User blog comment:Master Sima Yi/Future settings discussion/@comment-25095321-20131107232524/@comment-3046679-20131108020620

"the First Civilization bred a neurotransmitter into humanity, located deep within the brain, that forced them to abide by the Pieces of Eden,"

From Humans page. Common sense dictates all other species without the neurotransmitter are unaffected.

Seriously, half of your questions wouldn't be asked if you actually paid attention while playing.