Scientists at the University of Rochester have proposed that the Earth could have been inhabited by intelligent advanced civilisations long-before modern-humans.
Gavin Schmidt, director of NASA's Goddard Institute for Space Studies, and Adam Frank, professor of physics and astronomy at the University of Rochester, used a thought experiment to examine the concept that humans were not the first advanced species on Earth.
The researchers ask the question as to what advanced societies would leave behind in the event of a mass-extinction event, such as solar flares or a rapidly changing environment on Earth's surface.
The researchers believe that some disasters could be so great that almost all evidence could be buried or removed but that some indicators of the advanced species may still be left behind – even if we have not found them yet.
The researchers point out that both Mars and Venus had vastly different climatic environments millions of years ago and that these new hostile conditions could have swept away all traces of past life-forms. They propose that the same situation may exist on Earth, and that Earth's climate has rapidly changed over time, both allowing a species to thrive, but then also almost completely eradicating all trace of it.
The researchers have coined this theory the 'Silurian Hypothesis'.
When discussing traces that could be left by an ancient civilisation Frank says:
"As an industrial civilization, we're driving changes in the isotopic abundances because we're burning carbon. But burning fossil fuels may actually shut us down as a civilization. What imprints would this or other kinds of industrial activity from a long-dead civilization leave over tens of millions of years?"
The scientists have also pointed out that human advancements in technology could have led to the ancient civilisations' downfall, and that such progress could also lead to our own downfall, with climate change being one key danger.
Frank added:
"You want to have a nice, large-scale civilization that does wonderful things but that doesn't push the planet into domains that are dangerous for itself, the civilization. We need to figure out a way of producing and using energy that doesn't put us at risk. The point is not to 'save the earth'. No matter what we do to the planet, we're just creating niches for the next cycle of evolution. But, if we continue on this trajectory of using fossil fuels and ignoring the climate change it drives, we human beings may not be part of Earth's ongoing evolution."
[h/t: IFL Science]
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