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There were some speculations in the past that silicon (instead of carbon) in principle could form complex molecules, similar to proteins etc... possibly even equivalent to DNA ...
Also, water can be (in principle again) replaced by ammonia.. Life like that would operate at much lower temperatures (and possibly it would have been much slower) than our, carbon based example...
Some animals on Earth are using strange chemicals in their metabolism, like some spiders if I remember correctly, are using manganese instead of iron in what is their equivalent to our hemoglobin.... Also it is known that metabolism could be very strange, like near those volcanic vents in the depths of the Pacific, where animals "feed" on sulfur molecules, and live at elevated temperatures, near 100C
So there are other possibilities for life chemistry, it seems.
Last edited by bojan; 13-07-2007 at 06:12 PM.
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