Read Online The Magic of Reality by Richard Dawkins - Free Book Online Page B
Authors: Richard Dawkins
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because of changes in the numbers of genes in the gene pool. That is what evolution is.
Why should the numbers of different genes change as the generations go by? Well, you might say it would be surprising if they didn’t, given such immensities of time. Think of the way language changes over the centuries. Words like ‘thee’ and ‘thou’, ‘zounds’ and ‘avast’, phrases like ‘stap me vitals’, have now more or less dropped out of English. On the other hand, the phrase ‘I was like’ (meaning ‘I said’), which would have been incomprehensible as recently as 20 years ago, is now commonplace. So is ‘cool’ as a term of approval.
So far in this chapter, I haven’t needed to go much further than the idea that gene pools in separate populations can drift apart, like languages. But actually, in the case of species, there is much more to it than drifting. This ‘much more’ is natural selection, the supremely important process that was Charles Darwin’s greatest discovery. Even without natural selection, we’d expect gene pools that happen to be separated to drift apart. But they’d drift in a rather aimless fashion. Natural selection nudges evolution in a purposeful direction: namely, the direction of survival. The genes that survive in a gene pool are the genes that are good at surviving. And what makes a gene good at surviving? It helps other genes to build bodies that are good at surviving and reproducing: bodies that survive long enough to pass on the genes that helped them to survive.
Exactly how they do it varies from species to species. Genes survive in bird or bat bodies by helping to build wings. Genes survive in mole bodies by helping to build stout, spade-like hands. Genes survive in lion bodies by helping to build fast-running legs, and sharp claws and teeth. Genes survive in antelope bodies by helping to build fast-running legs, and sharp hearing and eyesight. Genes survive in leaf-insect bodies by making the insects all but indistinguishable from leaves. However different the details, in all species the name of the game is gene survival in gene pools. Next time you see an animal – any animal – or any plant, look at it and say to yourself: what I am looking at is an elaborate machine for passing on the genes that made it. I’m looking at a survival machine for genes.
Next time you look in the mirror, just think: that is what you are too.
4
W HAT ARE THINGS
MADE OF?
IN VICTORIAN TIMES , a favourite book for children was Edward Lear’s
Book of Nonsense
. As well as the poems about the Owl and the Pussycat (which you may know because it is still famous), The Jumblies and The Pobble Who Has No Toes, I love the Recipes at the end of the book. The one for Crumboblious Cutlets begins like this: ‘Procure some strips of beef, and having cut them into the smallest possible slices, proceed to cut them still smaller, eight or perhaps nine times.’
What do you get if you keep on cutting stuff into smaller and smaller pieces?
Suppose you take a piece of anything and cut it in half, using the thinnest and sharpest razor blade you can find.
Then you cut that in half, then cut that half in half, and so on, over and over again.
Do the pieces eventually get so small that they can’t get any smaller? How thin is the edge of a razor blade? How small is the sharp end of a needle?
What are the smallest bits that things are made of?
The ancient civilizations of Greece, China and India all seem to have arrived at the same idea that everything is made from four ‘elements’: air, water, fire and earth. But one ancient Greek , Democritus, came a bit closer to the truth. Democritus thought that, if you cut anything up into sufficiently small pieces, you would eventually reach a piece so small that it couldn’t be cut any further. The Greek for ‘cut’ is
tomos
, and if you stick an ‘a’ in front of a Greek word it means ‘not’ or ‘you can’t’. So ‘a-tomic’ means something
Why should the numbers of different genes change as the generations go by? Well, you might say it would be surprising if they didn’t, given such immensities of time. Think of the way language changes over the centuries. Words like ‘thee’ and ‘thou’, ‘zounds’ and ‘avast’, phrases like ‘stap me vitals’, have now more or less dropped out of English. On the other hand, the phrase ‘I was like’ (meaning ‘I said’), which would have been incomprehensible as recently as 20 years ago, is now commonplace. So is ‘cool’ as a term of approval.
So far in this chapter, I haven’t needed to go much further than the idea that gene pools in separate populations can drift apart, like languages. But actually, in the case of species, there is much more to it than drifting. This ‘much more’ is natural selection, the supremely important process that was Charles Darwin’s greatest discovery. Even without natural selection, we’d expect gene pools that happen to be separated to drift apart. But they’d drift in a rather aimless fashion. Natural selection nudges evolution in a purposeful direction: namely, the direction of survival. The genes that survive in a gene pool are the genes that are good at surviving. And what makes a gene good at surviving? It helps other genes to build bodies that are good at surviving and reproducing: bodies that survive long enough to pass on the genes that helped them to survive.
Exactly how they do it varies from species to species. Genes survive in bird or bat bodies by helping to build wings. Genes survive in mole bodies by helping to build stout, spade-like hands. Genes survive in lion bodies by helping to build fast-running legs, and sharp claws and teeth. Genes survive in antelope bodies by helping to build fast-running legs, and sharp hearing and eyesight. Genes survive in leaf-insect bodies by making the insects all but indistinguishable from leaves. However different the details, in all species the name of the game is gene survival in gene pools. Next time you see an animal – any animal – or any plant, look at it and say to yourself: what I am looking at is an elaborate machine for passing on the genes that made it. I’m looking at a survival machine for genes.
Next time you look in the mirror, just think: that is what you are too.
4
W HAT ARE THINGS
MADE OF?
IN VICTORIAN TIMES , a favourite book for children was Edward Lear’s
Book of Nonsense
. As well as the poems about the Owl and the Pussycat (which you may know because it is still famous), The Jumblies and The Pobble Who Has No Toes, I love the Recipes at the end of the book. The one for Crumboblious Cutlets begins like this: ‘Procure some strips of beef, and having cut them into the smallest possible slices, proceed to cut them still smaller, eight or perhaps nine times.’
What do you get if you keep on cutting stuff into smaller and smaller pieces?
Suppose you take a piece of anything and cut it in half, using the thinnest and sharpest razor blade you can find.
Then you cut that in half, then cut that half in half, and so on, over and over again.
Do the pieces eventually get so small that they can’t get any smaller? How thin is the edge of a razor blade? How small is the sharp end of a needle?
What are the smallest bits that things are made of?
The ancient civilizations of Greece, China and India all seem to have arrived at the same idea that everything is made from four ‘elements’: air, water, fire and earth. But one ancient Greek , Democritus, came a bit closer to the truth. Democritus thought that, if you cut anything up into sufficiently small pieces, you would eventually reach a piece so small that it couldn’t be cut any further. The Greek for ‘cut’ is
tomos
, and if you stick an ‘a’ in front of a Greek word it means ‘not’ or ‘you can’t’. So ‘a-tomic’ means something
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