Tajny.Mozga.4.Iz.6.Pervyj.Sredi.Ravnix
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00:00HUMAN BEINGS ARE THE MOST ADVANCED ANIMAL ON THE PLANET
00:11Human beings are the most advanced animal on the planet.
00:16We've invented machines which allow us to leave the Earth.
00:20We've designed instruments to study the furthest reaches of the universe.
00:25How did our brains come to have this extraordinary capacity
00:29for perpetual innovation?
01:00Although we share nearly 99% of our genes with chimpanzees,
01:05there is a gulf separating us from the animal most closely related to us.
01:11There's a fundamental difference between humans and chimpanzees.
01:15However clever they may appear,
01:17it seems to me that their agenda is still relatively basic.
01:21Their main concerns are education, health and safety.
01:25It seems to me that their agenda is still relatively basic.
01:28Their main concerns are eating, mating and avoiding danger.
01:33But we are different.
01:35Unlike any other animal on the planet,
01:37there's something special about our brains
01:39that gives us the unique ability to look way beyond mere survival.
01:51Chimpanzees may be highly intelligent
01:54and have complex social lives,
01:56but even the rudiments of human civilisation seem to be missing.
02:09Chimpanzees are capable of fine hand movements,
02:13but they have no interest in making art or clothing.
02:19They show no ability to invent new technologies
02:23and constantly improve them, the way we do.
02:27So what is the special feature exclusive to our human brains
02:31that has lifted us out of the jungle and placed us this side of the glass?
02:42The average human brain is roughly three times as big as a chimpanzee's.
02:47They look very similar, but how different is the inner circuitry?
02:53As our massive cortex expanded,
02:55what changes might have taken place inside
02:58which could transform our lives so completely?
03:11One mental skill which seems to lie at the heart of human behaviour
03:15is the ability to work towards a goal.
03:19To devise a plan of action, to juggle possibilities,
03:22to keep track of changing circumstances as we keep the end goal in mind.
03:28These are essential ingredients of modern life.
03:31We're always working to a mental plan.
03:37How might our brains achieve all this?
03:41Clues come from looking at people who have lost this fundamental ability.
03:53When I went to Vietnam, I got into a recon unit.
03:57I was there two weeks when they promoted me to sergeant.
04:00I followed the rules.
04:02I was not a garrison soldier, as the word goes.
04:06I was what they called a blood soldier.
04:12We were on patrol when we ran into a bloody nose ambush.
04:15And a grenade came in, the man in front of me and the man behind me were both killed.
04:23I just came out with a few holes in me.
04:31X-rays revealed that shrapnel from the grenade
04:34had penetrated the front of Michael's brain.
04:40Michael has undergone a rather dramatic transformation.
04:45Before his injury, he was a bright and very promising
04:49and assertive soldier.
04:52And subsequent to his injury, Michael became unemployable,
04:57made many mistakes in social behaviours and relations
05:02and has to live a much more limited life now.
05:12Demoted and eventually discharged from the army,
05:16Michael has been unable to hold down a steady job.
05:19He's now working under supervision as a hospital janitor.
05:27He's a troubled young man.
05:29He doesn't know himself what he's doing or where he's going.
05:33He has no rhyme or reason for what he wants to do,
05:38whereas before he did have.
05:40A lot of times when you see him or he comes to visit you,
05:44it's his loss, he's aimless.
05:48And you ask him, well, what would you do or what would you like to do?
05:53And it's, well, it depends on his mood that day.
05:56He either shrugs his shoulders and I don't know
05:59or I'd like to get a real nice car,
06:02which has nothing to do with anything.
06:05I'm going to start out by giving you ten chips.
06:08Each chip is worth five cents.
06:11Dr Jordan Grafman is trying to establish
06:14why Michael's life has fallen apart.
06:16What aspects of his mental abilities have suffered
06:19because of the damage to his frontal lobe?
06:25This gambling task is designed to test his ability
06:28to weigh up the likely consequences of his actions.
06:31The point of the test is to see at what stage in the game
06:35he decides to stop.
06:37Do you want to stop or do you want to continue?
06:41Continue.
06:43High cards, Mike wins a chip.
06:46Ten or less and he loses one.
06:50Continue.
06:52The cards are deliberately arranged to give him a good winning streak,
06:56followed by a steady run of losses.
06:59Normally, people stop while they're ahead.
