They're a kind of folk went mad out in the blackness of space. They're hard to explain without freakin' me completely out thinkin' 'bout 'em.
Turns out the Alliance back home made 'em, then denied they even existed. They was tryin' to control the population with some kind of chemical pumped into the atmo to keep folks all calm-like. Most folks just gave up and let themselves starve and die. The rest went all feral and aggressive.