120 DANIEL WILSON ON 



over a very prolonged period, iucludiug that of the illliug in of many of the eaves with 

 red-earth and gravel, embedding- implements closely resembling those of the drift. The 

 ossiferovis deposits, moreover, found in some of the oldest caves of England, France, and 

 Belgium, which have disclosed pahrolithic tools, include also remains of the mammoth, 

 cave-bear, fossil-horse, hya?na, reindeer, and other animals either wholly extinct, or such 

 as prove by their character the enormous climatic changes referred to. In so far, therefore, 

 as they afford any indication of the anticj^uity of man, they point to ages so remote that it 

 is unnecessary to investigate the bearings of eA'idence suggestive of comparative degrees 

 in time. Every new discovery does, indeed, add to our means of determining a relative 

 prehistoric chronology which for some aspects of the inquiry is replete with interest and 

 value. But I refer to the subject now, solely in its bearings on one very subordinate, yet 

 significant, question relative to the manipulation of the primitive tool-makers. 



The human hand is an organ so delicately fashioned that the biologist has, not unna- 

 turally, turned to it in search of a typical structural significance. By reason of its mobility 

 and its articulated structure, it is specially adapted to be an organ of touch ; and the fine 

 sense which education confers on it tends still further to widen the difference between 

 the human hand, and that of the ape. But also, whether solely as a result of education, 

 or traceable to some organic difference, the delicacy of the sense of touch, and the mani^ju- 

 lative skill and mobility of the right hand, in the majority of cases, is found so far to 

 exceed that of the left that a term borrowed from the former expresses the general idea of 

 dexterity. That education has largely extended the preferential use of the right hand is 

 iindoubted. That it has even unduly tended to displace the left hand from the exercise 

 of its manipulative function, I fully believe. But so far as appears, in the preference of 

 one hand for the execution of many special operations, the choice seems, by general con- 

 sent, without any concerted action, to have been that of the right. Not that there are not 

 many left-handed workmen, artificers, and artists, often characterized by unusual skill and 

 dexterity ; but, the farther investigation is carried, the more apparent it becomes that such 

 cases present exceptional deviations from what seems to be the normal usage of humanity. 

 If the source of this characteristic preference is referable to any peculiarity in the structure 

 of the hand, or of related organs, it ought to be easily explicable. Yet, thus far, after much 

 patient observation and research, it is still an undetermined question. Differences between 

 the right and left hand also manifest themselves in other ways. The right hand, for ex- 

 ample, M'hich is more sensitive to touch than the left, is affirmed to be less sensitive to 

 temperature. Mr. George Henry Lewes, in his " Physiology of Common Life," says, " If 

 the two hands be dipped in two basins of water at the same temperature, the left-hand 

 will feel the greater sensation of warmth ; nay, it will do this even where the thermo- 

 meters show that the water in the left basin is really somewhat colder than in the right 

 basin ; " and he adds : " I suspect that with " left-handed' persons the reverse would be 

 found." ' On the assumption that the former is a well established law, the latter seems a 

 leo'itimate inference ; but as will be seen from what follows, there is good reason for 

 doubting that the statement rests on an adequate amount of evidence. 



To determine the prevalence of this relative sensitiveness to heat of the right and 

 left hand, the test ought to be applied to uncxiltured and savage, as well as to civilized 



' Physiology of Common Life, ii. 298. 



