The Magic of Reality (19 page)

It is true that if you toss a penny 1,000 times, you’d expect approximately 500 heads and 500 tails. But suppose you’ve tossed the penny 999 times and it’s so far come up heads every time. What would you bet for the last toss? According to the widespread misunderstanding of the ‘Law of Averages’, you should bet on tails, because it is tails’
turn
, and it would be so
unfair
if it came up heads yet again. But I would place my bet on heads, and so would you if you were wise. A sequence of 999 heads in a row suggests that someone has tinkered with the penny, or with the method of tossing it. The misunderstood ‘Law of Averages’ has been the ruin of many gamblers.

Admittedly, with hindsight you can say, ‘Sangakkara was very unlucky to lose the toss, because it meant that India batted on a perfect pitch and that helped them to amass a huge score.’ There is nothing wrong with that. All you are saying is that this time around winning the toss really made a difference, so whoever won the toss on this particular occasion was very lucky to have done so. What you should
not
say is that because Dhoni has won the toss on many occasions before, it is Sangakkara’s turn this time! Nor should you ever say something like this: ‘Dhoni happens to be a good cricketer, but the real reason we should make him captain is that he is very lucky at winning the toss.’ Luck with coin tosses is not something that individual people possess. You can say of a cricketer that he is a good batsman or a bad bowler. You can
not
say that he is good at winning tosses, or bad at winning tosses!

For just the same reason, it is complete nonsense to think you can improve your luck by wearing a lucky charm around your neck. Or by crossing your fingers behind your back. These things have no way of influencing what happens to you unless it is by some effect on how you feel: giving you added confidence that calms your nerves before a tennis serve, for example. But that is nothing to do with luck; that is psychology.

True, some people are described as ‘accident prone’. This is fine, if it only means something like ‘clumsy’, or especially likely to fall over or otherwise suffer misfortune. If you want a really funny example of ‘accident prone’, see the hilarious film
The Pink Panther
, starring Peter Sellers as Inspector Jacques Clouseau. Inspector Clouseau continually has embarrassing and amusing accidents, but that is because he is a habitual bungler, not because he has constant bad ‘luck’, which is how some people use the phrase. (By the way, do try to see the original
Pink Panther
film itself, not the later run of inferior films with similar titles like
Son of Pink Panther, The Pink Panther’s Revenge
and so on, which it spawned.)

Pollyanna and paranoia

So, we have seen that bad things, like good things, don’t happen any more often than they ought to by chance. The universe has no mind, no feelings and no personality, so it doesn’t do things in order to either hurt or please you. Bad things happen because
things
happen. Whether they are bad or good from our point of view doesn’t influence how likely it is that they will happen. Some people find it hard to accept
this
. They’d prefer to think that sinners get their come-uppance, that virtue is rewarded. Unfortunately the universe doesn’t care what people prefer.

But now, having said all that, we should pause for thought. Funnily enough, I have to admit that something a bit like Sod’s Law is true. Although it is definitely not true that the weather, or an earthquake, is out to get you (for they don’t care about you, one way or the other), things are a bit different when we turn to evolution. If you are a rabbit, a fox is out to get you. If you are a minnow, a pike is out to get you. I don’t mean the fox or pike thinks about it, although it may. I’d be equally happy to say that a virus is out to get you, and nobody believes viruses think about anything. But evolution by natural selection has seen to it that viruses, and foxes, and pikes, behave in ways that are actively bad for their victims – behave as though they are deliberately out to get them – in ways that you couldn’t say of earthquakes or hurricanes or avalanches. Earthquakes and hurricanes are bad for their victims, but they don’t take active steps to do bad things: they don’t take active steps to do anything, they just happen.

