The outstanding new feature of the neolithic age is agriculture, with emmer wheat (_Triticum dicoccum_) and six-rowed barley (_Hordeum hexastichum_) as the main crops. Now the wild ancestors of these grains survive even to-day in Syria and Palestine. In the same region, in caves on Mount Carmel, were discovered remains of the earliest men who used sickles.[45] This does not prove, of course, that they _cultivated_ grain; they may merely have _harvested_ grasses which grew wild. The point is of importance since these people—known in archaeological literature as Natufians—belong to the very end of the Old Stone Age. Yet the Natufians were the initiators, or at least the early practitioners, of a technique of harvesting which survived in the earliest agricultural settlements of neolithic times. Their peculiar sickles consisted of a grooved haft of bone in which short pieces of flint—“teeth”—were mounted (Fig. 1 A, B).[46] Such sickles are also found in the oldest settlements in the Fayum (in Egypt) (Fig. 1 D),[47] at Hassuna in northern Iraq,[48] and at Sialk near Kashan in Persia (Fig. 1 C).[49] They date perhaps about 5000 B.C., possibly a thousand years or more after the Natufians. In Egypt, during the First Dynasty (about 3100 B.C.), the sickle-haft was improved by being curved; it was now made of wood but retained its cutting edge of small flints (Fig. 1 E),[50] and sickles of this type were used as late as the Twelfth Dynasty (about 2000 B.C.).[51] In Iraq, too, sickles with curved wooden handles in which flint teeth were set were used as late as the Second Early Dynasty period, about 2700 B.C.[52] In Asia Minor and Europe no trace of the hafts has survived, but the distinctive flint teeth have been found in Anatolia, South Russia, on the Danube, and at the western end of the Mediterranean at Almeria. They occur also throughout North Africa. It is clear, then, that the diffusion of agriculture consisted not merely in spreading the knowledge of emmer and barley but in a simultaneous diffusion of the odd and complex harvesting tool, first used, as far as we know, by the Natufians. Radiating from the Near East, the new knowledge spread in widening circles, reaching the shores of the Baltic and the North Sea about 2500 B.C.[53] However, many questions remain at present unanswered. When did men undertake to improve the wild grasses and to produce, by cross-breeding and selection, the vastly more nutritious grains which were known to the earliest farmers of the neolithic period? When, in fact, was the extraordinary first step taken and the satisfaction of immediate needs limited in order to save seeds, store them, safeguard them against insects and rodents, and sow them when the time was propitious? This may have been done by the Natufians, but of this we know nothing. Furthermore, we do not know how far agricultural methods had advanced when they began to be diffused throughout the Old World.