The great uniformity of simple gestures in all countries of the world is thus a cause predisposing to a considerable amount of uniformity among the pictorial signs into which this element enters. If we take, for instance, that pathetic monument of picture writing, the well-known rock-painting of the Tule River in California, we see a series of human figures with outstretched hands, signifying, in the American gesture-language, ‘Nothing here.’ Two outstretched arms, by themselves, appear in the sense of negation among the conventionalized Maya pictographs of Yucatan,[16] and the sign reappears in the same abbreviated form, and with the same meaning, among Egyptian hieroglyphs. So, too, the ideograph of a child or son--an infant sucking its thumb--is found alike in ancient Egypt, China, and North America. Gesture language, in fact, is constantly reacting on the pictographic method of expression, and may be said to supply it with moods and tenses even without the aid of words. It must, nevertheless, be borne in mind that simple pictography, whether or not aided by gesture language, is one thing. The evolution of a regular script is quite another matter. [Illustration: FIG. 8.] A conventionalized system of writing can only be thought of in connexion with a highly developed articulate speech. And this was certainly the achievement of a later world than that of these old Palaeolithic hunters. The physical condition now changes. The characteristic fauna of the Reindeer Period disappears, and with it the remarkable race to whom were due the first known products of high art. The close of the Pleistocene Age and the beginning of the New Era is marked in France by a curious deposit in the Cave of Mas d’Azil, on the left bank of the Arize, in which its explorer, M. Piette, found a number of flat oblong pebbles marked with red stripes and simple figures by means of peroxide of iron.[17] M. Piette has endeavoured to trace in some of these a definite system of numeration by means of lines and circles, and even particular signs for a thousand, ten thousand, and a million. That some of these represent simple numerical markings is possible, but beyond this point it is impossible to follow M. Piette. Among the other markings are several, sometimes repeated on the same pebble, of curiously alphabetiform aspect. Among these are signs resembling our E, F, and L, a Gothic M, the Greek _Theta_, _Gamma_, _Epsilon_, _Xi_ and _Sigma_, the Phoenician _Cheth_, and some terms that occur in the Minoan and Cypriote series.