07:05Continue.
07:07You should have kept it.
07:10Continue.
07:18Continue.
07:24That's it, we're at the end.
07:27You gave me back all your chips.
07:30Why didn't you stop earlier?
07:33I would have stopped on the third low card normally.
07:37If it was my own money.
07:39Since it was your chips I was playing with.
07:42You felt you didn't take a chance?
07:44I'd risk it all.
07:46Despite coming up with what seemed like a rational explanation
07:50for his poor performance on this test,
07:54we know that in real life,
07:56Michael has a tendency to give away money.
07:59So, in fact, it doesn't hold up
08:02under the strains and responsibilities of gambling.
08:07Michael's personal life has also suffered as a result of his brain damage.
08:12He seems unable to sustain relationships.
08:15He now lives alone after a series of impulsive marriages.
08:21The first girl I got married to was when I was in the army.
08:26My daughter was raised by my parents
08:29because when the wife and I got divorced,
08:32my mother thought that it would be better if she raised her than me
08:36because she didn't think I was fit to raise her.
08:39The second girl that I married, she was a runaway.
08:44And the reason she ran away from home
08:48was because her stepmother slapped her.
08:51And I don't even remember asking her to get married.
08:55And the third girl, she was a prostitute.
09:00So, she was in a hurry to get married. I don't know why.
09:08The damage to Michael's frontal lobe
09:10has destroyed his ability to work towards a long-term goal
09:14or to think through the consequences of his actions.
09:18If the situation is well-structured
09:21and he's given instructions as to what to do,
09:25Michael can perform quite well,
09:28particularly if the instructions are laid out in a stepwise manner.
09:32However, as the situation becomes less structured
09:35and Michael's forced to rely on his own internal thinking
09:39to develop and then execute activities and plans,
09:43that's where he begins to have trouble.
09:46That's where his distractibility begins to show
09:49and his difficulty in following ideas
09:52and his social problems.
09:58Michael's brain damage also seems to prevent him recognising
10:02how much his life has been affected.
10:05I believe it did change me from what everybody else has told me.
10:11Being on one side of the fence, I don't see it,
10:14but they see me changed.
10:16So I kind of figure, well, yeah, it's changed me,
10:19because I know some things I did I wouldn't have done.
10:24Cases like Michael's strongly suggest that the frontal lobe
10:28plays a vital part in allowing us to develop
10:31mental action plans for the future and then to follow them through.
10:35Without this ability, however intelligent Michael may be,
10:39the opportunities open to him are severely limited.
10:43OK there. I'm going to move you back into the scanner.
10:47At Cambridge University, researchers have developed a series of tests
10:51to pinpoint more precisely what special mental skills
10:55might arise from our frontal lobes.
10:58Unlike many other areas of the brain,
11:01the frontal lobe is the only part of the brain
11:04that has the ability to function properly.
11:07The frontal lobe is the part of the brain
11:11Unlike many other areas in the brain that have been pretty well mapped now,
11:16we really know very little about the frontal lobe.
11:19It remains something of an enigma.
11:22So, for example, things like seeing, hearing, our ability to move,
11:26we understand which parts of the brain enable us to do those things.
11:30But the frontal lobe, we still know very little about what it actually does.
11:36I volunteered to take part in an experiment
11:39designed to probe how we think things through in our heads.
11:45The aim is to reorganise the balls at the bottom to match the top pattern.
11:50You can't move a ball if there's another one covering it.
11:54Touch again.
11:56Well done. Are you happy with that?
11:59OK, well we'll start the first scan then.
12:02As soon as you see the first problem, just start creating solutions.
12:08The task is designed to make me plan the whole sequence of moves in my head
12:12before I start.
12:14Then I have to hold that sequence of moves in mind
12:17as I work through the solution.
12:33That's it.
12:42A second scan, when I don't have to plan the moves,
12:46I just follow instructions,
12:48helps filter out any brain activity not directly involved in planning.
12:54We're homing in on which areas of the brain
12:57are involved in the higher aspects of planning,
13:00the areas that are involved in moving and vision
13:03and all the other components of a normal planning task.
13:07The scans reveal increased activity in a surprisingly small area,
13:11so it seems there are specialised regions in the frontal lobe.
13:15Precisely what they're doing at the nuts and bolts level,
13:18we can't yet say.
