So let us talk seriously about that:
Why do awoken eyes glow?
I don't even know that...
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In D1 their skin had the Zavala skin glow too. During the collapse(might have still been during the golden age) a group of humans went into space and lived on their ships. Something about being in deep space caused their bodies to adapt to the void, causing them to look the way they do and extending their lifespan to hundreds of years instead of the normal lifespan. [spoiler]pretty much space magic[/spoiler]