September 2, 1897 



NA TURE 



427 



it by the higher intelligence of man that, pagan though he was, 

 he regarded its construction as evidence of design in nature, and 

 as a sincere hymn to the praise and honour of the Deity. 



It is not my intention to dwell upon the multitudinous details 

 of those features of structure which distinguish man from other 

 vertebrates, for these have been considered and described by 

 numerous writers. The leading structural differentiit constitute 

 the merest commonplaces of the human anatomist, and are 

 already sufficiently imprinted on the popular mind. But it may 

 not be out of place to refer to certain aspects of the subject which 

 are not so generally known, and the significance of which has 

 been brought into greater prominence by recent researches. 



If we compare the new-born infant with the young of verte- 

 brates generally, we find a striking difference in its capability of 

 immediately assuming the characteristic attitude of the species. 

 A fish takes its natural posture and moves freely in its element 

 as soon as it is hatched. A chicken can stand and walk when it 

 is liberated from the egg, though, from its wings not being de- 

 veloped, it is not at once able to fly. A lamb or calf can assume 

 the quadrupedal position a few minutes after its birth. But, as 

 we all know, the infant is the most helpless of all young verte- 

 brates, and is months before it can stand on two feet and move 

 freely on them. During the period of transition, from the stage 

 of absolute dependence on others to the acquisition of the power 

 of bipedal progression, important modifications in the structural 

 arrangements both of the spine and lower limbs have to take 

 place. At the time of birth the infant's spinal column exhibits 

 only two curves ; one, corresponding to the true vertebrre, ex- 

 tends from the upper end of the neck to the lowest lumbar 

 vertebra, and the concavity of its curve is directed forwards ; 

 the other and shorter corresponds to the sacro-coccygeal region, 

 and also has its concavity directed forwards. In the nuinber and 

 character of the curves, the new-born infant differs materially 

 from the adult man, in whose spine, instead of one continuous 

 curve from the neck to the sacrum, there are alternating curves, 

 one convex forwards in the region of the neck, succeeded by one 

 concave forwards in the region of the chest vertebrre, which again 

 is succeeded by a marked convexity forwards in the vertebme of the 

 loins. The sacro-coccygeal region continues to retain the forward 

 concavity of the new-born child. The formation and preserva- 

 tion of this alternating series of curves is associated with the 

 assumption of the erect attitude, and the development of the 

 lumbar convexity is correlated with the straightening of the lower 

 limbs when the child begins to walk.^ 



When the child is born, the curvature of its spine in the dorso- 

 lunibar region approximates to that of an ordinary quadruped in 

 which there is no lumbar convexity, so that the spine in that 

 region presents one continuous curve concave forwards. For 

 some time after its birth the infant retains the quadrupedal 

 character of the spinal curve in the dorso-lumbar region, and, as 

 it acquires nervous and muscular power and capability of inde- 

 pendent movement, its mode of progression in the early months 

 by creeping on hands and knees approximates to that of the 

 quadruped. It is only after it has attained the age of from a 

 year to sixteen months that it can erect its trunk, completely ex- 

 tend the hip and knee joints, and draw the leg into line with the 

 thigh, so as to form a column of support, which enables it to 

 stand or move about on two feet. Hence there is this great 

 difference between the young of a quadruped and that of a man, 

 that whilst the former is born with the dorso-lumbar curve 

 proper to its attitude, and which it retains throughout life, the 

 child does not possess, either when born, or for some months 

 after its birth, the characteristic spinal curves of the man. These 

 curves are therefore secondary in their production ; they are 

 acquired after birth, and are not imprinted on the human spine 

 from the beginning, though the capability of acquiring them at 

 the proper time is a fundamental attribute of the human 

 organism.* 



It has sometimes been assumed that the acquisition of the erect 

 altitude by the young child is due to the fostering care of the 

 mother or nurse ; that it is a matter of training, encouragement 

 and education, without which the child would not raise itself 

 ufxjn its feet. I cannot, however, agree with this opinion. If 

 one could conceive an infant so circumstanced that, though duly 

 provided ^yith food fitted for its nutrition and growth, it should 

 never receive any aid or instruction in its mode of progression, 



1 Prof. Cleland, in Reports of British Association, 1863, p. 112. 



- In his work on the " Origin and Progress of Language" (vol. i. p. 173, 

 Edinburgh, 1773), Lord Monboddo held that the erect position in man is an 

 acquired habit, and, like speech, is acquired with difficulty and as the result 

 of training. 



there can, I think, be little doubt that when it had gained 

 sufficient strength it would of itself acquire the erect attitude. 

