I think in general a bit much is made out of 'why' did primitive peoples do things. For some things there were logical reasons. After that came some mix of aesthetics, culture, superstition, religion, and habit. They may have been trained to add grooves to keep the shaft straight and never bothered to see if it was necessary. They have been a good luck symbol. A guy may have seen some super straight arrows with drying checks and jumped to conclusions and grooved his shafts and it stuck. I would not be surprised if all these options are likely, and more. They didn't have stuff like internet or phone, so they may not have even known why they were doing it, perhaps just that they "found another dude's arrow and it had grooves in it so maybe I should do it too." I am not saying they were dumb, far from it, but this is one of those topics that seems to come up regularly enough and nobody seems to have figured out a real solid reason to do it-which makes me think there wasn't a real solid reason (from a performance point of view anyway) and that some of them just kind of did do it.
SOM
