"Do the races or species of men, whichever term may be applied, encroach on and replace one another, so that some finally become extinct?" - Charles Darwin, "THE DESCENT of MAN, and Selection in Relation to Sex." Princeton University Press, 1981, Chapter 1, Page 10 ===================== 1 Is Charles Darwin using the terms 'races' and 'species' of 'men' interchangeably here according to "whichever term may be applied" by the reader or is there a definite biological distinction between human 'races' and 'species?' 2 Did Charles Darwin confuse "races" with "species" when he applied his evolutionary thesis to Humankind? 3 Are there separate and distinct Human 'species' or did Charles Darwin just imagine there were based on his perception of different and separate Human races? 4 Why would Charles Darwin imagine that separate and distinct human species ever existed in Human history if modern-day biologists have proved that humanity can't be divided racially? 5 Are Charles Darwin's racial theories of Human evolution merely an intellectual aberration or mutation in the mainstream of Human thought, development and progress in history?