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ОглавлениеA defining characteristic of many brain science books is a macho and rather sadistic nihilism. In The Brain: The Story Of You, Professor David Eagleman lords it over us puny mortals:
What if I told you that the world around you is an illusion, an elaborate show put on by your brain? … If you could see reality as it really is you would be shocked by its colourless, odourless, tasteless silence.
I actually had to do a book festival debate with this guy. He was representing science, progress and the light of reason, and I was there for balance. At one point he turned to me and said : ‘What if I told you that in the real world sound doesn’t actually exist?’ To which I replied: ‘Pardon?’
Now I know many of you are smitten by counter-intuitive ideas such as a colourless, soundless, odourless world, but I urge you to reflect that a colourless world is incompatible with natural selection, because you have left yourself no way to account for the survival of the chameleon – unless you also believe in the existence of extremely patronising birds of prey. How kind of nature to select for hawks and shrikes prepared to humour the chameleons’ pathetic attempt at camouflage! Yet how wasteful of nature to select for chameleons with subcutaneous photonic crystals! All the energy that the male adult panther chameleon (Furcifer pardalis) spends on lugging these photonic crystals around is energy wasted, because in a colourless world they confer no selective advantage whatsoever.
If Eagleman is right and it is indeed a colourless world, then the whole science of co-evolution must be wrong, everyone from Darwin first observing the selective advantage of a scarlet throat pouch for the Great Galapagos Frigate Bird, down to and including a 2016 Nature article headed ‘Lizards Tailor Tails For Local Predators’. The article was about how, in three different areas of Japan, the same species of skink lizard, Plestiodon latiscutatus, has evolved a different coloured tail in response to different predators: for weasels a blue tail, for snakes an ultraviolet tail, for birds a brown tail. There was an interview with the project’s chief scientist Dr Takeo Kuriyama, who said:
When I first told my colleagues that I’d discovered a link between the blue-tailed lizard and the weasel they were frightened for their very lives, or pleasantly surprised. Hard to tell. One or the other.
Brightly coloured Plestiodon latiscutatus tails evolved to attract snakes and weasels to the one disposable part of its body. The lizard can shed its tail with the snake’s fangs still in it, scuttle away and grow a new one. Ditto weasel. But birds have such sharp sight they are less likely to fall for this misdirection trick. If they see a lizard’s tail they’ll see its head and belly too. Against birds, the lizard’s only hope is not to be seen in the first place, and so the brown tail has evolved as simple, old-fashioned camouflage. It’s the least likely colour to be seen among the sticks and twigs littering the forest floor.
Imagine an organism that actually had to live in Eagleman’s nuclear winter wonderland. In a colourless, odourless world, how could the orchid attract the bee it needs for pollination? You might argue that all that is needed for pollination to occur is for just one bee to land on one orchid however accidentally. Maybe it just lands on the orchid for a rest. Once the bee has found the orchid’s pollen, it would then return to its hive, perform its waggle dance to inform the other bees where the pollen is at, and the other bees will follow it back to the orchid. To this argument I say: Prasophyllum fimbria.
The orchid Prasophyllum fimbria offers nothing but colour. From a distance Prasophyllum displays what looks like a pollen-spattered anther. But there is no pollen, no food reward for the bee at all. The blotchy yellow splodges are a 2D trompe l’oeil. The bee gropes around for ages, trying to find something that lives up to the tasty promise of the picture that drew him in, like someone eating in Harry Ramsden’s, which has created a Pavlovian connection in the human brain between tartar sauce and regret.
Or consider the monarch butterfly. The monarch’s colouring is what’s called aposematic, warning predators ‘TOXIC! DO NOT EAT!’ In a world of austere monochrome, the monarch has no warning signal with which to deter hungry frogs and birds. Instead its only hope of survival is to blend in with all the other graphite butterflies, slate-grey macaws, and pumice parakeets flitting through electrostatic skies that fizz like out-of-tune TV sets. Safely camouflaged in this way, the monochrome monarch may survive, but I fear for the scarlet kingsnake and all other practitioners of Batesian mimicry.