13:21Fundamentally, it seems that our frontal lobe
13:24allows us to keep an overall goal in mind
13:27while we simultaneously deal with the here and now.
13:30But how different is that from what chimps can manage?
13:41For 30 years, scientists at Georgia University outside Atlanta
13:45have been studying the mental skills of chimpanzees.
13:48Recently, they've been trying to find the limits of their abilities
13:52to plan ahead.
13:54OK, I'm going to set up the computer right here.
13:56The beauty of the maze task is that it allows us
13:59to get a quantitative estimate
14:01of the chimpanzee's ability to look ahead in time.
14:06We, in our egocentrism, have wanted to view that
14:09as being a uniquely human characteristic.
14:12But indeed, there's no reason to believe
14:14that the chimpanzee wouldn't have this capability.
14:17After all, they have to forage for food,
14:19they have to deal with defence of themselves and their own kind.
14:23They have a lot of yearly planning to do.
14:27So just how good are chimpanzees at planning?
14:37One of our chimpanzees, Pansy, is essentially a genius at this.
14:41Not only is she excellent in running very complex,
14:44multiple-choice mazes that she's never seen before,
14:47but she can do it better than humans in many instances.
14:52This is a remarkable finding.
14:54Not only does Pansy take very few wrong turns,
14:57but she can sometimes see the solution to the maze
15:00faster than a human.
15:02To be able to look ahead and to find that clear way
15:05between where she starts and where she ends
15:08reflects a very active prefrontal lobe system.
15:12She's a genius.
15:15So, the ability to imagine possible solutions,
15:18to plan before acting, is not a uniquely human skill.
15:23Chimpanzees do plan ahead.
15:25I don't believe that they can plan ahead nearly so far as we can.
15:29I think also that they reflect upon the past,
15:32but not to the degree that we do.
15:35I would suggest that chimpanzees are able to plan ahead
15:38in a way that is not limited to what we do.
15:41I would suggest that chimpanzees are able to plan ahead
15:45over the course of several days,
15:48whereas we can plan ahead for years or centuries if we wish.
15:56Our modern city life might appear very different
15:59from that of any other animals,
16:01but it seems in one respect it is very similar.
16:07Our ability to mull over endless possibilities,
16:10deal with distractions and still keep multiple goals in mind
16:15appears mostly to have grown out of a simple expansion in brain size.
16:32But what about the one human ability
16:34which for centuries was seen as an absolute divide
16:38between us and other animals?
16:41Language.
16:48It's language that has triggered the awesome complexity
16:51of modern civilisation.
16:53By giving us a means of transmitting knowledge to our children,
16:56language short-circuits the need for each generation to start from scratch.
17:00In just a few short years of life,
17:02each human being will possess thousands of years of experience.
17:08The rapid development of human culture since the Stone Age
17:11would have been impossible without a sophisticated language.
17:15So is there some special physical structure
17:18lacking in chimpanzees' brains
17:20which accounts for our unique linguistic skills?
17:30Somewhere in each of our brains
17:32the sounds and meanings of thousands of words are stored.
17:37Somewhere there are also mechanisms for stringing words together
17:41to express what we want to say.
18:01A hundred years ago,
18:03scientists believed language depended on two key areas in the left hemisphere.
18:08A region behind the ear, identified by a German doctor, Carl Wernicke,
18:13seemed to be responsible for overall meaning.
18:16It handled word selection and sentence construction.
18:20An area further forward, found by a French doctor, Paul Broca,
18:25was thought to control the last stage of generating the speech sounds.
18:29Since then, a far more complex picture has emerged.
18:40Ladies and gentlemen, I'm pleased to participate
18:43in this evening's discussion of health considerations
18:46in the development of energy sources.
18:49These considerations have been with us for some time...
18:52Dr Wilson Talley, award-winning nuclear physicist,
18:55scientific adviser to the American government,
18:58will never be able to speak like this again because he suffered a stroke.
19:04Much very nice.
19:06It's March this...
19:081958.
19:10The stroke.
19:12March the 6th.
19:14Sleep.
19:16And I'm here about 2pm.
19:19I got up.
19:21The bathroom was here.
19:23I went...
19:25HE GROWLS
19:27And I found him.
19:29This and very strange.
19:37Wilson has since tried to write an account
19:40of what happened in his hotel room the night he had his stroke.
19:44But the brain damage has affected his ability to express himself
19:48and even to read what he has written.
19:51One, two, two.
