0:00:02 > 0:00:03'Animals are amazing.'
0:00:03 > 0:00:05That's astonishing!
0:00:05 > 0:00:09'And the more we find out about them, the more amazing they seem.'
0:00:09 > 0:00:11That feels pretty harsh!
0:00:11 > 0:00:15'That's why scientists all over the world are trying their best
0:00:15 > 0:00:18'to copy them.' This is the future!
0:00:18 > 0:00:19'Making brand-new inventions...'
0:00:19 > 0:00:21Tomato juice.
0:00:21 > 0:00:23'..based on what animals can do.
0:00:23 > 0:00:25'Some are astounding...'
0:00:25 > 0:00:27We've just dived under the sea!
0:00:27 > 0:00:30'Some bizarre...' This is not at all pleasant.
0:00:30 > 0:00:32BOOM!
0:00:32 > 0:00:34Yes! It's gone!
0:00:34 > 0:00:38'But they're all inspired by the miracles of nature.'
0:00:40 > 0:00:42Episode Four.
0:00:44 > 0:00:48How these little flying rodents might revolutionise life
0:00:48 > 0:00:50for the visually impaired.
0:00:54 > 0:00:57I want you to watch the next 30 seconds very carefully.
0:01:23 > 0:01:26In just a few minutes,
0:01:26 > 0:01:29a second rider is going to come down this track,
0:01:29 > 0:01:32through the same twists and turns,
0:01:32 > 0:01:34over the same humps and bumps.
0:01:34 > 0:01:37But with one big difference -
0:01:37 > 0:01:39this rider is blind.
0:01:44 > 0:01:46But how is that possible?
0:01:47 > 0:01:50To find out, we need to start with a creature
0:01:50 > 0:01:54that spends the majority of its life in permanent darkness.
0:01:54 > 0:01:58A creature that can navigate its way around these caves and caverns
0:01:58 > 0:02:00without using a head torch.
0:02:00 > 0:02:03In fact, without using its eyes at all.
0:02:06 > 0:02:10I'm talking about bats, of course,
0:02:10 > 0:02:13because we all know that bats can get around in the dark.
0:02:15 > 0:02:18But bat expert Dr Dean Waters is about to show me
0:02:18 > 0:02:22that their senses are far cleverer than that.
0:02:22 > 0:02:23- Have you got one? - I've got one here.
0:02:23 > 0:02:26- This is an Egyptian fruit bat. - Hello, Egyptian fruit bat.
0:02:26 > 0:02:30Beautiful big eyes and they also have these lovely ears that are very, very mobile
0:02:30 > 0:02:31that they wiggle around a lot.
0:02:31 > 0:02:34And they echolocate through their mouth.
0:02:34 > 0:02:37They'll open their mouth and click from side to side with their tongue.
0:02:37 > 0:02:38HE CLICKS
0:02:38 > 0:02:40- That's it?- That's it, very simple.
0:02:40 > 0:02:42So it's not like a special... It's just their tongue...
0:02:42 > 0:02:44Just a click, that's it.
0:02:44 > 0:02:45HE CLICKS
0:02:45 > 0:02:49But that simple clicking noise bounces off solid objects
0:02:49 > 0:02:52and by listening carefully to the echo,
0:02:52 > 0:02:55the fruit bat can find its way about.
0:02:58 > 0:03:01But just how accurate is it?
0:03:01 > 0:03:05Time to put the bat's super sense to the test.
0:03:07 > 0:03:09We're using a very hi tech combination
0:03:09 > 0:03:12of cup hooks, bells and string
0:03:12 > 0:03:15to make a type of bat slalom course.
0:03:17 > 0:03:20But we really haven't made it easy for them.
0:03:20 > 0:03:24The strings are less than a centimetre wide
0:03:24 > 0:03:28and the gaps between them are much narrower
0:03:28 > 0:03:30than the bat's two-foot wingspan.
0:03:30 > 0:03:34We'll be watching the action using an infrared camera.
0:03:36 > 0:03:39The bats will still be in pitch black,
0:03:39 > 0:03:44but now, we should be able to see them via Dean's laptop.
0:03:44 > 0:03:47OK, then, Dean. Lights out. Let's see what we've got.
0:03:50 > 0:03:52We don't have to wait long.
0:03:54 > 0:03:57A single bat appears.
0:03:59 > 0:04:03And what he does next is remarkable.
0:04:05 > 0:04:08Nearly, go on, you're going to go through...
0:04:10 > 0:04:12Oh, that's perfect, no, that's absolutely perfect.
0:04:12 > 0:04:14That was... He was bringing his wings in,
0:04:14 > 0:04:16he knew they were either side, exactly where they were.
0:04:20 > 0:04:23By emitting a series of high-pitched clicks
0:04:23 > 0:04:27then listening for echoes bouncing off objects in front of them,
0:04:27 > 0:04:31the bats are picking up even these narrow strings.
0:04:33 > 0:04:37And by pulling their wings in at exactly the right moment,
0:04:37 > 0:04:40they just sail through.
0:04:42 > 0:04:46So if a bat can use sound,
0:04:46 > 0:04:50a series of small clicks, to see in the dark,
0:04:50 > 0:04:52maybe it could work for human beings.
