Comment The real question is step 1... (Score 0) 667
From the Cosmos show, the key ingredient of all life is the DNA factory in the cell. Where the DNA is stripped and duplicated and new cells are created. This is true for all life, and the process of accidental mistakes that result in desirable traits become part of the life tree because the life is more sustainable or competes well compared to previous versions, ultimately over an extremely long time, 100's of millions of generations results in the totality of life on earth.
The unanswered question, is how does this DNA duplication factory happen by accident? Not to mention the accidental creation of DNA in the first place. I believe that these are unanswered and unduplicated in any experiment or theory (one theory are that it isn't accidental everywhere, but somehow happened accidentally once, and redistributed in the universe by some form, an alien invasion), (Other theories are that is a divine spark), (Others is that the universe in a perverse form of chemistry and physics demands that life spontaneously appears wherever the conditions are ripe). It's not a question of the eye, or the complexity of the brain. But life itself.
The next question becomes why small ever more complex that life is, how does this accidental creation of life itself, does the basic operating system, which is I suppose essentially chemistry, how does this chemical thing that happened, how in the world of I suppose anything, is rich enough in the get-go to ultimately support the ability to create all life and all life functions. (I think that this question may indeed be easier than the step 1 questions). Why is the first accidental step to life a single cell microbe, and not say a full grown human being. Why is accident 1 not more complex? We share 50% of our DNA with Bananas. We both have the same DNA factory inside our cells.