19:53And the toilet right here.
19:55And you have...
19:57Right.
19:59All the way.
20:01And it was crawl.
20:03And I'm not sure, maybe six minutes.
20:06I'm not sure.
20:08Where were you?
20:10Oh, sorry.
20:12UC...
20:14No.
20:16New York City.
20:18Wilson took a taxi to catch a flight home to San Francisco.
20:22Only after circling Manhattan
20:24did he finally manage to say the name of the airport.
20:31He touched down in San Francisco 12 hours after his stroke
20:36and was taken to hospital.
20:40Well, you just got your licence again, right?
20:42Yes.
20:44And you've been driving here every day?
20:46Right. Perfect.
20:48A year on, he's now able to speak
20:50and can even drive himself to the hospital.
20:53But his language skills have been badly damaged.
20:56Dr Talley has a great deal of difficulty
20:58understanding anything that's said to him
21:00or even things that he reads.
21:02And he also has a great deal of difficulty in producing language.
21:06Now, what happens when he tries to talk
21:08is that the words come out very fluently,
21:11but what he says doesn't have a lot of content to it.
21:14He has difficulty in finding the words that he wants
21:16and he has a great deal of difficulty also
21:19in producing sentences that are coherent,
21:21that really reflect what it is he wants to say.
21:26A brain scan revealed that a hemorrhage
21:28had destroyed large parts of Wilson's left hemisphere,
21:32including the whole of Wernicke's area.
21:37But the more stroke patients like Wilson are studied,
21:40the more it seems that Wernicke's area
21:42cannot be where all comprehension and sentence construction
21:45takes place in the brain.
21:56The pattern of brain damage in every stroke patient is different
22:00and measuring precisely how badly someone's linguistic abilities
22:03have been affected is also difficult.
22:06Which one?
22:08Aspirin. Aspirin.
22:10Aspirin.
22:12Wilson is constantly trying to use non-verbal cues
22:15to make sense of things.
22:30Did you get round?
22:32Yes.
22:34In a conversational setting,
22:37Dr. Talley relies very heavily on lots of other kinds of information.
22:43You want me to do it?
22:45Forget it. You can do it. I can't do it.
22:47Okay.
22:49He relies on facial expressions, on people's gestures,
22:51on the way they use the intonation in their voice,
22:54and he picks up on all of this information
22:57to help him understand the situation.
23:00So he gives the impression of understanding almost everything.
23:04Now, when we put him in a more controlled testing situation
23:07where we remove all of those kinds of cues,
23:10we find that, in fact, he has, unfortunately,
23:13a very profound language disorder.
23:15Now I'm going to show you a picture,
23:17and I'd like you to tell me what's going on in that picture.
23:21Okay.
23:23Um...
23:25The people right here, uh, from here,
23:28and look, uh...
23:30The people is right here,
23:33and we have come in here, very bad,
23:36and the window's right here.
23:39Wilson seems to understand what's going on here,
23:42but he's lost the ability to find the right words
23:45and then to put them into sentences.
23:48So who do you think broke the window?
23:51This one here and that one right there.
23:55Okay.
23:57Nina Dronkers has assembled a unique collection of brain scans
24:01of stroke patients with language disorders.
24:04It turns out that many have indeed damaged the two classic language areas,
24:08but the broader picture reveals a network of many different brain areas
24:13which handle specific aspects of language.
24:19We've seen that there are certain patients
24:21who have a great deal of trouble really just naming things.
24:24We've found patients who have difficulty
24:26understanding the grammatical rules of language.
24:29All of those different kinds of patterns tell us, first of all,
24:33that the process of language is incredibly complex,
24:36and also that there must be many different brain areas
24:39that subserve each and every one of those different functions.
24:43Touch the white circle.
24:48Patients often seem to recover some of the basic aspects of language,
24:52like the ability to recognise word sounds,
24:55which suggests that these functions
24:57don't require their own specialised brain structures.
25:00Touch the green square.
25:05Unfortunately, we rarely see complete total recovery in our aphasic patients.
25:13And the fact is that in most of them,
25:15a fairly significant amount of brain has been affected by their injuries,
25:20and that it is difficult for other brain areas
25:23that have for such a long period of time been doing something else
25:26to suddenly take on this new function.
25:29And what we think happens is that the remaining brain areas
25:32try to take on this task of language, but they do it in their own way.
