Life on Earth started with the Last Universal Common Ancestor (LUCA), dated to 4.2 billion years ago (as deduced here). Humanity’s first artificial satellite was Sputnik, launched away from Earth’s surface on October 4, 1957. It is commonly assumed that this was the first technological satellite around Earth.
However, suppose intelligent life emerged when Earth was 94% of its current age (which is 4.54 billion years), namely 272 million years ago. In that case, a technological civilization could have started launching satellites a few million years after their intelligence emerged — similarly to humanity’s case. About 252 million years ago, this 20-million-years-old civilization could have polluted the Earth’s atmosphere with greenhouse gases, enough to trigger the largest extinction in Earth’s history, ending the Permian period by killing 96% of marine species in a global warming event that left ocean animals unable to breathe. This well-known “great dying” event in Earth’s history is often interpreted as the natural consequence of the release of greenhouse gases by volcanic eruptions (as reported here). But what if this global catastrophe was technologically-driven instead? Would we have noticed any “smoking gun” left in the crime scene?
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