Natural selection, the struggle for existence as Darwin called it, means that every living creature has enemies that are working hard for its downfall. And sometimes the tricks that natural enemies use give the appearance of being cleverly planned. Spider webs, for example, are ingenious traps laid for unsuspecting insects. A fearsome little insect called an ant lion digs booby traps for its prey to fall into. The ant lion itself sits under the sand at the bottom of the conical pit that it digs, and seizes any ant that falls into the pit. Nobody is suggesting
that
the spider or the ant lion is ingenious – that it has
thought up
its cunning trap. But natural selection makes them evolve brains that behave in ways that
look
ingenious to our eyes. In the same way, a lion’s body looks ingeniously designed to bring about the doom of antelopes and zebras. And we can imagine that, if you were an antelope, a stalking, chasing, pouncing lion might seem out to get you.

It’s easy to see that predators (animals that kill and then eat other animals) are working for the downfall of their prey. But it’s also true that prey are working for the downfall of their predators. They work hard to escape being eaten, and if they all succeeded the predators would starve to death. The same thing holds between parasites and their hosts. It also holds between members of the same species, all of whom are actually or potentially competing with one another. If the living is easy, natural selection will favour the evolution of improvements in enemies, whether predators, prey, parasites, hosts or competitors: improvements that will make life hard again. Earthquakes and tornadoes are unpleasant and might even be called enemies, but they are not ‘out to get you’ in the same ‘Sod’s Law’ kind of way that predators and parasites are.

This has consequences for the sort of mental attitude that any wild animal, such as an antelope, might be expected to have. If you are an antelope and you see the long grass rustling, it could be just the wind. That’s nothing to worry about, for the wind is not out to get you: it is completely indifferent to antelopes and their well-being. But that rustle in the long grass could be a stalking leopard, and a leopard is
most
definitely out to get you: you taste good to a leopard and natural selection favoured ancestral leopards that were good at catching antelopes. So antelopes and rabbits and minnows, and most other animals, have to be constantly on the alert. The world is full of dangerous predators and it is safest to assume that something a bit like Sod’s Law is true. Let’s put that in the language of Charles Darwin, the language of natural selection: those individual animals that act as though Sod’s Law were true are more likely to survive and reproduce than those individual animals that follow Pollyanna’s Law.

Our ancestors spent much of their time in mortal danger from lions and crocodiles, pythons and leopards. So it probably made sense for each person to take a suspicious – some might even say paranoid – view of the world, to see a likely threat in every rustle of the grass, every snap of a twig, and to assume that something was out to get him, a deliberate agent scheming to kill him. ‘Scheming’ is the wrong way to look at it if you think of it as deliberate plotting, but it is easy to put the idea into the language of natural selection: ‘There are enemies out there, shaped by natural selection to behave as though they were scheming to kill me. The world is not neutral and indifferent to my welfare. The world is out to get me. Sod’s Law may or may not be true, but behaving as if it is true is safer than behaving as if Pollyanna’s Law is true.’

Maybe this is one reason why, to this day, many people have superstitious beliefs that the world is out to get them. When this goes too far, we say they are ‘paranoid’.

Illness and evolution – work in progress?

As I said, predators aren’t the only things that are out to get us. Parasites are a more sneaky threat, but they are just as dangerous. Parasites include tapeworms and flukes, bacteria and viruses, which make a living by feeding off our bodies. Predators such as lions also feed off bodies, but the distinction between a predator and a parasite is usually clear. Parasites feed off still-living victims (though they may eventually kill them) and they are usually smaller than their victims. Predators are either larger than their victims (as a cat is larger than a mouse) or, if smaller (as a lion is smaller than a zebra), not very much smaller. Predators kill their prey outright and then eat them. Parasites eat their victims more slowly, and the victim may stay alive a long time with the parasite gnawing away inside.

Parasites often attack in large numbers, as when our body suffers a massive infection with a flu or cold virus. Parasites that are too small to see with the naked eye are often called ‘germs’, but that’s rather an imprecise word. They include viruses, which are very very small indeed; bacteria, which are larger than viruses but still very small (there are viruses that act as parasites on bacteria); and other single-celled organisms like the malarial parasite, which are much larger than bacteria but still too small to be seen without a microscope. Ordinary language has no general name for these larger singled-celled parasites. Some of them can be called ‘protozoa’, but that’s now rather an outdated term. Other important parasites include fungi, for example ringworm and athlete’s foot (big things like mushrooms and toadstools give a false impression of what most fungi are like).

