0:00:14 > 0:00:16What is intelligence?
0:00:17 > 0:00:218175 backwards?
0:00:21 > 0:00:25- 57118. - What does an entomologist study?
0:00:29 > 0:00:32Wow! That was tough. Did a lot of people get this one in two minutes?
0:00:34 > 0:00:37And why do some people apparently have so much more of it than others?
0:00:44 > 0:00:47Where does intelligence come from?
0:00:47 > 0:00:49Is it a matter of luck, biology
0:00:49 > 0:00:53or just a good education that makes this guy cleverer than me?
0:00:53 > 0:00:57Is there anything that I or my parents could have done to make me more intelligent?
0:00:57 > 0:01:01Well, scientists have been battling thorny questions like these for
0:01:01 > 0:01:05decades, making intelligence one of the most studied traits in science.
0:01:05 > 0:01:08But it's only really now that we are beginning to get some answers.
0:01:10 > 0:01:11For nearly 50 years,
0:01:11 > 0:01:17Horizon has been following that search to understand our mysterious mental power,
0:01:17 > 0:01:23looking at everything from our evolutionary history to whether a computer could outsmart us.
0:01:23 > 0:01:27And asking the questions, how do you test for intelligence?
0:01:27 > 0:01:29Is it inherited or innate?
0:01:29 > 0:01:32Nature or nurture?
0:01:32 > 0:01:39In so doing, science has begun to redefine our understanding of what makes every one of us unique.
0:01:52 > 0:01:56The benchmark for measuring one person's intelligence against
0:01:56 > 0:02:00another is the iconic IQ or Intelligence Quotient test.
0:02:08 > 0:02:12Most of us will have sat through one of these at one time or another.
0:02:12 > 0:02:18It is the dreaded IQ test, with sections on spatial awareness, general knowledge and reasoning.
0:02:18 > 0:02:22And it tots up different areas of skill to create one score.
0:02:22 > 0:02:28A single mark that can brand you with either a low, high or maybe an average IQ.
0:02:28 > 0:02:32Now, we've been judged on the merits of this test for years now.
0:02:32 > 0:02:35What's remarkable about it is that it was introduced in 1912.
0:02:35 > 0:02:39So, essentially, this has remained the same for almost 100 years.
0:02:42 > 0:02:48In 2006, Horizon tested the IQs of seven experts in their field to see who would come out on top.
0:02:50 > 0:02:53Seven people from seven very different backgrounds.
0:02:57 > 0:02:59All highly successful.
0:03:04 > 0:03:09And all seven prepared to do battle over the elusive nature of intelligence.
0:03:13 > 0:03:15The test lasts 30 minutes.
0:03:15 > 0:03:19What it revealed would show how our understanding of intelligence
0:03:19 > 0:03:22has changed since the IQ test was first devised.
0:03:27 > 0:03:34We have spent 100 years on IQ tests that are basically the same.
0:03:34 > 0:03:42Imagine if physics or chemistry or medicine or biology were the same today as they were 100 years ago.
0:03:42 > 0:03:46That's essentially the state of the testing industry.
0:03:47 > 0:03:51It's unusual to find a methodology that has changed so little.
0:03:51 > 0:03:57And perhaps this reflects the century-long struggle to work out how intelligence develops.
0:04:01 > 0:04:07In their bid to understand human intelligence, scientists have looked for evidence of it in other animals.
0:04:12 > 0:04:15During the 1980s, Dr James Gould searched for
0:04:15 > 0:04:19signs of intelligent behaviour in the complex lives of bees.
0:04:19 > 0:04:24Even now, when I look at bees, it's hard to imagine that these tiny,
0:04:24 > 0:04:27nervous little insects could be intelligent.
0:04:27 > 0:04:30Yet, in all this apparent chaos, there is a tremendous amount of order.
0:04:30 > 0:04:36Bees are not behaving randomly, they are going about the task of solving a series of specific problems.
0:04:36 > 0:04:40They spend the first few days feeding the queen and taking care of her.
0:04:40 > 0:04:43And then they spend a few days building honeycomb in the hive.
0:04:43 > 0:04:45And then a few days guarding the hive's entrance and
0:04:45 > 0:04:50then, finally, several weeks gathering food from flowers.
0:04:50 > 0:04:54These are all clever things and yet this behaviour is driven by biological cues.
0:04:54 > 0:04:57All through the life of a bee,
0:04:57 > 0:05:02an innate sensitivity to certain cues helps guide its behaviour.
0:05:02 > 0:05:05And this is by no means an exception, this is the rule in the animal world.
0:05:05 > 0:05:07And it makes sense, too.
0:05:07 > 0:05:11If the behaviour is sufficiently predictable and the cues are sufficiently predictable,
0:05:11 > 0:05:17it makes sense for an animal not to reason out what it ought to do, but to simply respond automatically.
0:05:17 > 0:05:22A good example of this is tits open milk bottles
0:05:22 > 0:05:26because instinctively they peel back bark to look for grubs.
0:05:28 > 0:05:34Gould concluded that, unlike humans, the short lifespans of many insects and animals means they simply don't
0:05:34 > 0:05:37have enough time to work out solutions to problems.
0:05:37 > 0:05:43Their apparently intelligent behaviour is just a response to a series of biological cues.
0:05:45 > 0:05:51However, there are animals that do appear to display a capacity for intelligent problem-solving.
0:05:53 > 0:05:57Research into one species - chimpanzees - has begun to
0:05:57 > 0:06:00reveal greater capabilities that go beyond pure instinct.
0:06:00 > 0:06:04Writer, Danny Wallace, went to Uganda to find out more.
0:06:08 > 0:06:14He was keen to investigate an experiment to test a chimp's ability to solve a complex problem.
0:06:19 > 0:06:22This box of bananas placed away from the cage poses a tricky problem.
0:06:26 > 0:06:28Ah.
0:06:31 > 0:06:33I see what you've done.
0:06:33 > 0:06:37'To get the bananas to come towards me, I would have to pull both ends of the rope.
0:06:37 > 0:06:39'But they were too far apart.'
0:06:41 > 0:06:44Right, OK. I can't.
0:06:44 > 0:06:47Diana? Will you be another chimp, please?
0:06:52 > 0:06:53Chimp-cam.
0:06:53 > 0:06:58'I could see that if I didn't get Diana involved, I'd get no bananas at all.
0:06:58 > 0:07:01'And that didn't bear thinking about.'
0:07:01 > 0:07:04One, two, three.
0:07:06 > 0:07:07We did it, we got the bananas.
0:07:07 > 0:07:11Now for the chimps. Chimp one has a rational choice.
0:07:11 > 0:07:16Share the bananas with chimp two or get no banana at all.
0:07:16 > 0:07:18Three, two, one. Release the chimp.
0:07:22 > 0:07:25OK. So, he's going a bit mad.
0:07:27 > 0:07:30Chimp one can't get the bananas.
0:07:32 > 0:07:35Chimp two is going mad, chimp one is wondering what's going on.
0:07:35 > 0:07:39Oh, he has let him out. That's amazing.
0:07:42 > 0:07:43That's incredible.
0:07:45 > 0:07:48Chimp one, he's very happy, and off they go.
0:07:48 > 0:07:50That was brilliant.
