1. Insects have alkaline digestion.
2. Vertebrates have acidic digestion.
3. Don’t know what the common ancestor between insects and vertebrates had.
4. Evolution clearly sampled both modes of digestion and vertebrates ended up with acidic.
5. Could the extra need for calcium (for the hard endoskeleton), which is sparingly soluble in alkali and very soluble in acid, have driven the process toward acidity?
6. How foolish of us to interfere with nature with antacids and acid pump blockers.