EVOLUTION 1059 



Among Rodents, the Beaver and the Lemming have disappeared ; 

 the Common Hare and the Mountain Hare have increased, partly 

 through preservation and partly because of the more abundant food 

 afforded by the spread of agriculture. The Rabbit is a good instance 

 of naturalisation, for it was unknown in Britain before the Norman 

 Conquest. It was already common in Scotland by the thirteenth 

 century, but it cannot be called indigenous. Both the Black Rat 

 and the Brown Rat are aliens, the former dating from the time of 

 the Crusaders and the second from about the middle of the eighteenth 

 century. The small native Rodents, the Voles and Mice, hold their 

 own, and so do the Insectivores — the Hedgehog, the Mole, and the 

 Shrews. 



Taking a general survey, we see that there has been in Scotland 

 an introduction of domesticated sheep, cattle, horses, Fallow Deer, 

 dog, cat, poultry, Pheasants, and a few more. The wild Rabbits 

 were probably introduced deliberately^ the Rats unwittingly. Since 

 man settled in Scotland the fauna has lost about fourteen species 

 of mammals and birds, and while Ritchie points out in his careful 

 way that the total number of species is actually greater, the standard 

 is lower. The noble has been exchanged for the ignoble — the Elk 

 for the earthworm; the visible has been exchanged for the invisible 

 — the beaver for the bug! "In spite of statistics and of multitudes 

 of species, we have in effect lost more than we have gained; for how 

 can the increase of Rabbits and Sparrows and Earthworms and 

 Caterpillars, and the addition of millions of Rats and Cockroaches 

 and Crickets and Bugs ever take the place of fine creatures round 

 the memory of which the glamour of Scotland's past still plays — 

 the Reindeer and the Elk, the Wolf, the Brown Bear, the Lynx, 

 and the Beaver, the Bustard, the Crane, the bumbling Bittern, and 

 many another lost or disappearing." 



The case of Scotland is instructive, since the area is small and 

 the fauna well known, and Dr. Ritchie's careful study shows the 

 complexity of the factors that are often involved in faunistic change. 

 Besides the alterations in climate, there are those involved in 

 deforestation, drainage, the extension of arable land, and the 

 reduction of wild corners. Much has depended on man's often 

 vacillating attitude to the wild life of the country, for he sometimes 

 preserves and sometimes exterminates. The introduction of new 

 types has no doubt its influence on those in possession, but this is 

 often far from being a case of sheer competition. 



Where man plays a large part, two main processes may be 

 recognised. On the one hand, there is a diminution in the number 

 of larger and more highly evolved types, partly because they are 

 apt to be dangerous to human life or destructive of stock and crops, 

 partly because of fashion and a pride in "trophies", but partlj^ as 

 the result of slow processes, such as deforestation and the spread 



