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Asked by hollynsarah to Gioia, Iain, Jo, Leo, Mariam on 16 Jun 2010 in Categories: General.
Question: What has caused evolution?
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Leo Garcia answered on 16 Jun 2010:
Evolution is the general name we give to the process of random genetic mutation guided by natural selection – where genes which are good at surviving tend to get passed on, and genes which aren’t good at surviving die out. It is a natural process, and so has no ’cause’ as such.
Wherever there is genetic mutation (the ‘raw material’ for evolution to work with), heredity (genes being passed on from ‘parent’ to ‘children’) and an environment where only some genes survive long enough to reproduce, evolution will occur by itself.
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Joanna Watson answered on 16 Jun 2010:
Evolution happens because the plants or animals that have the best features for the environment that they live in are more likely to have babies (or have their seeds grow). So anything that is in our environment – like what food is available, what infectious diseases there are around, or whether there are any predators around can all cause evolution.
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Mariam Orme answered on 16 Jun 2010:
Evolution is a natural process. It works through mutation – changes in the DNA. A lot of mutations either make no difference or are bad for the animal. But sometimes a mutation can have a beneficial effect.
Take giraffes for example; they have evolved from an animal with a much shorter neck. But somewhere along the way, one of those animals ended up with a mutation that made its neck longer, and that meant it could reach the high-up leaves on trees that other animals couldn’t reach. So it had an advantage over the other animals – it had plenty of food – and so was fitter and survived longer, which in turn meant that it probably had more offspring than the less fit, shorter-lived animals. And since it passed on its genes to its young, this meant that there were lots of animals with longer necks, and they were also fitter and lived longer and themselves had lots of offspring. So in the end the longer-necked animals took over because they were more successful.
That’s a slightly simplified example, and in reality there wouldn’t have been one single mutation that suddenly made the giraffe’s neck as long as it is – it would have happened gradually over a very long time. But I hope it gives you an idea of how evolution works.
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