A possible explanation of why we haven't found anything is because intelligent live once developed will quickly overload the ecosystem and start causing things like climate change and quickly make the planet inhabitable, this could all happen in less than 2 million years which is nothing on the cosmological scale.
There was running water on Mars and it's within the goldilocks zone. Probably Venus too, both those planets had stable conditions for the emergence of life for billions of years.
Once a species like humans starts spreading like a virus and taking over the ecosystem, it can easily go downhill very fast (cosmologically speaking).
There was running water on Mars and it's within the goldilocks zone. Probably Venus too, both those planets had stable conditions for the emergence of life for billions of years.
Once a species like humans starts spreading like a virus and taking over the ecosystem, it can easily go downhill very fast (cosmologically speaking).