Pace Six 



EVOLUTION 



March, 1928 



Spheric Mirror Shows Human-Ape 



Relationship 



By a. L. Herrera 



j^> / 



THE study of the distortion of natural objects as re- 

 flected by a spheric mirror is instructive. It ex- 

 aggerates details of structure and form in such a way 

 that insignificant differences are remarkably accentuated, 

 and discovers the reciprocal relations of organic forms, 

 their common and differential characters. It confirm? 

 many of the presumptions of the theory of evolution and 

 discloses some important facts of morphogeny. In some 

 cases it even allows us to foresee the results of artificial 

 selection and cross-breeding. 



In a spheric mirror, the nearer the object is, the big- 

 ger is the image. The size of whatever is farther away 

 from the mirror is aparently reduced. Thus a kangaroo 

 iiiav acquire the normal aspect of a mammal having four 

 legs of the same size. If its head and fore-limbs point 

 toward the mirror its long hind-legs are apparently short- 

 ened. And thus the size of an ibis' beak whose base 

 is held toward a curved mirror diminishes so that it as- 

 sumes the shape of the normal bill of a small bird. 



It is a plain and practical manner of demonstrating the 

 old law of Geoffrev de St. Hilaire, or organic compen- 

 sation. 



As shown in the drawings (Figure 1) the orang- 

 outang's skull (a) reflected in a spheric mirror (a glass 

 of liquid air), with its maxillar region as far as possible 

 from the reflecting surface, assumes (b) the aspect of a 

 brachicephal human skull. The maxillar region could 

 not be shown satisfactorily in the drawing, but any one 

 can try the experiment and see that the maxillary and 

 dental prognatism disappears completely. 



Figure (d) shows a normal human skull placed before 

 the mirror so that the facial and maxillar regions may 

 appear larger. The result (c) is worth notice. It be- 

 comes the image of an ape's skull. Compare it with 

 (e), the Gorilla skull. Note its big oblique orbits, very 



narrow forehead, well marked maxillar and dental prog- 

 natism, and bent back chin. It looks very much like 

 the skulls of fossil men; its general aspect is beastly 

 and very far from human. 



We can see here how the development of the occipital 

 part and of the vault of the cranium in human skulls 

 reduces, bv organic compensation, the facial and maxil- 



lar parts. This even indicates that supeiincn will have 

 an enormous cranial vault and atrophied maxillaries. 



The second figure is a chimpanzee's head modelled in 

 wax. It seems human as reflected by the mirror. 

 (Figure 2). 



This demonstrates that the gap between man and ape 

 is small, and that a mere compensation of growth in 

 certain directions is sufficient to bridge it. 



