146 



KNOWLEDGE 



[JULT, 1902. 



to point in oortain directions so as to shoot off tli(^ rain 

 from the hody when climbing."* 



This strttomont is not only contrary to reason Imt to the 

 facts of the case, as may be seen at once on reference to 

 the tigures, e.g., at the back of the neck, tiie front of the 

 neck, the chest, the back of t.lie trunk, and the outer sur- 

 face of the arm as far as tlie mi<ldle. Tlieso few regions 

 alone are enough to disin-ove Mr. Leonard Hill's statement. 



In considering man's present covering of hair it is not 

 necessary to prove that, e.vcept in one or two exposed 

 regions where sexual selection may operate, selectionist 

 views as to the cause of the peculiarities in question cannot 

 hold. If it could be shown that they were survivals t>f 

 hair-slope useful to Simian ancestors, the case would l>e 

 different, but a glance at the figures shows this not to be 

 the ease, and some other cause for them must be sought. 



3. They may have been modified from a simple type of 

 hair-slope through use- inheritance, and this is the view 

 held here. 



According to the received view of man's physical descent 

 his prototype must have been Simian in form, pai-tially 

 assuming the erect posture, and perhaps combining some 

 of the characteristics of each of the four genera of existing 

 anthro]3oid apes. 



It follows then that he possessed a hairy covering little 

 differing from that of a gibbon or a chimpanzee. In 

 other words, the primitive stock of man showed a simple 

 and very slightly differentiated covering of hair, whose 

 direction was, broadly speaking, from the cephalic to the 

 caudal end of his trunk, from the proximal to the distal 

 end of his limbs, and on his head the hair-streams either 

 parted in the centre like those of a chimpanzee, or passed 

 backwards from the jirojecting eyebrows over the low 

 frontal and parietal regions, and fell down his neck in a 

 vertical direction. An hypothetical diagram of this hairy 

 covering may be constructed, and is shown in Figs. A, B. 

 If this representation of the primitive hair-slope of man's 

 early ancestors be not allowed there is an end to the 

 validity of comparative anatomy, and the findings of that 

 great science are set aside in this instance as not agreeing 

 with certain other tenets. But I may safely take it that 

 the direction of hair indicated iu Pigs. A, B, cannot be 

 challenged except in some entirely unimportant details. 

 There is an illustration iu " Living Races of Man," Part 

 IV., p. 110, which is most suggestive on this point, the 

 dorsal surface of the body of a girl two years old being 

 figured and showing a veiy primitive covering of thick 

 long hair arranged exactly as the hair of a gibbon is 

 arranged, and this vfould seem to be a reversion to type 

 and a latter-day illustration of the manner in which man's 

 hairy prototype had his hairy covering disposed. The con- 

 trast in this illustration between the hair-slope of the case 

 in point and that of man, as we know him, is very striking. 



The main tracts of hair on the body of man are repre- 

 sented on the accompanying diagrams and indicated iu 

 outline by arrows which point in the direction assumed by 

 the hair-stream of the parts covered by these arrows. Any 

 verbal description of these would be superfluous, and it is 

 only necessary to point out that the diagrams illustrate 

 the normal directions of man's hairy covering, and that 

 these are remarkablv (constant, whether in the fietus, as 

 described in 1839 by Eschricht, and 1857 by C. A. Voigt, 

 or in newly-born infants that I have examined, or in hairy 

 young adults, and even in older subjects whose hair has 

 not been worn oft' by friction. The only difference between 

 the direction of hair in an infant and an adult is that the 

 specially human peculiarities are more pronounced in an 

 adult. 



• See " Manual of Physiology," p. 82ti 



These hair-streams may be classified, bearing in mind 

 the direction of hair of man's early ancestors, and its 

 altered direction at the present day, into : — 



1. Primitive, derived from ape-like ancestor, marked by 



arrows with single heads ; 



2. Acunired (a) By morphological change, marked by 



arrows with two heads ; 

 (b) By habit or use. marked by arrows with 

 three heads. 



The division of man's hair into separate streams is, of 

 course, an artificial one, but is justified by a reference to 

 the diagrams, which show that the arrows merely indicate 

 th<! main direction in which a certain tract of hair separates 

 itself from surrounding tracts. 



Two considerations must be alwaj's kept in mind in 

 studying man's hair-slope: first, that it must be looked 

 u])on as a stream; secondly, that in accordance with ana- 

 logy, it moves in the lines of least resistayice. As the hairs 

 are set at an acute angle and the rate of growth is about 

 an inch in two mouths, and as the growth consists in the 

 shaft being pushed out of the hair-follicle by changes 

 there, until its normal length is attained, when the end 

 wears off, there are present just those mechanical condi- 

 tions needed to produce a sloivly moving stream passing in 

 the lines of least resistance. The best illustration of this 

 process afforded by nature is a glacier, though the forces 

 in operation are of a different kind, and I would suggest 

 that the direction taken by the hair of man in many regions 

 of his body is governed as much by purely mechanical 

 laws as the windings of a glacier, and is equally far 

 removed from the province of adaptation to needs and 

 selection. 



On the head the chief peculiarities are correlated with 

 morphological change, except at the edge of the scalp, 

 where varying methods of dressing the hair have availed 

 to produce a remarkable series of peculiarities found even 

 in infants, which cannot be here detailed.* Two are shown 

 in Pigs. E, F. 



The face presents certain changes from Simian type 

 probably due to sexual selection. 



The external ears conform rather closely to a Simian 

 arrangement. 



The neck jjresents in front a remarkable reverse of slope 

 at the level of the larynx ^Fig. C), which can only Ije due 

 to some special human habit or use. It occurs closely at 

 the sjwt where any clothing worn round the neck ter- 

 minates, and as may be seen in the neck of a man with a 

 beard not too long, the influence of clothing does tend to 

 draw the lower portions of the neck-streams upward. 



At the back of the neck two well-marked arrangements 

 (Pigs. G, H) are to be noted, and these occur about 

 equally frequently iu this country in any given number of 

 persons. It would appear that no other cause than varying 

 methods of dressing the hair in this "critical area " of the 

 hair-streams can have produced such entirely non-Simian 

 changes. t 



On the chest in front a remarkable arrangement is shown 

 in the Pig. C. The point of departure upwards of the 

 streams which go to form those of the neck, is found with 

 singular uniformity at the level of the second costal 

 cartilage or second intercostal sj>ace It is said in 

 Lydekker's " Royal Natural History " that something of 

 this arrangement is found in the gorilla. It is otherwise 

 in the young specimen at South Kensington, and not 



* Sue Proceedings of .4nat4imieal Society of Great Britain and 

 Ireland, 190i. 



t See "Journal of Anatomy and Pliysioloi;!,'' Vol. XXXV., p]i. 

 311,312,318; and " Use-lnliLritanie," " Walt.-v Kidd. (.i. and C^ 

 Black. 1901.) pp. 39, 10. 



