0:00:10 > 0:00:14Let's face it, our world is downright weird.
0:00:15 > 0:00:17Argh! Oh-ho!
0:00:17 > 0:00:20Crawling with creatures you've never heard of.
0:00:20 > 0:00:23I can't believe that's a living thing.
0:00:24 > 0:00:26Full of the unexpected.
0:00:27 > 0:00:31Like freak weather exploding out of the blue.
0:00:31 > 0:00:33I thought I was going to die.
0:00:33 > 0:00:36And rocks that spontaneously combust.
0:00:36 > 0:00:38I thought it was dynamite going off.
0:00:38 > 0:00:41And the unexplained.
0:00:41 > 0:00:46An unborn twin discovered inside a brain?!
0:00:46 > 0:00:50There were multiple hair follicles, bone and teeth.
0:00:54 > 0:00:58We've scoured the globe to bring you the very weirdest stories.
0:00:58 > 0:01:01Y-a-a-a-a-a-a-argh!
0:01:01 > 0:01:03I could feel this intense pain,
0:01:03 > 0:01:07as if you were being stabbed by hundreds of syringes.
0:01:12 > 0:01:15In this series, we're going to examine the evidence,
0:01:15 > 0:01:19test the science and unravel the mysteries.
0:01:19 > 0:01:25We're going to discover what in the weird world is going on.
0:01:35 > 0:01:37In this episode,
0:01:37 > 0:01:41we'll explore some truly bizarre goings on.
0:01:43 > 0:01:46How can a stroll along the beach end in catastrophic injuries?
0:01:48 > 0:01:52What's causing three suns to miraculously appear in our skies?
0:01:57 > 0:02:00Who is bringing gifts to a little girl?
0:02:00 > 0:02:04They're my friends and some of them are, like, family.
0:02:04 > 0:02:07And how can a person with perfectly good eyesight
0:02:07 > 0:02:10not recognise her own children?
0:02:18 > 0:02:21Now, most people love a trip to the beach in summertime.
0:02:21 > 0:02:25Paddle along the shoreline, take in the fresh sea air,
0:02:25 > 0:02:27maybe build a few sandcastles.
0:02:27 > 0:02:30But I've got to tell you, it can be quite a dangerous place.
0:02:30 > 0:02:34And I'm not just talking about forgetting your sunscreen.
0:02:34 > 0:02:37I'm taking about something far more sinister.
0:02:42 > 0:02:44Orange County, California.
0:02:45 > 0:02:48On a beautiful summer's day in 2012,
0:02:48 > 0:02:52the Hiner family headed out to take part in one of their favourite
0:02:52 > 0:02:54pastimes - beachcombing.
0:02:54 > 0:02:59The big prizes when you're down at the beach are sea glass.
0:02:59 > 0:03:03And on that day, we'd found a piece of blue sea glass,
0:03:03 > 0:03:06we'd found a piece of green.
0:03:06 > 0:03:08As we would find interesting things to look at,
0:03:08 > 0:03:11everyone would stop and we would, kind of,
0:03:11 > 0:03:15pick whatever was our favourite rock or shell. And I would...
0:03:15 > 0:03:17I was the one with shorts, so I had them in my pocket.
0:03:20 > 0:03:23We're all familiar with gathering trinkets along the shore,
0:03:23 > 0:03:27but Lyn's collection was about to change her life forever.
0:03:28 > 0:03:31We'd been down there for probably two or three hours.
0:03:32 > 0:03:36I came home, I was sitting at this counter
0:03:36 > 0:03:38and I was peeling an orange
0:03:38 > 0:03:41and all of a sudden, this intense heat,
0:03:41 > 0:03:45this intense, er...pain was hitting my leg.
0:03:48 > 0:03:51It felt like somebody had a magnifying glass outside the window
0:03:51 > 0:03:53and it was aimed at my leg.
0:03:53 > 0:03:57So logically, I felt like it must be a bug.
0:04:00 > 0:04:03The California coast is home to all manner of dangers...
0:04:04 > 0:04:07..from rip currents to sharks.
0:04:08 > 0:04:13But the cause of Lyn's pain was far weirder.
0:04:13 > 0:04:17Had she brought back an unexpected guest in her pocket?
0:04:17 > 0:04:20Was a scorpion hiding in one of the shells?
0:04:20 > 0:04:24Or a deadly cone snail, with barbs poised to paralyse?
0:04:29 > 0:04:33I decide to smack my leg to kill whatever is on my leg
0:04:33 > 0:04:37and what ends up happening is, I look down,
0:04:37 > 0:04:41and there are flames shooting off of my shorts.
0:04:46 > 0:04:51We were both, kind of, in this sort of panic of, why isn't it going out?
0:04:51 > 0:04:53My husband started yelling,
0:04:53 > 0:04:56"Get your shorts off, get your shorts off!"
0:04:56 > 0:04:58And I'm trying to undo them with one burnt hand
0:04:58 > 0:05:01and he was pulling them off. Um...
0:05:01 > 0:05:04the stones were coming out of the burnt hole
0:05:04 > 0:05:06and dropping on the ground
0:05:06 > 0:05:09and creating small fires each place they would land.
0:05:14 > 0:05:19Lyn's carefree trip to the beach cost her ten days in hospital.
0:05:22 > 0:05:25All in all, she had to have six operations,
0:05:25 > 0:05:27including a complex skin graft.
0:05:27 > 0:05:30So, what had caused her shorts to ignite?
0:05:30 > 0:05:33What had caused such terrible burns?
0:05:33 > 0:05:37Even the emergency services were completely baffled.
0:05:39 > 0:05:42Outside, the fire department was asking me what it could have been
0:05:42 > 0:05:45and I told them all I had in that pocket were rocks.
0:05:45 > 0:05:48And no-one could believe that that was what was causing it.
0:05:50 > 0:05:52There was no obvious explanation.
0:05:54 > 0:05:58So, the smouldering rocks found at the scene were sent for analysis.
0:05:58 > 0:06:03And one, in particular, stuck in Lyn's mind.
0:06:03 > 0:06:06One of the rocks actually looked like amber.
0:06:06 > 0:06:08That one little rock, I thought was... What a find!
0:06:08 > 0:06:13It was this beautiful, er...clear.
0:06:13 > 0:06:15It had ribboning going through it.
0:06:15 > 0:06:18It wasn't very big. It was very small.
0:06:18 > 0:06:20But I thought, "Wow, I've found a piece of amber".
0:06:24 > 0:06:28But the little orange stone wasn't amber.
0:06:28 > 0:06:32Lyn had picked up something much more deadly.
0:06:34 > 0:06:36There are many elements that can self-ignite.
0:06:38 > 0:06:42Some, like sodium, are stable in air...
0:06:43 > 0:06:46..but react violently in water.
0:06:48 > 0:06:51One, however, does the complete opposite.
0:06:52 > 0:06:54Phosphorous.
0:06:54 > 0:06:56In water, it's stable.
0:06:58 > 0:07:02But when taken out of water, it spontaneously combusts
0:07:02 > 0:07:04with the oxygen present in this flask.
0:07:08 > 0:07:12Burning at around 1,300 degrees Celsius.
0:07:19 > 0:07:22Now, you might have encountered phosphorus before.
0:07:22 > 0:07:25Perhaps in one of these, a flare, or even in matches.
0:07:25 > 0:07:28It's a reactive chemical. It's certainly flammable.
0:07:28 > 0:07:30But it's nothing compared to the type of phosphorus
0:07:30 > 0:07:34that Lyn inadvertently picked up on the beach.
0:07:34 > 0:07:37No, that was white phosphorous.
0:07:37 > 0:07:39The most explosive kind.
0:07:41 > 0:07:45Whilst Lyn's shorts were still damp from paddling,
0:07:45 > 0:07:48the pebble of phosphorus in her pocket was stable.