0:07:50 > 0:07:53That was quicker than me.
0:07:54 > 0:07:58The chimp appeared to be making a thoughtful decision,
0:07:58 > 0:08:01suggesting that chimps are intelligent enough to co-operate.
0:08:01 > 0:08:04A key human trait.
0:08:04 > 0:08:09Yet human intelligence still sets us apart from our closest evolutionary cousins.
0:08:09 > 0:08:14Thank you for taking part in this experiment. This is for you.
0:08:17 > 0:08:20Scientists have delved deep into our prehistoric
0:08:20 > 0:08:25past to try to find out when we developed superior intelligence.
0:08:28 > 0:08:31When did our ancestors cease being brute animals
0:08:31 > 0:08:36and first become truly human?
0:08:36 > 0:08:39When did we learn to think?
0:08:45 > 0:08:49Thinking is the defining trait of humankind.
0:08:49 > 0:08:51It has given us machines.
0:08:51 > 0:08:54Technology. Power.
0:08:56 > 0:09:02No other animal has the ability to look at the world outside and transform it.
0:09:09 > 0:09:15Where all other animals live from day to day, we alone plan ahead.
0:09:15 > 0:09:18Dream. And create.
0:09:20 > 0:09:24Find the day we learned to think and you would have identified perhaps
0:09:24 > 0:09:28the single most important moment in human history.
0:09:33 > 0:09:37But it was not going to be simple. Thinking leaves no traces.
0:09:39 > 0:09:44There are no fossilised thoughts waiting to be dug out of the ground and dated.
0:09:45 > 0:09:49It was like investigating a murder scene without a body.
0:09:55 > 0:09:58So, scientists had to look for indirect clues.
0:09:59 > 0:10:03Not fossils, but other evidence for when thought began.
0:10:05 > 0:10:11And then they realised that thought must have come hand-in-hand with something else.
0:10:12 > 0:10:14What are we going to look for,
0:10:14 > 0:10:21first of all, that's going to give us evidence that humans were behaving in a modern way?
0:10:21 > 0:10:24So we look, in a way, for proxies.
0:10:27 > 0:10:30But there was one kind of evidence archaeologists could look for.
0:10:32 > 0:10:34The obvious line of evidence is art.
0:10:40 > 0:10:42When you get unquestionable art that's widespread and common,
0:10:42 > 0:10:47I think you can say you're dealing with people just like us.
0:10:47 > 0:10:51Only humans create and can make sense of art.
0:10:53 > 0:10:59I'm sure that dozens of dogs have walked down this street in the past years
0:10:59 > 0:11:05and perhaps not a one has glanced up in awe or wonder
0:11:05 > 0:11:08and thought to himself, what does this mean?
0:11:08 > 0:11:12For a dog, this is colour on a wall.
0:11:12 > 0:11:14Perhaps even less than that.
0:11:18 > 0:11:23But to a human being, a painting is far more than just a collection of colours.
0:11:23 > 0:11:25An expression of thought.
0:11:28 > 0:11:31Suddenly, what they had to look for was clear.
0:11:31 > 0:11:35Discover the earliest forms of human art
0:11:35 > 0:11:39and you would have found the day we learned to think.
0:11:46 > 0:11:47At Blombos, on the east coast of South Africa,
0:11:47 > 0:11:55anthropologist Chris Henshilwood had been quietly excavating his prehistoric cave for over a decade.
0:12:02 > 0:12:04This is Blombos cave here.
0:12:04 > 0:12:07A very special find.
0:12:13 > 0:12:17We're really looking at what has been left here
0:12:17 > 0:12:19almost as if it was put down here yesterday.
0:12:24 > 0:12:28As they dug down through the floor of the cave, his team were going back to
0:12:28 > 0:12:34an ancient time of human habitation tens of thousands of years ago.
0:12:40 > 0:12:45We came down onto this layer you can see over here, which really was quite remarkable.
0:12:48 > 0:12:52On the surface were lying the most beautifully made artefacts.
0:12:52 > 0:12:56Bone points, spear points as well.
0:12:56 > 0:13:00And immediately I realised we had gone back a very long way in time.
0:13:09 > 0:13:14The beautifully crafted objects were dated to over 70,000 years ago.
0:13:23 > 0:13:26But there was still not proof the people in the cave were thinking people,
0:13:26 > 0:13:28like us.
0:13:32 > 0:13:37One type of item started appearing over and over again.
0:13:40 > 0:13:42We noticed large numbers of pieces of ochre.
0:13:42 > 0:13:478,000 pieces of ochre in the old levels alone.
0:14:01 > 0:14:06Then, one day, Henshilwood found a piece of ochre that was different from the rest.
0:14:07 > 0:14:12We found this piece of ochre, brushed up the side and there was
0:14:12 > 0:14:16this absolutely remarkable pattern revealed.
0:14:16 > 0:14:19There was huge excitement, you can imagine.
0:14:26 > 0:14:31The ochre piece appeared to have been marked with a clear image.
0:14:31 > 0:14:34What seemed like an abstract geometric pattern.
0:14:36 > 0:14:41This was a deliberate construction of a series of crosshatches in each direction.
0:14:41 > 0:14:46A line across the top, a line through the middle and a line down the bottom.
0:14:46 > 0:14:50So it actually circumscribed that engraving.
0:14:50 > 0:14:55As if they had made the crosses and deliberately surrounded it with these other lines as well.
0:14:59 > 0:15:07Here is the first example of the ability of humans to store something outside of the human brain.
0:15:07 > 0:15:12You're storing a message that somebody else who is part of
0:15:12 > 0:15:16that same group can pick up and they will understand what that meant.
0:15:20 > 0:15:24This is the beginning of things like art, writing and everything else that follows.
0:15:27 > 0:15:31It was the earliest evidence of the thinking brain.
0:15:33 > 0:15:38There is still much that we don't know about the evolution of human intelligence.
0:15:38 > 0:15:42But it was during the second half of the 19th century that the ideas of
0:15:42 > 0:15:46Charles Darwin began to profoundly influence our thinking.
0:15:48 > 0:15:51Francis Galton was the first scientist
0:15:51 > 0:15:55to propose that intelligence was a biologically-based mental faculty.
0:15:58 > 0:16:04He was Darwin's cousin and was much inspired by reading his book, On The Origin Of Species.
0:16:04 > 0:16:10Galton thought that human mental abilities were inherited in just
0:16:10 > 0:16:14the same way as the plant and animal traits outlined by Darwin.
0:16:14 > 0:16:16And he set out to prove it.
0:16:16 > 0:16:20Galton was obsessed with measuring things.
0:16:20 > 0:16:25He was convinced that everything was inherited, from arm length to reaction time.
0:16:25 > 0:16:29According to his theory, people with bigger heads, such as himself,
0:16:29 > 0:16:32would have a greater capacity for intelligence than others.
0:16:32 > 0:16:35So he started to measure the heads of a group of Cambridge students
0:16:35 > 0:16:38and compared those measurements to the test results.
0:16:38 > 0:16:43But, disappointingly for him, the correlation between those two sets of data was low.
0:16:43 > 0:16:45The evidence simply didn't stack up.
0:16:47 > 0:16:52But Galton stuck doggedly to his conviction that intelligence was inherited.
