I picked up a copy of PA the other day but just got around to reading the article. I think it was very well done and provided concrete evidence for a theory people have had for some time (i.e. that "bird" points were really used on large game). Since the adoption of the bow by the tribes here in VA, the points got progressively smaller over time. I believe this is the case for a number of reasons- smaller points are easier to make and make better use of the lithic resource, the original, larger points were just smaller versions of dart points, and they came to the realization that large points were just not needed to take deer. If anyone is interested, there's an interesting article in the April 2006 issue of "American Antiquity" entitled "Projectile point shape and durability: the effect of thickness: length". It's got lots of good info for modern abos wanting to hunt with stone points. Here's the abstract:
We describe an experiment that tests the hypothesis that projectile points with high thickness:length ratios are more durable than points with low thickness:length ratios. Fifty obsidian projectile points were manufactured to specific lengths, widths, and thicknesses. These were then fired into a deer carcass with a bow repeatedly until each point broke. None of the points were resharpened. The hardness of the material struck was a significant predictor of a point's durability. Controlling for this variable, however, we found that points with a high thickness:length ratio (> .121) were slightly albeit significantly more durable than those with a low ratio. No other attribute of size or shape was a significant predictor of durability
Will