"This week, Liz traces her lineage with the help of DNA." "Everyone alive today can be traced back in time through their female relatives all the way to one common ancestor." "Dr Yan looks at the science of Dad-dancing." "And this is actually my dad." "(LAUGHTER)" "And Jem builds a singing road." "That's, err, two metres done, so only another 248 to go." "That's Bang Goes The Theory, revealing your world with a bang." "Hello there and welcome to the show." "First up, two of Jem's passions combined - music and welding." "There was a time, before MP3s or even ODs, when we used to listen to music by playing one of these - a record, a vinyl disc with a series of grooves cut in it." "And within those grooves... ..are tiny, weeny little bumps that make a needle vibrate as it goes over them, and that is where the music comes from." "(OATTLE grid OLATTERS) I love the fact that we can make music by bobbling things up and down over a series of closely spaced bumps." "And it's got me wondering if we can't make music in a similar but bigger way." "And just down here gives me a bit of an idea." "(grid OLATTERS)" "Did you hear that?" "When I drive over that cattle grid, my tyre hits every single one of those rungs, and it makes a "v-rr-rrm" noise." "And if I drive over faster, it goes "v-rr-rrm", and it's like a higher note." "And I think there's a way of driving cars over cattle grids to play music." "(grid OLATTERS) lf you imagine you get the correct spacing on the cattle-grid rungs, and the correct length of cattle grid, and I drive at exactly the right speed, it should or could play a tune." "It's not wholly convincing at the moment, but I fancy seeing if I can turn my car into a stylus, and a road into a record player." "(MAOHlNE BEEPS in THREE different TONES) lf l'm going to try to make musical notes by getting something like the rungs of a cattle grid to vibrate the wheels of a car, I need to know exactly how fast to wobble those wheels" "to get the notes that I need." "And for that, I've got this." "(HE PLAYS first NOTES OF "HAPPY birthday TO YOU")" "When I play a note on here, then that vibrates the air, and this microphone detects that vibrating air like an ear does." "But convert it to an electrical signal, that then comes out as a wavy line on here." "(MAOHlNE REPEATS "HAPPY birthday" NOTES)" "And from that I can find out how fast the air's vibrating, what the frequency of the note is." "So, um, let's see what we need." "I can read that the first note that I want is E... lt's a G." "Here's my G." "(MAOHlNE PLAYS G TONE)" "And that tells me... the frequency I need to wobble the air at to get a G is 196 hertz, which means the air's kind of vibrating" "196 times a second, like that." "So that's what the wheel of my car's got to do, which means it's got to be knocked by the rungs on the cattle grid" "196 times a second." "For easy maths, I figure if I drive at 20 metres a second - about 45 miles an hour - then, that means for the one that's 196 knocks a second, that means in 20 metres it's got to have 196 rungs," "so I just need divide 20 metres by 196." "So it's about...ten centimetres per run." "So then it'll go..." "(BUZZlNG TONE)" "..except a lot faster, and we should hear it as the note G." "Making music this way seems great in theory, but the practical reality of it, once we did all the calculations, for just 12 and a half seconds of music, it means we've got to lay about 250 metres of home-made cattle grid" "with rung spacings on average about 60 millimetres apart, meaning, welded to this steel is going to be over 3,000 of these bars, each with about four welds on it, meaning 12,000 welds to do." "'That's a stack of welding!" "'So I figure it's a good idea to test a short section 'before we commit to the whole 250 metres.'" "(THRUMMlNG MUSlOAL TONE PLAYS)" "'Yes!" "I can definitely hear a note." "'l think we might be on to something.'" "That's, err, two metres done." "So, err, only another 248 to go." "Oh, watch out for the hot bits!" "(DALLAS LAUGHS)" "OK." "So you've got the G note down." "But you don't speed up or slow down to get the other notes." "You space out the bars?" "No. imagine driving..." "With the music in front of you, going, "Whoa!" "Err..." "Whoa!" "Err..."" "You can't do it." "So to get a lower note, you space the bars out." "(HE MAKES LOW-PlTOHED buzzing)" "And a higher note, put them closer." "Br-rr-rm!" "Loving the sound