25:36And unfortunately, they're not as good at it
25:39as those left hemisphere language mechanisms
25:42because they haven't been doing that all of those years.
25:45I'm better, much better,
25:48but I'm not the same the way that I'm here.
25:51But maybe we can do it. Maybe.
25:55We're keeping our fingers crossed.
25:57Yeah, this one. Not this one.
25:59And if anybody can do it, you can do it.
26:01All of them. It's good.
26:10Further evidence that language arises from a network of sites in the brain
26:15comes from the work of Professor George Ogerman.
26:20Here at Washington University in Seattle,
26:23he has pioneered an impressively direct way to study language in the brain.
26:29His research began as part of a last-ditch effort
26:32to treat severe epilepsy through surgery.
26:36The challenge is to remove enough of the epileptic brain tissue
26:40without destroying key functions like speech.
26:44To plan exactly what tissue I want to take out,
26:47there are two pieces of information I want to have.
26:51One is that I want to know where the local epileptic activity is in the brain,
26:56and I get that by recording the brainwave activities
26:59directly from the cortical surface.
27:02The other is that I want to know where the functionally important things are
27:06so I can stay out of them.
27:08A little wider. Hi.
27:10You're in the operating room.
27:13Can you wake up a little bit so we can talk to you?
27:16Uh-huh.
27:17Dr. Ogerman's doing his work.
27:22Does your nose itch? Let me get that for you.
27:24In order to test for language, George Ogerman needs his patients fully awake.
27:29It's a fantastic opportunity to probe the workings of the living brain.
27:33That's Dr Ogerman.
27:35Do you recognise this voice?
27:38OK, now be real, real still.
27:40OK.
27:42Ogerman stimulates the brain with a tiny electric current.
27:45The patient feels no pain since there are no pain sensors in the brain.
27:52He maps out the exposed surface with paper numbers,
27:55then he stimulates each area in turn.
27:59OK, don't move your arm, OK?
28:02I'd like you to count for me now.
28:04I'd like you to start at one and just keep counting until I tell you to stop.
28:08OK. Nice and loud.
28:10Good and loud. Start, please.
28:12One, two, three...
28:14Ogerman has shown that even a basic language function, like counting,
28:19relies on a widespread network of sights.
28:22If he hits one of these essential speech areas,
28:25the electric current will stop the patient in her tracks.
28:2814, 15, 16...
28:33Ah. 17, 18...
28:36He's also found that everyone's network is laid out differently.
28:41Thank you. You can stop. That's very nice.
28:44In any individual subject, the sights involved in language are very focal,
28:49very localised ones, about the size of the end of my thumbnail.
28:53But if you look across the population and you say,
28:56how are these distributed, there's a lot of variance.
28:59They're in somewhat different locations in most people.
29:04The team here have mapped over 200 people,
29:07and they've never found exactly the same mosaic of language sights twice.
29:12These are just the essential ones.
29:14They probably represent key intersections
29:17in an even wider network of areas involved in language.
29:23We're going to go to electrode number one, four milliamps.
29:27You are at four.
29:31This is a barn.
29:33When George Ogerman asks his patients to respond to a slideshow,
29:37then we can really see the awesome sophistication
29:40of the brain's language system.
29:43Chicken. 27, inferior.
29:48Piano. Uh-huh.
29:53This and my boom mic. Keep going, please.
29:57This is a band.
29:58This remarkable technique reveals separate networks
30:01for many different aspects of language.
30:0330.
30:05What we find is that the cortex is organised in these separate areas.
30:09For different language functions.
30:11So, for example, in a multilingual patient,
30:14you'll find one area that's involved in naming in one language,
30:17another area that's involved in naming the same items in another language,
30:21at least partly separated.
30:23This is a line.
30:26The brain mapping has even shown that there are separate areas
30:30for different categories of word.
30:32We seem to have a network dedicated to naming fruits.
30:36And another for naming tools.
30:39This is a straw. Saw.
30:43This is an eye.
30:4532.
30:48Screwdriver.
30:50In a general sense, Wernicke and Broca got it right.
30:52But we've certainly learned that the details are different,
30:56in the sense that the areas that are crucial for a language function
31:01are more focal than we thought,
31:03there's more individual variability than we thought between them,
31:06there's more subdivisions than we thought.
31:17For me, the Bonobos at Georgia University provide the strongest evidence
31:22that language doesn't necessarily require special processes
31:26unique to the human brain.
