BBC.Wonders.of.Life.2of5.Expanding.Universe
Category
📺
TVTranscript
00:00These are the waters of Catalina, a tiny island 20 miles off the coast of Los Angeles, California.
00:18These are kelp forests. They grow here in tremendous abundance because the waters here around Catalina are extremely rich in nutrients.
00:33That's because of the California current, which brings this beautiful, rich, cold water up from the depths of the Pacific and allows this tremendously rich ecosystem to grow.
00:48It's a remarkable place.
00:56Oh, look!
00:58And I'm not here to marvel at these kelp forests, beautiful as they are.
01:20I'm here to search for a little animal that lives not in this forest of nutrients, but out there in the muddy ocean floor.
01:30There he is, look!
01:53Camouflaged in its burrow on the seafloor, the mantis shrimp is a seemingly unremarkable creature.
02:04It's not a real shrimp, but a type of crustacean called a stomatopod.
02:10I've come to see it because in one way, the mantis shrimp is truly extraordinary.
02:17The way it detects the world.
02:23You see those big eyes in the sea?
02:30These are some of the most sophisticated eyes in the natural world.
02:37Each is made up of over 10,000 hexagonal lenses.
02:42And with twice as many visual pigments as any other animal, it can see colors and wavelengths of light that are invisible to me.
02:53These remarkable eyes give the mantis shrimp a unique view of the ocean.
02:59And this is just one of the many finely tuned senses that have evolved across the planet.
03:06Sensing the ability to detect and to react to the world outside is fundamental to life.
03:13Every living thing is able to respond to its environment.
03:18In this film, I want to show you how the senses developed.
03:23How the mechanisms that gather information about the outside world evolved.
03:27How their emergence has helped animals thrive in different environments.
03:32And how the senses have pushed life in new directions and may ultimately have led to our own curiosity and intelligence.
04:27These are the woods of Kentucky.
04:47The first stop on a journey across America that will take me from the far west coast to the Atlantic through the heart of the country.
04:58It's the animals that I'll find on the way that will illuminate the world of the senses.
05:06And I'm going to start by going deep underground.
05:10These are the mammoth caves in Kentucky.
05:25With over 300 miles of mapped passages, they're the longest cave system in the world.
05:41But this is also the place to start exploring our own senses.
05:47We're normally dependent on our sight, but down here in the darkness, it's a very different world.
05:54And I have to rely on my other senses to build a picture of my environment.
06:00It's completely dark in this cave. I can't see anything at all.
06:09You can see me because we're lighting it with infrared light.
06:14And that's at a wavelength that my eyes are completely insensitive to.
06:18So as far as I'm concerned, it is pitch black.
06:23And because it's so dark, your other senses become heightened, particularly hearing.
06:33It's virtually silent in here.
06:39But if you listen carefully, you can just hear the faint drop of water from somewhere deep in the cave system.
06:51You'd never hear that if the cave were illuminated.
06:55But you focus on your hearing when it's as dark as this.
07:00Now, as well as sight and hearing, we have, of course, a range of other senses.
07:06There's touch, which is really a mixture of sensations, temperature and pressure and pain.
07:13And then there are chemical senses, so smell and taste.
07:18And we share those senses with almost every living thing on the planet today.
07:23Because they date back virtually to the beginning of life on Earth.
07:39And even here, in water that's been collected from deep within a cave,
07:44there are organisms that are still alive.
07:47And even here, in water that's been collected from deep within a cave,
07:52there are organisms that are detecting and responding to their environment
07:57in the same way that living things have been doing for over a billion years.
08:18Ah, there it is.
08:22Now that is a paramecium.
08:25It may look like a simple animal, but in fact it's a member of a group of organisms called protists.
08:33And you'd have to go back around two billion years to find a common ancestor.
08:38Paramecia have probably changed little in the last billion years.
08:45And although they appear simple, these tiny creatures display some remarkably complex behaviour.
08:52They have a very unique sense of smell.
08:56They have a very unique sense of taste.
09:00They have a very unique sense of smell.
09:03Although they appear simple, these tiny creatures display some remarkably complex behaviour.
