As a sequel to this brief examination of the geographic control considered by itself it would be interesting, if space allowed, to append a study of the distribution of the arts and crafts of a more obviously economic and utilitarian type.  If the physical environment were all in all, we ought to find the same conditions evoking the same industrial appliances everywhere, without the aid of suggestions from other quarters.  Indeed, so little do we know about the conditions attending the discovery of the arts of life that gave humanity its all-important start—­the making of fire, the taming of animals, the sowing of plants, and so on—­that it is only too easy to misread our map.  We know almost nothing of those movements of peoples, in the course of which a given art was brought from one part of the world to another.  Hence, when we find the art duly installed in a particular place, and utilizing the local product, the bamboo in the south, let us say, or the birch in the north, as it naturally does, we easily slip into the error of supposing that the local products of themselves called the art into existence.  Similar needs, we say, have generated similar expedients.  No doubt there is some truth in this principle; but I doubt if, on the whole, history tends to repeat itself in the case of the great useful inventions.  We are all of us born imitators, but inventive genius is rare.

Take the case of the early palaeoliths of the drift type.  From Egypt, Somaliland, and many other distant lands come examples which Sir John Evans finds “so identical in form and character with British specimens that they might have been manufactured by the same hands.”  And throughout the palaeolithic age in Europe the very limited number and regular succession of forms testifies to the innate conservatism of man, and the slow progress of invention.  And yet, as some American writers have argued—­who do not find that the distinction between chipped palaeoliths and polished neoliths of an altogether later age applies equally well to the New World—­it was just as easy to have got an edge by rubbing as by flaking.  The fact remains that in the Old World human inventiveness moved along one channel rather than another, and for an immense lapse of time no one was found to strike out a new line.  There was plenty of sand and water for polishing, but it did not occur to their minds to use it.

To wind up this chapter, however, I shall glance at the distribution, not of any implement connected directly and obviously with the utilization of natural products, but of a downright oddity, something that might easily be invented once only and almost immediately dropped again.  And yet here it is all over the world, going back, we may conjecture, to very ancient times, and implying interpenetrations of bygone peoples, of whose wanderings perhaps we may never unfold the secret.  It is called the “bull-roarer,” and is simply a slat of wood on the end of a string,