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One Above All

    Posts: 12226
  • Darwins +385/-43

I've been thinking about the origins of life and evolution lately, and a question popped into my head - is there a "point of no return" for evolution? For example, could a species of tree evolve in such a manner that would "turn it"[1] into a new species of photosynthetic bacteria? Could we, descendants of photosynthetic bacteria[2], "develop" a random mutation that would make us photosynthetic again? Or has our DNA changed too much since that time? Could all life on Earth "go back" to being little more than protozoa through evolution[3]?

I've thought about these questions and I was unable to conceive of a scenario in which being "simpler" would be an advantage, save for situations that would result in a mass-extinction event. What do you guys think?
EDIT: Just to emphasize - I'm not looking for mass-extinction events as a solution to this.
 1. For lack of a better term.
 2. Even if life didn't begin with such beings, they're still one of the oldest types of beings in existence.
 3. No mass-extinction event(s).
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