 The greater growth in length of the lower limbs, as compared 

 with the upper, would render it inconvenient to retain the 

 creeping or the quadrupedal position. 



We cannot lose sight of the important influence which, alto- 

 gether independent of education, is exercised by parents on their 

 offspring. The transmission of hereditary qualities, through the 

 germ from which each individual organism is derived, is one of 

 the fundamental and most striking properties of the germ plasm.. 

 Characters and peculiarities which appertain not only to the 

 family of which the individual is a member, but also to the 

 species to which he belongs, are conveyed through it from one 

 generation to another. Hence, as the capability of assuming 

 the erect attitude and of thus standing and moving on two feet 

 have been attributes of the human form from its beginning, there 

 can be little doubt that this power is potential in the human 

 organism at the time of birth, and only requires a further de- 

 velopment of the nervous and muscular systems to become a 

 reality, without the aid of any special training. 



The spinal column in the region of the true vertebrae consists 

 of numerous bones joined together, and with discs of soft fibro- 

 cartilage interposed between and connecting the bodies of ad- 

 joining vertebrae with each other. It is to their presence that 

 the .spinal column owes its flexibility and elasticity. These discs 

 are larger and thicker in the region of the loins, where the lum- 

 bar convexity is situated, than in any other parts of the column, 

 and there can be no doubt that the acquisition of this convexity 

 is intimately associated with the presence of these discs. 



It is a matter for observation and consideration to what ex- 

 tent the bodies of the vertebrae contribute to the production of 

 this curve. A few years ago Prof. Cunningham, of Dublin,' and 

 r^ undertook much about the same time researches into the 

 form and dimensions of the bodies of these bones. Our observ- 

 ations were made independently of each other and on two dif- 

 ferent series of skeletons, and as we arrived at practically the 

 same conclusions, we may, I think, infer that, in their main 

 features at least, these conclusions are correct. 



The method followed in the investigation was to measure the 

 diameter from above downwards of the body of each of the five 

 lumbar vertebra, both in front and behind. If the upper and 

 lower surfaces of the bodies of the vertebra: were parallel to 

 each other, it is obvious that, so /ar as they are concerned, the 

 column formed by them would be straight, as is the case of a 

 column built of hewn stones possessing similar parallel surfaces. 

 But if the surfaces are not parallel, the body of the vertebrae is- 

 wedge-shaped ; should the front of the collective series of bones 

 have a greater vertical diameter than the back, it is equally 

 obvious that the column would not be straight, but curved, and 

 with the convexity forwards. From the examination of a consider- 

 able number of spinal columns of Europeans, we found that, 

 although the vertical diameter of the bodies of the two highest 

 vertebra; was greater behind than in front, in the two lowest the 

 anterior vertical diameter so greatly preponderated over the pos- 

 terior that the anterior vertical diameter of the bodies of the 

 entire series of lumbar vertebrae in each spine was collectively 

 greater than the corresponding diameter of the posterior surface- 

 In twelve European skeletons I observed that the mean dif- 

 ference was between 5 and 6 mm. in favour of the anterior 

 surface. If we are to regard the collective vertical diameter 

 anteriorly of the five bones as equal to 100, the same diameter 

 posteriorly is only equal to 96, which may be regarded as the 

 lumbar index in Europeans. Dr. Cunningham obtained a similar 

 index from the examination of a much larger number of Euro- 

 pean skeletons, and he further showed that in women the lumbar 

 convexity forwards is more pronounced than in men. It follows, 

 therefore, from these observations, that when the broad end of 

 the wedge-.shaped bodies is in front the bones themselves 

 would by their form give a forward convexity to the spine in the 

 lumbar region. But a similar wedge-shaped form is also pos- 

 sessed by the lower intervertebral discs in this region, and 

 especially by that interposed between the last lumbar vertebrae 

 and the sacrum. Hence it follows that both vertebral bodies 

 and intervertebral discs contribute in the white races to the pro- 

 duction of the lumbar convexity. 



When we pass to the examination of the corresponding regioiv 

 in the spines of those races of men that we are accustomed to call 



1 " The Lnmbar Curve in Man and the Apes," Cunningham, Memoirs 0/ 

 the Royal Academy, Dublin, 1886. 



2 " Report on Human Skeletons," " CAa//<-«f<rr Reports," P.irt xlvii.,. 

 1886. 



NO. 1453, VOL. 56] 



