Nice article. Too bad the author, as an angler from Devon, made no mention of the great Cutcliffe who hailed from Devon and wrote in the 1860s about movement induced by the fly materials and the angler as the key to takes. For this reason he had a very simple fly design that used stiff rooster hackles which would respond better to the fast water and pulses by the angler.
Thanks for the great article
Maybe I’m harvesting mushrooms in the mountains 
Thank you for the energy to tie Kebari
Went way down this road with some biologists some years ago when I was deep into tuna fishing.
It overwhelmingly came down to “movement”.
If it’s somehow moving under its own power it’s certainly living, and if it fits in your mouth it’s food.
There are certainly exceptions, but that was the main point.
Works for me, makes fishing simple.
Your mileage may vary…