09:11You can even see them responding to their environment.
09:16The cell swims around, powered by a cohort of cilia.
09:20Tiny hairs embedded in the cell membrane.
09:24If it bumps into something, the cilia change direction and it reverses away.
09:33They're clearly demonstrating a sense of touch.
09:41Even though they're single-celled organisms, they have no central nervous system,
09:47they can still do what all life does.
09:50They can sense their environment, and they can react to it.
09:54And they do that using electricity.
10:06The mechanism that powers the paramecium's touch response lies at the heart of all sensing in animals.
10:13And it's based on an electrical phenomenon, phytonutrients.
10:17And it's based on an electrical phenomenon found throughout nature.
10:24An electric current is a flow of electric charge.
10:28And for that to happen, you need an imbalance between positive and negative charges.
10:33Now, usually in nature, things are electrically neutral.
10:37The positive and negative charges exactly balance out.
10:41But there are natural phenomena in which there is a separation of electric charge.
10:47A thunderstorm, for example.
10:51As thunderclouds build, updrafts within them separate charge.
10:57The lighter ice and water crystals become positively charged and are carried upwards,
11:02while the heavier, negatively charged crystals sink to the bottom.
11:08This can create a potential difference,
11:11a voltage between the cloud and the ground of as much as 100 million volts.
11:18Now, nature abhors a gradient.
11:23It doesn't like an imbalance, and it tries to correct it by having an electric current flow.
11:29In the case of a thunderstorm, that's a bolt of lightning.
11:48And it's the same process that governs the paramecium's behaviour, but on a tiny scale.
11:56In common with virtually all other cells, and certainly all animal cells,
12:01the paramecium maintains a potential difference across its cell membrane.
12:07And it does that, in common with a thunderstorm, by charge separation.
12:11By manipulating the number of positive ions inside and outside its membrane,
12:16the paramecium creates a potential difference of just 40 millivolts.
12:23So when a paramecium is just sat there, not bumping into anything, floating in this liquid,
12:29then it's like a little battery.
12:32It's maintaining a potential difference across its cell membrane.
12:35And it can use that to sense its surroundings.
12:40When it bumps into something, its cell membrane deforms,
12:44opening channels that allow positive ions to flood back across the membrane.
12:50As the potential difference falls, it sets off an electrical pulse
12:55that triggers the cilia to start beating in the opposite direction.
12:59That electrical pulse spreads around the whole cell in a wave called an action potential.
13:07And the paramecium reverses out of trouble.
13:13Now, this ability to precisely control flows of electric charge across a membrane
13:20is not something that can be done by humans.
13:22Now, this ability to precisely control flows of electric charge across a membrane
13:29is not unique to the paramecium.
13:32It actually lies at the heart of all animal senses.
13:36In fact, every time I sense anything in the world with my eyes, with my ears, or with my fingers,
13:43at some point between that sensation and my brain,
13:48something very similar to that will happen.
13:52And that's what the paramecium does.
14:07Although the same electrical mechanism underpins all sensing,
14:12every animal has a different suite of sensory capabilities
14:17that is beautifully adapted to the environment it lives in.
14:22This is the Big Black River, a tributary of the mighty Mississippi in America's deep south.
14:33And these dark and murky waters are home to a ferocious predator.
14:43Even though it's impossible to see more than a couple of inches through the water,
14:47this predator has found a way to track down and catch its prey with terrifying efficiency.
14:53To help me catch one, I've enlisted the support of wildlife biologist, Don Jackson.
14:58Don,
15:00come on!
15:02Come on!
15:05Don,
15:08come on!
15:11Don!
15:13Don!
15:14Don!
15:16Don!
15:20Don!
