The Unpersuadables: Adventures with the Enemies of Science (12 page)

*

They are everywhere, these invisible forces. In the effects of placebo, in the power of authority figures, in the awful physics of the situations that can push us silently into evil. What connects them seems to be some species of illusion. It tells us that these forces do not exist, that we are in control of who we are, what we do and how we think. Having spent ten days being menaced by proximity to my unconscious, it is clear where I now have to lead my search – to the place where all these forces work their magic, and where so many discomforting illusions are summoned. The brain.

The first surprise is how new brains are. The earth has existed for a full four and a half billion years, and yet it was just
six hundred million years ago
that the earliest of them began to form. It has taken almost all of that time for nature to work out the stunning mechanics of the human iteration. The
first neurologically recognisable
Homo sapiens
, known as ‘Mitochondrial Eve’
(to whom, incredibly, genetic studies have shown that everyone on earth is related), lived only two hundred thousand years ago. Nobody knows what caused the human brain to accelerate its form and function until it was so dramatically in advance of our fellow creatures, but for some reason we gained an oversized
prefrontal cortex, which enabled us to strategise, socialise and make lateral associations
.

We left our sunny Eden in East Africa
sixty thousand years ago and began colonising the world. Then, around forty thousand years ago, the next evolutionary mystery took place. For reasons that remain unclear, there was
a sudden explosion in creativity
that saw paintings springing up on cave walls from Australia to Europe and the crafting of intricate articles such as rope, oil lamps, drills and sewing needles as far away as Siberia. We began painting our bodies, wearing jewellery and burying our dead.

It is for behaviours such as these that we humans like to flatter ourselves that we are made of a different metaphysical stuff than the animals. But our DNA does not lie.
Even today, we remain
a specific
variety of African ape that evolved in the Great Rift Valley. The last survivors of the hominins, we once lived alongside at least four other varieties of nearly-humans. In terms of time alone, though, we are nowhere near the most successful hominin to have inhabited the planet. We might have been here for two hundred thousand years, but some of our cousins lived for more than two million.

From the confidence that is exuded by some neuroscientists, it might be easy to assume that the riddles of the brain have mostly been solved. But that is not so. How does it generate thoughts? How, exactly, does it store memories? How does it create that sensation of oneness, of coalescence, of having an identity, a narrative purpose, a soul? Although there are plenty of theories, the answers to all of these questions remain far from clear. In truth, this most magical of organs remains deeply mysterious.

It begins its formation in the embryo as a tiny fluid-filled tube. Pinched off in the centre as the foetus develops, one end of the sac becomes the spinal cord, while on the other grows – at the rate of
two hundred and fifty thousand cells a minute
– a piece of organic technology that is so advanced, and yet so wondrously strange, that nothing in the known universe is comparable. Built from what has been described by neuroscientist Professor David Eagleman as
‘an alien kind of computational material
,’ it is pink, has the texture of almost-set jelly, consumes 20 per cent of our bodily energy and is said to be
capable of receiving millions of pieces of information at any given moment
.

It might weigh little over a kilogram but, taken on its own scale, the brain is unimaginably vast.
One cubic millimetre
contains between twenty and twenty-five thousand neurons.
It has eighty-six billion of these cells
, and
each one is as complex as a city
and is in contact with ten thousand other neurons just like it. Within just one cubic centimetre of brain tissue, there is the same number of connections as there are stars in the Milky Way. Your brain contains a hundred trillion of them. Information in the form of electricity and chemicals flows around these paths in great forking trails and in circuits and feedback loops and fantastical storms of activity that bloom to life at speeds of up to
a hundred and twenty metres per second
.
According to the neuroscientist V. S. Ramachandran, ‘The number of permutations
and combinations of activity that are theoretically possible exceeds the number of elementary particles in the universe.’
And yet, he continues, ‘We know so little about it
that even a child’s questions should be seriously entertained.’

Those still desperate for evidence that we are of a special category of being should start their hunt for clues in early childhood.
Other mammals give birth to their young when their brains have developed
enough that they can control their own body. But not us. We arrive into life, in the words of anthropologist Clifford Geertz, as an ‘unfinished animal.’ Our brains are so monstrously oversized that we are born about two years prematurely, at the point at which our skulls can still be squeezed agonisingly, bloodily and dangerously through a birth canal. We are then effectively useless for years, relying entirely upon a parent for survival until the gigantic computational device that sits on our neck is finally capable of running the body it is attached to.

Between the ages of zero and two,
babies create around 1.8 million synapses per second
.
Throughout childhood, the brain is extraordinarily alive
with the activity of warring neurons, fighting for connection space across its epic territories. Although it never stops changing, it remains in this heightened learning phase until late adolescence.
In his book
Brain and Culture
Professor Bruce E. Wexler writes
that ‘During the first part of life, the brain and mind are highly plastic, require sensory input to grow and develop, and shape themselves to the major recurring features of their environment. By early adulthood, the mind and brain have a diminished ability to change those structures … much of the [brain] activity is devoted to making the environment conform to the established structures.’

It may have passed you by as you read it, just now, but what that rather formal, rather dry sentence is saying is amazing. It is the keyhole through which the first, fuzzy outlines of my answer can be spied. Although the context is neurological rather than psychological, it actually speaks to the whole picture: to the brain’s form and the mind’s function. To me, Wexler’s words are an ancient spell, a revelation of long-hidden magic. They contain the essence of the brain’s sly modus operandi – the organising principle behind the worrying fact
that a central function of this wondrous machine is to deceive you. By the time you have reached adulthood, your brain has decided how the world works – how a table looks and feels, how liquids and authority figures behave, how scary rats are. It has made countless billions of little insights and decisions. It has made its mind up. From then on, its treatment of any new information that runs counter to those views can sometimes be brutal. Your brain is surprisingly reluctant to change its mind. Rather than going through the difficulties involved in rearranging itself to reflect the truth, it often prefers to fool you. So it distorts. It forgets. It projects. It lies.