Batesian mimicry is a twist on aposematic colouring, by which edible snakes and frogs deter predators by mimicking toxic snakes and frogs. The edible non-toxic scarlet kingsnake, for example, copies the patterns and colours of the poisonous and venomous coral snake. The kingsnake’s life depends on falcons, weasels and monitor lizards falling for the bluff.
‘What these astounding phenomena teach,’ the great art historian E. H. Gombrich wrote,
is precisely that there is a limit to perceptual relativism. What looks like a leaf to modern European must also have looked like a leaf to predators in fairly distant geological epochs. Likeness is not only in the beholder’s eye.*
* E. H. Gombrich, Art and Illusion, 2002.
But colour, for Eagleman, is only in the eye of the beholder. ‘Colour,’ he says, ‘is an interpretation of wavelengths, one that only exists internally.’
How could there be colours in our head if there were none in the world? From where would we get the concept? And why is colour the illusion rather than, say, colour-blindness? Why is the one supposed to happen only in the head but not the other?
In 1894 Arthur König demonstrated the fovea to be blue-blind. Does this mean the fovea is one step closer to seeing reality-as-it-really-is than the rest of the eye? Only the fovea has been able to rid itself of the blue delusion. It alone has escaped the shackles of blue to see the sky for the fizzing Alka-Seltzer electrostatic it really is. Now we just need to figure out how to communicate the fovea’s disillusion to the rest of the eyeball.
The fact that the human brain perceives only one ten-trillionth of the spectrum of electromagnetic radiation is evidence enough for Eagleman to declare that ‘in the outside world colour doesn’t actually exist.’ Shouldn’t the fact that we can only see a narrow band of broader spectrum, suggest that the world is more colourful than we can possibly imagine, not less? That would be the logical conclusion, wouldn’t it? And it would be consistent with zoology, too.
In 2016 it was discovered that reindeer not only see ultraviolet light but, in stark contrast to other mammals, their eyes have evolved to resist the damage caused by UV. This resistance allows them to spend longer staring at snow for any clues of food or foe, without becoming snow blind. It enables them to do better than humans or pine martens at discerning patches of hollow snow, which will give way if stepped on.
Reflectance spectrophotometry has revealed that blue tits ought really to be called ultraviolet tits, since females prefer males with the most dazzlingly UV crests. All this dazzle passes us by. Human eyes can’t see it, but blue tits are not making it up. Their eyes just have different cones to ours, cones which are ‘visually sensitive to wavelengths in the near-ultraviolet.’*
* S. Hunt et. al., ‘Blue tits are ultraviolet tits’, Proc. Biol. Soc., 1998.
We cannot hear the high-end kilohertz laughter of tickled rats, nor the deep clicking of long-tusked narwhals echolocating their way through the black depths of the Arctic Ocean.
All of which goes to show only that there are biological constraints to what different animals can discover in their environments. Eagleman himself puts it very clearly when says that ‘each creature picks up on its own slice of reality.’ That is absolutely right. But it is not very melodramatic or spooky. It doesn’t have the macho tone of ‘can you handle reality as it really is?’ And so Eagleman cannot stop there, but goes on to commit himself to the disastrous doctrine that animals have no access to reality at all:
In the blind and deaf world of the tick, the signals it detects from its environment are temperature and body-odour … No one is having an experience of the objective reality that really exists.
If ‘no-one is having an experience of the objective reality that really exists’, then what is this temperature and body-odour that the tick thinks it detects? And didn’t Eagleman just now say that the world was odourless? Or did I only imagine he said that. Did you imagine it too? If we both imagined it then maybe it is an objective reality that really exists. If so, then how can the deaf-blind tick detect body-odour? To detect means ‘to discover or identify the presence or existence of.’ But in an odourless world odour has no presence or existence. You can’t detect odour in an odourless world.