31:29They can't speak,
31:31so they've been taught to link written symbols with specific words.
31:35Look here. It says,
31:37Pambinisha, that's you.
31:40The cooler...
31:42The food cooler is hiding at the river.
31:47Thank you, bunny.
31:49Pambinisha began with a few simple symbols.
31:53We had the names of six different foods,
31:56a location, outdoors, and a specific activity, grooming.
32:00We added some other things.
32:02For example, one of the words we added was the word quiet,
32:05which is a fairly abstract term.
32:08Pambinisha, when she was about 3 1⁄2 years old,
32:12she used the word quiet for the first time with me.
32:15And it was one night when I was pretty upset with something she was doing,
32:20and I was kind of giving her a lecture
32:23in a very loud tone of voice that we should not be doing that right now.
32:27And Pambinisha went to the keyboard and very quietly
32:30just looked at me with a very serious expression and she said, quiet.
32:35Perrier, Pambinisha?
32:39That's correct.
32:41That's right, Pambinisha, you found Perrier.
32:43Very, very nice. Thank you.
32:45Oh, you're showing me again.
32:47Pambinisha has now learnt the meaning of over 200 symbols.
32:53Pambinisha, can you find egg?
32:58That's correct.
32:59Egg. Oh, good.
33:00Very good, Pambinisha, very, very good.
33:02Very nice. TV, Pambinisha?
33:07Yes.
33:08That's right.
33:09Good job, Pambinisha, good job.
33:11Most impressive of all,
33:13she even seems to appreciate the importance of word order.
33:17You want juicy juice, all right.
33:19Would you give a bite of your hot dog to the doggie, please?
33:25Would you give him some of your hot dog?
33:29You can have more.
33:31Pambinisha, please give the doggie a bite of your hot dog.
33:38One bite.
33:44Thank you very, very much.
33:47Even though you didn't want to do that, that was really nice.
33:50Now, if you think about how to teach Pambinisha a sentence like that,
33:54you find yourself in kind of a quagmire
33:57because dog is used in many different ways.
34:00It's used in the word hot dog and it's used in the word dog.
34:04And if you think about the word hot,
34:07well, the dog could be hot or the hot dog itself could be hot
34:11or the hot dog could be cold but still called a hot dog.
34:14Can you put the toy snake on your hand?
34:24Sue Savage-Rambaugh is convinced that bonobos can understand
34:28spoken English as well as a human child.
34:32Oh, that's very nice!
34:34Their comprehension is at least between that of a five- and seven-year-old.
34:40That may be higher in some cases.
34:43That's the subjective impression that one has in working with them.
34:48Could you put the gorilla mask on?
34:51Go ahead, put it on your head.
34:53Oh, can you scare Paula?
34:55They can comprehend entire dialogues.
34:57They can comprehend extensive narratives.
35:00They can understand stories about things that happened elsewhere
35:03or stories about something that happened the previous day,
35:07if they're interested.
35:09You're not just sleeping in here, are you?
35:11You're very tired.
35:13The researchers here believe that we and our ape cousins
35:17both have brains which can acquire language
35:19as part of a natural upbringing.
35:23You want to come in? OK.
35:25I think that the idea that our brain is the only brain capable of language
35:29on the planet is now something that's completely open to question.
35:35This is where Bunny was yesterday.
35:37I can accept that chimpanzees are capable of learning
35:40the rudiments of language,
35:42but there is a difference between us and them.
35:45We humans have a universal ability to use complex language as a way of life.
35:53OK. Hang on, let me open this one up.
35:56So where does the difference lie?
35:59Are the superior language abilities that we possess
36:02purely the result of having bigger brains than chimpanzees?
36:05Yeah.
36:06Recently, the team here in Georgia have begun a series of experiments
36:10which may one day answer that question.
36:14Onion. Show me the onion. Onion.
36:21For half an hour, Pansy matched symbols to spoken words.
36:25Then she was taken to a brain scanner
36:27to measure which areas of her brain
36:29had been most active during this simple language task.
36:33Shoe. Where's the shoe?
36:35Then John was scanned after doing the same thing,
36:38and the two results were compared.
36:40All right.
36:44As expected, in the human, the activity is mainly in the left hemisphere
36:50around the known language regions.
36:52But in the chimpanzee, there's a much more symmetric pattern
36:56across both halves.
