Did Earthly life originate on Mars?

Here’s more on scientific studies of how life originated.

Robert Hazen is a staff scientist at the Carnegie Institution of Washington, D.C. He talked to us about where signs of life off the Earth are most likely to be found.

Robert Hazen: Right now, scientists are focusing their attention on Mars. Mars had lakes, or even oceans, very early in its history. And, indeed, if life is a cosmic imperative, if it arises quickly, then it’s possible that Mars was habitable before Earth. Mars may have even generated life before Earth. And what’s amazing, is that it’s very possible that asteroid impacts on Mars could have transferred living cells from the surface of Mars to Earth.

Hazen said that, according to current scientific models, Mars was habitable 4 1/2 billion years ago – half a billion years before the earliest traces of life on Earth known so far.

Robert Hazen: It is very possible, according to some scientists, that all life on Earth is indeed martian life. It arose on Mars first, because Mars was habitable before Earth, and then was transferred to Earth. And then Earth became a living planet as a result of this seeding of life from another planet, our planetary neighbor Mars. Now we don’t know if Mars is alive now, but even if it isn’t, we might be able to find fossil evidence for that very early life if we go to Mars. That’s an exciting prospect.

Robert Hazen also told EarthSky: We don’t have a real good idea of what Mars life would look like. Chances are it was microscopic, very much like microbes on Earth today, tiny single cells that you’d have to use a microscope to see. These martian microbes might have made the early oceans of Mars a little bit cloudy . . .

Our thanks to:
Robert Hazen
Carnegie Institution of Washington