These untrustworthy processes run far deeper than the realms of opinion and belief. Your mind contains internal models of everything, from the physical geography of the room you are sitting in to the rights and wrongs of the conflict in the Middle East. The brain loves its models. It guards them like a bitter curmudgeon, making adjustments only when it has to. It uses these models as a shortcut, in order to more easily conjure an illusion of a sane, whole and coherent reality. This illusion is so complete that we don’t believe it is one. It is hard to underplay the brilliance of this lie:
up to 90 per cent of what you are seeing right now
is constructed from your memories.

Practitioners of lucid dreaming know how convincing these mental models of reality are.
When writer Jeff Warren was trained to ‘wake up’
during a dream by expert Dr Stephen LaBerge of Stanford University, his mind’s projection of the room that he had gone to bed in was so accurate he didn’t realise that he was still asleep. ‘It was my room, seamlessly modelled by my brain,’ he writes in
Head Trip
. ‘I could see the outlines of furniture from under the bottom edge of the mask, feel my bed underneath me, hear Kelly’s breathing – everything was perfect. It even smelled like my room. At that moment there was no recognisable difference between my waking and my dreaming perception.’ This experience is so common in students of lucid dreaming that Dr LaBerge teaches a variety of ‘reality tricks’ – such as looking at a clock’s second hand to see if it is behaving predictably – to enable them to check if their eyes are open or closed. We all have these models. When we dream, and it feels real, it is because our models of reality are so detailed and textured and perfect it might as well be. It is all there: the
sights, the noises, the textures and touches and scents. Our brains contain worlds. And it is mostly those worlds that we are seeing when we are awake.

If you are thinking that you must be misunderstanding all this, because it is just too spooky, too grotesque, too much like a disturbing science fiction film, then I am sorry to tell you that you are not. The truth really is this weird. We think of our eyes as open windows and our ears as empty tubes. We experience the
out-there
as if we are a tiny homunculus gazing from holes in our heads at a world that is flooded with light, music and colour. But this is not true. The things that you are seeing
right now
are not
out there
in front of you, but
inside your head
, being reconstructed in more than thirty sites across your brain.
The light is not out there
. The objects are not out there.
The music
is not out there. A violin has no sound without a brain to process it; a rose petal has no colour. It is all a re-creation. A vision. A useful guess about what the world might look like, that is built well enough that we are able to negotiate it successfully.

Of course, real versions of everything
are
out there – but not the versions that you are seeing. Those are merely your brain’s impressions of how the world appears. Our eyes, skin, tongue and ears receive information, not as pictures, touches, tastes or notes, but as pulses of electricity. That is all we
really
know – the pulses. Your brain translates those pulses into a re-creation of reality that it can sensibly interact with. It is not known how all this disparate electrical data coalesces into the experience we all have of viewing some kind of inner television screen – but we do know that there is no television in your head; no single area, that is, which all the neural wiring leads to. We also know that the brain has a great many sleights and shortcuts and mirage-generating powers in its arsenal, and that it somehow manages to bring them together into one central, magisterial illusion: that reality and your place within it is simple, understandable and clear. Under its spell, you have become,
in the words of neuroscientist Professor Chris Frith
, ‘the invisible actor at the centre of the world.’

We naturally assume that our senses are our principal source of information about what is happening at any given moment. They are not. They are mere fact-checkers. Consider your face as if it is a
machine. There is barely a space on its surface that is not dedicated to the analysis of new information. When our environment is as we expect it to be, we mosey through life, wandering peacefully through the neurological illusion, thinking about the weather or the shops or the fight we have just had with our Internet provider. But as soon as we detect something unexpected, we become alert. The brain, concerned that its illusion might break down, is ever watchful for surprises. It directs the powers of the face and mind at the disturbance. Anxious to discover its source, so that it can integrate whatever it is into its projection of reality, it moves your neck so that you can focus squarely on the weirdness. Your skin, eyes, ears and nose are pointed towards it, your train of thought is interrupted as you seek to answer the question, ‘What
is
that?’

Even when your surroundings contain no surprises, your brain is continually checking its guesses against what your senses are telling it. It uses them to make running adjustments to its projection, ensuring greater accuracy now and in the future. But because the brain is so heavily reliant upon what it already knows, it is difficult for us to experience things we have no prior knowledge of.
In a startling 1974 experiment that tested these principles
, cats were raised from birth in an environment where they only ever saw vertical lines. When a horizontal bar was placed in their cage, they walked straight into it. Until that painful point of learning, their visual cortices had never received any information about horizontal lines, and so to them the bars were invisible.

Humans, too, suffer when their brains have been deprived of information. When deaf people are successfully operated upon they can initially make no sense at all of the novel experience of hearing. Their brains have not yet learned how to translate all those new electrical pulses into their model of the world.
Scott Krepel, who was fitted with a cochlear implant
, enabling him to hear for the first time, told a reporter from the US radio show This
American Life
, ‘It didn’t feel like hearing; it felt more like a vibration in my whole body. I was sitting there and nothing was happening, except for like a little thing that was tingling throughout my body. But eventually, after a while, the vibrations localised to my ears. I didn’t really know that it was sound at first.
And eventually I came to realise, “Wait a minute, this must be it!” … I couldn’t understand any of the sounds. It was just all noise.’ After five years, his brain had still not caught up. Krepel abandoned his implant, preferring the safety and sanity of the silent world in which he had grown up.