evolution
0:55:16 > 0:55:19is just a task that's not going to be accomplished.
0:55:19 > 0:55:21It's here. It's not going away.
0:55:28 > 0:55:30The technological and ethical problems
0:55:30 > 0:55:33with genetic engineering may be vast,
0:55:33 > 0:55:37but our ability to manipulate our genomes
0:55:37 > 0:55:42is likely to have a profound effect on our future evolution.
0:55:42 > 0:55:46We're about to turn the page of a new chapter
0:55:46 > 0:55:48in the history of our species.
0:56:12 > 0:56:15It's clear that we'll never stop evolving.
0:56:15 > 0:56:19But how we evolve depends on how the world changes,
0:56:19 > 0:56:21and how we change the world.
0:56:24 > 0:56:29And right now, the world we live in has never changed more quickly.
0:56:31 > 0:56:35And that means we might be evolving faster than ever.
0:56:36 > 0:56:39Who knows where it might take us?
0:56:39 > 0:56:44But there is something about our future that is inevitable.
0:56:44 > 0:56:47In the long term, the world around us
0:56:47 > 0:56:52will change dramatically, and when that happens, there are two possibilities.
0:56:52 > 0:56:56We'll either evolve, and evolve in a big way, or die.
0:56:56 > 0:57:02So humans as we know ourselves today will no longer exist.
0:57:04 > 0:57:08Humans are pretty special, but they're not that special.
0:57:08 > 0:57:1299.9% of all animals have gone extinct and I'm pretty sure
0:57:12 > 0:57:14we'll go extinct in the end as well.
0:57:15 > 0:57:20A global catastrophe could wipe us all out.
0:57:20 > 0:57:27But if some people managed to survive and adapt to whatever new world they lived in,
0:57:27 > 0:57:30they would continue our evolutionary journey -
0:57:30 > 0:57:35a journey that began 3.5 billion years ago.
0:57:39 > 0:57:43I think we'll become extinct as we know ourselves now,
0:57:43 > 0:57:46but I think we've already done that several times in the past.
0:57:46 > 0:57:50If we are to compare ourselves to the cavemen, we're not the same animal.
0:57:50 > 0:57:57In the broadest possible sense, we haven't always been human,
0:57:57 > 0:57:59and we won't always be in the future.
0:57:59 > 0:58:03We are neither the pinnacle of evolution,
0:58:03 > 0:58:08nor its endpoint. We're just part of the journey of life on Earth,
0:58:08 > 0:58:14and evolution will continue as long as the planet can support life.
0:58:14 > 0:58:20Our species is just a tiny twig on this massive tree of life,
0:58:20 > 0:58:22and it's a twig that's still growing,
0:58:22 > 0:58:28still changing, and I don't think it's about to be pruned just yet.
0:58:38 > 0:58:42Subtitles by Red Bee Media Ltd
0:58:42 > 0:58:46E-mail subtitling@bbc.co.uk