We can't know for sure how flagella evolved. However, studying the genes involved suggests a step-by-step process where existing bacterial proteins, initially used for other functions, eventually created a structure enabling movement, which was then refined by natural selection (14-Sept-2024).
In essence, flagella likely evolved because they provided a selective advantage by enabling:
- Mobility: This allowed bacteria to move towards nutrients.
- Escape: The bacteria could move away from harmful substances.
- Adaptation: Increased range to adapt to various environments.
Therefore, the evolution of flagella, while not fully understood in its intricate steps, probably happened because it improved survival and reproductive success for bacteria in different environments. The gradual adaptation and refinement of existing protein structures into a functional flagellum is the most accepted theory.