0:16:52 > 0:16:55He coined the phrase, "nature versus nurture",
0:16:55 > 0:17:01which has proved to be one of the most enduring questions at the heart of the intelligence debate.
0:17:01 > 0:17:05But it was Galton's disciple, a psychologist named Cyril Burt,
0:17:05 > 0:17:12whose research was to have a huge impact on both our thinking about and our testing of intelligence.
0:17:14 > 0:17:17Horizon dramatised Burt's youthful idealisation of Galton,
0:17:17 > 0:17:20which would have an enduring influence on his work.
0:17:22 > 0:17:25Galton was one of Burt's heroes, maybe the only one.
0:17:28 > 0:17:30Of all the psychologists whose names were mentioned
0:17:30 > 0:17:37in my discussions with Burt, I think the only one that he seemed to talk about admiringly was Galton.
0:17:39 > 0:17:41This is young Loddy, Sir Francis.
0:17:41 > 0:17:43- Loddy? - Loderick, sir. It's a shortening.
0:17:43 > 0:17:46My first name is Cyril, then Loderick.
0:17:47 > 0:17:50Are you good at your schoolwork, Loddy?
0:17:50 > 0:17:52Oh, yes, sir. Very good.
0:17:52 > 0:17:54He's a very diligent boy.
0:17:54 > 0:17:56He has a diligent father.
0:17:56 > 0:17:59He will have inherited his father's intelligence.
0:18:00 > 0:18:03Burt seemed to worship Francis Galton.
0:18:03 > 0:18:07He kept on mentioning the one occasion on which he met him.
0:18:07 > 0:18:11And he certainly tried to follow in his footsteps.
0:18:11 > 0:18:13Oh, no. Do you read classics?
0:18:13 > 0:18:16I want to be a scientist.
0:18:16 > 0:18:20Burt was particularly drawn to one of Galton's ideas.
0:18:20 > 0:18:25In 1883, Galton had coined the term eugenics, meaning good birth.
0:18:25 > 0:18:29He believed that people of high rank had greater intelligence and should be encouraged to marry and have
0:18:29 > 0:18:35children to preserve these traits, while the poor be strongly discouraged from breeding.
0:18:35 > 0:18:38Burt adopted this idea with enthusiasm.
0:18:39 > 0:18:43For example, Burt has written out on his hand: "The problem of the very poor.
0:18:43 > 0:18:49"They must be segregated, prevented from reproducing their own kind".
0:18:49 > 0:18:54This is the kind of atmosphere, obviously, to which he was exposed.
0:18:54 > 0:19:01Working in the 1930s, Burt was determined to prove intelligence was inherited.
0:19:02 > 0:19:06He brought together more evidence for the inheritance of intelligence
0:19:06 > 0:19:09than any other person had done at that time.
0:19:09 > 0:19:12His papers were more impressive in terms of the number of different
0:19:12 > 0:19:15kinds of kinships on which heritables had been estimated.
0:19:15 > 0:19:22The fine grain detail in which the analyses were carried out. And so on.
0:19:23 > 0:19:29Burt introduced the IQ test as a way of measuring schoolchildren's intelligence.
0:19:31 > 0:19:34He was also to influence the introduction of the 11 Plus test,
0:19:34 > 0:19:38which was to become a key decider of a child's academic future.
0:19:40 > 0:19:44By 1945, every child's intelligence was tested.
0:19:46 > 0:19:51In order to study the inherited element of intelligence, Burt looked for subjects that were
0:19:51 > 0:19:55the same in every way, except the environment they were brought up in.
0:19:55 > 0:19:58Identical twins who had been separated at birth.
0:20:00 > 0:20:07So now, if you can find, when they are old enough to be IQ tested, a fair number of pairs of such twins,
0:20:07 > 0:20:14you can give them all IQ tests, and if their measured IQs resemble one another, that must be due to the only
0:20:14 > 0:20:17thing they have in common, namely their identical genetic make-up.
0:20:17 > 0:20:22It cannot be due to their environment, in theory, because they don't have that in common.
0:20:22 > 0:20:26Burt announced his findings with a great flourish, stating that he had
0:20:26 > 0:20:30found genetics were responsible for 80% of his subjects' IQ.
0:20:30 > 0:20:35In the crucial matter of separated monozygotic twins,
0:20:35 > 0:20:40and the measurement of the genetic heritability of intelligence,
0:20:40 > 0:20:44over the years we have been fortunate enough to steadily increase our
0:20:44 > 0:20:52sample size to the point where our data, based on 52 pairs of twins,
0:20:52 > 0:20:56is some 30% greater than that of its closest rival.
0:20:58 > 0:21:05Burt's research was highly respected and in 1946 he became the first British psychologist to be knighted
0:21:05 > 0:21:09for his contributions to psychological testing.
0:21:09 > 0:21:14But his ideas on eugenics had rather lost their appeal.
0:21:14 > 0:21:21Adolf Hitler adopted this philosophy to murder thousands of people he labelled mentally defective.
0:21:21 > 0:21:24The scientific community began to distance itself
0:21:24 > 0:21:29from the idea of engineering society according to intelligence.
0:21:32 > 0:21:38Burt continued to defend his ideas, but it was only after his death in 1971
0:21:38 > 0:21:45that scientists, including Professor Leon Kamin, scrutinised his results and came to some uneasy conclusions.
0:21:47 > 0:21:51As the sample size increased progressively, in successive papers,
0:21:51 > 0:21:54one noted an absolutely incredible thing.
0:21:54 > 0:22:01The correlations, the statistical results that he reported, remained identical to the third decimal.
0:22:01 > 0:22:04Well, theoretically, that sort of thing could happen.
0:22:04 > 0:22:10Also theoretically, the sun might not rise tomorrow morning, and that's probably a more probable event than
0:22:10 > 0:22:14what one would have had to have believed if one took Burt's number seriously.
0:22:14 > 0:22:18All of them remain identical to the third decimal place.
0:22:18 > 0:22:21Clearly something was drastically wrong.
0:22:21 > 0:22:24There's universal agreement among psychologists that Burt
0:22:24 > 0:22:27couldn't possibly have tested 53 pairs of twins.
0:22:27 > 0:22:31That at least the last 32 pairs must be figments of his imagination.
0:22:31 > 0:22:34I take perhaps an even more sceptical view of Burt.
0:22:34 > 0:22:38I think it's reasonable to suppose that he may never have laid eyes on
0:22:38 > 0:22:41a separated twin in his entire lifetime.
0:22:41 > 0:22:47But Kamin was convinced that Burt was motivated only by his genuine belief in inherited intelligence.
0:22:47 > 0:22:52I don't think Burt thought of himself as a manipulator and misleader of the public.
0:22:52 > 0:22:58I think Burt had the intellectual audacity to think that he knew the truth prior to any
0:22:58 > 0:23:03actual investigation of the facts, and therefore on account of noblesse oblige, he was letting the rest of
0:23:03 > 0:23:08us get a handle on the truth by presenting us numbers that would help us to accept it.
0:23:08 > 0:23:12And he did us the courtesy of inventing the numbers for us.
0:23:17 > 0:23:23Comprehensive proof of the part genetics play in intelligence still remained elusive,
0:23:23 > 0:23:29but as the '70s got underway, that didn't deter one man from adopting a radical new approach.
