Life, "as we know it"...

When you read and / or hear reports on the upcoming Mars missions you almost immediately hear that scientists are searching for signs of life, past or present, on the Red Planet. Certainly aware of the horrid conditions that most of the rest of the solar system harbors for living organisms, many scientists are quick to point out that such extreme conditions are only detrimental to "life, as we know it." The implication being that there may be life forms out there in the cosmos that are built on systems so completely foreign to our understanding that we have no way of predicting what environments they may be found in. That's an interesting implication. It's also a conclusion based completely on science fiction. Think about it. Ask a proponent of "life as we don't know it" to give you an example of said life forms and they will probably respond that since we don't know about them how can we present any examples? Okay... let's try something a bit more easy on the brain for them - ask them, then, what they base their premise on that there may be "life, as we don't know it" out there? What do you want to bet that they don't produce results from peer reviewed science journals? About the closest they'll get to true science is a technical advisor on Star Trek: the Next Generation. My point is this: Science tells us that life, even in its simplest forms, is a very complex thing. The molecules needed to build the complex pathways of life have to be based on Carbon. Silicon and Boron exist in sufficient quantity to build molecular pathways, but they still won't do. Silicon cannot hold together the required complexity, and Boron is always superceded by Carbon. Life, as we know it, is Carbon-based. And that bit of knowledge goes a long ways to our understanding of the conditions necessary for life's existence, whether on the Earth or on Mars.