You Don't Understand The Fundamental Principle Of Microbial Competition
The microbe that wins the battle of evolution is the one that grows and reproduces the fastest in a given environment. Higher life forms compete with speed, size, and special defenses. Microbes compete with metabolism. Using food and energy to support structures designed to survive harsh environments that are not needed are a disadvantage not an advantage. They waste energy. The super radiation tolerant microbe radiodurans is a fine exmaple of this principle. It does not rule the microbial world due to it's toughness. It is only the dominant organism in environments where others can not survive.
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Mark