I am developing a form of humanoid very closely related to humanity, and I am trying to see both what differences are possible, and what the explanation for various features are possible.
For example, is there a reason behind humans develop a pale blue skin tone, somewhat like Argyria, particularly Paul Karason, but a somewhat lighter and paler tone. I know it comes about due to silver poisoning, but is there any way it can develop naturally for a humanoid? It appears possible due to the Blue Fugates, but I am wondering if its theoretically feasible for this to spread out more across a species. For an example somewhat like how some monkeys have blue skin, but do not have severe disorders which effect oxygen levels like Argyria or Methemoglobinemia.
Also, what would the reasoning for a development of white/silver hair along with this?
Notes, they are a people that typically inhabited the mountains, which would allow greater isolation and divergence, and would also, from my study into the genetics and biology of the Tibetan Peoples, and they have higher nitric oxide to deal with lower oxygen levels.