Friday, May 1, 2009

Origin of life may not have been from hot soup

Darwin wrote that some "warm little pond" that contained all the necessary ingredients of life such as ammonia, light, heat, electricity, etc. would beget the first living creatures. This is not far from our current understanding of the primordial soup based on experiments by Urey and Miller that life had a "hot start". However, this belief has been under fire for some time because hot temperatures cannot support a stable environment for structures appropriate for life to form. However, new theories have emerged that so-called "psychrophiles", or cold-loving microbes, might be the new instigators of life. If we can imagine thermophiles living in hot sulfur springs, it's not too much of a stretch to imagine bacteria living in polar ice sheets and temperate glaciers. The sun's luminosity was 30% lower than now, producing a subzero earth.

Research in the past 10 years shows that freezing can concentrate and stabilize molecules more and allow formation of more complex structures. Experiments have shown that simple molecules trapped in ice veins can produce simple nucleic acids in the course of 30 years. However, I'm curious to know whether 30 years is an appropriate time frame for structure formation comparable to that in a hot environment. 30 years seems quite a contrast to the hot trigger from Urey and Miller's applied electricity. If a cold start is still questioned, the cold could've still acted as a selection factor for the common ancestral organism that gave rise to all life forms. Could that be defined as the more significant origin of life then? Well, the cold hypothesis can be quite powerful if seen in light of current exploration of possibilities of life on other worlds, i.e. Mars and various moons of Saturn. These are all very cold places!

-Bonnie Chien

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