The other two constraints are that metal is heavier and more expensive than stone or wood. If you put a metal point on a throwing spear, then you've got to redesign the whole thing to get the balance right, and you've got the chore of getting the metal. And you may worry more about losing it, too.
And, to be very blunt, it might be simpler to get a rifle than to get or make a metal spear head. The Arnhem Landers do talk about using the two tool-kits (aboriginal and modern) after all, and a metal spear doesn't fit in either kit.
Best,
F
|