Credit: AP Photo / Sebastian Scheiner

Humanity is simultaneously incredibly kind and incredibly violent. We commit indescribable atrocities, but also acts of incomprehensible compassion. There is both horror and beauty in our history. Which leads to the question… how do we reconcile this inherent contradiction? It all goes back to our biology, according to Robert Sapolsky, a neurobiologist at Stanford and author of the book Behave: The Biology of Humans at Our Best and Worst. In fact, all questions about human behavior are, at their core, about biology. 

Three Takeaways: 

• One of the reasons that we’re simultaneously kind and violent is our ability to put others in one of two categories, “us” or “them”. And we can process these group categorizations in less than 100 milliseconds. 
• Sapolsky says that even a simple action, like throwing a punch, is the product of countless different biological factors. We’re influenced by subliminal sensory cues, (for example, if you put someone in a room with smelly garbage, they become more socially conservative) hormone levels in the bloodstream, our adolescence, our childhood, even our fetal life. And that’s just scratching the surface. 
• When you look at all these biological factors… Sapolsky thinks free will doesn’t exactly seem plausible. “I don’t think there’s a shred of free will out there. I think free will is what we call the biology we haven’t uncovered yet,” he says. 

More Reading: 

• Here’s a look at the legacy of Hugh Thompson, the man who stopped the My Lai massacre during the Vietnam War, and someone whose life really brings Sapolsky’s ideas into focus. 
• Smithsonian Magazine examines what twin studies can tell us about genetics. 
• Another perspective on free will, this time from The Atlantic.