0:07:49 > 0:07:53But when her shorts began to dry out,
0:07:53 > 0:07:55that's when the rock ignited.
0:07:58 > 0:08:01So, are we talking about a new discovery in the world of geology?
0:08:04 > 0:08:07A naturally-occurring, phosphorus-rich mineral?
0:08:07 > 0:08:09Sadly not.
0:08:09 > 0:08:12The pebble that Lyn happened upon
0:08:12 > 0:08:14was most likely the explosive remnants
0:08:14 > 0:08:16of an old artillery shell
0:08:16 > 0:08:19left over from military exercises.
0:08:20 > 0:08:25Certainly not the usual type of shell you'd expect to find on the beach.
0:08:26 > 0:08:30Had the kids been the ones who carried the rocks,
0:08:30 > 0:08:33a very different scenario that I would not like to even consider.
0:08:40 > 0:08:42Well, what a sobering story.
0:08:42 > 0:08:44Makes me think that the next time I go beachcombing
0:08:44 > 0:08:46and find something a bit weird,
0:08:46 > 0:08:48I probably won't put it in my pocket.
0:08:48 > 0:08:50Just have an ice cream instead.
0:08:50 > 0:08:53But it also reminds me of another story.
0:08:53 > 0:08:55An astonishing discovery made
0:08:55 > 0:08:57when someone was just out for a stroll.
0:08:57 > 0:09:02Something that redefined the world of sound forever.
0:09:06 > 0:09:10OK, what's the loudest animal on the planet?
0:09:10 > 0:09:11ROAR!
0:09:11 > 0:09:14No.
0:09:14 > 0:09:16HOWL! Not quite.
0:09:16 > 0:09:18TRUMPET! Nearly.
0:09:18 > 0:09:21CLICK! That's it.
0:09:23 > 0:09:24The blue whale.
0:09:24 > 0:09:28The largest and the loudest animal on Earth.
0:09:29 > 0:09:34With a call at over 188 decibels,
0:09:34 > 0:09:36louder than a jet engine.
0:09:40 > 0:09:43For decades, this ocean giant has held the title.
0:09:43 > 0:09:46That it, until recently.
0:09:49 > 0:09:53You see, scientists have discovered a new contender.
0:09:53 > 0:09:57That, relative to its size, can give the blue whale
0:09:57 > 0:09:59a run for its money.
0:10:04 > 0:10:08So, what is this cacophonous creature?
0:10:10 > 0:10:15Well, I can tell you one thing, it's a tad smaller than a blue whale.
0:10:16 > 0:10:19The discovery was made by an inquisitive scientist
0:10:19 > 0:10:22experimenting with a new area of research.
0:10:25 > 0:10:28Some of the group were just walking along by a lake.
0:10:31 > 0:10:34And they could suddenly hear a very high-pitched chirping sound,
0:10:34 > 0:10:37as you'd expect to hear from an insect.
0:10:37 > 0:10:40But they couldn't actually see any of the insects.
0:10:43 > 0:10:45It was then it dawned on them
0:10:45 > 0:10:48that there must be something actually in the water.
0:10:48 > 0:10:50After much exploration of the riverbank,
0:10:50 > 0:10:55James and his team discovered the unlikely source of the sound.
0:10:55 > 0:10:57CHIRPING
0:10:57 > 0:11:00It was the tiny water boatman.
0:11:05 > 0:11:07I know what you're thinking.
0:11:07 > 0:11:10What you're thinking is that that's just a little squeak.
0:11:10 > 0:11:13But at just two millimetres long,
0:11:13 > 0:11:18the water boatman is producing a sound at 99.2 decibels.
0:11:18 > 0:11:23That's the same as me revving up this engine!
0:11:23 > 0:11:26And then, imagine if the thing was the size of a whale.
0:11:26 > 0:11:29ENGINE REVS The noise would be deafening!
0:11:34 > 0:11:37Unable to believe their ears, James and his colleagues
0:11:37 > 0:11:40collected a few water boatmen and took them back to the lab.
0:11:41 > 0:11:44You could hear them singing in the tubs.
0:11:44 > 0:11:48And, of course, that then told us that these must be very loud insects
0:11:48 > 0:11:53because sound doesn't transfer out of water and into air very well.
0:11:56 > 0:12:00In fact, 99% of the sound in water
0:12:00 > 0:12:04is lost when it transfers to the air.
0:12:06 > 0:12:10So just imagine how powerful it would be out of the water.
0:12:15 > 0:12:19But what's weirdest of all is how the boatmen actually produce this sound.
0:12:19 > 0:12:22You see, they don't do it by rubbing their legs together.
0:12:22 > 0:12:25They don't do it by rubbing their wings together.
0:12:25 > 0:12:30They do it by using an altogether different part of their anatomy.
0:12:34 > 0:12:36So this tiny insect makes this sound
0:12:36 > 0:12:39by rubbing one part of their hard exoskeleton against another.
0:12:39 > 0:12:41In essence, it's called stridulation.
0:12:41 > 0:12:44So a similar thing to what grasshoppers and crickets do
0:12:44 > 0:12:47to produce these rasping, er...scratchy sounds.
0:12:50 > 0:12:52What really sets this story apart
0:12:52 > 0:12:54is the fact that this lesser water boatman
0:12:54 > 0:12:57uses part of its penis to make the sound.
0:12:58 > 0:13:00That's right, you've heard it correctly.
0:13:00 > 0:13:04The water boatman sings with its penis.
0:13:07 > 0:13:11By rubbing the structure against a grooved section of their abdomen,
0:13:11 > 0:13:13water boatmen sing, to attract females.
0:13:15 > 0:13:17The fact that it's so loud is also very weird,
0:13:17 > 0:13:20because the area it produces the sound with is very small.
0:13:20 > 0:13:22It's about the width of a human hair.
0:13:22 > 0:13:25So, water boatmen produce their massive sound
0:13:25 > 0:13:27with a microscopic instrument.
0:13:30 > 0:13:33Just goes to prove, size isn't everything.
0:13:38 > 0:13:41Well, it's an earth-shattering serenade, that's for sure.
0:13:43 > 0:13:47But from record-breaking sounds to record-breaking size.
0:13:47 > 0:13:52Our next story is an assault on the senses of a very different kind.
0:13:56 > 0:13:57Sumatra.
0:13:59 > 0:14:03Home to some of the world's most rare and beautiful plants.
0:14:06 > 0:14:10Whilst most compete to attract pollinators with delicate blooms...
0:14:13 > 0:14:15..and sumptuous smells...
0:14:17 > 0:14:21..one species has taken a very different path.
0:14:23 > 0:14:26A bizarre turn off of the evolutionary highway.
0:14:27 > 0:14:32And there just happens to be a specimen of this floral rebel
0:14:32 > 0:14:35lurking in the Cambridge Botanic Gardens.
0:14:40 > 0:14:42Meet the titan arum.
0:14:44 > 0:14:46Reaching up to three metres in height,
0:14:46 > 0:14:51this is the largest flowering structure in the world.
0:14:52 > 0:14:55Blooming just once every ten years,
0:14:55 > 0:14:59this is a true botanical oddity.
0:14:59 > 0:15:02But it's not just its looks that are unusual.
0:15:02 > 0:15:04It's also its smell.
0:15:07 > 0:15:11This misfit is not interested in attracting bees or butterflies.
0:15:11 > 0:15:16It aims to lure in a much more unconventional group of pollinators.
0:15:17 > 0:15:19Carrion beetles -
0:15:19 > 0:15:22the undertakers of the natural world.
0:15:22 > 0:15:26Just as honeybees are attracted by the sweet smell of nectar,
0:15:26 > 0:15:29these gruesome insects are attracted by
0:15:29 > 0:15:31the scent of decomposing carcases.
