Highly Recommended 

These are the books that talk more in detail about the evolutionary perspective outlined in The Purpose of Life:

 The Moral Animal: Why We Are, the Way We Are: The New Science of Evolutionary Psychology by Robert Wright

The Red Queen: Sex and the Evolution of Human Nature by Matt Ridley

Why Beautiful People Have More Daughters: From Dating, Shopping, and Praying to Going to War and Becoming a Billionaire– Two Evolutionary Psychologists Explain Why We Do What WeDo by Alan Miller and Satoshi Kanazawa

The Elephant in the Brain: Hidden Motives in Everyday Life by Kevin Simler and Robin Hanson

Also Recommended

The Selfish Gene by Richard Dawkins

The Blind Watchmaker by Richard Dawkins

The Hedonistic Imperative by David Pearce