Colors of blood/skin (WoK spoilers)

[old aggie]

My theory: The different colors of blood/skin indicate that not all these races/species originated on Roshar.

- - Only the Parshmen are native, and un-evolved Parshmen (NOT the Parshendi) cannot resist the Void when it takes over their minds.

- - The off-worlders have been brought (by the Heralds? Knights Radiant? other world-hoppers?) to Roshar from their planets of origin, centuries ago, so that their magic can be used to fight the Void when it reaches this world.

[CabbyHat]

I'd assumed that the diversity of humanoid life was just another way to keep the coral reef feel of the world going. You walk through a city and you're surrounded by not only a whirlwind of different cultures, but different colours of skin and other differences in appearance. Given the sheer number of diverse species in the ocean, it just felt like a natural part of Roshar to me.