0:04:56 > 0:04:59This man, Professor Brian Hoyle,
0:04:59 > 0:05:03believes he's found a way to do just that,
0:05:03 > 0:05:06by putting bat-tech in a stick.
0:05:06 > 0:05:09So, this isn't just a bit like the way a bat works.
0:05:09 > 0:05:10This is echolocating.
0:05:10 > 0:05:15- It is very, very similar indeed. Over to you.- Right, it's beeping at me!
0:05:15 > 0:05:18- That was you!- It was me. - It's found you! Look at that!
0:05:18 > 0:05:19And if I move it off, it stops.
0:05:19 > 0:05:22I'm going to go behind you, so I can see what's going on.
0:05:22 > 0:05:23I felt you walk through.
0:05:23 > 0:05:25So, what I'm doing now, this is sending out a noise,
0:05:25 > 0:05:28the same as a bat does, and then listening for it bouncing back,
0:05:28 > 0:05:32echoing back off objects, which is exactly what our bats did.
0:05:32 > 0:05:35- It then tells me, by buzzing, on this.- Absolutely.
0:05:35 > 0:05:37And you can feel it. So if I walk towards that...
0:05:37 > 0:05:39- Ooh, it's found something. - Just take it slowly.
0:05:39 > 0:05:41- It's buzzing through my thumb.- Good.
0:05:41 > 0:05:44- If I move off, it's not.- Great.
0:05:44 > 0:05:46So, it's telling me there's an object to my left.
0:05:46 > 0:05:48You found a safe path to the right.
0:05:48 > 0:05:50Bring on the blindfold.
0:05:50 > 0:05:51Let's give this a proper go.
0:05:52 > 0:05:56Right, let's see if I can pick up in a matter of minutes
0:05:56 > 0:06:00what it's taken the fruit bat millions of years to perfect.
0:06:02 > 0:06:04Nothing - oh! Something to my right.
0:06:04 > 0:06:06Hang on, there's a gap there.
0:06:06 > 0:06:10I've got something to my left, there. And to my right, there.
0:06:10 > 0:06:12Picked up something, then.
0:06:12 > 0:06:15Oh, that's a mannequin, isn't it?
0:06:19 > 0:06:24Slowly but surely, I can see how somebody could build up a picture.
0:06:24 > 0:06:28Right, the only thing is, I have no idea where I've ended up.
0:06:28 > 0:06:30Right, I had no idea that I was here.
0:06:30 > 0:06:32Well, I think you did really well,
0:06:32 > 0:06:34and I don't think you bumped into anything.
0:06:34 > 0:06:36I didn't hit anything.
0:06:38 > 0:06:42So I thought, what if we take this whole idea a step further,
0:06:42 > 0:06:45and use bat sonar to enable blind people to do something
0:06:45 > 0:06:47they wouldn't normally even attempt.
0:06:47 > 0:06:50So I've taken apart a couple of canes,
0:06:50 > 0:06:53and I've come up with this, the Bat Bike.
0:06:53 > 0:06:56Now, let me talk you through this.
0:06:56 > 0:06:59Essentially, it's a prototype at the moment, but it shows the principle.
0:06:59 > 0:07:01We've got two Bat Cane handles up here on the bars,
0:07:01 > 0:07:05with the contact pads, feeding back information to the rider from
0:07:05 > 0:07:07the sensors in the handles themselves,
0:07:07 > 0:07:09then we've got two more down here.
0:07:09 > 0:07:11I reckon that should be enough information feeding back
0:07:11 > 0:07:15to the rider to enable a blind person to ride
0:07:15 > 0:07:18a mountain bike down a mountain bike course.
0:07:18 > 0:07:22Now I say it out loud, that is quite a big ask, but it could work.
0:07:24 > 0:07:28By the time engineers have built our Bat Bike properly
0:07:28 > 0:07:34a few of the details have changed, but the theory remains the same.
0:07:35 > 0:07:38These sensors send out and receive a series of clicks
0:07:38 > 0:07:43and a couple of vibrating buttons tell the rider what's up ahead.
0:07:44 > 0:07:48That rider is 21-year-old Dan Smith.
0:07:49 > 0:07:53A keen cyclist, Dan tragically lost his sight nine months ago
0:07:53 > 0:07:55from a rare genetic condition.
0:07:56 > 0:07:59He hasn't been able to ride a bike on his own since.
0:08:02 > 0:08:05Although most of the damage to his eyes is invisible, trust me,
0:08:05 > 0:08:10Dan can't see anything in front of him.
0:08:10 > 0:08:15Five, four, three, two, one, go!
0:08:17 > 0:08:21HEART BEATS
0:08:45 > 0:08:48My heart's in my mouth, but Dan sets off brilliantly.
0:08:55 > 0:08:59BAT BIKE BEEPS
0:09:04 > 0:09:09Dan only had a few short hours to practise on this bike...
0:09:12 > 0:09:16..but bat technology is allowing his brain to see the course.
0:09:28 > 0:09:30So how did Dan find it?
0:09:30 > 0:09:32Yeah, very good, actually.
0:09:32 > 0:09:35The technology works, because I've just navigated
0:09:35 > 0:09:38the whole track by myself, so I'm very pleased, yeah.
0:09:38 > 0:09:43Well, there could be no clearer proof that bat-tech works.
0:09:43 > 0:09:47It's just another example of the miracles of nature.