0:23:29 > 0:23:35In a rather sinister echo of Burt and Galton's theories, Californian doctor Robert Graham
0:23:35 > 0:23:41reasoned that if there were intelligence genes to be had, he could find a way of passing them on.
0:23:41 > 0:23:48In 2006, after Graham's death, Horizon looked back at his extraordinary quest.
0:23:51 > 0:23:57My name is Robert Klark Graham and I had a dream.
0:23:57 > 0:24:02To single-handedly saved the human race, one child at a time.
0:24:02 > 0:24:10Robert Graham believed that the gene pool was going downhill and that we needed to do something about that.
0:24:10 > 0:24:15He had this grandiose plan to remake all of humanity.
0:24:15 > 0:24:20It had the air of James Bond movie meets Disney, or something.
0:24:20 > 0:24:27Using the sperm of clever men, I hope to create intelligent kids.
0:24:27 > 0:24:30He was this strange scientist
0:24:32 > 0:24:37that was trying to breed the super race.
0:24:37 > 0:24:43What we're doing is exploring the possibilities of genetics.
0:24:43 > 0:24:48I was accused of being a racist and a Nazi.
0:24:48 > 0:24:52I can't say that I know much about Hitler or his vision.
0:24:52 > 0:24:58Yet my sperm bank was operational for nearly 20 years.
0:25:00 > 0:25:08Despite tremendous controversy, I was responsible for the creation of over 200 children.
0:25:10 > 0:25:16I would not be here without Robert Graham, without his existence, and in a way, I owe him my life.
0:25:20 > 0:25:26Well, I'm Tom Grunwal, and live here in Temecula in southern California.
0:25:26 > 0:25:29I'm Andrea Grunwal and I live with Tom.
0:25:34 > 0:25:38I had had two children with my first wife,
0:25:38 > 0:25:42then with my second wife, I took the steps to have a vasectomy.
0:25:42 > 0:25:46The next thing you know, I'm divorced.
0:25:46 > 0:25:52I never really thought I would ever have another child in the rest of my life.
0:25:52 > 0:25:54Until I met Andrea.
0:25:54 > 0:25:57I finally just spilled my gut and said, Tom, I don't know
0:25:57 > 0:26:03how to say this, but I would really like to have a baby and I don't know how you feel about that.
0:26:03 > 0:26:07And I said, OK, if you can figure out how,
0:26:07 > 0:26:09let's go for it.
0:26:13 > 0:26:17I wanted to offer these women the seed of clever men,
0:26:17 > 0:26:22and for me, scientists were the pinnacle of intelligence.
0:26:22 > 0:26:27With proven, measurable, practical ability.
0:26:29 > 0:26:31I figured, let's start at the top.
0:26:31 > 0:26:33We were trying to have
0:26:33 > 0:26:40outstanding genes and Nobel Prize winners possessed them.
0:26:45 > 0:26:49Due to your outstanding achievements, you
0:26:49 > 0:26:55would be an excellent donor for our Repository for Germinal Choice.
0:26:55 > 0:27:01We hope to create some very bright children, possibly a genius or two.
0:27:01 > 0:27:10I managed to convince three Nobel laureate scientists to each provide an anonymous sample for my bank.
0:27:12 > 0:27:18I actually was a little surprised that some of these older fellows were able to produce specimens so quickly.
0:27:19 > 0:27:26Bob was very pleased when we took that first look at the specimen under the microscope and saw
0:27:26 > 0:27:29thousands of sperm swimming vigorously.
0:27:33 > 0:27:34He beamed with joy.
0:27:36 > 0:27:39Good job!
0:27:39 > 0:27:42It's peculiar, but I didn't think it was weird.
0:27:42 > 0:27:44My name is Dr Afton Blake
0:27:44 > 0:27:49and I live in Los Angeles, California, in a little place called Mount Washington.
0:27:49 > 0:27:54Om....
0:27:54 > 0:27:59When I first called the repository, they were very friendly.
0:27:59 > 0:28:03They came up the next day to meet me and interview me.
0:28:03 > 0:28:07And I think the very next month I tried my first insemination.
0:28:07 > 0:28:11Choose me as your mother.
0:28:11 > 0:28:16Then, 10 months after I had tried the first time, I conceived.
0:28:18 > 0:28:22In August 1982, having been impregnated with donor
0:28:22 > 0:28:31codenamed Red 28, Dr Afton Blake gave birth to a boy she named Doran.
0:28:31 > 0:28:37It was ecstasy from the moment he came out, looked in my eyes, and stopped crying,
0:28:37 > 0:28:42immediately that we made contact and the bond was like so incredible.
0:28:42 > 0:28:49Everybody liked the name Doran, which means in Greek, a gift from the gods.
0:28:51 > 0:28:54I could never imagine life without him. It was like suddenly,
0:28:54 > 0:28:57what did I have before I had Doran?
0:28:57 > 0:29:00I didn't know, because this was everything.
0:29:02 > 0:29:07Do you want to hand me the dog?
0:29:07 > 0:29:16I am immensely pleased with the outcome of the mating between Dr Blake and Number 28.
0:29:16 > 0:29:21We've had a splendid result.
0:29:21 > 0:29:23I think no question about it.
0:29:23 > 0:29:29Doran is about as ideal, as nearly as we can judge at his early age,
0:29:29 > 0:29:34about as ideal as we could hope.
0:29:39 > 0:29:44Everyone wanted to know about my genius sperm bank child.
0:29:46 > 0:29:51Doran represented what Dr Graham was trying to achieve.
0:29:51 > 0:29:54Smart, beautiful.
0:29:54 > 0:29:56Everybody wanted a Doran.
0:29:56 > 0:29:59They just wanted to come to our bank and get a Doran.
0:30:02 > 0:30:04The phone rang off the hook.
0:30:04 > 0:30:07We had arrived.
0:30:07 > 0:30:11After 20 years in operation, my genius sperm bank was
0:30:11 > 0:30:18ultimately responsible for the production of 217 children.
0:30:18 > 0:30:21We've got lots of baby pictures.
0:30:22 > 0:30:27Jessie ended up being the 15th baby born to the repository.
0:30:27 > 0:30:31People used to just be amazed at his abilities.
0:30:33 > 0:30:37I look at myself as being an intelligent person and I think that
0:30:37 > 0:30:40I'm achieving in the world all that I can achieve.
0:30:40 > 0:30:42And that's something that
0:30:42 > 0:30:47I don't think can be said for a lot of people around me.
0:30:47 > 0:30:53I really need to make a contribution to realise myself or my potentials.
0:30:58 > 0:31:05And what about the repository's poster boy, our second born child, Doran Blake?
0:31:07 > 0:31:10He had showed such great promise as a youngster.
0:31:11 > 0:31:16I'm exceptional statistically.
0:31:16 > 0:31:18You know what I mean? I've always understood it that way.
0:31:18 > 0:31:23I'm like, OK, so most people have an IQ here and my IQ is here.
0:31:23 > 0:31:26As a child, Doran was good at everything.
0:31:26 > 0:31:34- "I".- He was in a highly gifted programme from first grade on.
0:31:36 > 0:31:40By the time he got to Exeter, Doran was taking existentialism and
0:31:40 > 0:31:46Buddhism, and he took six separate music lessons.
