When I was an undergraduate, I took my Fluid Mechanics course in one of those summer terms where you sprint through the material and yet still feel somewhat laid back. My professor loved to grab our attention by using real world examples and anecdotes.
Professor: Most of you were Boy Scouts, right?
Professor: What is the number one thing that all Boy Scouts love to do?
Class: <in unison> BURN THINGS!
Professor: And that is only followed in close second by?
Class: <once again, in unison> PUSH BIG ROCKS DOWN HILLS! (or over cliffs - same thing really)
I was the only girl (I think) in that class so I just stared at my classmates roaring enthusiasm. I could have guessed about the playing with fire. But pushing rocks down hills?? And they all said it in unison, as though it were a given.
I was baffled, thoroughly baffled. (Now you're wondering about the real world application - it had to do with the natural axes that objects rotate on)
A year later, I was on a week-long hiking/camping trip with my roommates and one of my roommates parents. And what was my roommate's dad doing the entire time we were ever on a cliff edge? Picking up rocks and tossing it over the edge. The bigger the rock, the better.
Last Friday, after inviting two guys from work to a hike, we sat around and shared some camping stories. I told them the experience of the things boy scouts like to do. They laughed.
Colleague 1: Yeah, I have to admit. Pushing rocks down hills or throwing things off of cliffs is pretty great.
Colleague 2 (who is from Japan): Yes, we do that in Japan too.
Me: So, it's the same for men all around the world? I just have to ask, Why do you all feel the need to do this?
Colleague 1: Caveman instinct? It's there so we do it.
Colleague 1: Yes.
I went back from that conversation and talked to my other lab colleague who not only agreed but then proceeded to tell me all of the times in his life when he threw rocks off of cliffs.
Saturday morning found me on a hike with four men. It was one of those hikes where it was foggy the entire time and we get to the top and realize that we are above the clouds which is nice but because all we can see below are big white billows that we felt like we were at the edge of the world with nothing above us and nothing below us. Needless to say, there wasn't a lot of rock throwing but there was a lot of careful navigating on wet and slippery rocks.
However, when we got down the mountain and were hiking back to the car (about 2 miles away), I was walking along and checking my phone for messages when they all yelled.
"Erin! You walked over the stick!"
I looked up in shock. So?
Friend: We're kicking the stick.
Me: Oh, ok. <I kick the stick> So...umm...how long are we going to be kicking this stick?
Friend: Until we get to the car?
Me: But that's over 2 miles away!
They all shrug.
Me: Why are we kicking this stick again?
Colleague: Erin, haven't you learned by now? Because it's there.
I started laughing and sure enough, we kicked that stick for 2 miles. When it broke into 2 pieces, we kicked both pieces all the way back to the car. It was fun and we chatted about random things as we walked and kicked. At one point, one of my friends suggested that kicking was bad for our soles and I thought he had meant 'souls' and stopped in shock while everyone laughed at me.
Today, I was walking to meet up with my lab for lunch and tried the theory again. There was a rock in the drive so I kicked it ahead of me and then passed it up to the guy walking in front of me. He picked up where I left off and kicked the rock in front of him until we got to our destination. Not a word was said between us about it. It just happened because it was there.