Nope. Read the cards. Listen to the cutscenes. The Traveler made HUGE advancement in sciences, including robotics and AI, possible and the Exo's were part of that. I believe it says they were originally created for war. Seriously, go read the grimoire, not fan fics, and listen to what's said about them as you play. I just went and reread to verify. It's literally all right there. /:)