Yep, clarified in post 447. Relative to environment.
Fair enough. And to address the issue there, it is true that science has been reluctant to address genetic differences among the varying peoples of the Earth, probably owing to politics, the shameful legacy of people in the past who used everything from religion to science to notions of "nation greatness" to advance their ideas of racial hatred and the fear of perpetuating that hatred.
There is some interesting data showing that various groups (not races, but groups smaller than "races") display differing abilities owing to their genetic makeup. (Compare, for example, the dominance of West Africans and East Africans in sprinting and distance running, respectively) But that doesn't make any group "more evolved" or "superior" than any other. It just means that their genetic makeup varies. Yet, even with that variety, there is more genetic variety within racial groups than between them.
Further, it is simply not true that "Changing the environment of one group should put them at the disadvantage when placed in a different environment." It can put them at a disadvantage, but it also can put them at an advantage, depending on the particular changes in the environment and the particular adaptations of the various groups.
Finally, a true thorn is a modified stem. Although I've never researched the evolution of the thorn, I would venture to guess that it would consist of a mutation which stunted the growth of some of a plant's stems. But the negatives associated with the loss of that stem's productivity was off set by the protection the stunted stem provided from predation. As the generations went along, those whose stunted stems were sharper and more ridged were disproportionately more successful in keeping browsers at bay, and therefore, reproduced at a higher rate. Eventually, you get thorns.