effects." "How many welds went into that music?" "A lot. 12,000 to 15,000." "That's an insane amount." "I know you love welding." "I don't mind a bit of it." "Are you a better welder, having done 15,000 welds in a row?" "." "I can sadly report, probably not." "There's just so much metal to stick together in such a short amount of time." "The bars have to be completely accurate, but the welds just have to be good enough to hold it together." "is your workmanship getting shoddy?" " lt's like the Tailor of Gloucester." "As time runs out, you just make the stitches fit." "Fair enough." "Ok, next up genealogy and with the internet you can get a lot of information these days." "You've got your marriage certificates, your birth cert, census data..." "Tagged photos on Facebook." "Tagged photos on Facebook, but... with a little clever bit of science, you can actually trace back part of your ancestry to 200,000 years ago." "I think my family were still gibbons back then!" "I've never had a proper look at my genealogy, but here's what I know from talking to Mum and Dad and from some of the photographs that I have." "First of all, here's me and my sister." "There's Mum and Dad." "On Dad's side I've got Granny and Pappy." "This is Julie and Pappy, as we used to call him." "I've actually got pictures of my grandmother's parents," "Oharlotte and Achille." "Now, my mum's side - this is, um, Phyllis, my mum's mum, and this is Merlyn, her dad, and..." "Oh, this is Merlyn's mother, my great-grandmother." "I love this photograph." "So that's about it." "That's all I know." "And this is where the science comes in, because there is another way I can find out about my mother, her mother before her, all the way back to the beginning of modern man, round about 200,000 years ago." "And that's by looking at a little bit of my DNA." "Genetics dictates that everything about us is passed down from our parents and from our parents' parents and so on, all through parcels of DNA called chromosomes." "So it might seem possible that I can trace my DNA back through time to get to my distant ancestors." "But tracing back your DNA is like solving a giant puzzle, because every child born carries a random mix of genetic information from their mum and their dad." "Imagine this pretty puzzle broadly represents my genetic information, my DNA, and I'm going to try and figure out where it all came from by only going back as far as my grandparents." "Now, these are my grandparents on my mum's side." "This is their DNA." "They have my mum, and her DNA is completely distinct from either of her parent's." "It's a brand-new pattern." "Not only does she get a mix of both her parents' DNA, but each of her parent's individual DNA is also shuffled around in a process called recombination." "And the same applies for my grandparents on my dad's side, and...my dad's DNA." "Which means that by the time my parents have me, my DNA is completely unique." "I can hardly trace it back to my parents, never mind my grandparents." "'And that's in just three generations.'" "Now, extend that back by many more generations, and tracing the very origins of my DNA becomes very complicated altogether." "But there is one solution." "Not all of your DNA comes in the form of chromosomes inside the nucleus of every cell." "Some DNA is also found in tiny little structures called mitochondria." "They're basically the powerhouses of your cells." "And the great thing is, the DNA in your mitochondria doesn't get mixed up or recombined between generations, because you get them directly from your mum's egg cell, and you don't get any from your dad's sperm cell." "'So my mitochondrial DNA can only have come from my mother 'and her mother in turn, 'and so on back in time as far as you care to go.'" "All of this provides an incredible opportunity for geneticists, a very clear window into our past." "To look into this window, geneticists have been looking at mitochondrial DNA samples from across the globe and thousands of years back into history to create a giant family tree that spans the whole world." "Now, the really brilliant thing here is that everyone alive today can be traced back in time through their female relatives all the way to one common ancestor, one woman who lived here in Africa 200,000 years ago," "and she's known as Mitochondrial Eve." "Obviously she wasn't the only person alive at the time." "She was part of a larger group