Question

What are some possible alternate environments in which life may have originated?

We don't know in what environment life originated. Most astrobiologists think it was in mildly salty nutrient-rich water, either in the early ocean or in a smaller sea or pond. Some think that wave action might have been important (suggesting a large body of water), while others note the possible role of clay minerals (suggesting shallow water). An alternative suggestion is that life may have originated near submarine thermal springs like the black smokers we have today; in this case it would have happened deep in the ocean. Yet another possibility, of course, is that life arose elsewhere and was bright to Earth (so-called panspermia), but that only removes the original habitat from earth without solving the basic problem of the conditions under which life began. There is a detailed discussion of all of these topics in Wikipedia under "origin of life". David Morrison
NAI Senior Scientist
February 21, 2008