What would you think of a detective who, baffled by a murder, was too lazy even to try to work at the problem and instead wrote the mystery off as ‘supernatural’? The whole history of science shows us that things once thought to be the result of the supernatural – caused by gods (both happy and angry), demons, witches, spirits, curses and spells – actually do have natural explanations: explanations that we can understand and test and have confidence in. There is absolutely no reason to believe that those things for which science does not yet have natural explanations will turn out to be of supernatural origin, any more than volcanoes or earthquakes or diseases turn out to be caused by angry deities, as people once believed they were.
Of course, no one really believes that it would be possible to turn a frog into a prince (or was it a prince into a frog? I can never remember) or a pumpkin into a coach, but have you ever stopped to consider why such things would be impossible? There are various ways of explaining it. My favourite way is this.
Frogs and coaches are complicated things, with lots of parts that need to be put together in a special way, in a special pattern that can’t just happen by accident (or by a wave of a wand). That’s what ‘complicated’ means. It is very difficult to make a complicated thing like a frog or a coach. To make a coach you need to bring all the parts together in just the right way. You need the skills of a carpenter and other craftsmen. Coaches don’t just happen by chance or by snapping your fingers and saying ‘Abracadabra’. A coach has structure, complexity, working parts: wheels and axles, windows and doors, springs and padded seats. It would be relatively easy to turn something complicated like a coach into something simple – like ash, for instance: the fairy godmother’s wand would just need a built-in blowtorch. It is easy to turn almost anything into ash. But no one could take a pile of ash – or a pumpkin – and turn it into a coach, because a coach is too complicated; and not just complicated, but complicated in a useful direction: in this case, useful for people to travel in.
Let’s make it a bit easier for the fairy godmother by supposing that, instead of calling for a pumpkin, she had called for all the parts you need for assembling a coach, all jumbled together in a box: a sort of Ikea kit for a coach. The kit for making a coach consists of hundreds of planks of wood, panes of glass, rods and bars of iron, wads of padding and sheets of leather, along with nails, screws and pots of glue to hold things together. Now suppose that, instead of reading the instructions and joining the parts in an orderly sequence, she just put all the bits into a great big bag and shook them up. What are the chances that the parts would happen to stick themselves together in just the right way to assemble a working coach? The answer is – effectively zero. And a part of the reason for that is the massive number of possible ways in which you could combine the shuffled bits and pieces which would not result in a working coach – or a working anything.
If you take a load of parts and shake them around at random, they may just occasionally fall into a pattern that is useful, or that we otherwise recognize as somehow special. But the number of ways in which that can happen is tiny: very tiny indeed compared with the number of ways in which they will fall into a pattern that we don’t recognize as anything more than a heap of junk. There are millions of ways of shuffling and reshuffling a heap of bits and pieces: millions of ways of transforming them into … another heap of bits and pieces. Every time you shuffle them, you get a unique heap of junk that has never been seen before – but only a tiny minority of those millions of possible heaps will do anything useful (such as taking you to the ball) or will be remarkable or memorable in any way.
Sometimes we can literally count the number of ways you can reshuffle a series of bits – as with a pack of cards, for instance, where the ‘bits’ are the individual cards.
Suppose the dealer shuffles the pack and deals them out to four players, so that they each have 13 cards. I pick up my hand and gasp in astonishment. I have a complete hand of 13 spades! All the spades.
I am too startled to go on with the game, and I show my hand to the other three players, knowing they will be as amazed as I am.
But then, one by one, each of the other players lays his cards on the table, and the gasps of astonishment grow with each hand. Every one of them has a ‘perfect’ hand: one has 13 hearts, another has 13 diamonds, and the last one has 13 clubs.
Would this be supernatural magic? We might be tempted to think so. Mathematicians can calculate the chance of such a remarkable deal happening purely by chance. It turns out to be almost impossibly small: 1 in 53,644,737,765,488,792, 839,237,440,000. If you sat down and played cards for a trillion years, you might on one occasion get a perfect deal like that. But – and here’s the thing – this deal is no more unlikely than every other deal of cards that has ever happened! The chance of any particular deal of 52 cards is 1 in 53,644,737,765,488,792, 839,237,440,000 because that is the total number of all possible deals. It is just that we don’t notice any particular pattern in the vast majority of deals that are made, so they don’t strike us as anything out of the ordinary. We only notice the deals that happen to stand out in some way.
There are billions of things you could turn a prince into, if you were brutal enough to rearrange his bits into billions of combinations at random. But most of those combinations would look like a mess – like all those billions of meaningless, random hands of cards that have been dealt. Only a tiny minority of those possible combinations of randomly shuffled prince-bits would be recognizable or good for anything at all, let alone a frog.
Princes don’t turn into frogs, and pumpkins don’t turn into coaches, because frogs and coaches are complicated things whose bits could have been combined into an almost infinite number of heaps of junk. And yet we know, as a fact, that every living thing – every human, every crocodile, every blackbird, every tree and even every Brussels sprout – has evolved from other, originally simpler forms. So isn’t that just a process of luck, or a kind of magic? No! Absolutely not! This is a very common misunderstanding, so I want to explain right now why what we see in real life is not the result of chance or luck or anything remotely ‘magical’ at all (except, of course, in the strictly poetic sense of something that fills us with awe and delight).
