GENERAL CONSIDERATIONS. 1037 



degradation that is occasionally to be met with in particular groups of the higher 

 tribes which have been subjected for several generations to the influence of 

 depressing causes. Of such degradation, occurring under circumstances that 

 permit its successive steps to be traced, we have a remarkable example in the 

 conversion of certain tribes of the Hottentot race into Bushmen ( 1058) ; and 

 there is very strong ground for the belief that similar influences have operated, 

 at a more remote period, in the production of the peculiar characters of the 

 Guinea Coast Negroes and Australian Bushmen. 



1045. Independently, however, of the obvious modifying influence of external 

 circumstances, much allowance must be made for that tendency to variation, 

 which presents itself, more or less, in all those races of animals which possess 

 such a constitutional capability of adaptation to changes in climate, habits of 

 life, &c., as enables them to live and flourish under a variety of conditions. 

 Thus we find that the offspring of any one pair of domesticated animals do not 

 all precisely agree among themselves, or with their parents, either in bodily 

 conformation or in psychical character; but that individual differences, as they 

 are termed, exist among them. Now, as this tendency to variation cannot be 

 clearly traced to any influence of external circumstances, it is commonly dis- 

 tinguished by the term " spontaneous ;" but there is no effect without a cause ; 

 and as the widest differences of this kind present themselves in those races which 

 are most obviously amenable to the influence of external conditions, we seem 

 justified in attributing them to agencies operating unostensibly upon the parents, 

 either previously to their intercourse, or at the time of coition ( 975), or in 

 the female during the period of utero-gestation ( 1014). The difference 

 between wild and domesticated animals in regard to color affords a very good 

 illustration of this general fact ; for the uniformity among the former is no less 

 remarkable than the want of constancy among the latter ; and whilst variety of 

 color soon gives place to uniformity, when domesticated races return in any 

 considerable degree towards their primitive state, 1 it very speedily develops 

 itself in races which are undergoing the converse process. 3 Now it is by taking 

 advantage of those "spontaneous" departures from the ordinary type which 

 present features of value to the breeders of domesticated animals, that new races 

 are developed from time to time among these; any strongly marked peculiarity 

 which thus appears in only a single individual being usually transmitted to some 

 of its offspring, and being almost certainly perpetuated when both parents are dis- 

 tinguished by it, as happens when the products of the first procreation become 

 capable of breeding with each other. 3 Now there can be no hesitation in ad- 

 mitting that the tendency to the so-called u spontaneous" variation prevails in 

 the Human race to a greater degree than in any other ; since we find most 

 remarkable diversities in features, complexion, hair, and general conformation, 



1 This has been especially noticed in the horses, cattle, sheep, hogs, and dogs, introduced 

 by the Spaniards into South America. 



2 Thus Mr. T. Bell informs us ("British Quadrupeds," 2d edit. p. 203) that an 

 Australian bitch, or dingo, in the Zoological Gardens, had a litter of puppies, the father 

 of which was also of that breed ; both parents had been taken in the wild state ; both were 

 of the uniform reddish-brown color which belongs to the race, and the mother had never 

 bred before ; but the young, bred in confinement, and in a half domesticated state, were 

 all more or less spotted. 



3 See the history of the introduction of the ancon breed of sheep, characterized by a 

 peculiar conformation of its limbs, in Massachusetts, given by Col. Hutchinsonin the " Phil. 

 Trans." for 1813. A very similar account has been i-ecently given by Prof. Owen (in a 

 Lecture delivered before the Society of Arts, Dec. 10, 1851), respecting the recent introduc- 

 tion of a new breed of merino sheep, distinguished for the long, smooth, straight, and silky 

 character of the wool, and now known as the Mauchamp breed. In both instances, the 

 breed originated in the spontaneous appearance of a male lamb possessing the peculiarities 

 in question ; and from its offspring such a selection was made by the breeder as enabled 

 him to bring together males and females both of which were distinguished by them. 



