QI: The Book of General Ignorance - the Noticeably Stouter Edition (35 page)

One hundred per cent.

Or 3 per cent.

It’s commonly said we only use 10 per cent of our brain. This usually leads to discussions of what we might do if only we could harness the other 90 per cent.

In fact, all of the human brain is used at one time or another. On the other hand, a recent paper by Peter Lennie of the New York University Center for Neural Science indicates that the brain should ideally have no more than 3 per cent of neurons firing at any one time, otherwise the energy needed to ‘reset’ each neuron after it fires becomes too much for the brain to handle.

The central nervous system consists of the brain and the spinal cord and is made of two kinds of cells: neurons and glia.

Neurons are the basic information processors, receiving input and sending output between each other. Input arrives
through the neuron’s branch-like dendrites; output leaves through the cable-like axons.

Each neuron may have as many as 10,000 dendrites but only has one axon. The axon may be thousands of times longer than the tiny cell body of the neuron itself. The largest axon in a giraffe is 4.5 metres (15 feet) long.

Synapses are the junctions between axons and dendrites, where electrical impulses are turned into chemical signals. The synapses are like switches, linking neurons to one another and making the brain into a network.

Glia cells provide the structural framework of the brain, they manage the neurons and provide a housekeeping function, removing debris after neurons die. There are fifty times more glia than neurons in the brain.

There are nearly five million km (about three million miles) of axons, one quadrillion (1,000,000,000,000,000) synapses, and up to 200 billion neurons in a single human brain. If the neurons were spread out side by side they would cover 25,000 square metres (nearly 30,000 square yards): the size of four football fields.

The number of ways information is exchangeable in the brain is greater than the number of atoms in the universe. With such astonishing potential, whatever percentage of our brains we use, we could all, clearly, do a little better.

So long as you’re alive, it’s pink. The colour comes from the blood vessels. Without fresh oxygenated blood (as when it’s removed from the body) the human brain appears grey.

To confuse things, about 40 per cent of the living brain is
made of so-called ‘grey matter’ and 60 per cent of ‘white matter’. These terms are not accurate descriptions of the colours you see, but thinly sliced, and in section, they are clearly two different kinds of brain tissue.

Using brain scans, we have begun to understand what functions they each perform. Grey matter contains the cells where the actual ‘processing’ of information is done. It consumes about 94 per cent of the oxygen used by the brain.

The white matter is a fatty protein called
myelin
which sheathes and insulates the dendrites and axons that extend out from the cells. It is the brain’s communication network, linking different parts of the grey matter together and linking the grey matter to the rest of the body.

A good analogy is the computer. The grey matter is a processor, the white matter is the wiring. What we call intelligence requires both to work together at high speed.

Now it gets even more interesting. Recent studies at the Universities of California and New Mexico scanned the brains of men and women with identical IQs. The results were surprising: the men had six and a half times more grey matter than women, and women had nearly ten times more white matter than men.

The women’s white matter was found in a high concentration in the frontal lobes, whereas the men had none. This is significant, as the frontal lobes are believed to play a key role in emotional control, personality and judgement.

So, all the various ‘Mars and Venus’ theories of gender difference might find soon find a physiological justification. Men’s and women’s brains do seem to be differently wired and configured. The output (intelligence) is the same, but the way it is produced is very different.

Good news. Alcohol doesn’t ‘kill’ brain cells. It just makes new cells grow less quickly.

The idea that alcohol destroys brain cells dates back at least as far as the temperance campaigners of the early nineteenth century, who wanted all alcoholic drinks banned. It has no basis in scientific fact.

Samples from alcoholics and non-alcoholics show no significant difference in either the overall number or the density of neurons between the two groups. Many other studies have shown that moderate drinking can in fact help cognition. A study in Sweden showed that
more
brain cells are grown in mice that are given alcohol.

Alcohol abuse does causes serious damage, not least to the brain, but there is no evidence that these problems are to do with the death of cells – it’s more likely that alcohol interferes with the working processes of the brain.

A hangover comes from the brain shrinking due to dehydration, causing the brain to tug on its covering membrane. It’s the membrane which is sore. The brain itself feels nothing, even if you stick a knife in it.

The philtrum is the vertical groove on your upper lip that nobody knows the word for. It allows you to drink beer from the bottle by letting the air in.

If you were to open a beer can in zero gravity all the beer would come out at once and float around in spherical droplets.

Astronomers have recently discovered a massive amount of alcohol in our region of the Milky Way. The giant cloud of methanol measures 463 billion km (288 billion miles) across. Although the alcohol we like to drink is grain alcohol
(otherwise known as ethyl alcohol or ethanol) and methanol would poison us, the discovery goes some way to supporting the theory that the universe is here so that we can drink it.

