It's a stunning new study that shows that the same chemical in our brain that is most known for mood (serotonin) is also linked to how our brain has evolved over the course of mankind. Is it possible that serotonin not only impacts our mood, our memory, and how our brain ages, but even how it evolved in the first place? Here is what the medical literature suggests and 14 holistic health tips for you to protect and preserve your brain health as you age.