Then there’s the temperature the tick thinks he feels. If feeling cold is not ‘an experience of the objective reality that really exists’, the coldness the tick thinks it detects, therefore, is a creation of itself and not out in the world. This begs the question: if icebergs, snow or permafrost are not in and of themselves cold, then how do they form?
I would like to propose a compromise. What about this? I believe the tick’s perception of coldness might happily coincide with there being some actual coldness out there. I hope you agree with me. But, I’m afraid that if we want to stay true to Eagleman, this happy compromise is, alas, quite out of the question. His stern philosophy does not, we shall see, allow even this.
‘The real world is not full of rich sensory events,’ writes Eagleman. ‘Instead our brains light up the world with their own sensuality.’
If the real world is not full of rich sensory events then why do animals suffer so badly from sensory deprivation?
In the 1960s at the University of California, Mark Rosenzweig and Michael Renner showed that if you take two rat pups from the same litter, give them the exact same diet, same light, same warmth, but raise one in a bare cage and the other in a cage with running wheel, rope walk, mud, junk rubble and – best of all – other rats, then by simply comparing the two brains in autopsy, you can tell which rat grew up in a world full of rich sensory events and which did not. The brain of the rat raised in the impoverished conditions of a bare cage will have 25 per cent fewer synapses. Its cerebral cortex will measure up to 7 per cent thinner. There will be less capillary vasculation, and less dendritic arbourisation, unlike the rich bowers of dendrites all budding with fresh synapses observable in the rat raised in enriched conditions.
A lack of complexity in physical surroundings and social interactions leads to a lack of complexity in synaptic connections. Autopsies deduce the stunted conditions of a rat’s life from the stunted brain. The proof that animals have access to the world outside their heads, therefore, is found inside their heads! The outside world, however imperfectly we perceive it, lights up our brain.
Environmental complexity has since been found critical for children between birth and six. Never again will your brain create so many new brain cells and new connections between them as it does in your first six years of life. (After that you’ve peaked). But for the brain to proliferate wildly, toddlers and young children need complex environments to play in. If not they will never fulfil the ‘exuberant synaptogenesis’ that is their birthright. Complex public spaces are especially critical if the child lives in a small, homogenous box surrounded by other small homogenous boxes. And so, in one of those weird and wonderful connections between totally different worlds, what was discovered in those Californian laboratories in the 1960s influences the design of inner city playgrounds to this very day. Thanks to those Californian experiments, the London Borough of Camden now makes sure that all its playgrounds include rope walks, rubble, mud, junk and rats.
Bishop Berkeley
Those discoveries about the effect of environmental enrichment on the brain were made at the University of California at Berkeley, a city named after the most famous proponent of the idea that the outside world cannot be known.
‘Colours, sounds, taste,’ wrote Bishop George Berkeley (1685–1753), ‘have certainly no existence without the mind.’
Bishop Berkeley was very upset by Newton’s Optics, and he responded with a series of anti-Newtonian tracts. Starting with An Essay Towards a New Theory of Vision (1709), he then broadened his attack in successive treatises and essays to include Enlightenment empiricists and materialists more generally. His philosophy, says Isaiah Berlin, is ‘rooted in a pre-Renaissance medieval spiritualism,’ * and yet it is this philosophy which makes a comeback in modern brain science books.
* Isaiah Berlin, Age of Enlightenment, 1984.
In A Treatise Concerning The Principles of Human Knowledge, Berkeley writes:
It is indeed an opinion strangely prevailing amongst men that houses, mountains, rivers … have an existence natural or real, distinct from their being perceived by an understanding.
To insist on the independent existence of houses, mountains, rivers and every last particle of matter ‘must needs be a very precarious opinion; since it is to propose without any reason at all, that God has created innumerable beings that are entirely useless, and that serve no purpose.’
