Download PDF by J. Desmond Clark: From Hunters to Farmers: The Causes and Consequences of Food

By J. Desmond Clark

ISBN-10: 0520045742

ISBN-13: 9780520045743

conventional farming -- Philosophy -- To 1964 -- Biography -- Africa.
Agriculture -- beginning -- To 1964 -- Biography -- Africa.
Neolithic interval -- foundation -- To 1964 -- Biography -- Africa.

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Iovita et al. In terms of the scar lengths, there are no significant differences between thrusting and projected points of similar energies (see Fig. 8). The projectiles in the fastest quarter of the speed range obtained significantly larger damage scars than any of the thrusting spears, confirming the expectation that kinetic energy determines the size of the flake(s) removed at impact. However, when the data are analyzed in raw form, there appears to be no relationship between kinetic energy and scar length, unless the impact angle (IA) is kept constant at 90°.

3), featuring an inner compartment which pivots around an axle at the bottom, allowing the control of the AI in 15-degree intervals, from 90° to 30°. A further slot for a 20° angle was never used in the experiments, because the spear frequently hit the upper part of the tilted steel frame by accident. The inner compartment is further divided in two sections, both filled with 20% ballistic gelatin, and separated by interchangeable plates of bone-like polyurethane. The synthetic bone plates, manufactured by SynBone AG, are 6 mm thick, and are specially designed to be used in ballistic testing.

15, well within his “rapid” range. 10. It is possible that we used slightly higher velocities for our thrust spears, but it is difficult to compare our results directly with those of hand-thrust spears. 38, that is, within the “dynamic range”. The obvious explanation for this is that the speeds we used are within the lower part of the range of darts and arrows used by Hutchings (2011) and derived from his earlier performance experiments with spearthrowers (Hutchings and Brüchert 1997). In the latter experiments, initial velocities in average of ≈42 m/s for a dart of similar weight were recorded, estimating ≈38 m/s at target entry.

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From Hunters to Farmers: The Causes and Consequences of Food Production in Africa by J. Desmond Clark

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