of humans." "But she is the only one that every single one of us is related to through the female side of our ancestry." "'Scientists can work this out because, 'although mitochondrial DNA doesn't get jumbled up 'between the generations, it does vary slightly between us.'" "And it's these tiny but very important differences that can tell us an incredible amount about our past - how closely related we are to each other, where our ancestors lived, and when they moved around the globe." "'From time to time, people get harmless mutations 'in their mitochondrial DNA, just like they do in ordinary DNA." "'But because it's just one small change 'between mother and child, it's fairly easy to work out 'where it came from.'" "Right, then. imagine I live in Morocco, cos l can't reach London from here." "Now, I've got a brand-new mutation in my mitochondrial DNA." "I'm going to pass that on to my children, and if any of them are daughters, they'll pass it on to theirs, and so on." "And assuming that nobody emigrates from Morocco, that mutation will be localised and clustered in and around this country." "But if one of my descendants does decide to emigrate, to Spain, for example, they'll carry that mutation with them and then their descendants will have it also." "And the beautiful thing here is that you can link back that mutation to the people who carry it here in Morocco." "'By tracing these mutations, 'we can also work out the movements of the people who carry them, 'and it's this that has allowed us to work out 'how early man moved across the globe." "'And geneticists have created 30 main groups, 'a bit like the main branches of a human family tree.'" "With all the information they've gathered from people's mitochondrial DNA around the world, geneticists can now map out the ancestry of each of those 30 groups." "And now, by finding out which of those groups you belong to, you can trace the movement of your ancestors around the globe over countless generations, ever since the human race first spread out from Africa to populate the planet." "The descendants of Mitochondrial Eve." "I'm sorry, Liz." "Do you not find that's just utterly mind-blowing?" "I find it utterly fascinating." " That we can trace our lineage back that far, to this small group of people..." "Thanks to biology." "It's a wonderful thing." "Are you ready to find out about your ancestry down the females in your lineage?" " l don't know." "You are." "You're so ready." "The boys and I got our saliva sampled and our mitochondrial DNA analysed, and here are the results." "As you know, we all started off in Africa," "East Africa, the Rift Valley, 200,000 years ago, OK?" "And then only 300 to 400 humans - that's it - started moving north out of Africa." "So 70,000 years ago, they moved across the Pool of Tears into Arabia." "Then they travelled along... the coast of the Indian Ocean, and ended up in the Persian Gulf." "There they got stuck for a bit." "It's thought it's because they were surrounded by deserts." "But this is where it gets interesting." "After about 20,000 years, we started moving towards Europe." "Jem's ancestors and my ancestors are the same." "30,000 years ago..." " Oousins!" "Yeah." "..they moved through Mesopotamia, through Turkey, Greece, the Balkans, into Western Europe." "OK?" "Then the ice Age hit." "It peaked at about 18,000 years ago, when we had to retreat back into the Med and into northern Spain, and that's where all those cave paintings, those really cool cave paintings, come from." "Then the ice Age began to retreat about 1 1 ,000 years ago or so, and we moved back through Western Europe into Great Britain." "My ancestors went to the sun in Portugal." "Good move." "I always knew me and Jem had a connection." "There's a family resemblance." " Yeah." "Obvious." "Fascinating stuff!" " Yeah." "Do you want to know about you?" " OK. I did something different?" "Yeah, because when we moved west 30,000 years ago, you actually stayed here in an area called the Fertile Orescent, around here, and you, your ancestors..." "Yeah?" "..invented farming." " Of course we did. lt's on my OV." "It's a beautiful thing." "You planted crops, domesticated wild animals, and you share the same ancestors as Dr Yan." "Well, it's obvious, isn't it?" "It's obvious now you say it." "Remember, his father is Ohinese but his mother is British, and it's the females in the lineage, so you have the same