Thanks for responding.
You first make the point that the semitone is not constant. The example
you give is a good one but it relates only to 'chamber music' - i.e.
music involving small groups of players and representing a negligible
percentage of the total of music performed. That the twelfth root of two
is the 'natural' division of the octave can hardly be denied - the
universally acknowledged masterpieces of the classical and popular
repertoires surely confirm this as fact.
Your later comments re the experiments with alternative divisions put me
in mind of the sterile attempts to depart from the God-ordained working
week of 7 days. Clearly, as far as man is concerned, the present,
time-honoured, arrangement is the only acceptable one.
However, interesting as these matters are, you have failed to address
the nub of my question: "What advantage does a singing hominid have in
the evolutionary scheme of things?"
Regards,
Vernon