0:00:02 > 0:00:04'Animals are amazing.'
0:00:04 > 0:00:05That's astonishing.
0:00:05 > 0:00:07'And the more we find out about them,
0:00:07 > 0:00:09the more amazing they seem.'
0:00:09 > 0:00:11That feels pretty harsh.
0:00:11 > 0:00:14'That's why scientists all over the world
0:00:14 > 0:00:16'are trying their best to copy them.'
0:00:16 > 0:00:17This is in the future...
0:00:17 > 0:00:19'Making brand new inventions...'
0:00:19 > 0:00:20Tomato juice!
0:00:20 > 0:00:22'..based on what animals can do.
0:00:24 > 0:00:25'Some are astounding.'
0:00:25 > 0:00:27We've just dived under the sea.
0:00:27 > 0:00:28'Some bizarre.'
0:00:28 > 0:00:30This is not at all pleasant.
0:00:30 > 0:00:32EXPLOSION
0:00:32 > 0:00:34Yes, it's gone!
0:00:34 > 0:00:39'But they're all inspired by the Miracles of Nature.'
0:00:41 > 0:00:43'Episode Six.
0:00:43 > 0:00:47'How engineers decided elephants might be able to
0:00:47 > 0:00:50'help them rescue trapped miners.
0:00:55 > 0:00:59'To prove it, I've come to a disused Californian gold mine
0:00:59 > 0:01:02to take part in a pretty unusual experiment.'
0:01:07 > 0:01:10Hello. Right, I'm in the gold mine.
0:01:10 > 0:01:13'I'm in, like, a very narrow corridor, it's very cramped.'
0:01:16 > 0:01:21'But above me, at the surface, it's suddenly a hive of activity.'
0:01:31 > 0:01:33I've come to like an old, broken...
0:01:33 > 0:01:35STATIC HISSES
0:01:35 > 0:01:38Of course, they can't hear me - the radio doesn't work down here.
0:01:38 > 0:01:43And my cellphone? Well, that's long since given up the ghost. No signal.
0:01:43 > 0:01:47So I have no means of communication between here and the surface.
0:01:47 > 0:01:51And that is a problem, because, in about 30 seconds' time,
0:01:51 > 0:01:55they're going to explode the doorway into this gold mine.
0:02:13 > 0:02:15RUMBLING
0:02:28 > 0:02:30So here's the situation.
0:02:30 > 0:02:33I am now trapped in the mine.
0:02:33 > 0:02:35I've got no means of telling anybody on the surface
0:02:35 > 0:02:37where I am or how I am.
0:02:37 > 0:02:40The only thing that stands a chance of saving me
0:02:40 > 0:02:43has its roots on the other side of the planet -
0:02:43 > 0:02:44in Africa.
0:02:52 > 0:02:57Scientist Dr Kate Evans has offered to show me just what that is.
0:03:07 > 0:03:12'We're installing a massive loudspeaker to test Kate's theory
0:03:12 > 0:03:16'that elephants can pick up vibrations through solid rock.'
0:03:18 > 0:03:21Well, what we really want to do is kind of pretend it's an elephant,
0:03:21 > 0:03:23if you see what I mean.
0:03:23 > 0:03:27'Kate hopes this speaker will act like an elephant's foot...'
0:03:27 > 0:03:30- This is genuinely quite exciting. - SHE CHUCKLES
0:03:30 > 0:03:35'..and transmit low frequency sounds straight into the ground.'
0:03:35 > 0:03:38'To copy the huge weight of an elephant,
0:03:38 > 0:03:42'we pile heavy sandbags on top.
0:03:42 > 0:03:45'With our elephant-tech transmitter finally complete,
0:03:45 > 0:03:48'Kate and I retreat to a safe distance.'
0:03:48 > 0:03:53This sound - who's saying what in it?
0:03:53 > 0:03:55We previously recorded a known female.
0:03:55 > 0:03:59And so, what we hope is that this call will attract the males in.
0:03:59 > 0:04:00'So, basically,
0:04:00 > 0:04:04'we're broadcasting the offer of a girlfriend.'
0:04:05 > 0:04:08But even with an offer like that,
0:04:08 > 0:04:10there is no guarantee of success.
0:04:14 > 0:04:16Because the nearest male elephants
0:04:16 > 0:04:18our camera team have been able to find
0:04:18 > 0:04:22are more than a mile away, drinking at a bend in a noisy river.
0:04:27 > 0:04:30Is it even remotely possible that they'll pick up on our signal?
0:04:32 > 0:04:34Time to find out.
0:04:38 > 0:04:40The call isn't being transmitted through the air,
0:04:40 > 0:04:42so we can't hear it.
0:04:43 > 0:04:47But we can see the speaker moving.
0:04:49 > 0:04:55And astonishingly, the elephants move straight away as well.
0:05:02 > 0:05:06Within moments, the three males are moving away up the bank.