0:31:48 > 0:31:51Throughout my life, I've felt like I have not had to work as hard for the
0:31:51 > 0:31:55level of achievement that I've reached as most of my peers did.
0:31:57 > 0:32:00I turned out very well. You know, my IQ was off the charts
0:32:00 > 0:32:04and is basically everything that Robert Graham wanted.
0:32:04 > 0:32:06While at least some of the children did appear to have inherited their
0:32:06 > 0:32:12donor's intelligence, the sperm bank's success at producing geniuses could never be fully tested.
0:32:14 > 0:32:16Most of the children remained anonymous.
0:32:18 > 0:32:22Scientists continued to search for the inherited component of intelligence throughout the
0:32:22 > 0:32:281980s and '90s, as genetic research became increasingly sophisticated.
0:32:30 > 0:32:33But even though the genome was fully sequenced in 2003,
0:32:33 > 0:32:37no specific genes for intelligence have yet been identified.
0:32:41 > 0:32:44Behavioural geneticist Professor Robert Plomin
0:32:44 > 0:32:48has analysed the little we do know about intelligence genes.
0:32:49 > 0:32:53We don't know how many genes we're talking about and if there are very, very many, they're going to
0:32:53 > 0:32:57have very, very small effects and be very, very difficult to find.
0:32:57 > 0:33:00But I think these genetic differences, when they're expressed,
0:33:00 > 0:33:03are going to show up throughout the brain.
0:33:03 > 0:33:07It's not going to be this gene does that bit of the brain, this gene affects another bit of the brain.
0:33:07 > 0:33:11Now, that's a hypothesis for now but it's a very testable one when we find
0:33:11 > 0:33:14these damn genes, if we ever do find them.
0:33:17 > 0:33:20Scientists have now gathered data from combined studies of
0:33:20 > 0:33:25over 11,000 pairs of twins to give a more up-to-date measure of nature versus nurture.
0:33:25 > 0:33:30And it shows that Galton, Burt and Graham were at least partly on the right track.
0:33:30 > 0:33:34A large part of intelligence is inherited.
0:33:36 > 0:33:40You know, this is one of the most highly heritable characteristics around, intelligence.
0:33:40 > 0:33:44In adults, we're talking about at least 50 or 60%
0:33:44 > 0:33:49of the variance in the population is due to genetic differences among us.
0:33:51 > 0:33:56So, if according to current estimates, about 50% of our intelligence is genetic,
0:33:56 > 0:34:02then that of course leaves the other half up for grabs, and that's where environment or nurture comes in.
0:34:02 > 0:34:05Scientists began to look at the impact of everything, from diet and supplements,
0:34:05 > 0:34:11to good old pushy parenting when fostering intelligence in children.
0:34:11 > 0:34:14David Baddiel investigated just how far
0:34:14 > 0:34:19a fertile educational environment could affect a child's abilities.
0:34:20 > 0:34:22- Hello. - Hello, David. Please do come in.
0:34:22 > 0:34:23Hello, nice to meet you.
0:34:23 > 0:34:25- Hello.- Hi.
0:34:25 > 0:34:27Now, let's deal with...
0:34:27 > 0:34:30Zaheib, the younger brother, answers the first question.
0:34:30 > 0:34:35- So if this is theta... - OK, so theta is that angle?
0:34:35 > 0:34:39- This angle. - Right.- The vertical must be T...
0:34:39 > 0:34:42- cos theta.- That's very good. OK.
0:34:42 > 0:34:46When do you first remember, either of you, doing a maths problem?
0:34:46 > 0:34:48- When I was a toddler.- Really tiny?
0:34:48 > 0:34:50- Addition.- Really?- Addition, yeah.
0:34:50 > 0:34:52- And what about you?- Yeah, same.
0:34:52 > 0:34:56You remember when you were counting 99s?
0:34:56 > 0:35:01Oh, yeah. In nursery, I knew my 99 times table.
0:35:01 > 0:35:04- How old were you then?- In nursery you did your 99 times table?- Yeah.
0:35:04 > 0:35:06You were about three-and-a-half or something.
0:35:06 > 0:35:11I can't do my 99 times table! Apart from 99 times one is 99, that's it!
0:35:11 > 0:35:13Beyond that, I'm slightly struggling.
0:35:13 > 0:35:15And I'm 44.
0:35:15 > 0:35:18Which I think is a multiple. No, it's not!
0:35:18 > 0:35:22- OK, so you are starting on A level maths now?- Yeah.- It is that right?
0:35:22 > 0:35:27- Yes. And when are you planning to take your A level maths?- In January.
0:35:27 > 0:35:30And what's very special about that?
0:35:30 > 0:35:32If I get A, I'll break the world record.
0:35:32 > 0:35:34- You'll be the youngest... - Ever. Ever, ever.
0:35:34 > 0:35:37Child ever to get A level maths.
0:35:43 > 0:35:44Why has it become important to you to push your children?
0:35:44 > 0:35:46Why is that important to you?
0:35:46 > 0:35:54To give them something to think about so that their mind is engaged in something useful all the time.
0:35:54 > 0:35:58- Right.- It's very important for them to be independent thinker.
0:35:58 > 0:36:02So do you feel that mathematics specifically is almost a spiritual
0:36:02 > 0:36:06training, then, for kids, in that it will actually train their brains and
0:36:06 > 0:36:11their minds to become better thinkers, better opinion formers? Is that what you're saying?
0:36:11 > 0:36:15That's exactly right because I did mention maths is the key thinking tool.
0:36:15 > 0:36:19- Most of the time, they are not actually studying. - So how much time do they spend?
0:36:19 > 0:36:24- When they don't go to school, they spend on average about five hours.- Right.
0:36:24 > 0:36:26During school days, about three hours.
0:36:26 > 0:36:29So they'll have their school day and then another three hours of study?
0:36:29 > 0:36:31- Yes, yeah, on average. - It seems quite a lot to me.
0:36:31 > 0:36:34But that means most of the time they are not studying.
0:36:34 > 0:36:37Because there are 24 hours in the interval.
0:36:37 > 0:36:42- Yeah, but then they're sleeping for quite a lot of that. - Yes, sleeping, yes.
0:36:42 > 0:36:48But it isn't just a highly educational environment that can enhance intelligence.
0:36:48 > 0:36:54Baddiel also looked at a revealing experiment which showed that other behaviours instilled in very
0:36:54 > 0:37:00early childhood can predict a great deal about future academic success.
0:37:02 > 0:37:06Now, if you had to choose the one marshmallow or the
0:37:06 > 0:37:08three marshmallows, which one do you prefer?
0:37:10 > 0:37:11The three marshmallows? OK.
0:37:11 > 0:37:1740 years ago, a rather extraordinary experiment was carried out in this nursery at Stanford University.
0:37:17 > 0:37:22The nursery is re-running the experiment for David.
0:37:22 > 0:37:28All it consists of is a bell, a group of four-year-old children and a plate of marshmallows.
0:37:28 > 0:37:30The question is, can a child resist eating the
0:37:30 > 0:37:35one marshmallow in front of them for the promise of getting three later?
0:37:35 > 0:37:38If they don't want to wait the time, they can ring the bell.
