264 ADVENTURES AMONG BIRDS 



All these plants are perpetually springing into existence 

 everywhere on the downs, and are persistently fed down 

 and killed by the sheep; take the sheep away from any 

 down, and in a few years, as I have seen, it becomes 

 an almost continuous thicket, and that, one imagines, 

 must have been its original condition. We must sup- 

 pose that man in early times, or during the Neolithic 

 period when he had domestic animals and agriculture, 

 found the chalk hills a better place than the lowlands, 

 covered as they must have been with a dense forest 

 growth, the habitation of wolves and other rapacious 

 beasts. On the hills where the thin soil produced only 

 a dwarfish tree vegetation, it was easier to make a clear- 

 ing and pasture for his cattle. No doubt it was also 

 easier for him to defend himself and his possessions 

 against wild beasts and savage human enemies in such 

 situations. The hills were without water, but the dis- 

 covery and invention of the dew-pond, probably by 

 some genius of the later Stone Age, made the hill-people 

 independent of natural springs and rivers. In later times, 

 when the country was everywhere colonised and more 

 settled, the hill-people probably emigrated to the lower 

 lands, where the ground was better suited for cattle- 

 grazing and for growing crops. The hills were aban- 

 doned to the shepherd and the hunter; and doubtless 

 as the ages went on they became more and more a 

 sheep-walk; for it must have been observed from early 

 times that the effect of the sheep on the land was to 

 clirmge its character and to make it more and more 

 suited to the animal's requirements. Thus, the very 



