Whether Earth Once Harbored a Pre-Human Industrial Civilization

Complex life on our planet has existed for at least 400 million years.

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Yet as a species, we only created an industrial civilization around 300 years ago. But what if an earlier industrial civilization existed on Earth millions of years before us? Could we prove it? This is the crux of the Silurian hypothesis, a fascinating thought experiment that appeared in a study published in 2018 in the International Journal of Astrobiology.

The possibility of life elsewhere in the universe has long puzzled Adam Frank, a professor of astrophysics at the University of Rochester, New York, and one of the two study authors. "Is it common for any civilization that reaches our level of energy use to trigger their own version of climate change?" he wonders.