Well, it happened again. Yesterday, on the way to the store, I found myself behind a car that was going about 20 mph in a 25 mph zone. I couldn't pull around the car, but thanks to my genes, I didn't get impatient or upset. On the contrary, this was a time do to some Science!
As I'm driving, I hypothesize that the person in front of me is elderly. Old people tend to move more slowly, so they would probably move their cars more slowly. But wait! The old person doesn't have to move in his car. He just sits there, pushing a pedal, turning a wheel, and looks around. Then it hits me. A deeper understanding is called for – this may be another adaptive behavior that has arisen from the evolutionary games of survival and reproductive competition!
A long time ago, if grandpa had to travel far, he would have to use the family proto-horse. Now, since proto-horses were not sufficiently domesticated yet, there was a good chance of falling off, especially since saddles had not been invented. But if grandpa fell off the proto-horse, he'd likely break a hip and die.
So here is what happened. Certain grandpas began to ride their proto-horses very slowly. Other grandpas threw caution to the wind, rode their proto-horses at top speed, fell off, and died. Thus, slow-riding grandpas would be more likely to survive.
At this point, the anti-evolutionary critic may point out that grandpas are unlikely to reproduce. So how could these slow genes be passed on? Ah yes, but my hypothesis would predict they were more likely to reproduce than commonly thought. It predicts that older men should have children with younger women. And I believe there is evidence this is true!
What's more, the tribal communities with excess grandpas would have more individuals to watch over the tribe's offspring, thus increasingly the likelihood that children related to slow gramps would be more likely to exist.
Well, we finally come to a stop light. The slow car turns right onto a two lane road. Excellent. It's now time to test my hypothesis of Adaptive Puttering. I easily pull up beside the slow car and pass it. And just as my hypothesis predicts, the driver is elderly! As I watch the old man fall further and further behind in my rear view mirror, I bask in the deep understanding that I have just experienced our evolutionary history.
Update #1: An esteemed colleague noted that we can supplement the hypothesis of Adapative Puttering by noting that thrill-seeking behavior is genetic. Since thrill seekers are more likely to die by accident, the population of timid grandpas would likely be overrepresented. An intriguing point of view. I would simply add that those thrill seekers who, by chance, did not die by jumping out of trees or teasing predators would surely be at a higher risk when riding proto-horses in their advanced years.