Did Earth's Life Originate on Mars?

On August 7, 1996, NASA announced a startling discovery – by examining a meteorite that originated on Mars, they found what they believe is evidence for a primitive form of life that may have existed on Mars 3.6 billion years ago. More work needs to be done to confirm this preliminary result, and many scientists remain unconvinced by the present evidence. But if this preliminary result is confirmed, if the structures inside the meteorite turn out to be fossil evidence for cellular organisms, then some important steps can be taken.

First, we would need to launch a mission to Mars, manned or unmanned, to secure and return to earth core samples that might provide evidence for or against DNA as the organizing scheme for the Mars life form. Having accomplished the return of a biological sample and determined the presence or absence of DNA, we are then faced with a quandary.

If the Mars life form is not based on DNA, it supports the hypothesis that life is a likely outcome for a planet with the correct temperature range, atmospheric pressure, liquid water, and sufficient time with these conditions. This would be a very important finding – two planets with different histories, temperatures, atmospheric makeups and surface gravity, both producing life through random processes – life based on different models, but life nevertheless.

We could use this result to reinforce the theory that life is common in the universe. This single data point, the existence of life of a different form on our sister planet, would greatly aid the theory that life may be a likely event in a reasonably wide range of planetary conditions. This finding would re-energize our search for evidence of alien civilizations.

But if the Mars life form is based on DNA, this is an equally interesting result, for a different reason – because of the peculiar and ad hoc nature of DNA, and the number of equally viable alternatives to its specific structure, this outcome would strongly argue for a common origin for life on Earth and Mars.