Not as we know it
by Ian Simmons
[ people - january 03 ]
Ian Simmons talks to Professor Michael Russell, who may change the face of science. His researches into the origin of life have led him to conclude that instead of life beginning in the stew of a "primeval soup", it came about after primitive cell shapes were built up on the template of iron sulphide minerals under the conditions of an early Earth. This has far-reaching implications for what we know about our biosphere and for the possibility of life on other planets.
Ian Simmons (IS): The standard scientific theory has life originating in a warm pond, or possibly around a hydrothermal vent. You believe otherwise.
Michael Russell (MR): The idea of a warm pond does not sit well with what we know of the violent conditions obtaining on the hadean earth. There were no continents, and any volcanic landmasses would have been ephemeral. The moon was so close that high tides would have washed over most islands, the day was five hours long, and more meteorites of greater size than those that impacted the moon were continually bombarding the earth, raising debris as well as strong tsunamis. The earth then could be considered as a giant photo-electrochemical cell with an output of over half a volt. This power was focused at submarine seepages - seepages which also transported the building materials for the first cells.
IS: Other alternative theories for the origin of basic cells suggest clay minerals as a template for their construction from non-living precursors. How does your theory differ?
MR: All cells are derived from cells, so it seems likely to us that the first living systems arose within some kind of natural chamber that could select, catalyze and concentrate organic molecules and which could allow uncooperative molecules to escape as waste. Natural iron sulfide vesicles, inflated and reproducing as they were inflated hydrodynamically by warm alkaline seepage waters offer the best "culture chamber" for such a role.
IS: Does this mean that the biosphere is far deeper than is currently believed? How far down might it actually go?
MR: Yes, as deep as water penetrates into the crust though not at temperatures exceeding about 110°c. This equates to a depth approaching 4 km.
IS: If life originated as you suggest, is it possible that the formation of new life from scratch could still be occurring?
MR: Not only are conditions different (we now live in an oxygen atmosphere), but any attempt at de novo organic synthesis of what, after all, would be an inept replicator, would be immediately colonised by extant organisms.
IS: While the surface of planets such as Mars and Venus are inhospitable to life as we know it, would it be possible in their lithosphere if it formed the way you suggest?
MR: Yes, life probably existed on Venus before a runaway greenhouse destroyed it, and Mars may yet prove to harbour life in a deep biosphere, as I've said.
IS: What implications does your theory have for evolution?
MR: We suggest that the archaea and the bacteria had already differentiated within the hydrothermal "hatchery" mentioned above, perhaps in a response to the colonisation of hotter regions within the mound. Much of life may have evolved at springs and seepages, either submarine or at the surface between temperatures of 110 o and 0o centigrade.
IS: Your idea is purely theoretical at the moment. What physical evidence, if any, might it be possible to find which would provide corroboration?
MR: Although theoretical, it does draw on the experimental work of others who have shown that it is possible to generate organic acids - including amino acids - in hydrothermal conditions. And we have shown recently that an iron sulfide membrane is able to hold a tension of about 600 millivolts between two fluids, simulating hadean ocean water on the outside and alkaline seepage waters on the inside.
IS: Thomas Gold has made controversial claims that oil - and even some coal - is of non-fossil origin, but has been created inorganically in rocks. Does your theory support this idea?
MR: no, absolutely not.