Examples of bacterial diseases are tuberculosis, some kinds of pneumonia, whooping cough, cholera, diphtheria, leprosy, scarlet fever, boils and typhus. Viral diseases include measles, chickenpox, mumps, smallpox, herpes, rabies, polio, rubella, various strains of influenza and the cluster of diseases that we call the ‘common cold’. Malaria, amoebic dysentery and sleeping sickness are among those diseases caused by ‘protozoa’. Other important parasites, larger still – large enough to be seen with the naked eye – are the various kinds of worms, including flatworms, roundworms and flukes. When I was a boy living on a farm, I would quite often find a dead animal like a weasel or a mole. I was learning biology at school, and I was interested enough to dissect these little corpses when I found them. The main thing that impressed me was how full of wriggling, live worms they were (roundworms, technically called nematodes). The same was never true of the domesticated rats and rabbits we were given to dissect at school.

The body has a very ingenious and usually effective system of natural defence against parasites, called the immune system. The immune system is so complicated that it would take a whole book to explain it. Briefly, when it senses a dangerous parasite the body is mobilized to produce special cells, which are carried by the blood into battle like a kind of army, tailor-made to attack the particular parasites concerned. Usually the immune system wins, and the person recovers. After that, the immune system ‘remembers’ the molecular equipment that it developed for that particular battle, and any subsequent infection by the same kind of
parasite
is beaten off so quickly that we don’t notice it. That is why, once you have had a disease like measles or mumps or chickenpox, you’re very unlikely to get it again. People used to think it was a good idea if children caught mumps, say, because the immune system’s ‘memory’ would protect them against getting it as an adult – and mumps is even more unpleasant for adults (especially men, because it attacks the testicles) than it is for children. Vaccination is the ingenious technique of doing something similar on purpose. Instead of giving you the disease itself, the doctor gives you a weaker version of it, or possibly an injection of dead germs, to stimulate the immune system without actually giving you the disease. The weaker version is much less nasty than the real thing: indeed, you often don’t notice any effect at all. But the immune system ‘remembers’ the dead germs, or the infection with the mild version of the disease, and so is forearmed to fight the real thing if it should ever come along.

The immune system has a difficult task ‘deciding’ what is ‘foreign’ and therefore to be fought (a ‘suspected’ parasite), and what it should accept as part of the body itself. This can be particularly tricky, for example, when a woman is pregnant. The baby inside her is ‘foreign’ (babies are not genetically identical to their mothers because half their genes come from the father). But it is important for the immune system not to fight against the baby. This was one of the difficult problems that had to be solved when pregnancy evolved in the ancestors of mammals. It was solved – plenty of babies do manage to survive in the womb long enough to be born. But there are also plenty of miscarriages, which perhaps
suggests
that evolution had a hard time solving it and that the solution isn’t quite complete. Even today, many babies survive only because doctors are on hand – for example, to change their blood completely as soon as they are born, in some extreme cases of immune-system overreaction.

Another way in which the immune system can get it wrong is to fight too hard against a supposed ‘attacker’. That is what allergies are: the immune system needlessly, wastefully and even damagingly fighting harmless things. For example, pollen in the air is normally harmless, but the immune system of some people overreacts to it – and that’s when you get the allergic reaction called ‘hay fever’: you sneeze and your eyes water, and it is very unpleasant. Some people are allergic to cats, or to dogs: their immune systems are overreacting to harmless molecules in or on the hair of these animals. Allergies can sometimes be very dangerous. A few people are so allergic to peanuts that eating a single one can kill them.

Sometimes an overreacting immune system goes so far that a person is allergic to himself! This causes so-called auto-immune diseases (
autos
is Greek for ‘self’). Examples of auto-immune diseases are alopecia (your hair falls out in patches because the body attacks its own hair follicles) and psoriasis (an overactive immune system causes pink scaly patches on the skin).