Who says that biology is purely inductive? Nonsense- there are deductions to be had.
Consider the workings of our digestive system, far from perfect, but better than we know because we are doing so many harmful things to our system and then blaming our system for not adapting to our errors on the fly.
Our digestion is strongly acidic, as is that of every vertebrate tested. Calcium has to be solubilized. That probably drove this, but that is only the beginning.
That switch to acidic digestion during the evolution of vertebrates necessitated a gut that is adapted to acidophilus organisms and is likely averse to certain acidophobic organisms.
Since bacteria, yeast, and fat are present in our foods, and it appears that free fatty acids plus stomach acid is a strong germ killer, nature made use of the slight advantage that acidophilus organisms would have in that environment and sacrificed the rest of the microbes, some of which would be downright harmful, and sacrificed a large proportion of acidophilus as well, and harvested their enzymes, getting better digestion, less bloating, more nutrients and better intestinal motility in the process.