For one, we do not know what the exact environmental conditions were on Earth 4 billion years ago. Since we do not know: how can we reproduce them to possibly recreate. Second, even if we did know, do we have the capability and means to do so? Not yet. But we're getting pretty close. mountainhare: "Saying GOD DID IT doesn't answer anything... what mechanism did he use?" Why would you think that a "god" is what used a certain "mechanism"? What do you mean by "mechanism"? A mechanical process? Evolution is about random chance events, not a "mechanism." The pieces all fell in the right place at the right time under the right conditions to form what we have today.