15:21see
15:42you're gonna wrestle it to me
15:51there you go he can bite
16:04we'll show you the mouth of this thing head on so you can see what the prey sees when he comes
16:13anything that'll fit in that mouth he'll grab it and yeah and uh you can hold him if you just
16:17want to put your hands all the way under him come all the way all the way hold him up close to you
16:22yeah how about that got him yeah
16:30this is the top predator in this river this is a what a 25 pound flathead catfish you see those
16:38protrusions from it from his head those are barbels they sense vibration in the mud at the
16:45on the riverbed but the most interesting thing about the catfish is that she really is in some
16:51ways one big tongue there are taste sensors covering every every part of her body and she
16:57can build up a three-dimensional picture of the river by detecting the chemical scents of animals
17:04so her eyes are not much use as you can see this river is extremely muddy but it's the sense of
17:09taste that does the job of building up a picture of the world and that's how he hunts and he weighs a ton
17:22oh i can feel those teeth ow i'm gonna let go all right you go on
17:29wow
17:35the sensory world of the catfish is a remarkable one
17:40its map of its universe is built from the thousands of chemicals that can detect in the water
17:46a swirling mix of tastes and concentrations
17:50flavors and gradients it's a world we can hardly imagine
17:59there's an interesting almost philosophical point here because it's easy to imagine that we humans
18:06perceive the world in some kind of objective way but that's not the case at all you think about
18:12the catfish the catfish sees the world as a kind of swarm of chemicals in the river or vibrations
18:19on the riverbed whereas we see the world as reflected light off the forest and i can hear
18:25the sounds of animals out there somewhere in the undergrowth catfish sees the world
18:30completely differently so the way you perceive the world is determined by your environment
18:37and no two animals see the world in the same way
18:43so
18:53like every animal we have evolved the senses that enable us to live in our environment
19:05but as well as equipping us for the present those senses can also tell us about our past
19:14um
19:18now we have a sense of touch like the paramecium and we have the chemical senses taste and smell
19:25like the catfish but for us the dominant senses are hearing and sight and to understand them
19:33we first have to understand our evolutionary history
19:50and that's why i'm in the mojave desert in california
19:54to track down an animal that can tell us something about the origins of our own senses
20:11the creature i'm looking for is easiest to find in the dark using ultraviolet light
20:23so
20:33man did you see that
20:39look at that absolutely bizarre glowing absolutely bright green
20:44nobody has any idea what evolutionary advantage that confers
20:50although they now live in some of the driest most hostile environments on earth
20:55like here in the desert scorpions evolved as aquatic predators
21:00before emerging onto the land about 380 million years ago
21:08they've adapted to be able to survive the extreme heat and can go for over a year without food or
21:14and despite their fearsome reputation 98% of scorpion species have a sting that is no worse than a bee's
21:26but perhaps the most fascinating thing about scorpions from an evolutionary perspective
21:31is the way that they catch their prey you see that he spreads his legs out on the surface of the sand
21:39he spreads his legs out on the surface of the sand
21:43and that's because he uses his legs to detect vibrations
21:53scorpions hunt insects like this beetle it's almost impossible to see them in the dark
22:01so the scorpion has evolved another way to track them down by adapting its sense of touch
22:10as the insect's feet move across the sand they set off tiny waves of vibration through the ground
22:21if just a single grain of sand is disturbed within range of the scorpion
22:26it will sense it through the tips of its legs
22:29they can detect vibrations that are around the size of a single atom as they sweep past
22:45by measuring the time delay between the waves arriving at each of its feet
22:50the scorpion can calculate the precise direction and distance to its prey
23:29so
23:39now that ability to detect vibrations and use them to build up a picture
23:44of our surroundings is something that we share with scorpions
23:54while the scorpion has adapted its sense of touch to detect vibrations in the ground
24:00we use a very similar system to detect the tiny vibrations in air that we call sound
24:08and like the scorpions ours is a remarkably sensitive system
24:14our ears can hear sounds over a huge range
24:23we can detect sound waves of very low frequency at the base end of the spectrum
24:30but we can also hear much higher pitch sounds
24:35sounds with frequencies hundreds or even a thousand times greater
24:43and we can detect huge changes in sound intensity
24:51from the delicate buzzing created by an insect's flapping wings