0:37:40 > 0:37:45It's like watching a primeval battle between man or woman and their own desire.
0:37:47 > 0:37:52The waiting time is ten minutes, just five minutes shorter than in the original.
0:37:54 > 0:37:56First to go is Bridie.
0:37:56 > 0:37:59See, she's now thinking, when's he coming back?
0:37:59 > 0:38:03See, I'm not absolutely convinced that she is now thinking about the marshmallows.
0:38:03 > 0:38:07I think she might be thinking about whatever, kid's thoughts, now.
0:38:07 > 0:38:10Now she's thinking about the marshmallows.
0:38:10 > 0:38:16If Bridie is going to succeed, she will have to devise strategies like the children in the
0:38:16 > 0:38:22original study, to look away or stop thinking about the taste and smell of the marshmallow.
0:38:27 > 0:38:31Just 30 seconds to go and Bridie is still resisting.
0:38:34 > 0:38:36I'm feeling a bit sorry for her now.
0:38:37 > 0:38:39Ooh. Oh-oh.
0:38:39 > 0:38:40She's gone for the bell, she's gone for the bell.
0:38:40 > 0:38:44Is she ringing or is she just looking at the bell?
0:38:44 > 0:38:48Now she's rung the bell, she rang the bell. I'm so disappointed for her.
0:38:48 > 0:38:51Next up is Olivia.
0:38:53 > 0:38:55God, has she eaten one?
0:38:55 > 0:38:59Oh, my God, she's eaten a marshmallow before the experiment's started.
0:38:59 > 0:39:01But that's ruined it.
0:39:02 > 0:39:05That's a shame because she's clearly one with impulse control issues.
0:39:05 > 0:39:08So it's over to Jayden.
0:39:12 > 0:39:15I think I know which way she's going to go, I tell you.
0:39:19 > 0:39:22Finally, it's Keira.
0:39:22 > 0:39:28Welcome back to Stanford for round two of the marshmallow experiment.
0:39:30 > 0:39:33At first, she seems to be losing heart.
0:39:33 > 0:39:36I think she can't bear it.
0:39:36 > 0:39:41I can hear the devil on her shoulder saying, "eat the marshmallow!"
0:39:41 > 0:39:45This must seem so long if you're a child.
0:39:45 > 0:39:50If you think that children have a relative idea of time that is about ten times that of an adult.
0:39:53 > 0:39:57Some of the children who'd succeeded before had managed to stop thinking
0:39:57 > 0:40:00about the marshmallow as a real marshmallow.
0:40:00 > 0:40:04They'd imagined it away.
0:40:04 > 0:40:07I wonder if she's actually consciously thought, if I don't look at them,
0:40:07 > 0:40:09I won't desire them so much.
0:40:09 > 0:40:11So therefore I'll be able to get through it.
0:40:14 > 0:40:16She did it! She did it!
0:40:16 > 0:40:19She did it. I'm so pleased for her.
0:40:20 > 0:40:25The scientists tracked the lives of the original children for 40 years.
0:40:25 > 0:40:30What they found was that those who could resist the marshmallow did better at school.
0:40:30 > 0:40:35And not only that, they were less likely to fall ill, or get divorced.
0:40:35 > 0:40:43It seems being able to resist a sweet at four could predict academic success and a happier adult life.
0:40:45 > 0:40:50This experiment serves as just one example of the traits which can be affected by nurture.
0:40:54 > 0:40:58Now, after decades of scrutinising human intelligence, we are beginning
0:40:58 > 0:41:02to understand that it can be affected by many variables,
0:41:02 > 0:41:07not only by who your parents are, but also the environmental influences on your upbringing.
0:41:13 > 0:41:16And it's not just the causes of intelligence that are wide-ranging.
0:41:16 > 0:41:19We're also beginning to broaden our definition of intelligence itself.
0:41:19 > 0:41:22100 years ago, it was simple.
0:41:22 > 0:41:25Intelligence was a measure of problem solving ability,
0:41:25 > 0:41:30general knowledge and memory that could be assessed by one all-encompassing test.
0:41:30 > 0:41:33But now we have to look again at whether that stood the test of time.
0:41:37 > 0:41:42The IQ test has lasted so long because it's got an almost magical property.
0:41:44 > 0:41:49It seems to show that we have one general all-round ability, a kind of
0:41:49 > 0:41:54all-purpose thinking skill that can be represented by a single number, the IQ score.
0:41:54 > 0:41:57Very convenient, if you want to compare people.
0:42:02 > 0:42:08Horizon brought together seven experts from seven very different disciplines to sit the test.
0:42:16 > 0:42:21The IQ test consists of many sections that seem unconnected.
0:42:21 > 0:42:23What does an entomologist study?
0:42:23 > 0:42:27There are sections on vocabulary and general knowledge.
0:42:27 > 0:42:29What's the capital of Jordan?
0:42:29 > 0:42:35- Amman.- What's the distance between London and Hong Kong in miles?
0:42:35 > 0:42:41I would suspect it's around a third of the way around the globe, so about 8,000 miles.
0:42:41 > 0:42:43A section on memory.
0:42:43 > 0:42:46Eight, one, seven, five, backwards.
0:42:46 > 0:42:49Five, seven, one, eight.
0:42:51 > 0:42:54And a section to test spatial ability.
0:42:58 > 0:43:00- You're doing just fine. - Wow, that was tough.
0:43:00 > 0:43:02Do a lot of people get this one in two minutes?
0:43:02 > 0:43:04I can't see how that works.
0:43:04 > 0:43:08Common sense might tell us that we're good at some of these sections
0:43:08 > 0:43:11and bad at others. But that's not the case.
0:43:15 > 0:43:20On average, if we're good at one of these sections, we tend to be good at all of them.
0:43:20 > 0:43:27And from this comes the idea that intelligence is some kind of general, all-round ability.
0:43:32 > 0:43:38Based on a range of difficult IQ problems, the results were predictable. Well, almost.
0:43:40 > 0:43:44In third place, fighter pilot, Gary.
0:43:44 > 0:43:49In second place, IQ specialist, Nathan.
0:43:49 > 0:43:54But he was beaten to the top spot by quantum physicist, Seth Lloyd.
0:43:57 > 0:44:02But when the winner was announced, there was an immediate objection.
0:44:02 > 0:44:06So I'd actually like to say this is unfair because actually these
0:44:06 > 0:44:13tests were things that fit extremely closely with what I do on a day-to-day basis.
0:44:13 > 0:44:20Seth's modesty at coming top in the IQ-type problems shows why some people think the IQ test is flawed.
0:44:20 > 0:44:26That means the electron, in some funky quantum sense, reads zero and one at the same time.
0:44:26 > 0:44:31Was Seth good at the tests merely because of what he does every day?
0:44:31 > 0:44:35My job consists of trying to solve hard mathematical
0:44:35 > 0:44:40problems related to the physical world, like, you know, how does a black hole evaporate, for instance.
0:44:40 > 0:44:44I'm constantly pushed to the very edge of what I can actually do.
0:44:46 > 0:44:50So, it's actually fun for me to do something like these puzzles which are relatively easy.
0:44:50 > 0:44:55Or did the tests capture something essential about Seth?
0:44:55 > 0:45:00We could say he has a high general intelligence as revealed by the
0:45:00 > 0:45:04tests, and that this means he's the most intelligent.
