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Bulldog Drummond say: Excellent answer from "John."
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John say: The new trait has to start as something small and not very significant so that it can form randomly in the first place, but it also has to be useful enough to be consistently passed on to offspring. Over time, it becomes bigger and more useful until it can be considered a new trait. For example, the eye started off as small light-sensing clusters of cells, but even the most primitive eyes were still useful because they allowed organisms to sense the difference between light and dark. Over time, these cells changed shape and became more complex until eventually they were eyes.
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Jim Moor say: We need to observe it to see it happen. So far it's just historical data.
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Dixon say: I think it probably varies on a case by case basis. But unlike scientific experiments, nature changes a lot of variables at the same time, so species can evolve in several different aspects simultaneously.
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