QI: The Book of General Ignorance - the Noticeably Stouter Edition (14 page)

For crocodiles up to 2 m (6.5 feet) long, an ordinary rubber band should be sufficient for you to make your escape.

The muscles that close the jaws of a crocodile or alligator are so strong that they have the same downward force of a truck falling off a cliff. But the muscles that open their jaws are weak enough for you to hold their mouths shut with one hand.

The technical difference between alligators and crocodiles is that crocs have a longer, narrower snout, eyes further forward, and their fourth tooth sticks out from the lower jaw rather than fitting neatly into the upper jaw. Also, some crocodiles live in salty water; alligators generally live in fresh water.

‘Crocodile’ means lizard, from the Greek
krokodeilos
. This name was first recorded by Herodotus who remarked on them basking on the pebbly banks of the Nile. ‘Alligator’ is a corruption of the Spanish
el lagarto das Indias
, ‘the lizard of the Indies’.

Neither animal cries as it savages you to death. Crocodile
tears are a myth from medieval travellers’ tales. Sir John Mandeville, writing in 1356, observed, ‘In many places of Inde are many cokadrilles – that is, a manner of long serpent. These serpents slay men and eat them weeping.’

Crocodiles do have tear ducts, but they discharge straight into the mouth, so no tears are visible externally. The origin of the legend may be in the proximity of the throat to the glands which lubricate the eye. These can cause the eye to water a little from the effort of swallowing something large or reluctant. They can’t smile either: crocodiles and alligators have no lips.

The digestive juices of crocodiles contain enough hydrochloric acid to dissolve iron and steel. On the other hand, there is no need to worry about alligators living in city sewers. They can’t survive without the ultraviolet radiation from the sun that enables them to process calcium. This urban legend can be traced back to a
New York Times
article in 1935, which reported that some boys had dragged an alligator out of a sewer in Harlem and beat it to death with shovels. It probably swam up a storm conduit after falling from a boat.

The carrier pigeon, which has received more than half of all the Dickin Medals for Animal Bravery ever issued.

The medal was instituted by Mrs Maria Dickin, founder of the People’s Dispensary for Sick Animals (PDSA) in the UK in 1943. Between 1943 and 1949 the PDSA awarded fifty-four Dickin Medals to thirty-two pigeons, eighteen dogs, three horses, and one cat. Recently a few more awards have been given, most notably to two guide dogs that led their owners to safety down more than seventy floors of the World Trade Center on 11 September 2001.

Messenger pigeons were used throughout World War II, during communication blackouts and attacks. One of the first to win the DM was Winkie, who was on a plane when it crashed. Winkie broke free and found her way back to her owner in Scotland. From her oily and bedraggled appearance, Winkie’s owner could roughly estimate how long she had been flying. Using this information, along with the last known coordinates of the plane, the crew were saved.

A few years later, a pigeon named Gustav was issued to the war correspondent Montague Taylor, and braved a 150-mile trip to deliver the first account of the Normandy landings. Gustav came to a sticky end after the war when someone cleaning out his loft accidentally sat on him.

In 1942, behavioural scientist B. F. Skinner came up with the idea of using trained pigeons to guide weapons. The system worked by training pigeons to earn a food reward by pecking at the image of a ship. Three of them were then placed in the nose of a missile. Once launched, the pigeons would see the ship in their window and peck at it, triggering a corrective mechanism linked to the missile’s guidance system.

The closer the ship got, the bigger it appeared in the screen, and the more the pigeons pecked, so that just before
they hit the target and were obliterated, they were being showered with grain.

The system worked well in simulations but the Navy eventually balked at putting it into practice.

The pigeon guidance technology work wasn’t entirely wasted – for a while the US Coastguard used pigeons to guide rescue helicopters. They were trained to peck at orange dots, which meant they could be used in searches for orange lifejackets in open seas, their eyesight being ten times sharper than that of the pilots.

Wrong.

The correct answer is ‘grass snake’.

Vipers, cobras, rattlesnakes and mambas aren’t poisonous – they’re venomous. It’s an important distinction: poison harms you when you swallow it, venom when it’s injected into you. So, something’s ‘poisonous’ when you bite it, but it’s ‘venomous’ when it bites you.