The slow magic of evolution
To turn one complex organism into another complex organism in a single step – as in a fairytale – would indeed be beyond the realms of realistic possibility. And yet complex organisms do exist. So how did they arise? How, in reality, did complicated things like frogs and lions, baboons and banyan trees, princes and pumpkins, you and me come into existence?
For most of history that was a baffling question, which no one could answer properly. People therefore invented stories to try to explain it. But then the question was answered – and answered brilliantly – in the nineteenth century, by one of the greatest scientists who ever lived, Charles Darwin. I’ll use the rest of this chapter to explain his answer, briefly, and in different words from Darwin’s own.
The answer is that complex organisms – like humans, crocodiles and Brussels sprouts – did not come about suddenly, in one fell swoop, but gradually, step by tiny step, so that what was there after each step was only a little bit different from what was already there before. Imagine you wanted to create a frog with long legs. You could give yourself a good start by beginning with something that was already a bit like what you wanted to achieve: a frog with short legs, say. You would look over your short-legged frogs and measure their legs. You’d pick a few males and a few females that had slightly longer legs than most, and you’d let them mate together, while preventing their shorter-legged friends from mating at all.
The longer-legged males and females would make tadpoles together, and these would eventually grow legs and become frogs. Then you’d measure this new generation of frogs, and once again pick out those males and females that had longer-than-average legs, and put them together to mate.
After doing this for about 10 generations, you mig
ht start to notice something interesting. The average leg length of your population of frogs would now be noticeably longer than the average leg length of the starting population. You might even find that all the frogs of the 10th generation had longer legs than any of the frogs of the first generation. Or 10 generations might not be enough to achieve this: you might need to go on for 20 generations or even more. But eventually you could proudly say, ‘I have made a new kind of frog with longer legs than the old type.’
No wand was needed. No magic of any kind was required. What we have here is the process called selective breeding. It makes use of the fact that frogs vary among themselves and those variations tend to be inherited – that is, passed on from parent to child via the genes. Simply by choosing which frogs breed and which do not, we can make a new kind of frog.
Simple, isn’t it?
But just making legs longer is not very impressive. After all, we started with frogs – they were just short-legged frogs. Suppose you started, not with a shorter-legged form of frog, but with something that wasn’t a frog at all, say something more like a newt. Newts have very short legs compared with frogs’ legs (compared with frogs’ hind legs, at least), and they use them not for jumping but for walking. Newts also have long tails, whereas frogs don’t have tails at all, and newts are altogether longer and narrower than most frogs. But you can see that, given enough thousands of generations, you could change a population of newts into a population of frogs, simply by patiently choosing, in each of those millions of generations, male and female newts that were slightly more frog-like and letting them mate together, while preventing their less frog-like friends from doing so. At no stage during the process would you see any dramatic change. Every generation would look pretty much like the previous generation, but nevertheless, once enough generations had gone by, you’d start to notice that the average tail length was slightly shorter and the average pair of hind legs was slightly longer. After a very large number of generations, the longer-legged, shorter-tailed individuals might find it easier to start using their long legs for hopping instead of crawling. And so on.
Of course, in the scenario I have just described, we are imagining ourselves as breeders, picking out those males and females that we want to mate together in order to achieve an end result that we have chosen. Farmers have been applying this technique for thousands of years, to produce cattle and crops that have higher yields or are more resistant to disease, and so on. Darwin was the first person to understand that it works even when there is no breeder to do the choosing. Darwin saw that the whole thing would happen naturally, as a matter of course, for the simple reason that some individuals survive long enough to breed and others don’t; and those that survive do so because they are better equipped than others. So the survivors’ children inherit the genes that helped their parents to survive. Whether it’s newts or frogs, hedgehogs or dandelions, there will always be some individuals that are better at surviving than others. If long legs happen to be helpful (for frogs or grasshoppers jumping out of danger, say, or for cheetahs hunting gazelles or gazelles fleeing from cheetahs), the individuals with longer legs will be less likely to die. They will be more likely to live long enough to reproduce. Also, more of the individuals available for mating with will have long legs. So in every generation there will be a greater chance of the genes for longer legs being passed into the next generation. Over time we will find that more and more of the individuals within that population have the genes for longer legs. So the effect will be exactly the same as if an intelligent designer, such as a human breeder, had chosen long-legged individuals for breeding – except that no such designer is required: it all happens naturally, all by itself, as the automatic consequence of which individuals survive long enough to reproduce, and which don’t. For this reason, the process is called natural selection.
