This was a really interesting take on how future human evolution might unfold. Some time ago I wrote a magazine article on how people in the top and bottom socioeconomic classes in the U.S. are starting to diverge physically as well as mentally, and how the interbreeding within (and not among) these subsets will reinforce these divergences over time... with Brave New World consequences. When a "high caste" person can easily identify a "low-caste" one visually, via their unhealthy and unattractive physical attributes (as well as piercings, tattoos, and so on), it limits and eventually stops upward social as well as genetic mobility. Which is then disastrous for the society involved.