If there is one thing I've noticed about getting older, it's that fear comes more readily. Not that long ago I went rapelling in a homemade harness, rode a motorcycle in a street race, lay on a roof in a thunderstorm to watch the lightning strikes fill up the whole sky. Why is it now I won't even jump off a rope swing?

I guess it takes close to forty years of seeing crazy things happen to strangers, friends and loved ones before you realize they just might happen to you. I've had a pretty sheltered, easy life, and even I've seen bad news pile up. Had students die. At two separate universities had colleagues who were murdered. Saw father figures laid out in caskets. Had a fishhook caught in my eye, wrecked cars, been shot at. Now, at 38, many of the things my parents worried about--all that made them seem so foolish to me, once--now worry me, too.

Ever since I started driving, when I left my parents house they've reminded me to drive safely, because of all the "crazies" out there. "Watch out for the other guy," my father said. It didn't matter how good a driver you were, anymore. I used to think they were ridiculous.

Now, if Anne is driving to Little Rock by herself, I pace the house cursing that stretch of I-30 through Benton, imagining scenes out of Road Warrior.

Good or bad, this change is natural and probably inevitable. I recently heard about a psychological experiment showing that teenager's brains are less able to imagine the consequences of their actions. In contrast, older people tend to see a whole array of bad possibilities behind every potential decision.

So kids do crazy things sometimes, but they also take chances and achieve great rewards. Older people may not do as many stupid things (like the guy in Kansas who fell to his death from a water tower on which he'd been spray painting "No Fear") but on the other hand, they risk isolation, suspicion of anything new.

"The world is strange to me," my father said on my last visit home. I was trying to explain to him the internet for the third or fourth time. He finally said he didn't really want to know.

So far, there are plenty of foolish and juvenile behaviors I still enjoy. I give rides to hitchhikers when I'm alone. It takes no arm-twisting to get me up onto the roof of a car moving down on a country road at night. I will consume just about anything I'm offered.

But it doesn't take much to worry me, anymore. And soon, I won't do any of those things. The world will seem strange to me.

Perhaps its how we all end up: staring at the river below and thinking only of rocks beneath the surface.