0:15:33 > 0:15:39Which is why this bloom smells like a corpse.
0:15:40 > 0:15:44The distinctive stench is made up of a host of chemical compounds.
0:15:47 > 0:15:50One of the key components is dimethyl trisulfide.
0:15:50 > 0:15:55It's one of the principle ingredients in the smell of human faeces.
0:15:55 > 0:15:58So you can only imagine the stench.
0:15:58 > 0:15:59Well, you can imagine it,
0:15:59 > 0:16:02but a group of scientists had to get to grips with it.
0:16:02 > 0:16:04Because they broke it down to analyse it
0:16:04 > 0:16:07and found a ripe cocktail of ingredients.
0:16:07 > 0:16:11Yes. Instead of releasing just one awful smell,
0:16:11 > 0:16:14this plant releases a succession of aromas.
0:16:14 > 0:16:17Beginning with rotting fruit,
0:16:17 > 0:16:21then flesh and finally, rotten fish.
0:16:22 > 0:16:27No. The odour is only the start of the deception.
0:16:27 > 0:16:29If you imagine a plant flowering in a dense jungle environment,
0:16:29 > 0:16:32it's no good being brightly coloured or easy to see
0:16:32 > 0:16:34because you're in dense vegetation.
0:16:34 > 0:16:36So, it's much better to attract pollinators by having a smell
0:16:36 > 0:16:39which disperses over quite a big distance.
0:16:41 > 0:16:44The titan arum is effectively mimicking a piece of dead animal.
0:16:44 > 0:16:46It's got the colours,
0:16:46 > 0:16:48if you look at the deep red, it looks like blood.
0:16:48 > 0:16:51There's the yellowy textures in there.
0:16:51 > 0:16:53And then with that scent, as well, of rotting flesh,
0:16:53 > 0:16:56it's really doing a good job of pretending to be a dead animal.
0:17:02 > 0:17:04It's a convincing con.
0:17:04 > 0:17:08A plant that looks and smells like rotten meat.
0:17:08 > 0:17:10But the tricks don't end there.
0:17:12 > 0:17:15Using some clever chemical reactions, the titan arum
0:17:15 > 0:17:20can the turn the energy it normally uses for growth, into warmth.
0:17:20 > 0:17:23It's a feat that requires so much energy,
0:17:23 > 0:17:27the plant can only flower very rarely.
0:17:28 > 0:17:34And disturbingly, the temperature it reaches is 37-degrees C.
0:17:34 > 0:17:36Human body temperature.
0:17:37 > 0:17:40But, you know, it can get even hotter.
0:17:40 > 0:17:43So is this a plant pretending to be a mammal?
0:17:43 > 0:17:45Surely not!
0:17:45 > 0:17:46The first night it's open,
0:17:46 > 0:17:49the flower heats itself up to about 40-degrees centigrade.
0:17:49 > 0:17:50And that heating up allows
0:17:50 > 0:17:54the chemical compounds that are made to be released.
0:17:54 > 0:17:57So, for every ten degrees or so centigrade you increase temperature,
0:17:57 > 0:17:59you increase tenfold the distance
0:17:59 > 0:18:01that scent molecules will travel in the air.
0:18:01 > 0:18:03So by heating itself up,
0:18:03 > 0:18:06it's really increasing the chances of that scent getting out
0:18:06 > 0:18:08and being picked up by the pollinators.
0:18:11 > 0:18:15So, the heat spreads the rancid odour further into the jungle,
0:18:15 > 0:18:18to entice insects from far and wide.
0:18:18 > 0:18:20It's nothing sinister.
0:18:20 > 0:18:24It's a genius act of mimicry.
0:18:24 > 0:18:28Lured by the smell and the promise of food,
0:18:28 > 0:18:32the beetles wander around, searching for their non-existent reward.
0:18:32 > 0:18:36But in doing so, they inadvertently pollinate the plant.
0:18:36 > 0:18:39Exactly what it wanted.
0:18:41 > 0:18:43Poor little insects. I feel quite sorry for them,
0:18:43 > 0:18:45being led up the garden path.
0:18:45 > 0:18:48But what a weird story this is.
0:18:48 > 0:18:52A plant that generates enough heat to mimic a human body.
0:18:52 > 0:18:54Whatever next?
0:18:54 > 0:18:57Well, not a Day Of The Triffids-style takeover, I fear.
0:18:57 > 0:19:00Because, you see, the energy required to grow so big
0:19:00 > 0:19:02and to produce that central heating
0:19:02 > 0:19:06means that this plant can only ever flower for 48 hours.
0:19:06 > 0:19:09And, in fact, the titan arum is incredibly rare,
0:19:09 > 0:19:12probably because of this weird strategy.
0:19:12 > 0:19:15So, not much chance of a world takeover.
0:19:18 > 0:19:20From explosive rocks
0:19:20 > 0:19:25to tiny insects with something to shout about
0:19:25 > 0:19:28and flowers with stomach-churning fragrances.
0:19:28 > 0:19:31This is only the beginning.
0:19:37 > 0:19:38Right, then, what next?
0:19:38 > 0:19:41Well, we're going from a remarkable story
0:19:41 > 0:19:44about some surprisingly-generous garden visitors,
0:19:44 > 0:19:47via the typical circuitous route,
0:19:47 > 0:19:49to an unusual marine motel.
0:19:51 > 0:19:54We begin our journey in Seattle.
0:19:54 > 0:19:58Home to eight-year-old Gabi Mann and her family.
0:20:00 > 0:20:03Like many kids, Gabi likes to collect things.
0:20:05 > 0:20:08But her treasures aren't dolls or stickers.
0:20:09 > 0:20:11Metal, plastic,
0:20:11 > 0:20:14buttons, screws,
0:20:14 > 0:20:19rocks, more glass, bones.
0:20:19 > 0:20:20A lot of things.
0:20:20 > 0:20:24And it's not just the content of her collection that's unusual.
0:20:24 > 0:20:27It's who gave it to her.
0:20:27 > 0:20:31They are my friends and some of them are, like, family.
0:20:32 > 0:20:34They're really nice.
0:20:35 > 0:20:38At least, most of them, I think.
0:20:40 > 0:20:43Gabi's not referring to her friends at school,
0:20:43 > 0:20:46but to the crows in her backyard.
0:20:49 > 0:20:51Over the past two and a half years,
0:20:51 > 0:20:53these generous garden visitors
0:20:53 > 0:20:56have been regularly bringing her gifts.
0:20:56 > 0:21:01Her collection now contains over 100 different objects -
0:21:01 > 0:21:04some dropped right at her feet.
0:21:04 > 0:21:07And her collection is still growing.
0:21:08 > 0:21:10- Can I show you one right now?- Yeah.
0:21:11 > 0:21:13I have one right in my hand.
0:21:13 > 0:21:16It's a squid that I got a week ago.
0:21:22 > 0:21:24The million-dollar question is,
0:21:24 > 0:21:27are these birds really Gabi's friends?
0:21:27 > 0:21:33I mean, could these crows really be leaving gifts specifically for her?
0:21:33 > 0:21:34Now, don't get me wrong,
0:21:34 > 0:21:38I'm a massive fan of the crow family, the corvids,
0:21:38 > 0:21:40but I've never really seen them as
0:21:40 > 0:21:43caring, sharing, gift-giving birds.
0:21:43 > 0:21:46So could this behaviour be real,
0:21:46 > 0:21:49or is it just a figment of a child's vivid imagination?
0:21:51 > 0:21:53I'd heard about gifting before,
0:21:53 > 0:21:57but this was the most extensive collection by far I'd ever seen.
0:22:01 > 0:22:06A lot of animals use gifts of one sort or the other
0:22:06 > 0:22:09to convey either their status,
0:22:09 > 0:22:11or their interest in another partner.
