Evolutionary biologists are not content merely to explain how variation occurs within limits, however. They aspire to answer a much broader question-which is how complex organisms like birds, and flowers, and human beings came into existence in the first place.
Variation
The iambic pentameter owes its pre-eminence in English poetry to its genius for variation. Good blank verse does not sound like a series of identically measured lines. It sounds like a series of subtle variations on the same theme.
An aria in an opera – Handel’s ‘Ombra mai fu,’ for example – gets along with an incredibly small number of words and ideas and a large amount of variation and repetition. That’s the beauty of it. It’s not taxing to the listener’s intelligence because if you haven’t heard it the first time round, it’ll come around again.
Jazz and poetry both involve a structure that may be familiar and to some extent predictable. And then, you try to create as much surprise and spontaneity and feeling and variation while respecting that structure.