[A reader made these comments on my article about why haven't we found life in the universe. I have never considered the possibility that life might have existed on Mars earlier than Earth. Scientists do know that Mars had oceans, water, etc. Interestingly, enough, rocks from Mars are found in antarctica on earth. They are thought to have been sent here by meteors hitting the Martian surface at high speed after passing through its very thin atmosphere. Jan]

This is what the reader wrote:

Speaking of life and Mars, in the evolution of our solar system, Mars would have been capable of life long before the Earth would have become capable of sustaining life. In terms of our solar system being over 4 Billion years old, Mars would very conceivably have sustained life a full billion years before the Earth would have acquired that ability. (Due to planetary cooling.)

Its even conceivable that intelligent life on a dying planet (Mars loosing its atmosphere) might have migrated to Earth. As to why don’t we see any evidence of a civilization on Mars? What kind of evidence of civilization would we find on Earth after a Billion years of inactivity and erosion on the Earth?