A while ago I saw the History Channels interesting show on Life After People. I had also read articles on the subject of what would happen to our buildings and works after our time came to an end.
Interestingly, the remains of our civilization would be almost completely eradicated in about 50,000 years. While this seems like a long time, when compared with the estimated age of the earth (4 billion years give or take a few million) and even the origins of our own species (3-6 million years) it is but a blink in time.
Since I like science fiction, I started thinking about what another intelligent species would find if they were to come to earth after our fall. Then I started thinking about whether or not it is possible that we are not the first intelligent species to arise on earth.
Since we are here, we know that intelligent species can arise here. We also know that intelligent species can go extinct. After all, the Neanderthals were apparently quite close to us in capabilities and they passed from the stage of history. So, the idea that a pre-human race could arise and fall is not an impossibility.The fact that the earth has had billions of years to produce such a species also is a point in favor of the hypothesis that it could have happened before.
The obvious problem is, laying aside various conspiracy theories about government cover ups, that no evidence exists of any pre-human intelligent species. As such, claims about the existence of such a species would be pure speculation. However, the lack of evidence for such a species is not conclusion evidence against the claim that there was such a species.
First, consider the fossil record. We as of yet have no fossils that suggest the existence of a pre-human intelligent species. However, intelligent beings are generally good at avoiding situations that tend to produce fossils. Further, such fossils might have existed or might even exist now. We have hardly explored the earth thoroughly enough to be able to claim we have a complete picture of the past. In those gaps in our knowledge might exist a space for an intelligent species.
Second, consider the ruins. We have been able to dig up the ruins of ancient Troy and even much older settlements. It could be argued that if an intelligent race had existed before us, we would find the remains of their civilization. This is a reasonable concern and, obviously, without such evidence the claim that such a species existed would be unsupported. But, given how quickly the evidence of our own civilization would vanish, there is reason to think that such a species could have risen and fallen. Their buildings and works (assuming they were like us in this regard) could have long crumbled to unrecognizable dust.
Naturally, my claim is not that such a species did exist. My claim is much weaker-the evidence is such that such a species could have existed. Sadly, it seems likely that even if they did exist, then their story shall never be known to us or anyone else. Someday, perhaps, long after the end of humanity, some other species will be asking the same questions and wondering if anyone came before them.