0:22:11 > 0:22:13But as far as we know,
0:22:13 > 0:22:15corvids are the only birds that do this with people.
0:22:15 > 0:22:20Crows give gifts to people, really, to help cement a bond,
0:22:20 > 0:22:23an important relationship that they have with this person.
0:22:23 > 0:22:27So how common are crow companionships like Gabi's?
0:22:29 > 0:22:33There's probably 20 or 30 instances of this happening around the world.
0:22:33 > 0:22:36And they all have some consistency, in terms of a person
0:22:36 > 0:22:38that's been engaging quite actively with the birds.
0:22:38 > 0:22:42Feeding them a lot, consistently, maybe even rescuing them.
0:22:42 > 0:22:44We've had cases where a crow was stuck in a fence
0:22:44 > 0:22:49and a woman took the crow out of the fence and started getting gifts.
0:22:49 > 0:22:53The gifts seem to be a thank you for the food Gabi leaves out for them.
0:22:53 > 0:22:55Pretty good manners.
0:22:55 > 0:22:59But is there a motive behind their kindness?
0:23:03 > 0:23:07Crows are undoubtedly some of the smartest animals on our planet.
0:23:07 > 0:23:11They have an extremely large brain for their body size.
0:23:11 > 0:23:14And because they live a long life, sometimes more than 20 years,
0:23:14 > 0:23:17they can develop some cunning ways to find food.
0:23:18 > 0:23:21In addition to befriending people,
0:23:21 > 0:23:25studies have shown that crows are capable of using a sequence of tools
0:23:25 > 0:23:27to find a tasty reward.
0:23:29 > 0:23:33Something that previously, only humans and chimpanzees
0:23:33 > 0:23:35were thought to have the brainpower to do.
0:23:40 > 0:23:43Back in Seattle, Gabi's found that, over the years,
0:23:43 > 0:23:47the gifts she's been receiving appear to have been getting more human.
0:23:47 > 0:23:51So, could these super-smart crows
0:23:51 > 0:23:56really be picking out gifts they know she will like?
0:23:56 > 0:23:59I would not put it past these birds to make the association
0:23:59 > 0:24:02between these strange objects in their environment
0:24:02 > 0:24:04and humans having produced those.
0:24:06 > 0:24:10It may simply be that we notice human things more also.
0:24:10 > 0:24:13As humans ourselves, we don't pay attention to little bits of bark
0:24:13 > 0:24:16and rock as much as we would a rubber squid.
0:24:16 > 0:24:18You would notice that!
0:24:18 > 0:24:23Whatever the motive, Gabi certainly has a very special bond
0:24:23 > 0:24:25with the crows in her back garden.
0:24:29 > 0:24:32I think I'd like a crow as a friend.
0:24:32 > 0:24:34Although I did have a magpie when I was a kid.
0:24:34 > 0:24:36I gave it cat food and it redistributed it
0:24:36 > 0:24:39all over the bedroom, so maybe not.
0:24:39 > 0:24:41But whether this is an actual case
0:24:41 > 0:24:43of cross-species kindness,
0:24:43 > 0:24:47or the crows swapping a few odds and ends for food,
0:24:47 > 0:24:48I don't suppose we'll ever know.
0:24:48 > 0:24:52Although the pragmatist in me leans towards the latter.
0:24:52 > 0:24:57But there is an incredible and proven example of gift-giving
0:24:57 > 0:25:00which is happening on a truly global scale.
0:25:05 > 0:25:10The Amazon, one of the most biodiverse places on the planet...
0:25:12 > 0:25:16boasting 10% of all the world's species...
0:25:16 > 0:25:20and over 400 billion trees.
0:25:20 > 0:25:22But, you know, it wouldn't be anywhere near as abundant
0:25:22 > 0:25:25if it weren't for one element.
0:25:29 > 0:25:31Our old friend, phosphorus.
0:25:34 > 0:25:38Thankfully, not in the explosive man-made form we saw earlier,
0:25:38 > 0:25:40but in its naturally occurring form, phosphate.
0:25:43 > 0:25:46A vital nutrient for plant growth.
0:25:58 > 0:26:00But the Amazon has a problem.
0:26:00 > 0:26:03You see, every year when the rains come, they rinse through
0:26:03 > 0:26:08the top layers of the soil and wash away almost all of the phosphorus.
0:26:08 > 0:26:12And that's a disaster. Phosphorus is essential to life.
0:26:12 > 0:26:17It's in the very DNA, a key component of the DNA in the plants.
0:26:17 > 0:26:21So with no phosphorus, you've got no trunks, you've got no leaves,
0:26:21 > 0:26:23you've got no parrots, sloths, jaguars.
0:26:23 > 0:26:26Without the phosphorus, you've got no Amazon.
0:26:28 > 0:26:31So, with the phosphorus constantly getting washed away,
0:26:31 > 0:26:35how is this biodiversity hot spot still standing?
0:26:35 > 0:26:38There was some mechanism that was actually replenishing that
0:26:38 > 0:26:41phosphorus year-on-year.
0:26:41 > 0:26:44And so, we were looking at where that phosphorus may have come from.
0:26:47 > 0:26:49Potentially, it could have been
0:26:49 > 0:26:53drawn in locally, on stronger winds from South America,
0:26:53 > 0:26:58but actually, research has shown that it's come vast distances.
0:26:58 > 0:27:02Scientists confirmed a sneaking suspicion that the Amazon
0:27:02 > 0:27:03is getting a little help.
0:27:05 > 0:27:09And it's in the form of a very long-distance relationship.
0:27:11 > 0:27:14Because the Amazon forest...
0:27:14 > 0:27:15is getting help...
0:27:18 > 0:27:20from the Sahara Desert.
0:27:23 > 0:27:25A barren landscape,
0:27:25 > 0:27:30where temperatures can reach 57 degrees Celsius
0:27:30 > 0:27:34and wind speeds top 55mph.
0:27:34 > 0:27:38It's perhaps not the first place you think of helping solve
0:27:38 > 0:27:42a horticultural problem on a mammoth scale.
0:27:42 > 0:27:46When we think of the Saharan desert, we don't think of lush vegetation.
0:27:46 > 0:27:52It's a very dry, arid area, but it's full of nutrients.
0:27:52 > 0:27:58Nutrients, this place? Well, yes. It seems the Sahara also has a secret.
0:28:00 > 0:28:05And that secret lies in the Bodele Depression in Chad,
0:28:05 > 0:28:08a region that was once a giant lake.
0:28:09 > 0:28:11Over millions of years,
0:28:11 > 0:28:13aquatic animals lived,
0:28:13 > 0:28:16died and decomposed in the lake,
0:28:16 > 0:28:20depositing phosphorus into its sediment.
0:28:23 > 0:28:25Now the lake has long since dried up,
0:28:25 > 0:28:29but its dusty remains are still loaded with goodness.
0:28:30 > 0:28:34And it's these particles that have been found in the Amazon.
0:28:36 > 0:28:40But with 10,000km and an ocean between them,
0:28:40 > 0:28:42how is the phosphorus getting there?
0:28:44 > 0:28:48Well, NASA satellites have been able to shed some light.
0:28:49 > 0:28:51So the satellite data showed us
0:28:51 > 0:28:54a three-dimensional structure of the atmosphere,
0:28:54 > 0:28:56so we could clearly see that dust was being
0:28:56 > 0:28:58taken from the Saharan desert,
0:28:58 > 0:29:00from the surface of the Earth
0:29:00 > 0:29:01high into the atmosphere
0:29:01 > 0:29:05and then transported all the way across the Atlantic Ocean
0:29:05 > 0:29:07to be deposited in the Amazon basin.
