June 20, 1907] 



NATURE 



175 



in thf bulk of brain-substance — in animals as well 

 as in ancestral man — signifies the substitution in 

 large part of " educability " for a life con- 

 trolled by inborn hereditary nervous mechanisms. 

 An increased power of storing up and profiting by 

 individual experience takes the place of all but the 

 most fundamental and essential instinctive actions 

 which are the inevitable outcome of inherited brain- 

 structure. " The result is that the creature called 

 Man emerged with an educable brain of some five or 



six times the bulk (in proportion to his 



size and weight) of that of any other 



surviving Simian." One of the most 



astonishing facts in this history is that 



so much of it was accomplished by 



earlv Palfeolithic times, so that from 



this period to the present day " the bulk 



of his brain does not appear to have 



continued to increase in any very 



marked degree. " \\"e must, however, 



remember, as indeed the author re- 

 minds us, that Palaeolithic man was 



probably not much more monkey-like 



than some of the existing savage races. 



The best implements of that age "are 



manufactured with great skill and 



artistic feeling"; they certainly go 



bevond the bare necessities of use as 



weapons or tools, and imply a life of 



immense complexitv as compared with 



that of the highest animal. Although 



the subsequent increase in cranial capa- 

 city is surprisingly small, it is admir- 



abiv shown, by two pairs of figures, 



to be very significant. By the courtesy 



of the publishers these illustrations are 



here reproduced. The first pair of 



figures, together forming the frontis- 

 piece of the work, represent above the 



cranial dome of Pithecanthropus, be- 

 low the skull of a Greek, both seen 



from the left side. The former differs 



from the latter in the same features, 



but even more remarkably than do the 



Spev and the Neanderthal skulls. 



" The three great features of differ- 

 ence are : (i) the great size of the eye- 

 brow ridges (the part below and in 



front of k in the figures) in the Java 



skull ; (2) the much greater relative 



height of the middle and back part of 



the cranial dome (lines t' and /) in the 



Greek skull ; (3) the much greater 



prominence in the Greek skull of the 



front part of the cranial dome — the 



prefrontal area or frontal ' boss ' (the 



part in front of the line .\C, the depth 



of which is shown by the line d)." 

 " The parts of the cranial cavity thus 



obviouslv more capacious in the Greek 



skull are precisely those which arc 



small in the .\pes and overlie those 



convolutions of the brain which have 



been specially developed in Man as com- 

 pared with the highest .^pes." 



It is necessary to add a few sentences in explanation 



of the simple but extremely efficient set of lines by 



which the important differences between the skulls 



are indicated and can be assigned a quantitative value. 



The line .\-B, in both skulls, is drawn from ophryon 



(the inedian point of a line drawn across the narrowest 



part of the frontal bone) to the extra-tentorial point 



between the occipital ridges. A-B thus practically 



represents the base-line of the cerebrum. Lines e 



NO. 1964, VOL. 76] 



and / are perpendiculars drawn respectively from the 

 median point of A-B and the junction of the third 

 with the posterior fourth of the same line. 



The development of the frontal boss is clearly shown 

 bv the line A-C drawn from ophryon to bregma — the 

 point of contact of frontal with both parietal bones. 

 Line d is a perpendicular drawn from A-C to the most 

 prominent point of the frontal boss. 



The line .■K-B mav be divided into units, and the 

 lines d. c, f, indicating the depth of the brain-cavity 



at these three important points, expressed numerically 

 as percentages of the ophryo-tentorial length. 



The full significance of this method of comparison 

 is onlv realised when the figures already described are 

 considered in relation to those reproduced on the next 

 page. Fig. 3, of course, corresponding to the upper. 

 Fig. 4 to the lower of the preceding pair. It is 

 here shown that line A-C— appearing as a straight 

 line vi-hen the skulls were looked at from a little 



