There were three articles in the New York Times online edition on Monday that are of interest if you're writing about life on other worlds. The first is an interview with Jeffrey Bada, a marine chemist who studies how life began. He worked with Stanley Miller, one of the scientists who performed the classic Miller-Urey experiment. This experiment was meant to test if the chemical compounds of life could be made on our planet when it was very young. (Miller and Urey had to make several assumptions about conditions on Earth at that time.) Bada was able to analyze the extracts from the Miller-Urey experiment with modern equipment and found even more organic compounds then Miller and Urey had back in 1953, thirty versus five. (Personally, I wonder how good those extracts were several decades later. Could Bada be sure they hadn't become contaminated in the interim? But if the results are accurate, they're pretty cool.) What's even more interesting is that the range of amino acids (the building blocks of proteins) they found are similar to those found in a meteorite. Bada thinks if the Miller-Urey experiment were repeated today, scientists could potentially find thousands of compounds in the primordial soup.
Another article in the NY Times discusses new evidence that Titan, Saturn's moon, has a liquid sea. Unfortunately, the liquid is most likely a mixture of ethane and methane (with some nitrogen), not water. Water can dissolve a wide range of materials and is less dense in its solid form than its liquid form; these are just a couple of the reasons why water has been so critical to the development of life on Earth. If Titan's sea can support life, the chemistry of these lifeforms would be different from terrestrial ones. I would need to do more research before speculating about life on Titan.
While I was writing this post, a third interesting article appeared in the NY Times. This one has to do with a new fossil find in Morocco. Slightly over half a billion years ago, in the Cambrian period, complex multicellular life forms began appearing in the fossil record. One of the best sources for these fossils is in the Burgess Shale. Scientists thought for a long time that most of these life forms became extinct in a major event, since so few descendants could be found. But the fossils found in Morocco can be linked to the ones in the Burgess Shale. This suggests two things: one, the gap in the fossil record is due to lack of preservation, not extinction; and two, more of the Cambrian-era species survived or evolved for a longer time than previously thought. As a science-fiction writer, I think it would be cool to take one of these species and base a whole ecology around it and its descendants.
To summarize, evidence continues to mount that life on other worlds really is possible. While Bada thinks the chemistry of life is universal, Earth-like conditions may not be. Even if we do find another planet similar to ours, there's no guarantee that evolution took the same path there that it did on our world. Just by looking at our own past, we find tantalizing glimpses of what might have been. But in our imaginations, what might have been can become something more.