25:00to the roar of an engine which can be a hundred million times louder
25:14the story of how we developed our ability to hear is one of the great examples of evolution in action
25:22because the first animals to crawl out of the water onto the land
25:26would have had great difficulty hearing anything in their new environment
25:39these are the everglades
25:45a vast area of swamps and wetlands that has covered the southern tip of florida
25:50for over 4 000 years
26:08through the creatures we find here like the american alligator a member of the crocodile
26:13family we can trace this story of how our hearing developed as we emerged onto the land
26:21so
26:26and it starts below the water with the fish
26:31if you're a fish then hearing isn't a problem you live in water and you're made of water
26:37so sound has no problem at all traveling from the outside to the inside but when life emerged
26:44from the oceans onto the land and hearing became a big problem see sound doesn't travel well from
26:52air into water if i make a noise now and over 99.9 percent of the sound is reflected back
27:01off the surface of the water it's because of that reflection that under water you can hear
27:09from above the surface and it's exactly the same problem that our ears face
27:15because they too are filled with fluid
27:19so if evolution hadn't found an ingenious solution
27:23to the problem of getting sound from air into water then i wouldn't be able to hear anything at all
27:33and that solution relies on some of the most delicate moving parts in the human body
27:39if i just drop them give them a second oh i've done it again bloody hell idiot just flipped out
27:55these are the smallest three bones in the human body called the malleus the incus and the stapes
28:02and they sit between the eardrum and the entrance to your inner ear to the place
28:10where the fluid sits the bones help to channel sound into the ear through two mechanisms
28:19first they act as a series of levers magnifying the movement of the eardrum
28:25and second because the surface area of the eardrum is 17 times greater than the footprint
28:35of the stapes the vibrations are passed into the inner ear with much greater force
28:42and that has a dramatic effect rather than 99.9 percent of the sound energy being reflected
28:50away it turns out that with this arrangement 60 percent of the sound energy is passed from the
28:57eardrum into the inner ear now this setup is so intricate and so efficient that it almost looks
29:05as if these bones could only ever have been for this purpose but in fact you can see their origin
29:14if you look way back in our evolutionary history
29:25in order to understand where that collection of small bones in our ears came from you have to go
29:30back in our evolutionary family tree way beyond the fish that we see today in fact back around
29:38530 million years to when the oceans were populated with jawless fish called anathans
29:45they're similar to the modern lamprey now they didn't have a jaw but they had gills supported
29:53by gill arches now over a period of around 50 million years the most forward of those gill
30:01migrated forward in the head to form jaws and you see fish like these the first jawed fish
30:12in the fossil record around 460 million years ago and there at the back of the jaw
30:20there is that bone the higher mandibular supporting the rear of the jaw then around
30:27400 million years ago the first vertebrates made the journey from the sea to the land their fins
30:34became legs but in their skull and throat other changes were happening the gills were no longer
30:41needed to breathe the oxygen in the atmosphere and so they faded away and became different
30:48structures in the head and throat and that bone the hyomandibular became smaller and smaller
30:57until its function changed it now was responsible for picking up vibrations in the jaw
31:06and transmitting them to the inner ear of the reptiles and that is still true today
31:13of our friends over there the crocodiles
31:26once more with alligator
31:31but even then the process continued around 210 million years ago the first mammals evolved
31:40and unlike our friends the reptiles here mammals have a jaw that's made of only one bone a reptile
31:49jaw is made of several bones fused together so that freed up two bones which moved and shrank
32:00and eventually became the malleus the incus and stapes so this is the origin of those three
32:12tiny bones that are so important to mammalian hearing
32:22they're quite big isn't it
32:30so
32:52i think this is a most wonderful example of the blind undirected ingenuity of evolution that
32:59it's taken the bones in gills of fish and converted them into the intricate structures
33:05inside my ears that efficiently allow sound to be transmitted from air into fluid it's a
33:13remarkable thought that to fully understand the form and function of my ears you have to
33:18understand my distant evolutionary past in the oceans of ancient earth
33:26so
33:46all sensing has evolved to fulfill one simple function
33:50to provide us with the specific information we need to survive
33:54and nowhere is that clearer than in the sense of vision
