Okay, here's a quick, totally unscientific theory that I'm going to unspool today, because I'm short on time, I have an idea, I'm going to run with it, and it's my blog, gosh darn it!  

My fifteen-week-old son is just now starting to try to flip over onto his belly when we put him down on his back.  It's fun to watch the little critter gradually figuring out that he can actually control those odd, prehensile things on the ends of his arms, and that those floppy, curled-up things that swing from each hip joint are part of his body too.  

To date he's spent most of his life on his back:  looking up, often curling his body up into the familiar fetal position.  He's happy curled up in a ball:  he does it when he's scared or uncomfortable, reverting to his womb-state.

But on his belly, he comes out of that position.  He extends his neck and his spine so he can see what's in front of him.  His arms wing out to the side and before him, as if in preparation for crawling.  His hips extend and his legs kick and push behind him, as if he's scrambling for movement.  His posterior chain muscles--lower traps, rear deltoids, spinal erectors, glutes, and hamstrings--spring to life.  

In this position, Dylan looks a bit like he's doing an old-school 'Superman' stretch.  And I have to say, he loves it.

My theory is that I think he sees the possibilities when he's in that position:  he can move, he can survey the world; soon he'll be able to gather and grasp things. 

Now, as I said, this is a totally made-up theory, but stick with me:  the muscles on the front of the body appear to develop first--in part because you're on your back all the time.  The curled-up position feels safe, protected, hidden.  Only when you start to turn over--as Dylan is now--do the back muscles really start to fire.  

And that experience, I believe, was probably pretty profound for all of us back when, just as it is for Dylan now.  Those posterior-chain muscles are really the ones that propel us into action, into the world.  They allow us to stand tall, move and affect our environment.  

Our anterior musculature helps us hide, protect ourselves, push the world and its dangers away.  Important functions, to be sure--but I wonder if there's something primally comforting about doing a lot of pushing exercises as opposed to pulling?  I wonder if pushing exercises actually make us feel safer and more protected, whereas pulling movements challenge us to expand and expose ourselves a bit more to the world?

The real question then becomes, why do typical gym rats fall in love with bench pressing and crunches and curls while shunning deadlifting, chins, and rows?  Is it simply because the pecs, abs, and biceps are mirror muscles?  Or is it weirdly scarier to work the posterior chain, because of that inital programming?  

But maybe--and here's my way-out theory--doing deadlifts and rows will actually make us happier and feel more capable, because they fire up the muscles that make us face the world and help us move into it.   

As I said, I'm talking primal, but who hasn't felt a touch of kinship with our hairier, less eloquent forebears when heaving barbell and dumbbells around a sweaty gym?