Though Berkeley wrote ‘in Opposition to Sceptics and Atheists’, he infuriated his fellow Christians just as much. Boswell tells us how he sent Samuel Johnson half-barmy:
After we came out of the church, we stood talking for some time together of Bishop Berkeley’s ingenious sophistry to prove the nonexistence of matter, and that everything in the universe is merely ideal. I observed that though we are satisfied his doctrine is not true, it is impossible to refute it. I never shall forget the alacrity with which Johnson answered, striking his foot with mighty force against a large stone, till he rebounded from it – ‘I refute it thus.’*
* James Boswell, The Life of Johnson, 1791.
I love how personally Johnson takes this. When the most eloquent Englishman who ever lived kicks a rock in fury he reminds us that some propositions are best not answered in cold blood. To deny someone any claim to any kind of contact with reality, as Berkeley does, is an act of psychological violence. It is the weapon of bullies, the tactic of hostile interrogators who try to browbeat and bamboozle a private soldier out of making a complaint against senior officer. You didn’t see what you think you saw. They didn’t say what you think you heard them say. You weren’t even where you think you were when you saw what you thought you saw.
Why is there nothing not something?
For thousands of years one of the fundamental philosophical questions has been why is there something not nothing? With Eagleman we find ourselves in the strange position of asking why is there nothing not something? Why would the objects of the world have no texture, no taste, no sound, no smell – rather than something, anything, even if different from what we think? Why none at all? I could understand if he was saying everything was mauve, had the texture of tulip petals, and the taste of ash, but why sans taste, sans everything? This goes far beyond Berkeley, for whom the things of the earth, even though they depend on being perceived for their existence, are eternally real because forever under God’s good gaze.
To answer to the question ‘why is there nothing not something in Eagleman’s philosophy?’ we need to look at what is real for him. What is still standing once he has razed the outside world? And the answer, it turns out, is: wavelength frequencies.
The blueness of a Japanese lizard’s tail is an illusion entertained by the weasel, the snake and me. What is not an illusion, however, what is in fact irrefutable is the electronvolt energy value of the light bouncing off its tail. Why are wavelengths true but not a lizard’s bright blue tail? It is, I suggest, because we have left the real word of science for the virtual world of Neuropolis, where, inscribed above the city gates, is that great motto of scientism:
All science is either physics or stamp-collecting.
But Ernest Rutherford’s boorish remark is false. All science is not physics. If you want to find out how lizards are tricking weasels into attacking tails not heads, an isotopic triaxial probe is simply the wrong tool for the job, because the job isn’t about measuring electromagnetic frequency. The job is ecological, and ‘ecological events must be distinguished from microphysical and astronomical events.’*
* James Gibson, The Ecological Theory of Visual Perception, 1986.
It’s a question of scale, as much as anything else. Microphysics might accurately describe a stream as atoms colliding, or wavelengths oscillating, but when we wade barefoot across the stream our experience isn’t an experience of atoms and electromagnetic wavelengths. We experience wetness and cold. The stream’s pebbles are treacherously slippy, with a sort of slime on them, and wedge the feet bones apart in a surprisingly painful way.
Are these merely subjective impressions when what science demands are objective measurements? Not if science demands an accurate description of animal interacting with environment. If that’s what we want then an accurate description must be at the ecological level. That is the appropriate level for the job in hand, since our lives are lived at the ecological scale – not among the celestial objects of astronomy or the neutrons of the microphysical realm, ‘but in the very world’, as Wordsworth wrote,
which is the world
Of all of us, – the place where in the end
We find our happiness, or not at all!*
* William Wordsworth, ‘The French Revolution as It Appeared to Enthusiasts at Its Commencement’, The Prelude, 1805.