Given enough generations, ancestors that look like newts can change into descendants that look like frogs. Given even more generations, ancestors that look like fish can change into descendants that look like monkeys. Given yet more generations, ancestors that look like bacteria can change into descendants that look like humans. And this is exactly what happened. This is the kind of thing that happened in the history of every animal and plant that has ever lived. The number of generations required is larger than you or I can possibly imagine, but the world is thousands of millions of years old, and we know from fossils that life got started more than three and a half billion years ago, so there has been plenty of time for evolution to happen.
This is Darwin’s great idea, and it is called Evolution by Natural Selection. It is one of the most important ideas ever to occur to a human mind. It explains everything we know about life on Earth. Because it is so important, I’ll come back to it in later chapters. For now, it is enough to understand that evolution is very slow and gradual. In fact, it is the gradualness of evolution that allows it to make complicated things like frogs and princes. The magical changing of a frog into a prince would be not gradual but sudden, and this is what rules such things out of the world of reality. Evolution is a real explanation, which really works, and has real evidence to demonstrate the truth of it; anything that suggests that complicated life forms appeared suddenly, in one go (rather than evolving gradually step by step), is just a lazy story – no better than the fictional magic of a fairy godmother’s wand.
As for pumpkins turning into coaches, magic spells are just as certainly ruled out for them as they are for frogs and princes. Coaches don’t evolve – or at least, not naturally, in the same way that frogs and princes do. But coaches – along with airliners and pickaxes, computers and flint arrowheads – are made by humans who did evolve. Human brains and human hands evolved by natural selection, just as surely as newts’ tails and frogs’ legs did. And human brains, once they had evolved, were able to design and create coaches and cars, scissors and symphonies, washing machines and watches. Once again, no magic. Once again, no trickery. Once again, everything beautifully and simply explained.
In the rest of this book I want to show you that the real world, as understood scientifically, has magic of its own – the kind I call poetic magic: an inspiring beauty which is all the more magical because it is real and because we can understand how it works. Next to the true beauty and magic of the real world, supernatural spells and stage tricks seem cheap and tawdry by comparison. The magic of reality is neither supernatural nor a trick, but – quite simply – wonderful. Wonderful, and real. Wonderful because real.
2
WHO WAS THE
FIRST PERSON?
MOST CHAPTERS IN this book are headed by a question. My purpose is to answer the question, or at least give the best possible answer, which is the answer of science. But I shall usually begin with some mythical answers because they are colourful and interesting, and real people have believed them. Some people still do.
All peoples around the world have origin myths, to account for where they came from. Many tribal origin myths talk only about that one particular tribe – as though other tribes don’t count! In the same way, many tribes have a rule that they mustn’t kill people – but ‘people’ turns out to mean only others of your own tribe. Killing members of other tribes is just fine!
Here’s a typical origin myth, from a group of Tasmanian aborigines. A god called Moinee was defeated by a rival god called Dromerdeener in a terrible battle up in the stars. Moinee fell out of the stars down to Tasmania to die. Before he died, he wanted to give a last blessing to his final resting place, so he decided to create humans. But he was in such a hurry, knowing he was dying, that he forgot to give them knees; and (no doubt distracted by his plight) he absent-mindedly gave them big tails like kangaroos, which meant they couldn’t sit down. Then he died. The people hated having kangaroo tails and no knees, and they cried out to the heavens for help.
The mighty Dromerdeener, who was still roaring around the sky on his victory parade, heard their cry and came down to Tasmania to see what the matter was.
He took pity on the people, gave them bendable knees and cut off their inconvenient kangaroo tails so they could all sit down at last; and they lived happily ever after.
Quite often we meet different versions of the same myth. That’s not surprising, because people often change details while telling tales around the camp fire, so local versions of the stories drift apart. In a different telling of this Tasmanian myth, Moinee created the first man, called Parlevar, up in the sky. Parlevar couldn’t sit down because he had a tail like a kangaroo and unbendable knees. As before, the rival star god Dromerdeener came to the rescue. He gave Parlevar proper knees and cut off his tail, healing the wound with grease. Parlevar then came down to Tasmania, walking along the sky road (the Milky Way).
The Hebrew tribes of the Middle East had only a single god, whom they regarded as superior to the gods of rival tribes. He had various names, none of which they were allowed to say. He made the first man out of dust and called him Adam (which just means ‘man’). He deliberately made Adam like himself. Indeed, most of the gods of history were portrayed as men (or sometimes women), often of giant size and always with supernatural powers.
The god placed Adam in a beautiful garden called Eden, filled with trees whose fruit Adam was encouraged to eat – with one exception. This forbidden tree was the ‘tree of knowledge of good and evil’, and the god left Adam in no doubt that he must never eat its fruit.
The god then realized that Adam might be lonely all by himself, and wanted to do something about it. At this point – as with the story of Dromerdeener and Moinee – there are two versions of the myth, both found in the biblical book of Genesis. In the more colourful version, the god made all the animals as Adam’s helpers, then decided that there was still something missing: a woman! So he gave Adam a general anaesthetic, cut him open, removed one rib and stitched him up again. Then he grew a woman from the rib, rather as you grow a flower from a cutting. He named her Eve and presented her to Adam as his wife.