It happens organically under certain specific conditions. (entrepreneur.com)
Outside of a ketogenic diet possibly being of some help for Alzheimer's or cancer of what use is that type of diet being useful LONG TERM for someone without certain specific conditions? (bjjcaveman.com)
Now the answer is coming from the corpses of some modern - day birds and mammals, which look very similar when they have died under certain specific conditions. (discovermagazine.com)