4 8 4 



CHAINS OF CIRCUMSTANCE 



added securely to their original territory. Along with these 

 influences, in conjunction with the one or the other, or inde- 

 pendently of either, man has both consciously and uncon- 

 sciously shared in bringing about changes in the physical 

 structures as well as in the habits and temperaments of 

 many wild creatures. 



INFLUENCES TENDING TO INCREASE ANIMAL LIFE 



Man has enriched the fauna of Scotland in two different 

 directions in quantity, by encouraging an increase of num- 

 bers amongst certain animals, and in quality, by adding new 



IN PREHISTORIC SCOTLAND . 



PRESENT DAY 



Fig. 86. Comparison of the surface features of Scotland in prehistoric times 1 

 and at the present day; showing the extent of man's interference with the natural haunts 

 of animals. 



creatures from other lands. Both quantitative and qualita- 

 tive increases involve new demands on the food supply, and 

 these, under natural conditions, entail a decrease in other 

 living things whose food is appropriated by the new-comers. 

 But here again man has stepped in, and has to a certain 

 extent solved the problem of increase without decrease, first 

 and mainly by his cultivation of the soil, and more recently 

 and secondarily by his importation of food stuffs from other 

 lands. 



1 This diagram is based upon the estimated extent of the Upper Forest 

 of the Peat, checked, with allowance for the different physical configuration 

 of the countries, with the present condition of Scandinavia where only 

 6 per cent, of the land is cultivated. 



