Members of one subspecies differ morphologically or by different coding sequences of a peptide from members of other subspecies of the species. Subspecies are defined in relation to species. If the two groups do not interbreed because of something intrinsic to their genetic make-up (perhaps green frogs do not find red frogs sexually attractive, or they breed at different times of year) then they are different species. If, on the other hand, the two groups would interbreed freely provided only that some external barrier were removed (perhaps there is a waterfall too high for frogs to scale, or the populations are far distant from one another) then they are subspecies. Other factors include differences in mating behavior or time and ecological preferences such as soil content. Note that the distinction between a species and a subspecies depends only on the likelihood that in the absence of external barriers the two populations would merge back into a single, genetically unified population. It has nothing to do with 'how different' the two groups appear to be to the human observer.

As humans can't survive sub-zero temperatures, and as increasing the winter temperature is impossible, it's obvious that humans will never be able to live year-round outside of the tropical and sub-tropical zones.

How many walk away because their product will not make a profit... based on how many in the past have failed, due to piracy? You have to have one before the other will happen. So, the question is: have any actually failed? If not, why would they walk away?

There IS a benefit to using corn (for now). If we encourage ethanol use, then an infrastructure gets built up which can handle ethanol. When the cellulosic ethanol starts to become more widely available, that can replace the corn-based, and the infrastructure will be in place.