Yesterday I spent some time with year 13 students from Otumoetai High School, over in Tauranga. We were talking about human evolution & at the end of the session one of the students asked me a question about arrowheads. I wasn't able to answer it then, but I've had a bit of time since to come up with a testable hypothesis that might do it. So James - if you're reading this, read on :-)
James wanted to know why palaeolithic (early stone age) hunters used stone arrowheads, when wooden ones worked just as well. I guess I looked a bit puzzled, so he told me that the Mythbusters team had done some tests, & a fire-hardened wooden arrow tip appeared to pierce an animal carcass as effectively as a stone tip. What's more, they flew just as accurately & for about the same distance. So why spend all that time & energy making fancy stone arrowheads?
As I said, at the time I couldn't answer his question. I hadn't seen the Mythbusters program (& still haven't, & since I'm at work I won't be looking at it right now either), but I do know that some stone tools were obviously made for their beauty rather than utility (large spearheads so thin that the stone is translucent, for example), so suggested - rather weakly! - that perhaps there was an element of aesthetics involved.
But overnight it occurred to me - both tips might puncture an animal's hide equally well, but for a palaeolithic hunter that's only part of the equation. You also want it to kill the animal fairly quickly, so that you're not spending forever tracking it down. Stone arrowheads are broader, & with more in the way of sharp edges, than a hardened wooden point, so I would suggest that they would probably cause a bit more in the way of internal damage. And with that would come more shock, more bleeding, & maybe a quicker death.
And this, of course, is something the Mythbusters couldn't really look at, because of the ethical issues involved. Not unless they went out in the woods on a hunting trip & tested the two types of weapon. And then did an autopsy on their prey to look at what sort of internal damage was inflicted. So I guess an actual answer is only going to come from someone who's a hunter & interested in trying out the tools that their many-times-great-grandparents would have used...