You can still knock down some pretty large trees with a stone axe

Last year I read a very interesting book titled 1491.

It is an in depth view of indigenous civilizations in the Americas, "pre-contact." One of the interesting pieces I remember is the treating of the introduction of iron axes by the Spanish to some of the populations in the Amazon basin who had been using stone axes to fell trees. The iron axe dramatically increased their capabilities and subsequently their livelihood. The book indicated an effectiveness of the iron axe such that one chop of it was equal to about 100 swings of the stone axe.

There have been plenty of times over the years when I've felt like one of those pre-contact Amazonian folks--"swinging with a stone axe" and all. Then again, I have to consider that regardless of how much more efficient those iron axes must have been, they were still able to knock down some pretty large trees with those stone axes.