0:45:08 > 0:45:09But that's not the whole story.
0:45:12 > 0:45:18Not even test manufacturers would say the result of this test will tell you how intelligent somebody is.
0:45:18 > 0:45:21They would say it's a small component of making those
0:45:21 > 0:45:26judgments and that you should be looking at a much broader spectrum of skills, abilities and aptitudes.
0:45:26 > 0:45:32The IQ test looks at a lot of old knowledge, like, you know what the capital of Italy is, or, can you add
0:45:32 > 0:45:36two-plus-four, can you compare slavery and freedom, those are IQ-kinds of tests.
0:45:36 > 0:45:39But they don't tell you anything about whether the person will
0:45:39 > 0:45:42actually ever do anything that's productive in the world.
0:45:42 > 0:45:48Professor Howard Gardner has come up with a newer, broader way of testing intelligence.
0:45:48 > 0:45:51The major move I've made in the study of intelligence is to pluralise it.
0:45:51 > 0:45:56I've come up with an alternative view which is called multiple intelligence theory.
0:45:56 > 0:46:01To perform some kind of an action in the area of music, or in the area of navigation
0:46:01 > 0:46:05is very different than to perform in a scholastic kind of assignment.
0:46:05 > 0:46:09And my whole analysis over many years suggests it's a mistake.
0:46:09 > 0:46:14It's a category error to lump all these together and to call them intelligence.
0:46:17 > 0:46:22Professor Gardner is convinced we have at least eight relatively separate intelligences.
0:46:27 > 0:46:34This is completely opposite to IQ, which assumes that we all have just one general intelligence.
0:46:34 > 0:46:36So, you might be wonderful at understanding other people
0:46:36 > 0:46:40but a disaster at doing crossword puzzles, or flying an airplane.
0:46:40 > 0:46:44So we do know that an individual's high-performance in one area
0:46:44 > 0:46:47simply doesn't predict high performance in other areas.
0:46:47 > 0:46:51Horizon put its line-up of high-flyers through Professor
0:46:51 > 0:46:58Gardner's new intelligence tests to see if the outcome would be any different to the standard IQ tests.
0:47:00 > 0:47:03But there's no agreed system for measuring them.
0:47:06 > 0:47:10This could be a drawback for Professor Gardner's approach,
0:47:10 > 0:47:14but he still defends the value of non-academic intelligences.
0:47:16 > 0:47:17Wow, this collapsed.
0:47:17 > 0:47:21Football players may well not be scholastically intelligent and so they
0:47:21 > 0:47:24don't do well in a school with reading and writing and so on.
0:47:24 > 0:47:27If we lived in a non-literate society,
0:47:27 > 0:47:32the people who do well in school would not emerge at all, and perhaps people who are good at football
0:47:32 > 0:47:38would be better hunters, and better strategists about survival, and then we'd be calling them smart.
0:47:38 > 0:47:40And the people who had the potential to read and write
0:47:40 > 0:47:43would be irrelevant because there'd been no reading and writing there.
0:47:47 > 0:47:51Based on the combined outcomes of the IQ tests and the newer intelligence tests,
0:47:51 > 0:47:57the results should reveal who has the most mental flexibility and all-round intelligence.
0:48:00 > 0:48:07Tied equal in third place, fighter pilot, Gary, and musical prodigy, Alex.
0:48:07 > 0:48:11In second place, IQ specialist, Nathan.
0:48:11 > 0:48:14And in first place, an interesting tie.
0:48:14 > 0:48:18One of the winners did fantastically well on the standard IQ test,
0:48:18 > 0:48:23but the other one wasn't even in the IQ test top three.
0:48:25 > 0:48:32Taken across all the tests, quantum physicist, Seth Lloyd, shared higher scores with dramatist, Bonnie Greer.
0:48:41 > 0:48:45Horizon's assessment of the experts show that the IQ test
0:48:45 > 0:48:50only identifies a very particular type of intelligence.
0:48:50 > 0:48:55It couldn't predict how good someone would be at a wider ranging set of skills.
0:48:57 > 0:49:02But the IQ test hasn't been consigned to the history books just yet.
0:49:02 > 0:49:06It might not pinpoint everyone's unique intelligence type, but it
0:49:06 > 0:49:11has turned out to be useful in a way no-one could have predicted.
0:49:11 > 0:49:12You have 45 minutes to do the test, OK?
0:49:12 > 0:49:15OK.
0:49:16 > 0:49:19Write the three letters between A and E.
0:49:19 > 0:49:21And cross out of the middle one.
0:49:21 > 0:49:24Bill and Davina are 79 years old.
0:49:24 > 0:49:27This is the second time they've done this test.
0:49:27 > 0:49:33If H comes before K, write X, unless S comes before Q...
0:49:33 > 0:49:42The first time was in 1932 when every 11-year-old in Scotland was put through an intelligence test.
0:49:45 > 0:49:49The results were rediscovered recently in an Edinburgh basement.
0:49:51 > 0:49:53If you want to know how our intelligence changes as we
0:49:53 > 0:49:57get older, these results are a potential goldmine.
0:49:57 > 0:50:01We've brought hundreds of people back and we got them to sit the exact
0:50:01 > 0:50:05same test they had sat when they were aged 11.
0:50:05 > 0:50:07Now, these people were now 79 or 80 years old.
0:50:07 > 0:50:13We gave the same instructions, we gave the same test, and we gave the same time limit.
0:50:18 > 0:50:20It was a little stickier than I thought it would be.
0:50:20 > 0:50:22I walked through it quite happily, quite honestly.
0:50:22 > 0:50:27I felt I must have been very bright at 11 if I sat that exam and passed.
0:50:27 > 0:50:28There were some intriguing results.
0:50:28 > 0:50:33Almost everyone had a better score at 80 than they did at 11.
0:50:33 > 0:50:38But some had gone from being just averagely intelligent to a much higher level.
0:50:38 > 0:50:41Now that's what really drives our research.
0:50:41 > 0:50:47Why are those people who've gone from IQ 100 at age 11, up to 110 or 120?
0:50:47 > 0:50:52What have they done right? What can be the recipe for successful ageing?
0:50:52 > 0:50:56We're finding that the person with more education,
0:50:56 > 0:51:00even though they had the same IQ in childhood, is doing slightly better in old age, on average.
0:51:00 > 0:51:04The person who had a more professional job in old age is doing slightly
0:51:04 > 0:51:09better, on average, than the person who had a manual job despite the fact that they started at the same level.
0:51:09 > 0:51:15The people who smoked have got slightly less good mental ability than you would expect.
0:51:15 > 0:51:19What's even more remarkable is that the kids who had higher IQ scores at
0:51:19 > 0:51:2311 are the very ones still alive today.
0:51:25 > 0:51:28So it seems high IQ in childhood is good for survival.
0:51:30 > 0:51:37Maybe an IQ score is a record of how well wired together your brain is, and that might, highly speculative,
0:51:37 > 0:51:41that might be associated with how well wired up the rest of your body is.
0:51:46 > 0:51:52But if our intelligence can increase as we grow older, can we go one step further and boost it artificially?
0:51:55 > 0:51:58Marcus du Sautoy investigated one technique.
