On his web site, Dr. Gilbert V. Levin claims that his LR (Labeled Release) experiment had proven conclusively that there is indeed life on Mars.
His experiment, which was selected for use in the 1976 Viking mission to Mars worked on the premise that a drop of carefully engineered radioactive food would be squirted out into Martian soil then air samples above the droplet site would be monitored to detect radioactive gas that any microorganisms present might breathe out. Dr. Levin asserts that at both landing sites - some 4,000 miles apart - both test sites yielded positive results - evidence of active life on Mars.
Dr. Levin’s findings have been highly controversial and the subject of several decades of spirited debate. Personally, I highly doubt that this experiment offers anything conclusive in the way of reliably detecting life in an environment that the experiment could not possibly have accounted for. Without any understanding of the composition of the soils it’s a grab bag of possibilities and certainly possible that the experiment could return a false positive under such alien conditions.
While I find Dr. Levin’s claim to be somewhat sensational and unsubstantiated, my blog isn’t aimed at discrediting Dr. Levin’s findings. I wanted to address the issue of identifying life on Mars. I mean, what is life? If you find it, how will you know? What are the standards of calling something found life?
It only makes sense that because we are made out of what Carl Sagan called “star stuff,” we should find the basic building blocks for life everywhere we look. But finding copper ore doesn’t mean that if you dig deep enough you’ll find pennies. They are of a specific design which ore, by itself, could not produce in 4.6 billion years. If by some miracle we found a number of natural formed pennies, each being mostly identical to each other, would the find yet qualify as life? I don’t think so. What was found was a structure and design, not life.
It is inevitable that someone like Dr. Levin would proclaim to have found life on Mars. But what list of attributes do we use to differentiate between organic molecules and active life? How can we ensure that the list isn’t shortened in order to be the first to claim a discovery? To critique the finding, shouldn’t we define the minimum set of attributes to be found in an organic assembly necessary to call it life? So, here’s my best shot at defining what evidentiary findings I think should be found on Mars (or anywhere else) in order to call what is found life:
1) There must be evidence of a consistent, repeating blueprint – DNA, RNA, and mtDNA come to mind but it can be of a different set of building blocks.
2) There must be evidence of a capability of replication through passing on or reconstructing its own unique pattern of design at the individual level; a structured and exactly programmed form of procreation.
3) There must be evidence that it was able to consume nutrients (of whatever kind), process them, and convert them into energy necessary to sustain the individual’s existence. Dropping food which couldn’t possibly have existed in the natural setting offers no evidence whatsoever that life exists. It only proves that food breaks down naturally and perhaps faster than expected in the target environment. There must be evidence that a local food source exists, it is consumed, and converted by whatever processes the organisms use to convert it into energy. Those processes need to be identified.
4) There must be evidence of systemic / individual function which is common to all individuals – a collection of unique but common structures and stimulus and response characteristics that govern its existence. It must respond to changes in the environment around it in a way that compensates (rather than just changing states) in a manner which maintains it’s systems in equilibrium and function independent to detrimental external forces. Think active regulators, metabolism, and cellular barriers.
5) There needs to be evidence of a population built from generations of preceding individuals. Life begets life. The chances of finding life as it first forms is so astronomically impossible that it is ludicrous to even think it might happen at the exact moment when we happen to arrive on the scene. No, if we find life, we’ll find a population with a generational past.
I expect that some new scientist will jump the gun and proclaim, as Dr. Levin has done, that we have “proof” of life on other planets. I don’t dismiss that life could exist elsewhere. However, let’s make sure that what we’re calling life is really life and not a bunch of inanimate organic molecules that formed out of “star stuff” through fairly regular processes that happen all the time. Let’s make sure it passes the “living” test else all we found was an interesting rock.
And if we should find life on another planet, what will it say about our origins? Some will say it proves Darwin’s evolutionary model because life would have had to form randomly in two different locations using the same mathematical impossibilities. On the other hand I believe it will speak to a master creator who saw the universe as his pallet to create because He could. If there is intelligent life then like us, they too will have it instilled into their makeup to seek and know their creator.