The Greatest Show on Earth: The Evidence for Evolution

by Richard Dawkins

More than 40 per cent of Americans deny that humans evolved from other animals, and think that we – and by implication all of life – were created by God within the last 10,000 years.

Evolution is a fact. Beyond reasonable doubt, beyond serious doubt, beyond sane, informed, intelligent doubt, beyond doubt evolution is a fact.

modern species don’t evolve into other modern species, they just share ancestors: they are cousins. This, as we shall see, is also the answer to that disquietingly common plaint: ‘If humans have evolved from chimpanzees, how come there are still chimpanzees around?’

Any one of your eggs (or sperms if you are male) contains either your father’s version of a particular gene or your mother’s version, not a blend of the two. And that particular gene came from one and only one of your four grandparents; and from one and only one of your eight great-grandparents.

There is no intrinsic tendency in gene pools for particular genes to increase or decrease in frequency. But when there is a systematic increase or decrease in the frequency with which we see a particular gene in a gene pool, that is precisely and exactly what is meant by evolution.

When you notice a characteristic of an animal and ask what its Darwinian survival value is, you may be asking the wrong question. It could be that the characteristic you have picked out is not the one that matters. It may have ‘come along for the ride’, dragged along in evolution by some other characteristic to which it is pleiotropically linked.

Carbon-14 is special because it is continually being made by cosmic rays bombarding nitrogen atoms in the upper atmosphere. Nitrogen is the commonest gas in the atmosphere and its mass number is 14, the same as carbon-14’s. The difference is that carbon-14 has 6 protons and 8 neutrons, while nitrogen-14 has 7 protons and 7 neutrons (neutrons, remember, have near-enough the same mass as protons). Cosmic ray particles are capable of hitting a proton in a nitrogen nucleus and converting it to a neutron. When this happens, the atom becomes carbon-14, carbon being one lower than nitrogen in the periodic table. The rate at which this conversion occurs is approximately constant from century to century, which is why carbon dating works.

The human/dog cell should theoretically have an identical resemblance score to the chimpanzee/dog cell because humans and chimpanzees have exactly the same degree of relation to dogs. It should be identical, too, to the monkey/dog cell and the lemur/dog cell. This is because humans, chimpanzees, monkeys and lemurs are all connected to the dog via their common ancestor, an early primate (which probably looked a bit like a lemur). The same score should show up in the human/cat, chimpanzee/cat, monkey/cat and lemur/cat cells, because cats and dogs are related to all primates via the shared ancestor of all carnivores.

No new energy is added after the initial input from the sun.

Natural selection is an improbability pump: a process that generates the statistically improbable.

The opposite of simple is statistically improbable. Statistically improbable things don’t spontaneously spring into existence: that is what statistically improbable means. The beginning had to be simple, and evolution by natural selection is still the only process we know whereby simple beginnings can give rise to complex results.