398 NATURAL SCIENCE. Nov.. 



effect of disuse, or economy of growth ; or perhaps the possessors of extreme 

 strength and activity were more rash, combative, and foolhardy, and so more liable 

 to be killed. There was also a change in certain physical characteristics, consequent 

 on the enforced change in habits. Thus the change from ape to man was, so to 

 speak, sudden, the transformation being effected probably in a few thousand 

 years. 



The question of the unity or plurality of the origin of Man was at one 

 time a good deal debated. I am not sure that, upon the hypothesis of develop- 

 ment, the words have precisely the same meaning as upon the older hypothesis of a 

 special creation ; for we now regard the whole race as undergoing a gradual trans- 

 formation, and do not regard the new species as descended from a single ancestral 

 pair. Nevertheless, the words can be given a meaning ; either [a] did the evolution 

 take place in one spot and at one time, or in different places and at different times ? 

 or (i) was the evolution from a single " species," or from more than one ? 



In the latter sense, I am inclined to believe in the unity of origin. It seems, 

 however, just possible that, while one race arose as above suggested, another may 

 have arisen in the tropics, say in Equatorial Africa, where there was no Glacial 

 Epoch. In consequence, it was deficient in intelligence and essentially unprogressive. 

 The existing races are the result of the fusion in varying proportions of these 

 two. 



I think it more probable, however, that the whole race was, in a sense, 

 imprisoned by the Glacial Epoch, making locomotion difficult and dangerous. 

 When the first interglacial period set in, it was liberated, and in consequence spread 

 down to the tropics, which were thus peopled with Man, but a very primitive form 

 of Man. The tropical regions underwent no further glaciation, and consequently 

 their inhabitants were not compelled to improve ; the portion of the same race who 

 stayed at home underwent another glaciation, and were in consequence further 

 developed. When mild conditions again came round, this more highly-developed 

 race spread towards the tropics, driving their predecessors before them, and to 

 a certain extent amalgamating with them. In this way, successive waves — each 

 more highly developed than the former — spread out from the glaciated regions 

 towards the equator on the occasion of each interglacial period. So we might expect 

 to find that the lowest type has been driven into the equatorial forests. Here it 

 would hold its ground, being nearer to the anthropoid ancestor, and therefore better 

 suited to the environment than the succeeding races. 



It may be objected that a race which had passed through a glacial climate, and to 

 a certain extent acclimatised itself, would probably find even the interglacial climate 

 too warm, and would, therefore, be more likely to spread towards the pole than the 

 equator. I fancy that the first spreadings were more probably towards the pole. 

 It was the approach of the second glaciation that drove a portion toward the 

 equator. Those who had spread toward the pole were probably killed out by the 

 extreme severity of the climate when glaciation again supervened. 



To guard against possible misconception, I may remark that I do not attribute 

 the transformation merely to the severe conditions ; the intellectual transformation 

 was caused principally by the varying conditions, necessitating a certain power of 

 adaptation. Had the severe conditions prevailed unchanged until now, after the 

 first transformation the organism would have adapted itself to the new surroundings, 

 and, further power of adaptation being unnecessary, would have disappeared. The 

 Esquimaux show what unvarying severity of climate can effect ; and had the cold 

 of the Glacial Period continued unchanged, the human race would probably be lower 

 than the Esquimaux. It seems to me that, even at the present day, we can see that 

 in races which have long (2,000 years or more) inhabited a region with unchanging 

 climate, progressiveness and the power of assimilating new ideas die out. 



J. R. Holt. 



The Erect Posture of Man. 

 I HAVE several times seen it stated that the erect attitude of man 

 constitutes a very [serious difficulty in the way of those who believe that only 