34:10almost all animals can see 96% of animal species have eyes but what those eyes see
34:22but what those eyes see varies enormously
34:27so with an animal like the mantis shrimp you have to ask what it is
34:32about its way of life that demands such a complex visual system
34:42i'm gonna be very quick and very careful with this let him out
34:51the complex structure of the mantis shrimp's eyes give it incredibly precise depth perception
35:00we have binocular vision we look with two eyes from slightly different angles
35:06and judge distance by comparing the differences between the two images
35:11each of the mantis shrimp's eyes has trinocular vision each eye takes three separate images of
35:20the same object comparing all three gives them exceptionally precise range finding
35:28and they need that information to hunt their prey
35:35despite appearances he's a dangerous animal he has one of the hardest punches in nature those
35:43yellow appendages you can see on the front of his body are called raptoral appendages they're
35:48actually highly evolved front legs and they can punch with tremendous force
35:58the mantis shrimp's punch is one of the fastest movements in the animal world
36:05slowed down by over a thousand times we can clearly see its power
36:12it can release its legs with the force of a bullet
36:15in the wild they use that punch to break through the shells of their prey
36:21but it could easily break my finger
36:26the need to precisely deploy this formidable weapon
36:30is one of the reasons the mantis shrimp has developed its complex range finding ability
36:35and that punch can also help explain their sophisticated color vision
36:41because the colored flashes on their body warn other mantis shrimp that they may be about to
36:46attack while other color signals have a quite different meaning
36:53and yet reading these signals in the ocean can be surprisingly difficult
36:58in the deep ocean colors shift from minute to minute from hour to hour with change in lighting
37:04conditions changing conditions in the ocean but it's thought that even though the light
37:08quality can change tremendously the mantis shrimp can still identify specific colors very accurately
37:15because of their sophisticated eyes they're able to see very clearly what's going on
37:21the mantis shrimp's eyes are beautifully tuned to their needs
37:26but they're very different from our eyes with their thousands of lenses and complex color vision
37:32they have a completely different way of viewing the world
37:37and yet there's strong evidence that the mantis shrimp can still
37:41identify specific colors very accurately because of their sophisticated eyes
37:51mantis shrimp's eyes and ours share a common origin
37:58because on a molecular level every eye in the world works in the same way
38:16in order to form an image of the world then obviously the first thing you have to do
38:21is detect light and i have a sample here of the molecules that do that that detect light
38:30in my eye it's actually specifically the molecules that's in the black and white
38:35receptor cells in my eyes the rods it's called redoxin and the moment i expose this to light
38:43you'll see an immediate physical change
38:50there you go can you see that it was very quick it came out very pink indeed
38:56and it immediately went yellow this subtle shift in color is caused by the redoxin molecule
39:03changing shape as it absorbs the light in my eye is what happens is that change in structure
39:11triggers an electrical signal which ultimately goes all the way to my brain
39:16which forms an image of the world
39:21it's this chemical reaction that's responsible for all vision on the planet
39:28closely related molecules lie at the heart of every animal eye
39:34and that tells us that this must be a very ancient mechanism
39:42to find its origins we must find a common ancestor that links every organism that uses redoxin today
39:51we know that common ancestor must have lived before all animals evolutionary lines diverged
39:58but it may have lived at any time before then
40:04so what is that common ancestor well here's where we approach the cutting edge of scientific
40:09research the answer is that we don't know for sure but a clue might be found here in these little
40:19green blobs which are actually colonies of algae algae called volvox
40:28we have very little in common with algae we've been separated in evolutionary terms for over a
40:34billion years but we do share one surprising similarity these volvox have light sensitive
40:43cells that control their movement and the active ingredient of those cells is a form of redoxin
40:51so similar to our own that it's thought they may share a common origin
40:56so what does that mean does it mean that we share a common ancestor with the algae
41:06and in that common ancestor the seeds of vision can be found
41:14to find a source that may have passed this ability to detect light to both
41:18us and the algae we need to go much further back down the evolutionary train
41:26to organisms like cyanobacteria they were among the first living things to evolve on the planet
