32 THE DOMESTICATION OF ANIMALS 



acquainted with the majority of our present-day types of 

 domestic animals is abundantly clear from the bones which 

 have been found in the chambered or horned cairns; but at 

 what precise stage of Neolithic culture these were introduced 

 or subjugated is difficult to decide, owing to the impossibility 

 of placing such heterogeneous deposits as kitchen-middens 

 in a connected chronological sequence. One point seems 

 tolerably clear, however, that all our domestic animals did 

 not appear in Scotland at one and the same time. I have 

 gathered a definite impression from examination of the 

 records of kitchen-middens of Neolithic date that while 

 the remains of Oxen, Sheep and Pigs are common and are 

 often found together, those of the Horse and Dog are either 

 rare or absent. But this may be partly accounted for by 

 the different frequencies with which the animals were 

 used as food. The evidence most satisfactory in dealing 

 with such a question is that derived from long occupied 

 sites of human habitation, where excavations have been 

 carefully planned and carried out with the object of inter- 

 preting the separate periods of occupation indicated by 

 distinct layers of debris. Such excavations afford most 

 valuable chronological information, but unfortunately few 

 Neolithic sites in Scotland have been investigated with the 

 necessary precision. One series of excavations may be 

 cited Mr Symington Grieve's explorations in the shell- 

 mound of Caisteal-nan-Gillean on Oronsay and in the Crystal 

 Spring Cavern of Colonsay on account of the actual in- 

 formation it yields, and as an illustration of the method 

 which will decide the sequence of the introduction of domestic 

 animals and of prehistoric culture in general. Mr Grieve's 

 researches show that in both the shell-mound and the 

 neighbouring cave, distinct layers or periods of occupation 

 can be traced in the deposits, and that the formation of the 

 shell-mound was begun and completed some time before the 

 cave settlement was formed. The two together, therefore, 

 supply a series of successive strata covering a long period 

 which begins in early Neolithic times. Moreover, since 

 passage dryshod can now be made between Colonsay and 

 Oronsay at low tide, and since even in Neolithic times their 

 separation could only have been slight, the two islands may 

 be regarded as a geographical unit from a faunistic point of 

 view. 



