Zircons, Clue to Early Life?

I know next to nothing about geology, paleontology, planetary astrophysics, and the like. None of them are particular personal interests. But I do enjoy a well-written science article that teaches me something I didn't already know. This one in the International Herald Tribune on the early Earth by Kenneth Chang qualifies in spades.

The author discusses several scientists' attempts to tease out the history, geology, and climate of Earth over 4 billion years ago from the tiniest of clues. That effort alone would be interesting enough, if described as a well-told tale. Add to it that the author does so by sticking completely to the science and you have a highly dramatic story, told with balance and objectivity.

The story hinges on the role of zircons, crystalline bits of zirconium, oxygen, and silicon. From such small things do big theories grow. The real hook to the story is the evidence it provides for how early life might have arisen or developed in ways contrary to previous accounts.

Fascinating.