With regard to this question of functionalism and ‘efficiency’ Nature seems to have a sense of humour, or perhaps just a sense of proportion. She will construct the stem of a plant, for instance, with the uttermost regard for metabolic economy; the thing is a miracle of structural efficiency. Having done this, she will put a great big flower on top – for fun, as far as one can see. In the same way, peacocks have tails and girls have hair which cannot be considered strictly functional.