Though experts believe there may be others yet to be discovered, there are only two known species of ‘poisonous’ snake. One is the
yamakagashi
or Japanese grass snake (
Rhabdophis tigrinus
). It eats toxic toads and stores their poison in specially adapted glands in its neck. When attacked, it arches the front of its body to make the glands stand out, with the result that anything biting its neck (the usual place for predators to strike) gets a fatal mouthful of poison. As it happens, the yamakagashi is venomous as well, but its fangs are located right at the back of its mouth, so you have to really annoy it to get bitten.

The orange-bellied, rough-skinned newt (
Taricha granulosa
) of North America is not a snake, but it is one of the most poisonous creatures on earth, packed full of tetrodotoxin or TTF – the same poison contained in the puffer fish used to make the legendarily risky Japanese delicacy
fugu
. In 1979 a twenty-nine-year-old man in a bar in Oregon swallowed one of these newts for a bet. He was dead within hours.

The only creatures known to eat these newts and survive (and thus the only other known poisonous snakes) are a small population of garter snakes, also resident in Oregon, that have evolved a tolerance to the poison. This produces a deadly surprise for any of their predators, such as foxes and crows, which are partial to their livers.

Virtually all spiders are venomous – including the 648 species recorded in Britain – but most of them are too small for their tiny fangs to puncture human skin and deliver their venom.

The Anglo-Saxon word for spider was
attercop
, which meant literally ‘poison-head’, from
ator
, poison, and
cop
, head.

As far as we know, there are no poisonous spiders. Crispy tarantulas, for example, are eaten in Cambodia with no ill effects.

Work is a bigger killer than drink, drugs or war.

Around two million people die every year from work-related accidents and diseases, as opposed to a mere 650,000 who are killed in wars.

Worldwide, the most dangerous jobs are in agriculture, mining and construction. According to the United States
Bureau of Labor Statistics, in the year 2000, 5,915 people died at work – including those who had a heart attack at their desks.

Lumberjacks had the most dangerous job, with 122 deaths per 100,000 employed. The second most dangerous job was fishing and third was airplane pilots – with a death rate of 101 per 100,000. Nearly all of the pilots, you’ll be reassured to hear, died in small-plane crashes, not passenger jets.

Structural-metalworkers and people in mining and drilling came fourth and fifth, though the death rate for both was less than half that of timber cutters.

The third most common cause of death on the job in all occupations was murder, which claimed 677 workers. Fifty policemen were murdered. But so were 205 salespeople.

Falls were the second most common cause of death, accounting for 12 per cent of the total. Roofers and structural-metalworkers were the main victims.

The most common cause of death on the job was the car accident, accounting for 23 per cent of the total. Even police officers were slightly more likely to die behind the wheel than by homicide.

The single most dangerous specific job is said to be that of Alaskan crab fishermen working in the Bering Sea.

The risk of death can be calculated using the Duckworth scale, devised by Dr Frank Duckworth, editor of the Royal Statistical Society magazine. It measures the likelihood of dying as a result of any given activity. The safest kind of activity scores 0 and 8 will result in certain death.

One game of Russian Roulette carries a risk of 7.2. Twenty years of rock climbing weighs in at 6.3. The chances of a man being murdered are 4.6. A 160-km (100-mile) car journey by a sober middle-aged driver scores 1.9: slightly more risky than a destructive asteroid impact (1.6).

On the Duckworth scale, 5.5 is particularly perilous. It’s the risk of death by car crash or an accidental fall for men, as
well as the chance of either sex dying while vacuuming, washing up or walking down the street.

A nasty splinter.

Cannon balls fired from men o’ war didn’t actually explode (no matter what Hollywood thinks), they just tore through the hull of the ship causing huge splinters of wood to fly around the decks at high speed, lacerating anyone within range.

British naval ships of the period were often rotten and unseaworthy. Many of the officers had no idea how to sail, fight or control their men. Hernias caused by manhandling acres of wet canvas were so common that the navy was forced to issue trusses. To cap it all there wasn’t a single pay rise for a century.

At close range, a 32-pound ball was capable of penetrating wood to a depth of 60 cm (2 feet). The best way to stop splinters (other than by building a metal ship) was to use a type of wood found in the south-eastern USA which resisted splintering.

As well as being one of the hardest of all woods, the Live Oak (
Quercus virginiana
) is the state tree of Georgia and a symbol of strength and resistance for the southern states. It is
the tree draped with long garlands of moss in films like
Gone with the Wind.