It has long puzzled scientists why, after 3 billion years of nothing more complex than algae, complex animals suddenly started to appear on Earth.
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Can’t this be taken that complex life is rare?
If the life form is carbon based and the progressive planet geology is similar to earth, then you probably would be correct in saying than life would expand beyond the relatively simple single cell later in the geological history of the planet. Other life form bases require other conditions and may come to dominance earlier.