Yuval Harari - Homo Deus - A Brief History of Tomorrow

However, over the last few decades the life sciences have reached the conclusion that this liberal story is pure mythology. The single authentic self is as real as the eternal Christian soul, Santa Claus and the Easter Bunny. If you look really deep within yourself, the seeming unity that we take for granted dissolves into a cacophony of conflicting voices, none of which is ‘my true self’. Humans aren’t individuals. They are ‘dividuals’.

The human brain is composed of two hemispheres, connected to each other through a thick neural cable. Each hemisphere controls the opposite side of the body. The right hemisphere controls the left side of the body, receives data from the left-hand field of vision and is responsible for moving the left arm and leg, and vice versa. This is why people who have had a stroke in their right hemisphere sometimes ignore the left side of their body (combing only the right side of their hair, or eating only the food placed on the right side of their plate). 10

There are also emotional and cognitive differences between the two hemispheres, though the division is far from clear-cut. Most cognitive activities involve both hemispheres, but not to the same degree. For example, in most cases the left hemisphere plays a more important role in speech and in logical reasoning, whereas the right hemisphere is more dominant in processing spatial information.

Many breakthroughs in understanding the relations between the two hemispheres were based on the study of epilepsy patients. In severe cases of epilepsy, electrical storms begin in one part of the brain but quickly spread to other parts, causing a very acute seizure. During such seizures patients lose control of their body, and frequent seizures consequently prevent patients from holding a job or leading a normal lifestyle. In the mid-twentieth century, when all other treatments failed, doctors alleviated the problem by cutting the thick neural cable connecting the two hemispheres, so that electrical storms beginning in one hemisphere could not spill over to the other. For brain scientists these patients were a gold-mine of astounding data.

Some of the most notable studies on these split-brain patients were conducted by Professor Roger Wolcott Sperry, who won the Nobel Prize in Physiology and Medicine for his groundbreaking discoveries, and by his student, Professor Michael S. Gazzaniga. One study was conducted on a teenaged boy. The boy was asked what he would like to do when he grew up. The boy answered that he wanted to be a draughtsman. This answer was provided by the left hemisphere, which plays a crucial part in logical reasoning as well as in speech. Yet the boy had another active speech centre in his right hemisphere, which could not control vocal language, but could spell words using Scrabble tiles. The researchers were keen to know what the right hemisphere would say. So they spread Scrabble tiles on the table, and then took a piece of paper and wrote on it: ‘What would you like to do when you grow up?’ They placed the paper at the edge of the boy’s left visual field. Data from the left visual field is processed in the right hemisphere. Since the right hemisphere could not use vocal language, the boy said nothing. But his left hand began moving rapidly across the table, collecting tiles from here and there. It spelled out: ‘automobile race’. Spooky. 11

Equally eerie behaviour was displayed by patient WJ, a Second World War veteran. WJ’s hands were each controlled by a different hemisphere. Since the two hemispheres were out of touch with one another, it sometimes happened that his right hand would reach out to open a door, and then his left hand would intervene and try to slam the door shut.

In another experiment, Gazzaniga and his team flashed a picture of a chicken claw to the left-half brain – the side responsible for speech – and simultaneously flashed a picture of a snowy landscape to the right brain. When asked what they saw, patients invariably answered ‘a chicken claw’. Gazzaniga then presented one patient, PS, with a series of picture cards and asked him to point to the one that best matched what he had seen. The patient’s right hand (controlled by his left brain) pointed to a picture of a chicken, but simultaneously his left hand shot out and pointed to a snow shovel. Gazzaniga then asked PS the million-dollar question: ‘Why did you point both to the chicken and to the shovel?’ PS replied, ‘Oh, the chicken claw goes with the chicken, and you need a shovel to clean out the chicken shed.’ 12

What happened here? The left brain, which controls speech, had no data about the snow scene, and therefore did not really know why the left hand pointed to the shovel. So it just invented something credible. After repeating this experiment many times, Gazzaniga concluded that the left hemisphere of the brain is the seat not only of our verbal abilities, but also of an internal interpreter that constantly tries to make sense of our life, using partial clues in order to concoct plausible stories.

In another experiment, the non-verbal right hemisphere was shown a pornographic image. The patient reacted by blushing and giggling. ‘What did you see?’ asked the mischievous researchers. ‘Nothing, just a flash of light,’ said the left hemisphere, and the patient immediately giggled again, covering her mouth with her hand. ‘Why are you laughing then?’ they insisted. The bewildered left-hemisphere interpreter – struggling for some rational explanation – replied that one of the machines in the room looked very funny. 13

It’s as if the CIA conducts a drone strike in Pakistan, unbeknown to the US State Department. When a journalist grills State Department officials about it, they make up some plausible explanation. In reality, the spin doctors don’t have a clue why the strike was ordered, so they just invent something. A similar mechanism is employed by all human beings, not just by split-brain patients. Again and again my own private CIA does things without the approval or knowledge of my State Department, and then my State Department cooks up a story that presents me in the best possible light. Often enough, the State Department itself becomes convinced of the pure fantasies it has invented. 14

Similar conclusions have been reached by behavioural economists, who want to know how people take economic decisions. Or more accurately, who takes these decisions. Who decides to buy a Toyota rather than a Mercedes, to go on holiday to Paris rather than Thailand, and to invest in South Korean treasury bonds rather than in the Shanghai stock exchange? Most experiments have indicated that there is no single self making any of these decisions. Rather, they result from a tug of war between different and often conflicting inner entities.

One groundbreaking experiment was conducted by Daniel Kahneman, who won the Nobel Prize in Economics. Kahneman asked a group of volunteers to join a three-part experiment. In the ‘short’ part of the experiment, the volunteers inserted one hand into a container filled with water at 14°C for one minute, which is unpleasant, bordering on painful. After sixty seconds, they were told to take their hand out. In the ‘long’ part of the experiment, volunteers placed their other hand in another water container. The temperature there was also 14°C, but after sixty seconds, hot water was secretly added into the container, bringing the temperature up to 15°C. Thirty seconds later, they were told to pull out their hand. Some volunteers did the ‘short’ part first, while others began with the ‘long’ part. In either case, exactly seven minutes after both parts were over came the third and most important part of the experiment. The volunteers were told they must repeat one of the two parts, and it was up to them to choose which; 80 per cent preferred to repeat the ‘long’ experiment, remembering it as less painful.