how do we know there weren’t advanced human civilisations 50,000+ years ago?

Question

Recorded history only goes back around 5,000 years, but humans have been around for 200,000 years. Could there have been highly sophisticated ancient societies of which no trace remains?

In: 16

Answer 1

To get to a civilization like we know it today you leave traces on earth that still could be detected. Civilization as we know it requires resources mined from the ground to get metals and other stuff we use. We would see traces of that on earth today because most of earth’s surface is the same as it was 50,000 years ago. When humans started to mine we found ore with high metal content on the surface, that was what we first minded and most of it is gone today. If there was a civilization before what is know that metal would not bee left there.

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Recorded history might only go back 5000 years but there is other data sources that go back further like ice cores. There is 2.7 million years old ice cores [https://www.science.org/content/article/world-s-oldest-ice-core-could-solve-mystery-flipped-ice-age-cycles](https://www.science.org/content/article/world-s-oldest-ice-core-could-solve-mystery-flipped-ice-age-cycles) We can from them see what was in earth atmosphere in the past like how we fund lead from Roman silver mines in ice cores from Greenland. We can see that the production dropped at the same time as major plagues [ttps://www.pnas.org/doi/10.1073/pnas.1721818115](https://www.pnas.org/doi/10.1073/pnas.1721818115)

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If they reached out level and used nuclear reactors and weapons you will see elements in ice cores that do not exist naturally on earth.

But if you by civilization mean something that is “characterized by the development of a political state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language” to quote https://en.wikipedia.org/wiki/Civilization then it might be possible. There could be some locations where humans started to farm and live in cities but never build stone monuments that survived or mined ore from the ground. That might could have happened before because the types of trace that are left are easier to miss.

So if it is possible or not depends on what you call advanced. Something more advanced we knew existed at the time, that could exist but not something that reaches something that approaches our technology level.