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| Question | Answer |
| Who wrote his theory of natural selection 150 years ago? | Over 150 years ago Charles Darwin wrote his theory of natural selection. |
| What did this theory explain? | Over 150 years ago Charles Darwin wrote his theory of natural selection to explain how evolution might happen. |
| What does this theory say? | It says that if animals and plants are better adapted to their environment, they and the following generations are more likely to survive. |
| He did not know exactly how adaptations were passed on. We now know that when organisms reproduce, their genes are passed on to the next generation. How can the modern version of natural selection be summarised? | The modern version of natural selection can be summarised like this: - Within any species there is variation. - Organisms produce far more young than will survive, so there is competition for limited resources such as food. - Only those best adapted will survive, which is called survival of the fittest. - Those that survive pass on successful adaptations to the next generation in their genes. |
| Over time, the changes produced by natural selection may result in a new species. Only when can this happen? | This only happens if different groups of organisms cannot mate for a long time. |
| Why might organisms be prevented from mating? | The organisms may be prevented from mating because they live in different areas. |
| What is this? | This is geographical isolation. |
| How else may organisms also be prevented from mating? | They might be prevented from mating because of behavioural isolation. |
| If each group evolves differently over time what could happen? | If each group evolves differently they might over time become different enough to be classified as separate species. |
| Why is natural selection difficult to study? | Natural selection is difficult to study because it usually takes thousands of years to see the effect. |
| Some examples have been studied over shorter time spans. Give two examples of this. | - More and more bacteria are developing resistance to antibiotics. - Peppered moths are dark or pale in colour. Dark moths are better camouflaged in polluted areas, so more of them survive. |
| Why at first did many people disagree with Darwin's ideas? | At first many people disagreed with Darwin's ideas: - Some people thought he did not have enough evidence to back up his theory. - Many people disagreed because they thought God had created all species. |
| Why now is Darwin's theory much more widely accepted? | Now Darwin's theory is much more widely accepted. This is because: - it explains a lot of observations - it has been discussed and tested by a wide range of scientists |
| There have been other attempts to explain evolution. Before Darwin, Jean Baptiste de Lamarck had a different theory. What was this called? | Called the law of acquired characteristics. |
| What did this theory say? | This said, for example, that giraffes acquired long necks to feed, and this characteristic was passed on. |
| What have we discovered more about so that theories like Lamarck's have been proved incorrect and Darwin's theory has become more widely accepted? | As we have discovered more about how genes are passed on, theories like Lamarck's have been proved incorrect and Darwin's theory has become more widely accepted. |
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