Austerity on the brain
For David Eagleman, austerity is deeply woven into the fabric of nature. It is not an invention of humans, as he believes colour to be, but intrinsic to matter, to reality. Not only is nature austere as in grey and dour (a claim we examined earlier) nature is also austere as in pinched, frugal, economizing. Eagleman doesn’t apply austerity measures to the living world, he just discovers that the living world proceeds according to austerity principles. It turns out that organs such as the brain, for example, conduct a thorough review of all non-essential services:
So why doesn’t the brain give us the full picture? Because brains are expensive energy-wise… brains try to operate in the most energy-efficient way possible.
I know energy-efficiency would seem to be something you might expect from a clever organ like the brain, but, for better or worse, that appears not to be the case. Whereas a smart electrical appliance, for example, powers down when not being used, our brains are more active when we sleep.
One of the most wonderful features about how the brain works, in fact, is the sheer extravagance of neural activity, its superabundance. The technical term used to describe the synaptic proliferation that characterises early brain development is ‘exuberant synaptogenesis’. In the landmark paper ‘The Physiology of Perception’, Walter J. Freeman and his colleagues found that ‘perception depends on the simultaneous, cooperative activity of millions of neurons spread throughout expanses of the cortex.’*
* Walter J. Freeman, ‘The Physiology of Perception’, Scientific American, 1991.
Not exactly a slimmed-down organization. A rationaliser seeking ambitious saving targets would ruthlessly downsize such a sprawling operation, and would also take the axe to this sort of spare capacity:
vast collections of neurons … shift abruptly from one complex activity pattern to another in response to the smallest of inputs.*
* ‘Walter J. Freeman, ‘The Physiology of Perception’, Scientific American, 1991.
We are told every day that public sector social services should be streamlined. This is dunned into us with such monotony that it begins to look like a Law o’ Nature, rather than one political choice among many other possible ones. Defunct economic dogma does not apply to how the brain works. Whatever the political and economic weather the brain continues its extraordinarily successful policy of being extremely unstreamlined. Just take a look at the Spanish practices going on in entorhinal cortex.
The entorhinal is famous for spatial navigation and memory. Two paths – lateral and medial – lead from the entorhinal to Memory Central in the hippocampus. The lateral path is for spatial navigation ‘Where am I?’ and the medial for memory ‘What happened?’ Management consultants, who make it their business to rationalise a firm to its knees, have a horror of what they call ‘duplication of function’, but I’m afraid that’s what we have here. In a regrettable recidivism, wholly ignorant of best practice guidelines (helpfully supplied by Goldman Sachs) and the harsh new economic realities (also helpfully supplied by Goldman Sachs) the brain simply refuses to ‘operate in the most energy-efficient way possible’. I blame the unions.
The only time the entorhinal cortex is not guilty of ‘duplication of function’ is when it is busily triplicating. It’s not enough for the entorhinal cortex just to check sense data from the hands against data from the eyes, it also insists on cross-checking with the middle ear, in a process called reentrant mapping. Here we have unforgivable ‘triplication of function’. Yet it all works very well, and has done since before records began.
Now it is true that bodies need to conserve energy. But the reason the brain doesn’t give us the full picture has little to do with the brain being anxious about squandering the energy budget all in one go. (After all, the brain never seems bothered by wasting its 20 per cent share of our energy budget watching three-minute clips of The Sopranos on YouTube for five hours straight.) The reason the brain doesn’t give us the full picture is not to do with making energy savings, but because it has evolved to privilege motor activity above all else.
We need to act in real time. We need to do things now. We are surrounded by predators and prey, many of whom come equipped with vastly quicker reflexes than our own.
When Homo ergaster is sprinting to grab her toddler, she doesn’t need to know whether the puma is male or female, or in fact a jaguar. For now, Big Cat Prowling will do. Once you have your toddler in your arms, once your shouts and screams have brought stone-throwing elders to your aid, once the big cat is at bay, then and only then is it useful to notice second-order facts: that the puma is arthritic or old, or that is only a much less scary lynx or linsang. But in those split seconds of your initial reaction all you need to know is where and what in the roughest possible sense. Your picture does not at first need to be more detailed than that – in fact, more detail would not help but hinder.
