Complexity an Argument for Diffusion
The chief modern American proponent of diffusion is Harold S. Gladwin. What is his case? How does he come to his conclusions? He begins, of course, by noting a large number of random resemblances. Some are in simple objects. Some are in complex ones. As he seeks a scientific basis for his argument, he concentrates on the complex things. Complexity seems to rule out coincidence. If a tool has only one or two parts—like a curved throwing stick or a hafted knife—it is not difficult to conceive of two different men inventing it on opposite sides of the world. A bow and arrow with three essential parts presents a little more of a problem, but not too much, for the three parts are dependent on one another. If the bow has a back reinforced by sinew, if the arrow has feathers and a foreshaft, and the foreshaft has a flint arrowhead—making seven elements in all—then one begins to wonder at the mathematical chances of two men exactly duplicating the whole arrangement. Then, consider the vertical loom with nine separate elements, and eleven if it sports a shuttle and a reed fork.
From citing such coincidences, Gladwin turns to the second step of the diffusionist’s argument. This has to do not alone with one complex object, but with unrelated things grouped around it—let us say a vertical loom and bark cloth, painted tripod pottery, and metal casting by the lost wax method. Now if all these disconnected objects can be found in another locality and in use by another people, the suggestion of diffusion becomes far stronger than even in the case of a single complex machine. As Gladwin puts it:
If ... a man should report to the Chinese police that some copper bells, a vertical loom, some tripod trays, and a roll of bark cloth had been stolen from his house, and if, after broadcasting the details, the American police should find all these articles in the possession of a man in America, where such things had hitherto been unknown, would the authorities be satisfied with the explanation that the possessor had independently invented each item? I am inclined to think that, if I should happen to be the attorney for the defense, knowing that my client had recently come over from Asia, a plea of insanity might carry more weight with the jury than my client’s explanation.
He argues his point still more vividly:
If a Scotsman uses a split-bamboo trout rod, a waterproof silkline, and a barbed hook, it is not necessarily a case of diffusion if a man in Saskatchewan is found to be fishing with a willow twig, a piece of string, and a bent-pin, since each item is dependent upon the others. But if in addition to their fishing tackle, the Scotsman and the man in Saskatchewan are found to possess a shot-gun, a flask, a brier-pipe and bagpipes, then it would look like a case of diffusion since no one item of the assemblage is dependent upon any other.[9]