0:29:11 > 0:29:14What a remarkable journey.
0:29:14 > 0:29:17Although, when the dust is blown to the UK from the Sahara,
0:29:17 > 0:29:19a much shorter distance,
0:29:19 > 0:29:22it's often just a light sprinkling on cars and windows.
0:29:24 > 0:29:28So, how much dust actually reaches the Amazon?
0:29:31 > 0:29:34Every year, 182 million tonnes of dust
0:29:34 > 0:29:37is lifted from central Africa.
0:29:37 > 0:29:42Most of that dust falls into the ocean but about 30 million tonnes
0:29:42 > 0:29:44falls into the Amazon basin
0:29:44 > 0:29:47and that provides 22,000 tonnes of phosphorus
0:29:47 > 0:29:49to that region every year.
0:29:51 > 0:29:54And if you're wondering just how much phosphorus that is,
0:29:54 > 0:29:59it's almost 2,500 truckloads.
0:29:59 > 0:30:01That's quite an impressive aid package.
0:30:04 > 0:30:05So, there you go.
0:30:05 > 0:30:09Proof that a global love-in can actually help support
0:30:09 > 0:30:13one of the world's most complex, beautiful, impressive ecosystems,
0:30:13 > 0:30:16although I'm not sure the Bodele Depression gets too much out of it.
0:30:16 > 0:30:19It's a bit one-sided, this relationship.
0:30:19 > 0:30:21Reminds me of another one,
0:30:21 > 0:30:24which could frankly be described as a real pain in the backside.
0:30:28 > 0:30:30The Great Barrier Reef.
0:30:33 > 0:30:37Thousands of species live here and space is tight.
0:30:39 > 0:30:41It can make finding a home pretty tricky.
0:30:43 > 0:30:46Even out on the quieter reef edge -
0:30:46 > 0:30:50the exposed seabed offers few hiding places.
0:30:54 > 0:31:00If you're neither strong or well armed, like this tiny pearlfish,
0:31:00 > 0:31:04you'll need to get creative when it comes to looking for shelter.
0:31:04 > 0:31:08Perhaps set your sights slightly stranger.
0:31:11 > 0:31:16Enter the sea cucumber. Known as the vacuum cleaners of the sea,
0:31:16 > 0:31:20they move along the sea bed, sucking in sand at one end
0:31:20 > 0:31:23and then expelling it out of the other.
0:31:24 > 0:31:28And it's this bizarre creature that has the solution
0:31:28 > 0:31:31to the pearlfish's accommodation problem.
0:31:36 > 0:31:40To find out more, we need a marine biologist.
0:31:40 > 0:31:41Pearlfish, they're little fish.
0:31:41 > 0:31:43They're quite vulnerable,
0:31:43 > 0:31:46simply because coral reefs are full of hungry predators.
0:31:50 > 0:31:52You mostly would only see them
0:31:52 > 0:31:53out and about at night-time,
0:31:53 > 0:31:55where they go out hunting for plankton,
0:31:55 > 0:31:57the little creatures that live in the water column,
0:31:57 > 0:32:01and then, during the day, they need to find somewhere to hide.
0:32:01 > 0:32:03Well, all of that sounds fairly sensible
0:32:03 > 0:32:07but where does the sea cucumber come in?
0:32:07 > 0:32:10So sea cucumbers have, basically, a hole at the front end
0:32:10 > 0:32:11and the back end.
0:32:11 > 0:32:13The front end is where the food goes in
0:32:13 > 0:32:16and all sorts of things happen at that back end.
0:32:16 > 0:32:20It's where they breathe, it's where they will excrete the sand
0:32:20 > 0:32:22that they've been eating, any other
0:32:22 > 0:32:24digestive material will come out
0:32:24 > 0:32:27and that's also where they reproduce,
0:32:27 > 0:32:30so it's a, kind of, one hole does many things.
0:32:30 > 0:32:33And therein lies the clue.
0:32:33 > 0:32:37Because the pearlfish makes its cosy home
0:32:37 > 0:32:41inside the sea cucumber's bottom.
0:32:42 > 0:32:46It has to be one of nature's weirdest living arrangements.
0:32:46 > 0:32:52But is this honestly the best real estate available to the pearlfish?
0:32:52 > 0:32:55Well, if you can imagine those sandy areas next to a coral reef,
0:32:55 > 0:32:57there's really nowhere to hide. It's just flat sand.
0:32:57 > 0:33:01There aren't many rocks or any other holes or crevices to hide in.
0:33:01 > 0:33:03But there are sea cucumbers.
0:33:03 > 0:33:05Maybe. But whilst the pearlfish
0:33:05 > 0:33:08may have set its sights on a potential home,
0:33:08 > 0:33:11entry isn't always guaranteed.
0:33:11 > 0:33:15If a sea cucumber does have an idea there is a pearlfish around
0:33:15 > 0:33:17it might close up its bottom,
0:33:17 > 0:33:21so for a little while, it won't be open for guests.
0:33:21 > 0:33:25If I knew there was a pearlfish around, I'd close my bottom, too.
0:33:25 > 0:33:29But the resourceful fish has a solution to this problem.
0:33:29 > 0:33:33By sticking the tip of its tail into the sea cucumber's rear end...
0:33:34 > 0:33:38..the pearlfish cuts off its oxygen supply,
0:33:38 > 0:33:41knowing that the sea cucumber will have to open up
0:33:41 > 0:33:46to breathe eventually and when it does, it's home, sweet home.
0:33:47 > 0:33:51Pearlfish really have to be the worst tenants.
0:33:51 > 0:33:53But what's really weird, although, let's face it,
0:33:53 > 0:33:57what isn't weird about this story, is that the sea cucumber
0:33:57 > 0:34:01could evict the pearlfish if they really wanted to.
0:34:02 > 0:34:05If other fish come up and disturb a sea cucumber,
0:34:05 > 0:34:07it has a really great defence mechanism.
0:34:07 > 0:34:09What they'll do as a defence
0:34:09 > 0:34:13is spew their guts out through their bottoms.
0:34:13 > 0:34:17And this is to, basically, distract a predator that's coming along
0:34:17 > 0:34:19and then they can make their slow getaway.
0:34:19 > 0:34:21But this doesn't happen with the pearlfish.
0:34:21 > 0:34:25Somehow, they don't trigger this fear response in the sea cucumber.
0:34:25 > 0:34:29So, despite being armed with a gutsy defence, the hospitable
0:34:29 > 0:34:35sea cucumber lets the pearlfish stay, which isn't understood yet.
0:34:35 > 0:34:38But then, there's just no accounting for some behaviour.
0:34:42 > 0:34:47Crows that bring gifts, deserts that feed forests
0:34:47 > 0:34:52and sea cucumbers that put up with the very raw end of the deal.
0:34:52 > 0:34:57Nature, it seems, is most unremittingly generous.
0:34:57 > 0:35:00But sometimes, it's not accommodation or sustenance that it provides,
0:35:00 > 0:35:03it provides something altogether different.
0:35:03 > 0:35:05Inspiration.
0:35:06 > 0:35:12Our next story takes us to a very frozen Heathrow Airport.
0:35:12 > 0:35:15- NEWSREADER:- The drop in temperature has led to grounded planes being
0:35:15 > 0:35:17frozen into their parking stands,
0:35:17 > 0:35:20with the de-icer having little effect.
0:35:20 > 0:35:23Despite one runway being clear,
0:35:23 > 0:35:25there have been less than 10% of flights at Heathrow
0:35:25 > 0:35:30over the weekend, leaving 350,000 passengers stranded.
0:35:31 > 0:35:33Ice on grounded planes might cause misery
0:35:33 > 0:35:37for passengers heading off to sunnier climes,
0:35:37 > 0:35:40but ice forming mid-flight can be deadly.