A good illustration of this is the story of why, during the World War II, my Auntie Ada was discharged from the Women’s Auxiliary Air Force (WAAF). From 1940–42, Ada Newman, aged 22, worked in the map room of the RAF Group Operations HQ located in a secret bunker beneath the Strand in central London. Her job was to push model tanks and planes across a giant horizontal map with a croupier stick in response to grid references being called out by WAAFs on headphones. The map was enormous, the size of four table-tennis tables stuck together. It was a relief map with models of forests, mountain ranges, and painted streams and roads. When pushing a model tank through the model forest, or landing a model plane on the shore, Aunt Ada used to do engine noises and gunfire sounds.
Superiors gave her verbal warnings but she couldn’t help herself. She said she didn’t know she was doing it. The bending end came when Air Chief Marshal Hugh Dowding came to the map room with senior figures from the Admiralty on the eve of a joint sea-air attack. While Aunt Ada was moving a line of German infantry, the top brass overheard her saying:
Gott in Himmel! Once again Tommy’s air cover has proved superior to our anti-aircraft fire. But I die … for … ze … fatherla—aannnggh!
Minutes later, while moving an aircraft carrier from the open sea of grid reference A1 to the harbour of E3, it seems Ada Newman found herself doing a ship horn, followed by the sort of nautical rhubarb the Beatles get up to on Yellow Submarine. She was relieved of map room duties and then discharged from service. In her dismissal hearings, she claimed that she’d only been trying to concentrate the minds of top brass by giving them a more vivid picture of reality down on the ground. In response to this, her superior officer read out the transcript of what Auntie Ada had said:
‘Aye, Aye Cap’n. Full Speed Ahead. Steady As She Goes. Hard To Port.’ He then looked up from the transcript, and in a voice that Auntie Ada said was unnecessarily harsh, asked, ‘In what possible way is that concentrating minds?’
Family feeling aside, I suppose the superior officer had a point. The tanks in the wartime map room are not supposed ot be detailed or individuated. Their role is to give us a big picture at a glance so as to enable a rapid response. It’s the same with the brain in an emergency. The brain doesn’t give us the full picture straight away is because it has evolved to serve action in real time, like the fox in Ted Hughes’ poem The Thought Fox:
Two eyes serve a movement, that now
And again now, and now, and now.
Sets neat prints into the snow.
It’s bad enough that we have to endure a fake and made-up economic austerity, without having to accept an equally fabricated natural austerity. What makes this austere explanation of vision so very galling is that it comes in the middle of a hyper-inflationary bonanza of unregulated speculation that the world is in actual fact, silent and monochrome, and reality takes ‘place in the sealed auditorium of the cranium’ and all the rest of it.
‘Practical men’, wrote John Maynard Keynes, the most influential economist of the twentieth century, ‘who believe themselves to be quite exempt from any intellectual influence, are usually the slaves of some defunct economist.’
I think this great insight is true of those practical men who write neuroscience books full of handy tips, such as ‘the brain is a tool-kit.’
The most influential philosophers today are people who wouldn’t dream of calling themselves philosophers. They write books and make TV series about who we are and where we came from. They claim merely to extrapolate from what the science says. But, to paraphrase Keynes, those who believe themselves to be dispassionately reporting what the science says are usually the slaves of some defunct philosophy.
When we think we are most free from philosophy, we are most under its spell. If we are not aware of where ideas come from, then it’s harder to resist their influence. But by tracing the sources back to the philosophical stowaways, we may better glimpse ways to escape a deadening neuro-mythology.
The ‘Book of Joshua’ (in which God commands the earth to stand still) once stood in the way of understanding planetary motion. Today, the austerity model stops us understanding the first thing about how the brain works. Eagleman is standing in front of the stage filming the gig on his phone, and blocking our view of the brain’s funky moves.
