." >> guest: sam sorbo.com. >> host: sam sorbo.com. you are watching booktv on c-span2. >> now, one thing that is clear is who -- your brain tells your spine, tells your muscles to do something and you behave. what is incredibly complicated as understanding the meaning of the behavior because in one setting, firing the gun is one appalling act of another, heroic self-sacrifice and putting your hand on top of someone else is deeply compassionate and another a deeper trail. the challenge for us is to understand the biology of the context of our behaviors and not one is really, really challenging. one thing that is clear is you will never understand what is going on if you get into your head you were able to explain everything with the part of the brave or the gene or the hormone or childhood experience or evolutionary mechanism that explains everything because it doesn't work that way. instead, any behavior that occurs is the outcome of the biology that occurred a second before in an hour before and all the way to a million years before.