Thursday, 10 January 2008

Beach, Soup, Clay, Seed or Divine?

Life on Earth 'began on a radioactive beach' according to Zachary Adam, an astrobiologist at the University of Washington in Seattle.

The sifting and collection of radioactive material by powerful tides could have generated the complex molecules that led to the evolution of carbon-based life forms - including plants, animals and humans.
In work highlighted in this week's New Scientist magazine, Mr Adam suggests the more powerful tides generated by the moon's closer orbit billions of years ago compared to today could have sorted radioactive material from other sediment.
According to his computer models, deposits could collect at a beach's high tide mark in sufficient quantity to trigger the self-sustaining fission reactions - as occur in natural seams of uranium.
Mr Adam demonstrated in laboratory experiments that such a deposit could produce the chemical energy to generate some of the molecules in water which produce amino acids and sugars - key building blocks of life - when irradiated.
A deposit of a radioactive material called monazite would also release soluble phosphate, another important ingredient for life, into the gaps between sand grains - making it accessible to react in water.
Mr Adam told the New Scientist: "Amino acids, sugars and [soluble] phosphate can all be produced simultaneously in a radioactive beach environment."

Another theory of abiogenesis to confuse the fundies who can't separate the theory of evolution (how we arrived at the species whe have today) and abiogenesis (how life started).
The Telegraph article had an interesting paragraph -
a new theory for the origins of life - to be added to the existing long and varied list of hypotheses.
One is its emergence from a "primordial soup" of simple organic chemicals accumulated on the surface of bodies of water within the hydrogen-rich early atmosphere - formulated in the 1920's by English geneticist J. B. S. Haldane and Russian biochemist Alexander Oparin.
Others include early life forming in inorganic clay, the initial energy coming not from chemical reactions but from sunlight or lightening and the arrival of microscopic seeds of terrestrial life on chunks of meteorites or comets, and the intervention of a divine, intelligent designer.
(my bold)
One of the points in favour of the beach/soup/clay theories over the comet seed/god theories is that they can at least be supported by experiment, whereas you'll never find god in a petri dish.

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