Scientific Classification of Middle Earth Races

[Varda]

If we applied the scientific classifications (i know there is another term for this but i forget... has been since 9th grade that i had biology), what would we call all the various races? are hobbits and humans the same species? or just all the different varieties of hobbits? is gollum the sames species as hobbits or is he an ancient ancestor which later on lead to the evolution of hobbits? since humans and orcs have been shown to be able to breed are they the same species or is the difference between them something like the difference between horses and donkeys, which produce mules (or nonviable offspring)?

or is it simply absurd to try to fit science into a fantasy tale?

i just thought it was interesting to think of since there were so many divisions and yet crossovers between the various races... and some people who believe in creationism (as is shown in the sil) still believe in evolution but only as a guided evolution... in that where there are seeming gaps, God filled in those gaps... but that's not really my question..

the question is, if you could classify the races in ME in a scientific or pseudo-scientific way, how would you go about that?