Ask HN: Books on human nature that changed your interactions

After reading 48 Laws of Power, I started seeing interactions between 1) others & myself, 2) others & others in a completely different light. There were these mental "hooks" I could analyze human interactions through.

Neil Strauss's "Rules of the Game" did something similar.

I'm currently reading Robin Baker's "Sperm Wars" and it's again showing me human interactions through a new light.

So, HN: what are the books that presented new theories / ideas on human nature that has changed the way you view / analyze human interactions?