36:58These results are from just one chimp.
37:01But there seems to be a fundamental difference
37:04in the degree of brain symmetry.
37:12A few miles away, researchers at Yerkes Primate Research Centre
37:17have been studying another aspect of brain symmetry
37:20in a different colony of chimpanzees.
37:22Virginia, how are you doing? Hm?
37:25These food tubes, smeared with peanut butter,
37:28provide a simple way to measure
37:30whether a chimp is consistently left or right-handed.
37:34The results suggest that our ancestors' brains
37:37became more and more skewed to favour the right hand,
37:41with humans the most extreme of all.
37:55Offer a human being something to hold,
37:57and most of us will reach out with our right hand.
38:00In tasks involving manual dexterity,
38:02we're almost sure much better with one hand than the other.
38:05And this extreme handedness may reflect something very profound
38:09about the organisation of our brains.
38:25Increasingly, we're discovering that many cognitive skills,
38:29as well as physical abilities,
38:31seem to be handled predominantly by one side of the brain or the other.
38:36Human handedness is an outward sign
38:38that somehow our left and right hemispheres have become specialised.
38:42Effectively, we're all walking around
38:44with two slightly different half-brains inside our heads.
38:47And the benefit that this brings to us
38:49might ultimately be much more important.
38:52Be much more important than mere brain bulk.
39:02Take the remarkable case of Joe,
39:05known as JW in the scientific literature.
39:08To control crippling epileptic fits,
39:11the main connections between the two sides of his brain were severed.
39:23Joe's split brain allows researchers to explore
39:26the workings of the left and right hemispheres,
39:29which are now almost completely separated.
39:32His party trick is to draw two different objects simultaneously.
39:42There we go. Beautiful.
39:44OK, so, Susan, why don't you try it?
39:47I was dredging up.
39:49OK, so, as long as Joe promises not to laugh at me.
39:52I won't laugh.
39:58OK, you ready?
40:00Here we go. Draw them simultaneously as fast as you can.
40:06Oh, gracious!
40:08What is so different?
40:10Over 30 years' work with split brainers
40:12has convinced Mike Gazzaniga
40:14that asymmetry is the key to understanding our mental abilities.
40:19To him, intelligence comes only from the left.
40:22Oh, gracious!
40:24Take a split brain patient
40:26and you measure their pre-operative IQ
40:29and problem-solving skills and what have you.
40:32And then you split the brain,
40:34where you've now disconnected the two hemispheres,
40:37and you go back and measure the left hemisphere's problem-solving,
40:41verbal IQ and all that. It doesn't change a whit.
40:44The right hemisphere, on the other hand, is sort of dumb.
40:49But when he tested Joe's ability to recognise visual patterns,
40:53he was surprised how poorly the left performed.
40:56These are called illusory contours.
40:59The white discs create the illusion of a black shape
41:02which either curves inwards or bulges out.
41:05Both sides of the brain can tell the difference.
41:12But add a line inside the disc
41:14and the illusion of a shape is harder to see.
41:17Unexpectedly, Joe's left hemisphere is totally stumped.
41:23All of a sudden, the right hemisphere could do this test,
41:27still judge whether the rectangles were thin or fat,
41:31but the left hemisphere just fell apart, could not do the test.
41:37It turned out that a similar test had been tried once before, on mice.
41:42Astonishingly, the human's giant left hemisphere
41:46failed to distinguish two patterns
41:48that the tiny mouse brain could tell apart.
41:52Does this failure shed new light
41:54on the evolution of advanced human abilities?
41:58Maybe the left hemisphere begins to mutate
42:01in order to develop language.
42:04And as language requires more cortex and more cortex,
42:08perceptual processes that used to be in the left hemisphere
42:12sort of get squeezed out.
42:16Gazzaniga's theory is that as we evolved,
42:19our left hemisphere acquired more and more advanced cognitive functions,
42:24while our right changed very little.
42:27And he believes that this half is just an evolutionary relic.
42:34In fact, if you look at the great skills we have
42:37that the chimp doesn't have,
42:39there's every reason to believe
42:41that they're largely in the left hemisphere,
42:44that they're an outgrowth of some changes
42:47that must have occurred through mutations to the left cortex.
42:55I accept that we're an asymmetric species,
42:58but I don't believe that there's a complete division of labour
43:02between left and right.
