Originally published 9 September 1996
The first media reports of evidence for life on Mars were pure NASA gush. Scientists discover evidence of life on Mars. Give us a few billion bucks and we’ll go look for it.
The next round of reports were analytical. What exactly is the nature of the evidence? How reliable is it? What does it imply about the origins of life?
As time passed, skepticism grew. Doubters found their voice. The winnowing engine of science began to separate wheat from chaff.
The scientific story soon gave way to commentary on religious and philosophical implications of the purported discovery. One more bump from our throne of uniqueness. First, Copernicus bumped us from the center of the physical universe. Then Darwin bumped us from the center of time. Now we find that life on Earth, perhaps even intelligent life, may be nothing special.
Now that the excitement has died down, we can consider the implications of life on Mars more reflectively.
Here are some core facts that set a context for the new discoveries:
Certain molecules — such as DNA — have the ability to reproduce themselves.
When molecules reproduce, occasional copying errors are inevitable.
The vast majority of errors degrade the ability of the molecules to reproduce, but occasionally a change will make an offspring molecule more efficient at copying itself.
Geometric reproduction — two, four, eight, and so on — inevitably leads self-reproducing molecules into competition for the chemical resources necessary to make more molecules.
The rest, as they say, is history. Given any self-reproducing chemical system with random mutations, competition for resources, and enough time, evolution by natural selection will inevitably follow. In such circumstances, evolution is not just a theory but a logical necessity.
According to contemporary science, the diversity of life on Earth is a magnificent embroidery of chance and competition, both random and lawful, a logical consequence of the way the world is made. The human soul is part of the embroidery, a dazzling filigree of matter stitched into the fabric of time.
The big question is: Where did the first self-reproducing molecules come from?
Science doesn’t yet have an answer to that. But most molecular biologists believe that it is only a matter of time before we do have an answer, and that the answer will be natural, not supernatural; that is, the first self-reproducing molecules arose spontaneously, perhaps even inevitably, from inanimate matter.
The evidence from the Martian meteorite bears on this question. If life appeared independently on Mars, then the odds become very much stronger that self-reproducing molecules are common throughout the universe. And although we do not yet know how it happened, the appearance of life on Earth would seem much less miraculous.
The key word in the previous sentence is “independently.”
If those curious shapes in the meteorite turn out to be fossils of living organisms, and if the meteorite is definitely from our neighboring planet, it still doesn’t necessarily mean that life on Earth and Mars happened independently.
Life on Mars could have been seeded by life from Earth, riding there on a meteorite blasted from Earth early in the solar system’s history. Or life on Earth may be descended from Martian microorganisms blasted the other way. Or (and this seems unlikely given the extreme distance between the stars) life on Earth and Mars might both have been seeded from a ubiquitous life stream in the universe.
If one of these possibilities turns out to be true, it won’t do much to increase our confidence that life happens spontaneously. Life might still be, as far as we know, a miraculous one-off event, and the Earth would still retain the possibility of being a very special place indeed, perhaps the most special place among the galaxies.
The clues in the meteorite are tantalizing, but frustratingly inconclusive.
What’s to be done? We should look closely at the dozen or so other known Martian meteorites. And, of course, we should go to Mars, search for life, and return with promising materials that can be examined on Earth. We should prospect for life at other places in the solar system. And we should listen for signals from space of an intelligent origin.
Most important, we should continue experiments in the laboratory on the spontaneous origin of life from inanimate matter. If scientists can create the conditions where self-reproducing molecules appear in the lab without the help of already existing DNA, RNA, or proteins, then we can be reasonably certain that life in the universe is ubiquitous.
However, laboratory scientists lack one essential ingredient that was available to Mother Nature when she pulled off her biggest “miracle” of all. Time. Eons and eons of time.
To date, no conclusive proof for life ever having existed on Mars has been found. ‑Ed.
