When a friend passed on Louann Brizendine's The Male Brain ($17) I almost added it to my already sky-high tower of books, but her recommendation was so passionate, I cracked it open during my commute. And I couldn't stop reading. The follow up to Brizendine's bestselling The Female Brain, the XY edition looks at the lifespan of a man's brain — from conception to old age — and how hormones influence growth, behavior, and the stages of life. While many of the book's insights felt like common sense reminders from college courses and pregnancy preparedness guides, I learned (or re-learned) a few fascinating tidbits that have already helped me better understand the men in my life. I highly suggest you pick up a copy, but in the interim, here are a few titillating teasers.