43:05I don't go for the popular clichés about creativity and art
43:10coming from the right hemisphere,
43:12with the left being literal and logical.
43:15Instead, I'm sure both our specialised half-brains
43:18are involved in everything we do.
43:21We're the fusion of two different interpretations of the world
43:25inside one head.
43:28But there's one final missing ingredient
43:31to complete the transformation
43:33from the chimpanzee's range of skills to our own.
43:41300,000 years ago,
43:43the first human being was born.
43:46It was the first human being to be born.
43:49It was the first human being to be born.
43:52It was the first human being to be born.
43:55300,000 years ago,
43:57the first full-grown humans appeared,
44:00with a full-sized human brain.
44:02But these Neanderthals were not like us.
44:06And if evolution had stopped here,
44:08human civilisation would still be in the Stone Age.
44:14For many years, archaeologist Steve Mythen
44:17has been studying the tools our ancestors left behind,
44:21trying to gain insights into how their minds worked.
44:24So this is a small hand axe, as typically made by Neanderthals.
44:28You can see some very fine flake scars
44:31where pieces of flint have been removed
44:34by striking with a hammer stone,
44:37which are excellent butchery instruments
44:40for cutting through hide and sinews and tendons.
44:43So they really are very skilled.
44:45They are. They're tremendously skilled for work.
44:48There's nothing really modern humans are making
44:51that's more skilful in terms of the tool-making.
44:56But Neanderthals appear to have been astonishingly unimaginative,
45:00making the same stone tools for hundreds of thousands of years.
45:09And it's a rather little odd sort of behaviour,
45:12looking at it from a modern human perspective,
45:14because we normally think that the ability
45:16to make technically demanding things goes hand in hand
45:19with the ability to invent new types of tools
45:21and to innovate and to create and continue to improve one's technology.
45:25Steve believes that the same tunnel vision
45:28that held back the Neanderthals' tool-making
45:31might also have restricted their linguistic abilities.
45:35I suspect Neanderthals had words for flowers
45:38and I suspect they had words for their children,
45:41but I don't think a Neanderthal could ever have come up with a phrase
45:44that my daughter is as pretty as a flower.
45:46That's a creative thought, isn't it?
45:48And what you're doing, you're drawing on one type of knowledge
45:51about people and children,
45:52and you're drawing on another type of knowledge about flowers,
45:55and somehow you're making a new statement
45:57by drawing those two things together.
46:01Suddenly, with the arrival of modern humans,
46:04new kinds of tools appear.
46:07For the first time, these humans try using bone and antler,
46:12as well as stone.
46:15Neanderthals used bone,
46:16but they didn't carve it or manipulate it or change it at all,
46:20whereas modern humans started working bone
46:22and they carved it into harpoons and points and needles
46:26and jewellery, all sorts of things.
46:28And this really shows a big change
46:30from that tunnel vision way of thinking,
46:33because now they're taking technical skills
46:36that have been used for working wood and stone alone
46:39and applying it to brand-new material.
46:41So they're changing what was part of an animal
46:43into something fundamentally different.
46:48This revolution in tool-making
46:50marked a crucial change in mental abilities,
46:53which launched us on an accelerating journey
46:56of technological development.
46:58What seemed to happen, it snowballs.
47:00So you go from a very traditional hunter-gatherer life
47:04to a world in which people are making art
47:07and clearly have got religious ideologies,
47:09making very complex artefacts, using body decoration.
47:13And I go through that through the Ice Age,
47:15and as soon as the Ice Age finishes, people invent agriculture
47:18and we move very rapidly to towns and cities and civilisation.
47:24So all this was the result of our ability
47:27to see one thing in terms of another,
47:30to think laterally.
47:32It's a fascinating idea.
47:34But we'll never know what actual changes in the brain
47:37were required to achieve the modern human mind.
47:50It seems that the gradual evolution of the brain
47:52over millions of years
47:54merely equipped our ancestors with an array of modular mental abilities.
47:58Then suddenly, these distinct functions merged
48:01and our lives were transformed.
48:03There was an explosion of creativity and imagination
48:06that put us where we are today.
48:12We humans, unique among animals,
48:15can gaze at the planet we now dominate.
48:26In the next programme, we explore the extraordinary way
48:30in which your brain is constantly changing as you go through life.
48:34How everything you experience shapes your mind.
49:04Transcription by ESO. Translation by —