0:05:09 > 0:05:14But are they really going to come more than a mile to our loudspeaker?
0:05:20 > 0:05:21There you go!
0:05:21 > 0:05:25'And then, out of the blue, they appear.'
0:05:25 > 0:05:27There's three! Wow!
0:05:27 > 0:05:29- They're straight through.- Yeah.
0:05:34 > 0:05:36- He's definitely looking for something.- Yeah.
0:05:36 > 0:05:39He's got something on his mind, hasn't he?
0:05:41 > 0:05:44There's no doubt the lead male has heard our call.
0:05:49 > 0:05:53He makes his way straight towards the speaker.
0:05:54 > 0:05:56Remarkable!
0:05:56 > 0:05:59But can you imagine his disappointment when,
0:05:59 > 0:06:01instead of a female elephant,
0:06:01 > 0:06:04all he finds is a scruffy pile of stacks?
0:06:06 > 0:06:09I'd like to think we just had a bit of a chat...
0:06:09 > 0:06:10What did we say?
0:06:10 > 0:06:13Shot the breeze. I've no idea, no idea.
0:06:13 > 0:06:14SHE CHUCKLES
0:06:14 > 0:06:17'So, with the help of elephants,
0:06:17 > 0:06:21'we've successfully managed to send signals through the earth.
0:06:22 > 0:06:26'But how can that elephant technology
0:06:26 > 0:06:30'rescue me from a Californian gold mine?'
0:06:35 > 0:06:39Well, it's not quite an elephant, but it is an ELF -
0:06:39 > 0:06:41an extreme low frequency device.
0:06:41 > 0:06:44And it can do, hopefully, what elephants can do so effectively,
0:06:44 > 0:06:48which is transmit, communicate, through solid rock.
0:06:48 > 0:06:50Quite a lot of it, in this instance.
0:06:50 > 0:06:52All I've got to do is assemble it.
0:06:54 > 0:06:58'It works in exactly the same way as our artificial elephant's foot.
0:06:58 > 0:07:03'Only this time, the speaker is pointing upwards.'
0:07:03 > 0:07:08This bit here will connect the device with the rock.
0:07:08 > 0:07:11Obviously, you don't need me to tell you
0:07:11 > 0:07:14that people do get trapped in mines for real
0:07:14 > 0:07:16without the benefit of a TV crew
0:07:16 > 0:07:18and, more importantly, without the benefit
0:07:18 > 0:07:21of any means of communicating with the surface.
0:07:21 > 0:07:24Sometimes with terrible consequences.
0:07:24 > 0:07:27This device could give them a chance.
0:07:29 > 0:07:33The whole system has been designed so it can run from car batteries,
0:07:33 > 0:07:37which is pretty handy if you're stuck down a mine like this.
0:07:37 > 0:07:39So the control box, if I set this thing to five,
0:07:39 > 0:07:41that is telling them...
0:07:41 > 0:07:42And there it goes.
0:07:42 > 0:07:45That's telling them I'm in sector five, so they know where I am.
0:07:45 > 0:07:48And I can tell them the air quality is OK.
0:07:48 > 0:07:51So now, they know where I am and how I am.
0:07:51 > 0:07:53At least, I'm telling them,
0:07:53 > 0:07:57because I know the signal is leaving me and going up into the rock.
0:07:57 > 0:07:59What I've no way of knowing right now
0:07:59 > 0:08:02is whether or not they're receiving that vital information.
0:08:05 > 0:08:06In other words,
0:08:06 > 0:08:09have we the capability to do what the elephant does,
0:08:09 > 0:08:12and pick those vibrations up?
0:08:15 > 0:08:18100 feet above me, the ELF's inventors,
0:08:18 > 0:08:21Jim Squire and Jay Sullivan, believe we have.
0:08:24 > 0:08:28With the help of this small spiked cylinder.
0:08:28 > 0:08:30This is the ELF's ear.
0:08:31 > 0:08:33All right, let's start acquiring.
0:08:41 > 0:08:43At this sort of depth, we should have the answer
0:08:43 > 0:08:45in around ten seconds, if he's sending right now.
0:08:52 > 0:08:54OK, it looks like we're getting a signal now.
0:08:58 > 0:09:00And there it is.
0:09:00 > 0:09:02Location five, good air.
0:09:02 > 0:09:07And that's the point at which they'd normally send in the rescue teams.
0:09:07 > 0:09:09But...I don't really need them.
0:09:10 > 0:09:13Well, no, they didn't actually shut me in a gold mine
0:09:13 > 0:09:15and blow up the only exit.
0:09:15 > 0:09:16There'd have been a lot of paperwork.
0:09:16 > 0:09:21And, anyway, the point is we've proved it works. Thank you, guys!
0:09:23 > 0:09:27And thank you too to the African elephant,
0:09:27 > 0:09:30whose extraordinary super sense
0:09:30 > 0:09:33is definitely one of the Miracles of Nature.