By Adam Frank

"Get down from there!"

My 15-year-old son and I had just come out of the movie theater. After two hours of the usual explosions and mayhem (I can't really remember what movie we had seen) I made the mistake of telling him to wait outside while I chatted with a friend. Five minutes later I find him on the theater roof jumping from one large air conditioning unit to the other. "What are you crazy?" I yelled hoping to get him down, and us away, from there before the blue siren's arrived.

Well, yes. Of course he's crazy. He's 15. Ever since we made the mistake of watching District B13 my son has become a fan of Parkour, which is like freestyle skiing without skis or snow or mountains. Practitioners of Parkour (or its variant Free-running) believe that a good time equals climbing straight up the face of impossibly high walls or leaping from the roof of one 10 story building to another (even if there happens to be a city street in between them). It is a mix of gymnastics, rock climbing and insanity. It's beautiful, graceful and terrifying (if you are a parent). So of course my son loves it and yearns to be an adept. I am trying to guide him to something safer.

Which brings us to today's question. What is the balance between the hardwiring evolution has given us and the cultural programming we have given ourselves?

Brain researchers have found that thrill seeking like Parkour is, to some degree, programmed into the teenage brain. It's part of the need for intense learning. Eventually part of that learning will include internal dialogues like "Don't jump from that building. Its stupid and we will die." But until that kind maturation occurs teenagers need parents around to tell them "Don't jump from that building. Its stupid and you will die."

But we are more than just the hardwiring of our brains, aren't we? In many regards the brains we have now were set in place, genetically at least, some 50,000 years ago. But the difference in culturally constructed behavior between then (hunter-gathers living in small tribes) and now is so vast that we have clearly invented some powerful new behaviors. From the development of agriculture 9000 or so years ago to kingship based empires of the first few millennia BC to the crazy caffeine-fueled high-tech scramble we inhabit now, hasn't culture and not genetics driven our evolution?

This is a question of more than academic interest. One can imagine all kinds of genetically hardwired behavior that was really useful for small bands of social hominids a million years ago that present real problems for a now global species with nuclear weapons (among other toys). Evolutionary psychology combined with impressive advances in brain science is an exciting branch of research that lays bare the physical causes of some aspects of our behavior. But how much of that behavior is hardwired and how much lies in the "new" evolutionary domains of culture (created via the imagination)?

There is the world we are born into and the one we create. What are the boundaries between them and how much play do we have in pushing those boundaries around?

9:12 - January 25, 2010