Would it be possible to detect an advanced civilization in the geological record?

If an industrialized civilization had existed on Earth many millions of years before our era, what traces would it have left and would they be detectable today? That is the unheard-of premise that led Adam Frank, an astrophysicist at the University of Rochester, and Gavin Schmidt, director of the NASA Goddard Institute, to write an article in 2018 in which they proposed what is known as Silurian Hypothesis.

The term Silurian Hypothesis was inspired by an episode of the television series Doctor Who in which intelligent reptiles appeared, and the study was published in International Journal of Astrobiology.

In the article, both scientists wondered how the existence of a civilization older than ours several million years could be detected. Fossilization is a relatively rare process, otherwise we would be finding dinosaur fossils day in and day out. This, together with the fact that the earth’s crust is renewed and modified due to tectonic activity, and that very little of the current surface was exposed before the Quaternary, makes it very difficult to find physical traces or direct remains of a possible civilization of such antiquity.

Therefore, his conclusion is that it is most likely that we will find indirect evidence, such as anomalies in the chemical composition or in the ratio of isotopes in the sedimentary layers, due to the use of fossil fuels and nitrogen-based fertilizers, for example, which may be detectable in the fossil record for eons.

As for the objects that could indicate possible evidence of past civilizations, there would be plastic waste and nuclear waste, buried deep in the subsoil or on the ocean floor, which would make them very difficult to find. It would be easier if these civilizations had gone into space and left artifacts on the Moon or Mars, where they would be easier to find due to less erosion and tectonic activity.

Of course, both authors are aware that what they are proposing is highly unlikely:

We are aware that raising the possibility of a previous industrial civilization as the driver of events in the geological record could lead to quite limitless speculation. One could fit any observation to an imagined civilization in ways that would be basically unfalsifiable. Therefore, care must be taken not to postulate such a cause until positive evidence is available. The Silurian hypothesis cannot be considered probable simply because no other valid idea is presented.

Frank and Schmidt end their article stating that:

Perhaps unusually, the authors of this article are not convinced of the correctness of the proposed hypothesis. If true, it would have profound implications, and not just for astrobiology. However, most readers do not need to be told that it is always a bad idea to decide whether an idea is true or false based on the consequences of being true. Although we highly doubt that an industrial civilization existed prior to our own, posing the question in a formal way that explicitly articulates what the evidence for such a civilization might look like raises its own useful questions related to both astrobiology and scientific studies. anthropocene Therefore, we hope that this paper will serve as motivation to improve the limitations of the hypothesis, so that in the future we may be better able to answer our question about the title.

As an experiment it is an interesting hypothesis, but only that, because today there is no evidence of catfish or other intelligent beings before us, humans, on planet Earth.


The Silurian Hypothesis: Would it be possible to detect an industrial civilization in the geological record?, Gavin A.Schmidt and Adam Frank, International Journal of Astrobiology, doi: 10.1017/S1473550418000095 / Was There a Civilization On Earth Before Humans? (Adam Frank).

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