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Asked by cookiedoughmonster to Ed, Katie, Sam, Steve, Vera on 19 Jun 2011.
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Sam Tazzyman answered on 17 Jun 2011:
There are several ways things evolve, but the main one is via what is called “natural selection”, and was discovered by Darwin. This works because there are lots more of a species born than eventually get to survive and breed. All the individuals in the species look a bit different, because they have different DNA. Some are bigger than others, for example. Suppose these differences affect how likely the individuals are to survive, so that for example the bigger ones are more likely to survive and breed. Then the genes that make them bigger will be passed on to their offspring, and the genes that make individuals small will not be passed on so much because the small individuals will be more likely not to survive. So over time the species will get bigger. This is called evolution by natural selection.
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Ed Morrison answered on 17 Jun 2011:
This is a very big question – there are loads of textbooks all about evolution. I recommend The Blind Watchmaker by Richard Dawkins for a very readable introduction.
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Steven Daly answered on 18 Jun 2011:
This is a question lots of scientists have tried very hard to answer. As Sam said natural selection is a very important mechanism for evolution. What drives natural selection is pressures on an animal. If their environment changes so that an animal would survive better if taller, or faster, or with a longer neck, or with shorter legs, then mutation and natural selection will drive evolution.
One way in which new species can form is when two populations become isolated from each other. This can happen if, say, flooding occurs that creates a new permanent island, and the animals cannot swim. This will mean that they cannot breed, and so changes to the genes of each population will not be passed to the other. Over time this means that the animals could become different species. This will not always happen, but I think it is cool.
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