41:35and it's thought that the original redoxins may have developed in these ancient photosynthetic cells
41:45so the origin of my ability to see may have been well over a billion years ago
41:53in an organism as seemingly simple as a cyanobacterium
42:08the basic chemistry of vision may have been established for a long time but it's a long way
42:13from that chemical reaction to a fully functioning eye that can create an image of the world
42:23the eye is a tremendously complex piece of machinery built from lots of interdependent
42:28parts and it seems very difficult to imagine how that could have evolved in a series of small steps
42:35but actually we understand that process very well indeed i can show you by building an eye
42:53so the first step in building an eye would be to take some kind of light sensitive pigment
42:59redoxin for example and build it onto a membrane so imagine this is such a membrane with the
43:06pigment cells attached then immediately you have something that can detect the difference between
43:12dark and light now the advantage of this arrangement is that it's very sensitive to light
43:19there's no paraphernalia in front of the retina to block light but the disadvantage as you can see
43:27is that there's no image formed at all it just allows you to tell the difference between light
43:32and dark but you can improve that a lot by adding an aperture a small hole in front of the retina
43:43so this is a movable aperture just like the sort of thing you've got in your camera
43:49and now you see that the image gets sharper
43:56but the problem is that in order to make it sharper you have to narrow down the aperture
44:02and that means that you get less and less light so this eye becomes less and less sensitive
44:08so there's one more improvement that nature made which is to replace the pinhole the simple aperture
44:19with a lens
44:27look at that a beautifully sharp image
44:33the lens is the crowning glory of the evolution of the eye
44:38by bending light onto the retina it allows the aperture to be opened
44:43letting more light into the eye and a bright detailed image is formed
45:02so our eyes are called camera eyes because like a camera they consist of a single lens
45:11that bends the light onto the photoreceptor to create a high quality image of the world
45:19but that has a potential drawback because to make sense of all that information
45:24we need to be able to process it each one of my eyes contains over 100 million
45:30individual photoreceptor cells i mean that's about five or ten times the number in the average
45:35digital camera so if my visual system worked by just taking a series of individual still images
45:43of the world and transmitting all that information to my brain then my brain would be overwhelmed
45:48it's just not practical so that's not what animals do instead their visual systems have evolved
45:56to extract only the information that's necessary
46:04and this is wonderfully illustrated in the toad
46:10the toad has eyes that are structurally very similar to ours
46:16but much of the time it's as if it isn't seeing anything at all
46:21it seems completely oblivious to its surroundings
46:26until something like a mealworm takes its interest
46:32if you think about what's important to a toad visually then it's the approach of either prey
46:38or predators so the toad's visual system is optimized to detect them so there we put a worm
46:48in front of the toad and did you see that incredibly quickly the toad ate the worm
46:55as soon as the mealworm wriggles in front of the toad its eyes lock onto its target
47:02then it strikes in a fraction of a second
47:09it's an astonishingly precise reaction but it's also a very simple one
47:15because the toad is only focusing on one property of the mealworm the way it moves
47:24so
47:29these 1970s lab tests show how a toad will try and eat anything long and thin
47:35but only if it moves on its side like a worm
47:41and that's because the toad has neural circuits in its retina that only respond to lengthwise motion
47:48if instead the target is rotated into an upright position the toad doesn't respond at all
48:09at first sight the visual system of the toad seems a little bit primitive and imperfect
48:16and it is true if you put a toad in a tank full of dead worms it'll starve to death because
48:22they're not moving so it doesn't recognize them as food but it doesn't need to see the world in
48:29all the detail that i see it what it needs to focus on is movement because if it can see movement
48:35then it can survive because it can avoid predators and it can eat its prey i suppose in a sense if it
48:42moves like a worm in nature then it's likely to be a worm
48:58this ability to simplify the visual world into the most relevant bits of information
49:04is something that every animal does we do it all the time we also have visual systems that detect
49:12motion others identify edges and faces but extracting more information takes more processing
49:21power that requires a bigger brain and to see the results of this evolutionary drive
49:28towards greater processing power i've come to the heart of metropolitan florida
