H.— ANTHROPOLOGY. 149 



structure already fully developed. And the broch did not spring full-grown 

 from the brain of some architectural genius of the prehistoric period : 

 it was the outcome of a slow process of evolution. The southern brochs 

 can only have been built by intruders from the north. 



We may go further. Seventeen or eighteen years ago, in surveying 

 Sutherland and Caithness for the Royal Commission, Mr. Curie noted 

 certain points which seemed to him to indicate a gradual improvement 

 in the type as one moved inland from the western coast, and he saw in 

 this — rightly, as I think — a clue to the drift of the population. His 

 deduction has received remarkable confirmation from the Commission's 

 recently published survey of Skye and the Outer Isles, as well as from the 

 late Dr. Erskine Beveridge's investigations in Tiree. In the insular 

 region we find brochs in reasonable abundance — 44 are recorded there by 

 the Royal Commission — but we also find numerous specimens of what can 

 best be described as the broch in the making. The so-called ' semi- 

 brochs ' of Tiree, the ' galleried duns ' of the Hebrides and Skye, all alike 

 appear to represent experiments in the architectural form which was 

 destined to have its fullest expression on the mainland. As the broch- 

 builders moved farther north and then farther east, they carried with 

 them the fruits of their ripening experience. 



The facts of early Scottish history and the inferences as to the Bronze 

 Age and the Early Iron Age are thus in complete accord. They bear out 

 the view^ — ^in itself a priori probable — that for uncounted generations the 

 trend of migration was from the direction of Ireland through the islands 

 of the west coast to the north of Scotland. We may reasonably assume 

 that an exhaustive examination of the chambered cairns, in continuance of 

 the work carried out with such marked success by Professor Bryce, would 

 give a similar result for the Neolithic Period. But, once the set of the 

 current has been determined, it is not difficult to understand why regions, 

 where the sheep and the deer now wander at will, should have been thickly 

 populated in prehistoric times. Although the causes that prompted the 

 movements of peoples in those far-off days are obscure, one of the most 

 potent was certainly the demand that would be created for fresh means of 

 subsistence when the mouths to be fed were multiplied. At intervals a 

 surplus of humanity would be spilled from Ireland. In front there 

 stretched but one open road, and that was a cul de sac. For, to those who 

 followed this route. Northern Scotland was literally the end of the world. 

 Long afterwards, under the pressure of a similar urge, a similar stream 

 descended from Scandinavia. But the later immigrants came in stout 

 ships, and could at need deflect their course, as they did, to the Faroes, 

 to Iceland, even to Greenland. With the earlier wanderers it was different. 

 When they had reached Unst, they would scan the horizon in vain for any 

 sign of land to tempt their frail craft further. The ocean was an insur- 

 mountable barrier. The flow from the south would be brought to a 

 standstill on its shore, and the more nearly that limit was approached 

 the greater would the congestion of population tend to become. This, 

 I think, is the real secret of the abundance of Scotland's prehistoric remains. 