0:35:42 > 0:35:46It's caused over 600 aviation accidents
0:35:46 > 0:35:50and more than 800 deaths in the United States alone.
0:35:50 > 0:35:54The danger occurs when ice forms on the wing, distorting
0:35:54 > 0:35:59its precise aerodynamic shape and causing the aircraft to lose lift.
0:36:00 > 0:36:05It's something that has troubled aviation engineers for years.
0:36:05 > 0:36:08The problem is that ice comes in many different forms.
0:36:08 > 0:36:14You can imagine freezing rain, snow, sleet, freezing fog or frost.
0:36:18 > 0:36:20What we wanted to make
0:36:20 > 0:36:22is a paint
0:36:22 > 0:36:25or surface for the airplane
0:36:25 > 0:36:28that releases antifreeze when it's exposed to ice.
0:36:29 > 0:36:32The current solution to ice build-up is for planes to take
0:36:32 > 0:36:35a shower in antifreeze before flight.
0:36:36 > 0:36:40The wings also have a highly water-repellent surface.
0:36:42 > 0:36:44But there is a problem.
0:36:44 > 0:36:50When the wings get really cold, the nonstick surfaces simply don't work.
0:36:54 > 0:36:58Imagine this strip of cardboard is an aeroplane wing.
0:36:58 > 0:37:03And just like the wing, it's been treated with a hydrophobic coating
0:37:03 > 0:37:05so the water just runs off.
0:37:08 > 0:37:11But as the surface temperature drops -
0:37:11 > 0:37:14we've used liquid nitrogen for the same effect -
0:37:14 > 0:37:18the water droplets act very differently.
0:37:18 > 0:37:21They stick and clump together
0:37:21 > 0:37:24and the geometry of the wing is radically changed.
0:37:25 > 0:37:28And this will affect its ability to generate lift.
0:37:29 > 0:37:32So, what else can be done to prevent this build-up?
0:37:33 > 0:37:35This is where Konrad comes in.
0:37:39 > 0:37:41In the past 20 or 30 years,
0:37:41 > 0:37:44people started looking at nature,
0:37:44 > 0:37:49to try to find inspiration for current technological problems.
0:37:49 > 0:37:54And he found his inspiration in a very unexpected place.
0:37:54 > 0:37:58My wife and I were on holiday in Panama.
0:38:01 > 0:38:04And we went on a jungle tour.
0:38:04 > 0:38:07As we were going to the jungle, the guide lifted up
0:38:07 > 0:38:12a leaf on a palm tree and there was a little poison dart frog.
0:38:14 > 0:38:17So I was very excited, started coming up close
0:38:17 > 0:38:20and tried to take a picture and he said, "No, don't come up.
0:38:20 > 0:38:23"These things are really dangerous."
0:38:23 > 0:38:27So at that point, I got very interested. Why are they dangerous?
0:38:27 > 0:38:31The reason is that their skin is covered in a potent neurotoxin.
0:38:37 > 0:38:40But it wasn't the poison that Konrad was interested in.
0:38:40 > 0:38:45It was how the frogs release it that sparked his imagination.
0:38:45 > 0:38:49They have little glands in their skin and when they're very scared,
0:38:49 > 0:38:52when they see a predator or a tourist,
0:38:52 > 0:38:55they start releasing or secreting this toxin from the inner part
0:38:55 > 0:38:59of the body onto the outside of the skin.
0:38:59 > 0:39:03We made a surface that mimicked the structure of the frog,
0:39:03 > 0:39:06that releases, in this case, an antifreeze, instead of a toxin.
0:39:08 > 0:39:11Thanks to the amphibians, Konrad and his team are developing
0:39:11 > 0:39:15a porous surface that mimics the frog's skin
0:39:15 > 0:39:18and releases antifreeze on demand.
0:39:21 > 0:39:27Who'd have thought that deadly frogs might one day save lives?
0:39:27 > 0:39:33It just goes to prove inspiration can be found in the weirdest places.
0:39:37 > 0:39:40The natural world can be surprisingly charitable.
0:39:42 > 0:39:46Crows showing their appreciation with presents,
0:39:46 > 0:39:52a barren desert providing a nutrient lifeline to a bountiful jungle
0:39:52 > 0:39:57and, of course, a marine animal offering shelter to the homeless.
0:40:06 > 0:40:09And finally, our walk on the weird side is going to take us
0:40:09 > 0:40:11from strange lights in the sky,
0:40:11 > 0:40:16to blind people with perfectly good vision,
0:40:16 > 0:40:19via a drunken octopus in a toilet.
0:40:20 > 0:40:23And it all starts in Florida.
0:40:45 > 0:40:49Despite the caller's distress, she wasn't witnessing a UFO.
0:40:50 > 0:40:54What that caller was seeing was a sun halo.
0:40:54 > 0:40:59So what's producing these extraordinary light shows?
0:41:00 > 0:41:03Well, it's actually something remarkably ordinary.
0:41:12 > 0:41:15The haloes are made by tiny ice crystals
0:41:15 > 0:41:18floating high up in the atmosphere,
0:41:18 > 0:41:21like this hexagonal crystal here.
0:41:22 > 0:41:24And when the sunlight passes through them,
0:41:24 > 0:41:29it refracts, or bends, to a very precise angle - 22 degrees -
0:41:29 > 0:41:34and it's this that produces these astonishing halos.
0:41:35 > 0:41:40It takes millions of these microscopic crystals
0:41:40 > 0:41:43randomly floating high in the cirrus clouds,
0:41:43 > 0:41:45each scattering the sun's rays
0:41:45 > 0:41:48and creating these perfect rings of light.
0:41:50 > 0:41:52But if you think that's strange,
0:41:52 > 0:41:56things are only going to get more bizarre.
0:41:59 > 0:42:00The Alps.
0:42:00 > 0:42:04Clear, cold, beautiful.
0:42:07 > 0:42:12For skiers making their way onto the slopes,
0:42:12 > 0:42:16their morning was about to take a turn for the weird.
0:42:20 > 0:42:24Because what was about to emerge from behind the peaks
0:42:24 > 0:42:27was far from a normal sunrise.
0:42:30 > 0:42:34It was a thrilling spectacle for all of those who witnessed it.
0:42:39 > 0:42:41This is no trick of the lens.
0:42:42 > 0:42:46Either side of the rising sun where two smaller
0:42:46 > 0:42:50but unmistakable mirror suns.
0:42:50 > 0:42:53And this isn't the only footage of such a spectacle.
0:42:54 > 0:42:59Strange sunrises and sunsets have been popping up all over the world.
0:43:06 > 0:43:12Now, the footage of these triple suns is absolutely startling stuff.
0:43:12 > 0:43:13But don't worry,
0:43:13 > 0:43:16our solar system is not morphing into a set from Star Wars.
0:43:16 > 0:43:18You might also be forgiven for thinking
0:43:18 > 0:43:20that it could be camera flare,
0:43:20 > 0:43:23cheap lenses or the like, but I can tell you that it's not.
0:43:26 > 0:43:30But whilst ice crystals are causing sun halos,
0:43:30 > 0:43:32what causes a triple sun...
0:43:33 > 0:43:37..a spectacle inexplicably known as a sun dog?
0:43:39 > 0:43:42Now, to get to the bottom of its formation,
0:43:42 > 0:43:45we need someone who is well acquainted with the sky.
0:43:45 > 0:43:47Being a professional astronomer,
0:43:47 > 0:43:50you end up with is this ingrained habit, where you are just
0:43:50 > 0:43:52keeping that weather eye in the sky -
0:43:52 > 0:43:55is it going to be cloudy tonight? How you going to be observing?
0:43:55 > 0:43:58And just noticing many of these phenomena.
