Pathological bacteria are only 5% of the bacterial population. The other 95% promote the health and well-being of Earth. The digestive tract holds trillions of  archaebacteria from over 4 1/2 billion years ago. When in danger, bacteria create shells for protection. Are humans evolved shells in order to protect the bacteria from atmospheric oxygen? Life forms are descended from prokaryote archaebacteria, for whom oxygen is unnecessary. After millions of years of evolution, can bacteria now direct humans to return the planet, through pollution, ozone depletion, or a nuclear disaster, to a more manageable level of oxygen from a present 21% to less than 1%?  No bacteria reside in the cranial brain. Was the enteric nervous system the first brain?  Are the archaebacteria within the gastrointestinal tract directing the actions of the body? Are the archaebacteria the architects and directors of evolution?