ancestors." "And finally, both your and Yan's ancestors moved, 7,000 years or so ago, to Western Europe." "You followed us, and you brought your agricultural skills with you." "We thought you might find it useful." "We were the original hunter-gatherers." "I'm quite into that. lt's a fascinating bit of information, there's no question." "But, you know, the complicated bigger picture of our entire genome - finally we are actually able to find out about our ancestry through that." "Sophisticated computers allow it because they've mapped the entire human genome." "But we don't have as many samples of that as we do of mitochondrial DNA." "The more samples we get, the more interesting the history of the human race will become." "OK." "Now, all good weddings have a disco, and no wedding disco is complete without a drunk uncle or dad embarrassing their offspring with some slightly poor dancing." "Fear not!" "Dr Yan is on the case to explain the science behind this hideous exhibitionism." "(DlSOO MUSlO PLAYS) One, two... I'm at the Sadler's Wells' Oompany of Elders dance group, and they're showing me some of their best moves." "But I'm going to be showing them an incredible talent that they might not even realise they have." "Hello, everyone." "Hello!" "First of all, what I'd like you to do... is just look at this, actually." "So, what do you think this is?" "is it a shape?" "A human shape?" "Oould be a galaxy." "What if I do this?" "Oh!" "I can see people." "They're dancing." " Funny, isn't it?" "As soon as the dots start moving, it's really clear that it's people dancing, and that's because our brains are particularly well tuned to picking up movement, and in particular human movement." "When you watch something like this, you are actually processing it in a bit of your brain that you use to plan your own movements, and it's a bit like you're mentally rehearsing it so you get a feel for the action and you can work out what's going on." "But it's not just that." "Do you think you could tell people's sex from the dots?" "A woman." "And that's a man." "(THEY ALL OHATTER)" "That's a woman." "You think that's probably a female, yeah?" "And that one..." " Possibly a man." "Possibly male." "Right." "OK." "How about age?" "Which one do you think is over 60 and which is under 60?" "Ooh..." "Ah!" "The one on the left's over 60." " You think this one's over 60?" "Yes." " And this one probably younger." "Yeah." " Well, do you want to see who they are?" "Yes!" " Brilliant." "OK." "Let's see." "Moment of truth." "(HE LAUGHS) Yeah!" "There you go." "Oh!" "We were spot-on!" "I think you were right." "This is Liz here." "She's obviously a woman." "She's under 60." "And this is actually my dad." "Oh!" "(LAUGHTER)" "(THEY OHATTER AND LAUGH)" "But he's over 60, so, you know..." "And so what do you think it is that you were picking up here?" "You could tell by her hips." "Female." " She's using her arms more." "She's more extended." "Fitter." "You can pick up a lot of stuff, can't you, from the movements." "So I'm going to show you another video." "(DlSOO MUSlO PLAYS) These are both men, OK?" "And I'd like you to tell me which one you find more attractive." "(LAUGHTER)" "(MAN speaking) ls this for all the fellas?" "(WOMEN SHOUT AND HOOT) He wins." "(THEY OHATTER AND LAUGH)" "Most of you initially went for that one, because subconsciously we're trying to look for signals that indicate whether someone's a worthy mate or not." "And movement can give those sort of signals, and so it can act a bit like a mating display, really." "Wow!" "(THEY LAUGH) Yeah." "Steady!" " So, basically, the best signs are those that only a good, healthy mate could make." "OK?" "Do you want to see who these are?" "Yes." "Oh!" "(HE LAUGHS)" "Right." "OK." " l hope the person doesn't ever find out what we said about them." "(LAUGHTER)" "Well, let's have a look." "(LAUGHTER AND hooting)" "(THEY LAUGH)" "Right!" "What are you doing after the show?" "." "(THEY LAUGH) Practising more dance moves." "(THEY LAUGH)" "Terrifying." "You're crying laughing." "Before we move on, can we have another little look at Dr Yan throwing his shapes?" "Do it." " Have a look at this." "This is brilliant." " Look at that!" "Remember, this is the man who invented farming." "I'm having some weird, unexpected feelings for Dr Yan." "I'd keep them to yourself." " l will." "Just when you think you know a guy, he strips off and reveals