Taking a break from making tomorrow's lunches... I recall that there are 2 bio-chemical "paths" (lacking the proper term at the moment) that photo-synthesis can take here on earth. Was wondering if there are any botanists on the list who would speculate on the possibility of a form of photosynthesis that could work under the spectrum of a non-G type star? Or if the process could theoretically work effectively under a much brighter or dimmer source? Humans produce vitamin D, a substance required for good health, by skin exposure to sunlight. Can this process be considered photosynthesis in a similar sense as green plants using chlorophyl? That is, making a needed nutrient internally using sunlight as an energy source. Where I'm going is trying to speculate on possible extra-terrestrial variations on basic earthly botanic & biological processes dependent on sunlight. Parallel evolution, processes repeating themselves in isolated, independent ecosystems, etc. Aliens using familiar processes with variations...any thoughts? __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com