Suppose that after tens or maybe hundreds of thousands of years, civilization returns. The scientists of that day find a problem:
There are a group of related canine species of many sizes. It seems, from the fossil record, that there had been only a few species 100,000 years before, but suddenly, over seemingly less than 5,000 years, dozens of branches suddenly developed that further evolved into separate, though clearly related species.
Could those future scientists and interested laymen be having the same debate we are now: Was this branching of species (as well as that of cattle and several other creatures) the results of pure random chance or some intelligent intervention?
To a certain extent, Intelligent Design is proved: Humans have manipulated evolution, through breeding, hybridization, and, now genetic manipulation. We are a known "I" in ID.
Given that, is it inconceivable that there is some lost manipulator in our past. Perhaps life arose spontaneously, but was guided along in its development. Perhaps we are that future civilization with lost forebears, whose few survivors of catastrophe are now only remembered as Noah and his family.
Even the alien theory would work here -- one spontaneously rising intelligent species by chance could then guide further planets.
This is all science fictiony speculation, sure. But if there are aspects of evolution that don't appear entirely by chance, we need not have God or any deity enter the argument.
So, you want to teach fictiony speculation and call it science?
That'd be great for the creative writing class, but thats just not "science".
You are partially referring to a theory called "Directed Panspermia". It was put forth by Francis Crick about 30 years ago. It goes like this: Life originated somewhere and intelligent life evolved. They were "lonely". They packaged several types of microbes into spacecraft realizing that they couldn't go themselves. Whenever that space craft found an appropriate planet it dropped a packet of seeds ("spermia"). They grew and evolved into --- "Us". The time is there and the possibility is real. Is is a "good" theory? Probably not, but neither supported nor unsupported. It puts off the "abiogenesis" problem for Earth, but it doesn't say where it happened, only that maybe somewhere else conditions were more ideal than Earth. I don't look down on Crick fore this, he is just stating another idea. (He's dead now so, I guess he can't answer the question as to whether he really believes it - 30 years ago he told me it was partially a joke, but..... wink wink)
Maybe we should teach this in school too. Scientists love to play these mind games - it helps them to be more innovative in their thinking. Nothing is tossed out without thorough examination and even discarded ideas sometimes enjoy a new life if conditions warrant.