Mechanics of archery among Hadza hunter-gatherers

The development of the bow and arrow was an important milestone in the evolution of foraging technology. Experimental approaches to interpreting lithics and other archeological evidence for early archery have led to important insights into their manufacture and use, but these studies are limited by a lack of data on the mechanics of traditional archery among living hunter-gatherers. Here, we investigated archery mechanics among the Hadza, a population of traditional hunter-gatherers living in Tanzania, who build and use their own bows and arrows to hunt wild game for food. Ten Hadza men participated in an archery competition with targets set at 15, 30, and 50 m, similar to the range of target distances during hunting. We used a spring scale to calibrate the draw force for each bow, and a high-speed digital video to record shooting mechanics and arrow velocity for each shot. Arrow velocity (45.1 +/- 7.0 m/s(-1)) and estimated kinetic energy (36.9 +/- 13.4 J) were greater than typically employed in experimental archeology studies. Draw forces (311 +/- 98 N) were also greater, equivalent to +/- 70% of men's body weight. Approximately 70% of the strain energy from the drawn bow was converted to arrow kinetic energy upon release, similar to published efficiencies for modern recurve bows. Arrow kinetic energy and draw force were similar for 15 m and 30 m targets, but increased marginally for the 50 m target, suggesting that Hadza men adjust arrow trajectory for targets at short and middle distances, but may increase draw force and hence arrow energy for distant targets.