a whole new dimension." "Absolutely." "But now time to hit the road - the singing road." "We tried to turn a road into a record, and a car into the stylus, put them together, and make genuine heavy-metal music." "It's taken three very long days, three committed people and over 10,000 welds on two tons of steel, but finally we've produced something that's going to turn our little piece of tarmac from a road into a record." "(METAL grid MAKES SORAPlNG SOUNDS)" "What is this?" "This here?" "Yeah." "Err, they're a series of bespoke cattle grids..." "Right." "..that should have turned this section of runway into a singing road." "is this just one note?" "No." "These are the tiny gaps between the notes here." "So that's an E there, and that's a O." "You go down there, and it'll hopefully make an utterly recognisable tune." "From here, just looking at it, I'm going to go with Bohemian Rhapsody, Queen." "That's just a ballpark." " Your job, Dallas, is to guess the tune." "(RATTLlNG with OHANGlNG TONES, NO DlSTlNOT TUNE)" "You can hear the note changes." "Yeah?" "I'd be lying at this point if I could tell you what the tune was." "Good, because you're going far too slow." "You're - no disrespect - only cycling eight to ten miles an hour, whereas you've got to be going about 45 to get the proper notes." "OK." "So what do we do?" "Well, we need, err, a better stylus." "And we need to go slightly faster." " Yes." "The problem with using a standard car is that there will always be two wheels on your mini cattle grid, so it will be playing two notes at once." " Yes." "But luckily there was a company that made a non-standard car." "They made this one, and it's got one single pickup there at the front." "So provided, at 45 miles an hour on an ice-strewn runway, I can keep that on a narrow strip of cattle grid, we're in business." "What could go wrong?" "Well, this." "It doesn't start very easily." "You have to turn it like that, then let it back... (engine STARTS) Give it some choke." "Thank you!" "OK." "I'm about to roar away now, Dallas." "OK." "Be very, very afraid." "OK. I am very afraid." "This is the perfect vehicle." "It's got one single pickup point on the front, just like a record stylus, and that's just like the grooves on a record." "Some people might think that's a bit odd." "Some people have a car stereo to hear their music." "So what's the optimum speed?" " About 45 miles an hour." "So it's almost like a 45 RPM." "OK, brilliant. lt's a single." "Yes, it is indeed." "OK." "Ready?" " Here we go." "Here we go." "Oome on, come on!" "Oome on, Reliant Robin!" "30 miles an hour." " Will we go back to the future if we hit 40?" "Here we go." "Here we go." "(RATTLlNG)" "(TYRES AND grid PLAY NOTES) That is fantastic!" "("bridal MAROH" TUNE PLAYS)" "Did you get it?" " Of course!" "It's for a wedding!" "It's the wedding." "Yes!" "That is fantastic." "That is fantastic." " Oh!" "That is brilliant." "'Dallas is absolutely right." "'lt's the bridal march.'" "("bridal MAROH" TUNE PLAYS again)" "'The wheel of the car is knocked at the correct frequencies, 'and it plays the song that every happy couple wants to hear 'as they go down the aisle.'" "That was amazing!" "I know." "Just a bunch of mini cattle grids and a 38-horsepower stylus." " Maths is fantastic!" "I mean, it's simple maths, isn't it?" " Yes, and a vast amount of welding." "Maths and welding." "Maths and welding, and you're really on to something." " Does that mean we're married?" "We're married." "(THEY LAUGH) lt was getting quite romantic in the old Reliant Robin." "Nice and cosy." "Reliant Robin." " lt's a Reliant Robin, you must get that right." "Reliant Robin fanciers will get terribly cross." "It made a really good stylus, as well, I thought." "It did. I mean, what you don't see there is the nail-biting nature of that experiment." "Nobody knew with their hand on their heart whether that would really play a tune or not." "It looked so unlikely even on the day." "But also the fact that you put so much effort into it, you did so much welding, for a fairly speculative experiment, where the principle kind of worked, there were no guarantees." "And without testing it on the full scale, there's no way of knowing. I was overjoyed." "Are you going to make any more tunes for us?" "I take requests." "Good. I'm making up a list." "That's it for this week," "We'll see you soon." "Say goodbye, boys." "Bye!" "Bye."