0:44:04 > 0:44:08A sun halo is formed from the same ice crystals as sun dogs,
0:44:08 > 0:44:10but the difference is the orientation.
0:44:10 > 0:44:12Sun halos, you need just random orientations
0:44:12 > 0:44:15and all kinds of hexagonal ice crystals.
0:44:15 > 0:44:16But to get sun dogs,
0:44:16 > 0:44:19you need those ice crystals to be the flat tile-like ones
0:44:19 > 0:44:23that are all perfectly aligned, perhaps by currents that are shaping
0:44:23 > 0:44:27the clouds or the way that they are just drifting down in the sky.
0:44:27 > 0:44:31Because it's all on a level, you get two little rainbow patches.
0:44:31 > 0:44:35The sunlight is focused into areas the same distance out
0:44:35 > 0:44:38as the halo, but on a level with the sun.
0:44:38 > 0:44:42And it's much brighter and the colours are much more evident
0:44:42 > 0:44:44because you've got much more sunlight
0:44:44 > 0:44:46concentrated into those areas.
0:44:50 > 0:44:54So ice crystals are creating these spellbinding light shows, too.
0:44:56 > 0:44:58There is every chance you could have seen one...
0:45:00 > 0:45:03..but never looked up to glimpse it.
0:45:03 > 0:45:06Just think of what you're missing.
0:45:10 > 0:45:16So it's tiny ice crystals floating high up there in the atmosphere
0:45:16 > 0:45:20which produce these beautiful illusions of halos and triple suns.
0:45:20 > 0:45:23They really are very impressive.
0:45:23 > 0:45:26But, you know, when it comes to visual illusions,
0:45:26 > 0:45:30nothing at all can compete with the power of own minds.
0:45:34 > 0:45:36It's a slightly embarrassing story.
0:45:38 > 0:45:41It was in a bathroom stall in a public place.
0:45:46 > 0:45:48There was a little coat rack
0:45:48 > 0:45:51with the two little arms coming off of the coat rack.
0:45:51 > 0:45:53And underneath, it was written in magic marker,
0:45:53 > 0:45:55"drunk octopus wants to fight you."
0:45:59 > 0:46:01Once I looked up
0:46:01 > 0:46:02why I would recognise
0:46:02 > 0:46:06that that was an octopus and why that person expected that I would
0:46:06 > 0:46:11recognise it as an octopus is how I ended up interested in the topic.
0:46:12 > 0:46:15Laura is not alone in her octopus encounter.
0:46:16 > 0:46:18And it's not just coat hooks.
0:46:21 > 0:46:24We live our lives surrounded by expressions...
0:46:26 > 0:46:29..although some faces do seem to turn up more than others.
0:46:34 > 0:46:37And in the most unexpected places.
0:46:37 > 0:46:43In 1994, the Virgin Mary materialised in a grilled cheese sandwich.
0:46:44 > 0:46:48The edible effigy was eventually sold by its maker, Diane Duyser,
0:46:48 > 0:46:56for a whopping £14,000. That's one very expensive snack.
0:46:58 > 0:47:03But to this religious revelation was by no means a one-off.
0:47:06 > 0:47:09Jesus has appeared in a baking tray,
0:47:09 > 0:47:11a tortilla,
0:47:11 > 0:47:14and even the lid of a Marmite jar.
0:47:19 > 0:47:24It's not just deities in foodstuffs. We see faces everywhere.
0:47:24 > 0:47:29Even everyday objects sometimes seem to have an expression.
0:47:29 > 0:47:32And this phenomenon, finding faces in objects and places,
0:47:32 > 0:47:35even has a name. It's called pareidolia.
0:47:36 > 0:47:41And it's an area of serious scientific investigation.
0:47:47 > 0:47:51You can probably see the faces in this series of objects.
0:47:54 > 0:47:59But of course, we don't actually believe they are genuine faces.
0:47:59 > 0:48:02That's because of a region of the brain called the fusiform gyrus.
0:48:04 > 0:48:08It's working slightly differently in each side of your brain.
0:48:08 > 0:48:14The left side is suggesting that this object could be a face.
0:48:14 > 0:48:18But the right side is making the final decision.
0:48:18 > 0:48:22And in this case, no. It's just a plug socket.
0:48:25 > 0:48:30So, why is our first instinct to see a collection of shapes as a face?
0:48:33 > 0:48:35The reason that we try to take something
0:48:35 > 0:48:37and make it into something meaningful has to do with
0:48:37 > 0:48:41survival in the very earliest stages of evolution.
0:48:41 > 0:48:45Let's assume that you are out in the woods hunting and you hear
0:48:45 > 0:48:49something or you see something out of the corner of your eye.
0:48:50 > 0:48:53If there is not something there and you assume that there is,
0:48:53 > 0:48:56you'll react to it, but there's no harm done,
0:48:56 > 0:48:58if there wasn't actually something there.
0:48:58 > 0:49:01So conjuring up faces, real or otherwise,
0:49:01 > 0:49:04is about avoiding predators and staying alive.
0:49:06 > 0:49:11But that doesn't explain why we see so many messiahs.
0:49:11 > 0:49:12Our brain is always interpreting
0:49:12 > 0:49:14the information that we get from the world
0:49:14 > 0:49:17to be things that it recognises and can make sense of.
0:49:18 > 0:49:20The things that we're most familiar with
0:49:20 > 0:49:25or that we're expecting to see, like religion, like sex,
0:49:25 > 0:49:29will be the sort of things that we tend to notice more often.
0:49:33 > 0:49:35Well, that explains that cheesy conundrum.
0:49:35 > 0:49:38But exactly how long does it take us to develop
0:49:38 > 0:49:41this remarkable ability to recognise faces?
0:49:41 > 0:49:43A study at Stanford University
0:49:43 > 0:49:45produced some very surprising results.
0:49:48 > 0:49:52Babies. Cute? Well, sometimes.
0:49:52 > 0:49:56Clever? Well, perhaps not straightaway.
0:49:56 > 0:50:00You see, when it comes to making out the world around them,
0:50:00 > 0:50:03babies struggle to focus, identify colours,
0:50:03 > 0:50:08and even see beyond 30 centimetres during the first few months.
0:50:09 > 0:50:13So, all things considered, you might not expect these little brains
0:50:13 > 0:50:17to be very good when it comes to picking out a face.
0:50:20 > 0:50:24Faces are critical for all of us, but especially for babies.
0:50:28 > 0:50:29Faces are important
0:50:29 > 0:50:32for understanding emotion,
0:50:32 > 0:50:35being able to recognise different forms of expression,
0:50:35 > 0:50:38when your mom is happy, maybe when your mom is mad, comes from a face.
0:50:41 > 0:50:44Faraz's research has been looking into how soon
0:50:44 > 0:50:46babies can recognise a face.
0:50:48 > 0:50:50Using this harmless cap of sensors,
0:50:50 > 0:50:54she can monitor the electrical impulses in baby Ava's brain...
0:50:56 > 0:51:00to see how she responds to pictures of faces
0:51:00 > 0:51:04compared to inanimate objects.
0:51:04 > 0:51:05What do you see?
0:51:06 > 0:51:08What is that?
0:51:08 > 0:51:11The team compared the babies' responses
0:51:11 > 0:51:15to the same set of tests run in adults.
0:51:15 > 0:51:19We recognise faces through a process beginning with the basic
0:51:19 > 0:51:24contrast of the face, the lines of the face and we piece
0:51:24 > 0:51:28the information together, until we arrive at the temporal lobe.
0:51:28 > 0:51:32And the temporal lobe of the brain actually has specific cells
0:51:32 > 0:51:34that respond to faces.
0:51:36 > 0:51:39Given the immaturity of the babies' brains, the team weren't
0:51:39 > 0:51:45expecting them to be capable of complex adult-level processing.