49:35you know it may not look like it but underneath this flyover just out in the shallow water
49:40it's one of the best places in the world to find particularly interesting animals
49:47it's an animal that's evolved to make the most of the information its eyes can provide
49:59well what we're going to do is try and hunt for some octopus
50:04and it's um as you say in physics non-trivial
50:11because they develop a beautiful way of camouflaging themselves
50:19they change color their cells in their skin they change color
50:23to match their surroundings stability that we don't possess of course it makes it difficult to find
50:33so
50:55i don't know where he is he's hiding somewhere in there
51:04look at those colors what a remarkable creature
51:12although the octopus is a mollusk like slugs and snails in many ways it seems more similar to us
51:22it's believed to be the most intelligent invertebrate
51:25mikey holding his fists up look at that its brain contains about 500 million nerve cells
51:34about the same as a dog's what are you doing
51:41you know if you want an example of an alien intelligence here on earth
51:46that must surely be it and it's used that brain to develop some remarkable abilities
51:55so it's become a skilled mimic it can rapidly change not only its color
52:02but its shape to match the background
52:19some species even do impressions of other animals
52:25so
52:30they become cunning predators and adapt problem solvers
52:37they've even been reported to use tools
52:42all these skills are signs of great intelligence but they also rely on an acute sense of vision
52:55checking us out camera eyes just like mine and they're vitally important for allowing the octopus
53:04to live the lifestyle it does a visual animal in the same way that i'm a visual animal
53:15the octopus is one of the only invertebrates to have complex camera eyes
53:19like our eyes they capture detailed images of the world
53:24and their brains have evolved to be able to extract the most information from those images
53:33the optic lobes make up about 30 percent of the octopus's brain
53:38the only other group that is known to devote so much of its brain to visual processing
53:43is our group the primates the most intelligent vertebrates
53:51and i think it's a fascinating thought that intelligence is a result of the need to process
53:58all the information from those big complex eyes
54:06what's so compelling about the octopus's intelligence
54:10what's so compelling about the octopus's intelligence
54:14is that it evolves completely separately to ours
54:19we last shared a common ancestor 600 million years ago an ancestor that had neither eyes nor a brain
54:29but we both evolved sophisticated camera eyes and large intelligent brains
54:36it suggests a tantalizing link between sensory processing and the evolution of intelligence
54:54sensing has played a key role in the evolution of life on earth
54:58in the evolution of life on earth
55:05the first organisms were able to detect and respond to their immediate environment
55:10as paramecia do today
55:15but as animals evolved and their environments became more complex
55:20their senses evolved with them developing the mechanisms to let them decode vibrations
55:27and detect light allowing them to build three-dimensional pictures of their environments
55:35and stimulating the growth of brains that could handle all that data
55:49but for one species the desire to gather more and more sensory information has become overwhelming
55:57so
56:01that species is us
56:19this is the closest thing to hallowed ground that exists in a subject that has no saints
56:24because that telescope is the one that edwin hubble used to expand our horizons i would argue
56:30more than anyone else before or since
56:45in 1923 edwin hubble took this photograph of the andromeda galaxy you can see his handwriting on
56:52he did it by sitting here night after night for over a week exposing this photographic plate
56:58now at the time it was thought that this misty patch you see in the night sky was just a cloud
57:05maybe a gas cloud in our own galaxy but hubble because of the power of this telescope identified
57:11individual stars and crucially he found that it was way outside our own galaxy in other words
57:18hubble had discovered this is a distant island of stars we now know it's over
57:25two million light years away composed of a trillion suns like ours
57:37hubble demonstrated that there's more to the universe than our own galaxy
57:42he extended the reach of our senses further than we could have imagined
57:47with the help of the telescope we could perceive and comprehend worlds billions of light years away
58:02there's a wonderful feedback at work here because the increasing amounts of data delivered by our
58:07senses drove the evolution of our brains and those increasingly sophisticated brains became curious
58:15and demanded more and more data and so we built telescopes that were able to extend our senses
58:23beyond the horizon and showed us a universe that's billions of years old
58:27and contains trillions of stars and galaxies our insatiable quest for information is the making of
58:37us
59:07you