If agriculture had been discovered 60 thousand years ago, leading to a technological development equal or superior to the present one, only for humanity to collapse and go back to being hunter gatherers some 20 thousand years later, would there be any evidence?

by Frigorifico

I was thinking that we humans have existed for so long in this planet, that there's more than enough time for civilization to arise, collapse, and then do that a couple more times until our current rise that started some ~20,000 years ago with the invention of agriculture.

How would we know if this is the first time that humanity arose?

adirockets

While we cannot say for certain as concrete, plastics, etc. would all disappear there are some strong signs that such a thing would not exist.

  1. Invasive/Domesticated species: if humanity was at a similar point technologically we would likely be moving animals around and breeding them which would show up in evolutionary histories as weird anomalies.

  2. CO2: if such a society has discovered fossil fuels we would have likely seen a spike in CO2 higher than the normal cycle corresponding with their rise in the ice cores

  3. Radioactive Isotopes: The half life of uranium is around 4.5 billion years. Had this civilization ever used nuclear weapons or had nuclear power plants with leaks we would have seen much higher nuclear isotope concentrations in the atmosphere and oceans prior to WW2.

  4. Satellites: Current estimates suggest that Geosynhcronus orbit satellites if left to themselves will not uncontrollably deorbit for over a million years. Even if they collided to form space debris, which is unlikely, the space debris would still be in orbit.

  5. Bodies: This civilization would have likely been of much larger population that our hunter-gatherer predecessors. Any advanced civilization would need a way of dealing with bodies. Although they certainly could have all chosen cremation, cremation is more complex than burial in many aspects and it is likely that at least some would've opted for burial. In this case we would see far more humanoid skeletons /fossils than we currently do.

Although I'm sure there would be other signs as well. I believe these show that such a prior civilization likely did not exist, at least at the population or technology level we have currently achieved.

SeraLermin