H.— ANTHROPOLOGY. 149 



the fire-piston under experimental scientific conditions in Europe — and at 

 present the available evidence seems to justify a provisional acceptance 

 of this view — has no bearing on the general question of independent 

 invention, since the significance of this is in relation to its occurrence under 

 comparable cultural conditions. 



Contrasting with difficult discoveries are those easy and easily applied 

 discoveries, such as the flaking of stone and the cutting of wood, which 

 occurred so early in the history of man as to be outside the range of con- 

 troversy. Still more easy were the discoveries of new food-plants, though 

 these are scarcely comparable with the type of discovery with which we 

 are concerned. The baby who samples coal is pursuing knowledge and 

 making discoveries, by the ancestral method of trial and error, and no 

 instinct saves it from unpleasantness. It seems possible, however, that 

 this readiness to explore the dietetic values of unfamiliar substances — 

 which must often have been a condition of survival, if sometimes of 

 survival of the prudent — lies at the root of the habit of substituting one 

 material for another in human arts and crafts. At all events, it must have 

 helped to form the mind of man before he was human. It may perhaps 

 be accepted as one of our elusive common tendencies, even though it helps 

 towards diversity rather than coincidence in discovery and invention. 



In this discussion of discovery-complexes we have got no further than 

 the recognition that they are systems of methods, which must have 

 developed in a certain sequence, even though we cannot confidently 

 reconstruct such sequences in detail. In many cases, moreover, not one 

 but several sequences may be identified, a fresh start arising out of new 

 discoveries. The casting of copper, for example, did not emerge directly 

 from the method of percussion, but if the metal had never been hammered 

 into the form of implements, we may safely assume that casting would 

 only have been discovered and exploited, if at all, as a result of knowledge 

 of a method of casting some other metal. 



It is thus a further complication of the problem, that one process may 

 owe its origin, in part at least, to a transfer of method from one substance 

 to another, or to the influence of knowledge acquired in relation to another 

 substance. It may be, for example, that the casting of copper implements 

 was in part an outcome of the knowledge of the behaviour of waxes and 

 fats, melted and allowed to cool. This process of transfer of ideas in 

 technique is analogous with that factor of hybridisation in the evolution 

 of artefacts for which I have proposed the term cross-mutation, and of 

 which more will be said later. 



The general conclusion to which we are forced by our consideration 

 of the nature and results of discovery, is that there are no absolute criteria 

 by means of which we can decide what part may have been played by 

 independent discoveries in the production of similarities in human culture. 

 We are safe in assuming that simple primary discoveries, such as that of 

 the plasticity of clay, or the malleability of copper and gold, may or must 

 have been made more than once, but we are equally safe in assuming that, 

 with every step beyond the first, an independent repetition of the same 

 sequence becomes more and more unlikely, and also that the more difficult 

 a single discovery and the more difficult its application, the less likelv is 

 its fruitful repetition. It would be no great coincidence if in our own day 

 a. European and an American independently produced a similar mixture 



