Australian National University scientists have observed a link between asteroid and comet bombardment of the Earth and the emergence of primitive bacterial life forms in the ancient oceans billions of years ago. Studying ancient iron-rich sediments in Western Australia and South Africa, Dr Andrew Glikson and colleague Mr John Vickers, from the Department of Earth and Marine Sciences at ANU discovered that the formation of banded iron formations, jasper and iron-rich shale coincided closely with asteroid and comet <http://physorg.com/news64678130.html> impacts. The impacts of the asteroids and comets caused volcanic and hydrothermal activity including eruption of iron-rich basalt, according to Dr Glickson. This created an environment which suited primitive bacteria that lived on the floor of the early oceans, and which derived their energy by oxidising water-soluble (ferrous) iron into insoluble (ferric) iron. This bacterial activity is thought to have precipitated iron and silica-rich sediments, known as banded iron formations, in areas such as the Pilbara in Western Australia.

These banded iron formations host the huge Hamersley and Yarrie iron ore deposits of the Pilbara region. Dr Glikson made the link when studying whether extraterrestrial impacts could be one of the underlying factors in the appearance of these banded iron formations, spanning ages of 3.5 to 2.4 billion years, which extend over distances of hundreds of kilometres in Western Australia, South Africa, Brazil and Canada. He found that deposition of iron-rich sediments closely followed massive collisions between asteroids and the Earth at several points in Earth history, including at 3.47, 3.26, 3.24 and 2.63 billion years ago.

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Interesting....one more piece of the puzzle.

Hmmm, that reminds me of the quote from Fight Club "A regular f***ing Space Monkey, ready to be shot up into space" only the monkeys came off of an asteroid Wait no, I mean Primates !!!! sorry zandore !

Not many years ago some astronomers believed that life was unlikely on most planets in the galaxy. They reasoned that the exceptionally large moon that earth has acts as partial protection from asteroids and comets. They believed that impacts early in earth's history could have repeatedly wiped out primative life. The moon reduced the chances of this happening. A planet without a large moon would not have this protection so lif would never get a foothold.

Now it seems more than possible that life actually needs these impacts.

Its funny how ridiculous our assumptions turn out to be.

It's not that rediculous an assumption and could still be correct, after all it is only an assumption that the impacts triggered life. Life may have occured without these impacts or may have even occured more quickly without them. Unless we develop a time machine this will always remain just theory and assumption.

Or you can accept the "Organic Soup" theory proved in the famous experiment by Stanley Miler:

Stanley Miller's Experiment