Enos & Jarom

I need to qualify that my thoughts this morning in that they are my own personal thoughts and not doctrine. Nephi talks of the rebellion of the Lamanites in that they would not hearken to the word of the Lord. Nephi recognized a change that took place with Laman and Lemuel and his posterity and maybe because he was somewhat shocked with their appearance tells us the Lord -

"...caused the cursing to come upon them, yea, even a sore cursing, because of their iniquity. For behold, they had hardened their hearts against him, that they had become like unto a flint; wherefore, as they were white, and exceedingly fair and delightsome, that they might not be enticing unto my people the Lord God did cause a skin of blackness to come upon them.
22 And thus saith the Lord God: I will cause that they shall be loathsome unto thy people, save they shall repent of their iniquities." (Book of Mormon 2 Nephi 5:21 - 22)

As first the reader would have to assume that the Lord literally marked them with a "skin of blackness". There is no question that He did not cause them to harden their hearts or to commit iniquity, which as a result they had became like flint. But I wonder if this physical appearance of darkness was a result of their loathsome and iniquiteous lifestyle, which would be caused by the Lord by natural law. Nephi tells us -

"...because of their cursing which was upon them they did become an idle people, full of mischief and subtlety, and did seek in the wilderness for beasts of prey." (Book of Mormon 2 Nephi 5:24)

Enos reveals of the Lamanite lifestyle that they -

"...were led by their evil nature that they became wild, and ferocious, and a blood-thirsty people, full of idolatry and filthiness; feeding upon beasts of prey; dwelling in tents, and wandering about in the wilderness with a short skin girdle about their loins and their heads shaven; and their skill was in the bow, and in the cimeter, and the ax. And many of them did eat nothing save it was raw meat..." (Book of Mormon Enos 1:20)

No question that running around in a short skin girdle would definitely expose them to more sun which would darken their skin. And finally Jarom informs us -

"...they loved murder and would drink the blood of beasts." (Book of Mormon Jarom 1:6)

I just wondered if this lifestyle was really the curse that Nephi talked about and not a literal marking them with a dark skin as a punishment for rebelliousness.