They don’t drink at all.

Dolphins are like animals in a desert, without any access to fresh water. They get liquid from their food (which is mainly fish and squid) and by burning their body fat, which releases water.

Dolphins are whales – the killer whale is the largest member of the dolphin family. Their name is a reversal of the original Spanish,
asesina-ballenas
, meaning ‘whale killer’. They were so called because packs of them sometimes hunt and kill much larger whales.

Pliny the Elder didn’t help their reputation. According to him, an orca ‘cannot be properly depicted or described except as an enormous mass of flesh armed with savage teeth’.

Dolphins have up to 260 teeth, more than any other mammal. Despite this, they swallow fish whole. Their teeth are used solely to grasp prey. Dolphins sleep by shutting down one half of their brain

and the opposite eye at a time. The other half of the brain stays awake, while the other eye watches out for predators and obstacles, and remembers to go to the surface to breathe. Two hours later, the sides flip. This procedure is called ‘logging’.

Dolphins have been working for the US Navy since the
Vietnam War, where they saw extensive service. The US Navy currently employs about a hundred dolphins and thirty other assorted sea mammals. Six sea lions have recently been posted to join the Task Force in Iraq.

After Hurricane Katrina, a story circulated that thirty-six US Navy-trained attack dolphins had escaped and were roaming the sea armed with toxic dart guns. The story seems to have been a hoax; apart from anything else, ‘military’ dolphins aren’t trained for attack, only for finding things.

Not the vodka martini.

A painstaking study at www.atomicmartinis.com of Fleming’s complete oeuvre has shown that James Bond consumed a drink, on average, every seven pages.

Of the 317 drinks consumed in total, his preferred tipple was whisky by a long margin – he drinks 101 in all, among them fifty-eight bourbons and thirty-eight Scotches. He’s pretty fond of champagne (thirty glasses) and in one book,
You Only Live Twice
(1964), which is mostly set in Japan, Bond tries sake. He likes it: he has thirty-five of them.

Bond only opts for his supposed favourite, vodka martini, nineteen times, and he drinks almost as many gin martinis (sixteen – though most of these are bought for him by other people).

The famous ‘shaken, not stirred’ line appears for the first time in
Diamonds are Forever
(1956) but isn’t used by Bond himself until Dr No (1959). Sean Connery was the first screen Bond to utter ‘shaken, not shtirred’, in
Goldfinger
(1964), and it occurs in most of the films thereafter. In 2005, the American Film Institute voted it the 90th greatest movie quote of all time.

James Bond’s personal martini recipe, taken from the first book,
Casino Royale
(1953), is: ‘Three measures of Gordon’s, one of vodka, half a measure of Kina Lillet. Shake it very well until it’s ice-cold, then add a large thin slice of lemon-peel.’

This is the only time he drinks a gin and vodka mix. He calls it the Vesper, after Vesper Lynd, the double agent and love interest in the novel. She is also the girl who drinks most in all the novels and stories.

Why does Bond insist on ‘shaken’ martinis? Strictly speaking, a shaken gin martini is called a Bradford. Purists frown on them because the intake of air caused by the shaking oxidises – or ‘bruises’ – the aromatic flavourings in the gin. But there’s no such problem with vodka, and the action of shaking makes the drink colder and sharper.

Ian Fleming himself preferred his martinis shaken, and made with gin. On his doctor’s orders he switched from drinking gin to bourbon later in life, which may explain his hero’s predilection. Fleming and Bond were both men who knew what they liked.

Alcohol is fine. So are tea and coffee.

Virtually any fluid will help to hydrate you, although you
should steer clear of seawater.

There’s no scientific basis for the curious idea that fluids other than water cause dehydration. As a diuretic (something that makes you pass water), caffeine does cause a loss of water, but only a fraction of what you’re adding by drinking the coffee. Tea, coffee, squash and milk for children are all equally good at replacing fluids.

Ron Maughan, Professor of Human Physiology at the University of Aberdeen Medical School, has looked at the effects of alcohol, considered to be another diuretic, and found that, in moderation, it too has little impact on the average person’s state of fluid balance.

His results, published in the
Journal of Applied Physiology
, showed that alcoholic drinks with an alcohol content of less than 4 per cent, such as light beer and lager, can be used to stave off dehydration.

Seawater, on the other hand, is an emetic, so, if you drink it, you’ll throw up. If you do manage to keep any of it down, then all the water in your body’s cells will move towards the highly concentrated salty fluid, by osmosis, in an attempt to dilute it.

This will leave your cells dehydrated, and in severe cases can lead to spasms, the breakdown of brain functions, and liver and kidney failure.