0:52:02 > 0:52:05At the University of Goettingen in Germany, they're pioneering
0:52:05 > 0:52:11technology that could greatly extend our control over our own brains.
0:52:11 > 0:52:15They're developing a means to turbo-charge our grey matter.
0:52:22 > 0:52:27The aim is to improve the volunteer's ability to subconsciously learn.
0:52:27 > 0:52:28The test itself is simple.
0:52:28 > 0:52:36When Leila sees a dot appear on the screen, she has to tap a corresponding key on the keyboard.
0:52:36 > 0:52:39There is a pattern to when the dots appear.
0:52:39 > 0:52:42But it's impossible to detect.
0:52:42 > 0:52:47At least before the artificial stimulation of her brain begins.
0:52:47 > 0:52:51What we want to do is to facilitate the
0:52:51 > 0:52:54excitability of her motor cortex.
0:52:54 > 0:52:58- And in order to be able to do that, we have to fix an electrode. - I presume this is perfectly safe.
0:52:58 > 0:53:05I mean, I'd be a bit nervous about having electricity shot through my brain.
0:53:05 > 0:53:07Well, they're very weak currents.
0:53:07 > 0:53:10They're so weak, she doesn't notice anything.
0:53:10 > 0:53:16They're so weak that they just manipulate the membrane potential of nerve cells a little bit.
0:53:16 > 0:53:19So, now we will stimulate the motor cortex here.
0:53:19 > 0:53:26By anodal electricity, positive electricity, for 10 minutes.
0:53:26 > 0:53:29So, now stimulation starts.
0:53:29 > 0:53:32So there's now electricity passing through Leila's brain.
0:53:32 > 0:53:36- Can you feel anything?- No, nothing.
0:53:36 > 0:53:38There's no smoke. I can't see any.
0:53:38 > 0:53:46And during this stimulation, Leila will move her fingers and do the implicit learning paradigm.
0:53:46 > 0:53:53Then we will measure simultaneously how quick she can respond to the visual target during this time.
0:53:53 > 0:53:58What we expect to see is with motor cortex depolarisation
0:53:58 > 0:54:02that's more excitable and then her reaction time
0:54:02 > 0:54:04will improve.
0:54:04 > 0:54:10And then we'll see an increase in speed that she's not constantly picking up a pattern, but
0:54:10 > 0:54:13subconsciously, she's getting better at learning.
0:54:13 > 0:54:17The longer the stimulation lasts, the greater its effects will be.
0:54:17 > 0:54:25In previous experiments lasting 24 hours, permanent improvements to the brain were forged.
0:54:25 > 0:54:29We know from other research, basic animal research, that
0:54:29 > 0:54:36new connections between individual nerve cells will be built after about 30 minutes.
0:54:36 > 0:54:40And after about a day, they start to become functional.
0:54:40 > 0:54:45- So it's really changing the structure of the brain by doing this?- Yes.
0:54:45 > 0:54:46It's not just a temporary effect?
0:54:46 > 0:54:52Yes, so we have structural alterations which allow you to move your fingers quicker in this case.
0:54:54 > 0:55:00With measuring the reaction times, we will see that you'll probably speed up in the range of 10% or so.
0:55:00 > 0:55:0210%, and that's significant, is it?
0:55:02 > 0:55:0410%, you wouldn't expect that?
0:55:04 > 0:55:07- Not without stimulation.- Right.
0:55:13 > 0:55:17The idea of being able to enhance our intelligence, if you don't mind
0:55:17 > 0:55:21having your brain stimulated, hints at the dawn of a brave new world.
0:55:21 > 0:55:24But if you're going to involve computers, then why stop there?
0:55:24 > 0:55:28Some scientists think the creation of artificial intelligence
0:55:28 > 0:55:32could transport us to new levels of interaction and understanding.
0:55:34 > 0:55:39It's something that has occupied the minds of technology researchers for decades,
0:55:39 > 0:55:43and Horizon has featured some of their wilder predictions.
0:55:43 > 0:55:46Our descendant will not be the child of the loin,
0:55:46 > 0:55:49but the child of the brains, the thing we call the computer,
0:55:49 > 0:55:52which does not have to pass through the birth canal.
0:55:52 > 0:55:57And does not grow by a tablespoonful of grey matter every 100,000 years,
0:55:57 > 0:56:00which is the case in the rapid growth of our brain,
0:56:00 > 0:56:03but grows a factor of 10 in power every seven years.
0:56:03 > 0:56:05The computer generation.
0:56:05 > 0:56:10There's no question that it'll match us in narrow reasoning power by 1990,
0:56:10 > 0:56:16and go beyond us to become the great new intelligent race of the future.
0:56:16 > 0:56:18The artificial intelligences of the future will be worried about
0:56:18 > 0:56:21weighty problems that we simply can't understand.
0:56:21 > 0:56:27And they may condescend to talk to us. They may...
0:56:27 > 0:56:31amuse us on occasion, or play games that we like to play.
0:56:31 > 0:56:33And in some sense, they might keep us as pets.
0:56:38 > 0:56:43Although those predictions haven't been borne out, work on artificial intelligence has continued to race
0:56:43 > 0:56:47towards the goal of a man-made super-intelligence, leading one
0:56:47 > 0:56:53man to predict that a computer will equal a human brain's power by 2029.
0:56:56 > 0:57:00His name is Ray Kurzweil, inventor and visionary.
0:57:02 > 0:57:07He believes that our understanding of the human brain will soon be complete.
0:57:09 > 0:57:1325 years from now, we will have actually mastered human intelligence.
0:57:13 > 0:57:18We'll have both the hardware and the software to recreate human intelligence in a machine.
0:57:22 > 0:57:26Kurzweil was one of the first to make a computer that could read.
0:57:26 > 0:57:30MACHINE: 'For score and seven years ago, our fathers brought forth upon this...'
0:57:30 > 0:57:34If his latest prediction is right, then we will understand the human brain
0:57:34 > 0:57:39at almost exactly the same time as computers equal its power.
0:57:40 > 0:57:44It's this culmination of events that would lead to the singularity.
0:57:46 > 0:57:49There's really a point in human history where human society will be
0:57:49 > 0:57:53profoundly transformed by creating non-biological intelligence.
0:57:53 > 0:57:59Machines that are ultimately billions of times more capable than human beings today.
0:57:59 > 0:58:04And we will integrate with this technology, and it will enhance human potential.
0:58:06 > 0:58:11We'll have to wait until 2029 to find out whether Kurzweil's prediction is correct.
0:58:11 > 0:58:17Until then, science can only continue in its quest to fully fathom our unique mental abilities.
0:58:19 > 0:58:22Understanding what makes my intelligence different from
0:58:22 > 0:58:28that of someone like Einstein's could be a question of my genes, or the way I was brought up.
0:58:28 > 0:58:31Maybe I'm just intelligent in a different kind of way?
0:58:31 > 0:58:34He was pretty good at physics. I'm pretty good at...
0:58:34 > 0:58:37Well, anyway, 2029 is not so far away
0:58:37 > 0:58:41so maybe we'll just have to wait and see who's so clever then.
0:59:04 > 0:59:07Subtitles by Red Bee Media Ltd
0:59:07 > 0:59:10E-mail subtitling@bbc.co.uk