We all seek out stress. We hate the wrong kinds of stress but when it's the right kind, we love it - we pay good money to be stressed by a scary movie, a roller coaster ride, a challenging puzzle.

Fossey, Fossey, you cranky difficult strong-arming self-destructive misanthrope, mediocre scientist, deceiver of earnest college students, probable cause of more deaths of the gorillas than if you had never set foot in Rwanda, Fossey, you pain-in-the-ass saint, I do not believe in prayers or souls, but I will pray for your soul, I will remember you for all of my days, in gratitude for that moment by the graves when all I felt was the pure, cleansing sadness of returning home and finding nothing but ghosts.

Pulling a gun's trigger can be an appalling act. But if it is suicidal drawing fire to save someone, it has an utterly different meaning. Placing your hand on someone's arm can be an act of deep compassion or the first step of betrayal. The punch line? It's all about context, and the biology of context is vastly more complicated than the biology of the behavior itself.

Importantly, rather than promoting aggression, testosterone promotes whatever is needed to maintain status when challenged.

Until you appreciate something crucial - It is incredibly easy to manipulate us as to who counts as an Us, who as a Them.

As long as experiencing your optimal level of good stress doesn't damage others, it's hard to objectively define where normal enjoyment of stimulation becomes adrenaline junkiehood.

The regulation of genes is often more interesting than the genes themselves, and it's the environment that regulates genes.