0:51:45 > 0:51:48But their results proved very surprising.
0:51:48 > 0:51:50What we found was really interesting.
0:51:50 > 0:51:55Infants responded to faces the same way that adults respond to faces.
0:51:55 > 0:51:56The area of the brain that lit up
0:51:56 > 0:51:59when we show them the faces were very similar.
0:51:59 > 0:52:03It was in the temporal region of the brain that we know processes faces.
0:52:03 > 0:52:07So, if babies have a maturity beyond their years
0:52:07 > 0:52:11when it comes to facial recognition, has science got it wrong
0:52:11 > 0:52:12all this time?
0:52:12 > 0:52:17Are infants, in fact, very good at making out the world around them?
0:52:17 > 0:52:19Well, no. Unfortunately not.
0:52:19 > 0:52:22You see, when it comes to making out objects,
0:52:22 > 0:52:25babies still have an underdeveloped response.
0:52:25 > 0:52:31It's only the region responsible for making out faces which is advanced.
0:52:31 > 0:52:35Faces are such an important part of our lives that we have become
0:52:35 > 0:52:37tuned to seeing them in the world around us.
0:52:42 > 0:52:44Most of us have no trouble at all
0:52:44 > 0:52:47picking out a familiar face in a crowd.
0:52:47 > 0:52:53In fact, you could say that facial recognition is perhaps our one
0:52:53 > 0:52:56and only true human superpower.
0:52:56 > 0:52:58You see, during our lifetime,
0:52:58 > 0:53:01we have the staggering ability to remember
0:53:01 > 0:53:05no less than 10,000 different faces.
0:53:06 > 0:53:10It's remarkable, but it also begs the question, what happens
0:53:10 > 0:53:15when the facial recognition areas of our brain don't work properly?
0:53:15 > 0:53:18The answer can be found in Vermont.
0:53:19 > 0:53:22I just thought I was bad at remembering people.
0:53:22 > 0:53:24Sometimes, I can't tell who is in the picture.
0:53:24 > 0:53:28If there is just one of them, I have to ask Scott, "Which one is this?"
0:53:28 > 0:53:32If they're not wearing a piece of clothing that helps me
0:53:32 > 0:53:34or something else.
0:53:36 > 0:53:37Meet Karen Macaller.
0:53:39 > 0:53:42It's funny that we have so many pictures of them,
0:53:42 > 0:53:43since I can't tell them apart.
0:53:44 > 0:53:48She struggles to recognise her own children -
0:53:48 > 0:53:51Max and Emmy.
0:53:52 > 0:53:56Now, you might be thinking that Karen is short-sighted.
0:53:56 > 0:53:59When I am looking at sets of pictures,
0:53:59 > 0:54:02I can really be looking very carefully at everybody's nose
0:54:02 > 0:54:04and trying to find, like, the nose that's most like
0:54:04 > 0:54:06that person's nose.
0:54:06 > 0:54:09And I can see all the noses and I can see some are wider
0:54:09 > 0:54:10and all those things.
0:54:12 > 0:54:17Despite her keen observation, Karen isn't obsessed with noses.
0:54:17 > 0:54:20She is, in fact, face blind.
0:54:20 > 0:54:23So, it's not like there's a big blurry patch where your face is.
0:54:23 > 0:54:24I can see your face.
0:54:24 > 0:54:28I can see that you have a nose and eyebrows and all those things
0:54:28 > 0:54:31but then, if I look at another person,
0:54:31 > 0:54:33I can see they also have a nose and eyebrows
0:54:33 > 0:54:37but they don't all come together to mean something,
0:54:37 > 0:54:38to look like someone.
0:54:38 > 0:54:41Wondering what faces look like to Karen?
0:54:41 > 0:54:44Well, try identifying these two images.
0:54:44 > 0:54:48You can see the facial features of each, but it's not easy
0:54:48 > 0:54:52to piece them together, to actually recognise the faces.
0:54:54 > 0:54:56Until you turn them the right way up.
0:54:59 > 0:55:03Curiously, Karen only discovered that she was face blind
0:55:03 > 0:55:04relatively recently.
0:55:07 > 0:55:12I had not realised that other people perceive faces differently.
0:55:12 > 0:55:14It was maybe, like, three years ago.
0:55:14 > 0:55:16There was something on TV - they showed some examples of,
0:55:16 > 0:55:20like, "people who are face blind can't tell these two people apart."
0:55:20 > 0:55:22And I was looking at them
0:55:22 > 0:55:25and saying "that's the same person" and my husband, who is watching
0:55:25 > 0:55:28with me, was saying "No, that's not even close to being
0:55:28 > 0:55:29"the same person."
0:55:32 > 0:55:36It was an image like this one that highlighted Karen's condition.
0:55:38 > 0:55:42Most of us can see that, whilst the two images are similar,
0:55:42 > 0:55:45they are, of course, different people.
0:55:47 > 0:55:49For those with face blindness,
0:55:49 > 0:55:53it proves almost impossible to distinguish between the two.
0:55:56 > 0:56:00The condition is known medically as prosopagnosia,
0:56:00 > 0:56:02and a surprising number of people are affected.
0:56:04 > 0:56:09Although most, like Karen, never even know they have it.
0:56:10 > 0:56:13Often what happens is, they have an incident that really
0:56:13 > 0:56:16slaps them in the face, so to speak, showing them that
0:56:16 > 0:56:20their face recognition is really different from somebody else's.
0:56:22 > 0:56:25Prosopagnosics have told me things like they would, say,
0:56:25 > 0:56:28watch a movie where there's a line-up and the eyewitness is
0:56:28 > 0:56:31supposed to pick out the person who committed the crime.
0:56:31 > 0:56:34And the prosopagnosic says, "That's absurd. Nobody could do that.
0:56:34 > 0:56:37"You'd have to have superpowers to do that sort of thing."
0:56:39 > 0:56:43The best estimate out there suggest that maybe 2% of the population,
0:56:43 > 0:56:47so one out of 50 people, has really significant difficulties
0:56:47 > 0:56:50with face recognition.
0:56:50 > 0:56:53There are some people out there who, I'm sure, never realise
0:56:53 > 0:56:57that they have really significant face recognition problems.
0:56:58 > 0:57:02Just imagine a life where you couldn't instantly recognise
0:57:02 > 0:57:04actors in the latest blockbuster,
0:57:04 > 0:57:07your work colleagues or even members of your own family.
0:57:07 > 0:57:11And you didn't realise that life could be any different.
0:57:11 > 0:57:13It's one of those tectonic shifts in your brain,
0:57:13 > 0:57:16where you think, like, "I understand how I work
0:57:16 > 0:57:18"and I understand how the world works"
0:57:18 > 0:57:20and then you find out something new
0:57:20 > 0:57:22and it's very different than how you thought it was.
0:57:27 > 0:57:31From ice crystals with the power to create hysteria...
0:57:33 > 0:57:37..survival by seeing faces in sandwiches...
0:57:37 > 0:57:41and not seeing faces at all,
0:57:41 > 0:57:43in a weird world,
0:57:43 > 0:57:49what seems an illusion can often be explained by cold, hard facts.
0:57:54 > 0:57:58What a world of weirdery we live in! And do you know?
0:57:58 > 0:58:00It's only going to get weirder.
0:58:02 > 0:58:03Next time...
0:58:05 > 0:58:08What caused a glacier to flow blood-red?
0:58:08 > 0:58:11I've never seen anything like it before.
0:58:11 > 0:58:14And why did frogs start growing too many limbs?
0:58:16 > 0:58:19What could possibly create this weird work of art?
0:58:20 > 0:58:24And what is lurking in this South American mud?
0:58:24 > 0:58:27If that didn't exist and as I said it could exist,
0:58:27 > 0:58:29you would never believe me, right?