Page Four 



EVOLUTION 



June, 1937 



ventral asymmetry, the neural tube being abo\e the noto- 

 chord and gut. Like modern tlsh they were also adjusted 

 lor forward progression through the water by means of a 

 bilaterallv s\mmetrical arrangement of the muscle-segments 

 on either side of the midline. 



Among other fundamental adjustments of the basal 

 \ertebrate type which are retained by man is the back- 

 bone itself; this is a jointed axis in which the individual 

 \ertebrae comprise checker-like centra formed around the 

 notochord and arches spanning the nerve chord. The func- 

 tions of the column were complex but may be summariz- 

 ed as follows; first, each segment served as a fulcrum or 

 pivot upon which those in front of and behind it turned; 

 secondly, the arches and processes served as levers for 

 turning the body in the directions of the tendons of the 

 axial muscles. The vertebrae also served as pivots for the 

 ribs, to which were attached the muscle segments of the 

 llanks and back. 



Progression through the water in the earlier vertebrate 

 forms was and is today largely by means of lateral undu- 

 lations of the body as a whole, the fins being at first merely 

 keel-like outgrowths of the body wall. The legs of quad- 

 rupeds were merely fieshy outgrowths of the lateral 

 muscles, supported internally by bones secreted in the 

 spaces between the muscle masses. There is strong e\i- 

 dence for the view that the hands and feet of the four- 

 footed or tetrapod vertebrates were formed by modifica- 

 tion of the stout pectoral and pelvic paddles of the lobe- 

 finned fishes. In any case, by the time of the Coal 

 .Measures the five-rayed appendage had already appeared. 

 Thus the foundations of the decimal system may be said 

 to have been provided by the first amphibians of the Car- 

 boniferous .Age, some 250,000,000 years ago. 



The limbs are bent levers and act like springs and 

 throwing sticks. .At first the limbs were short and sharpl\- 

 crooked outward at the elbows and knees, but by the time 

 of the more advanced mammal-like reptiles the body was 

 raised well off the ground and the trackv\'ay began to 

 narrow. Very early in the Tertiary period, when mam- 

 mals became dominant land forms, the ancestors of the 

 Primates are shown by fossils to have been tree-climbing 

 forms with grasping hands and feet. This was the be- 

 ginning of our prehensile hands, but did we also at one 

 time have prehensile feet? Space is lacking here to discuss 

 this question but it may be said that the convergence of 

 evidence from paleontology, comparative anatomy and 

 embryology afl^ords strong support for the view that the 

 peculiar foot of man has been derived from a primitive 

 anthropoid type with a di\ergent big toe. This change 

 took place chiefl\' by the drawing of the big toe towards 

 the others and by the marked lessening in length of the 

 second to the fifth digits inclusive. In brief, there is very 

 convincing evidence that the early Primates ancestral to 

 man were forestliving arboreal animals, and that the im- 

 mediate ancestors of man, probably through the disap- 

 pearance of the forest in certain areas in central .Asia, had 

 to accustom themselves at first to life on the ground in a 

 more open countr\'. It is difficult to escape the conclusion 

 that man owes the general ground-plan of his foot to his 

 long-extinct anthropoid ancestors but that he owes to his 

 more immediate prehuman ancestors those special modi- 

 fications of his feet which fit them for his upright posture. 



With the assumption of the upright gait new- stresses 

 were put upon the backbone, which responded b\' greatly 

 widening the sacral vertebrae, by forming the so-called 

 lumbar cur\e and by remodelling the hip bone so as to in- 



crease the width of the area for the gluteal and iliacus 

 muscles and at the same time to bring the center of gravity 

 of the thorax more directly above the transverse line 

 connecting the sockets of the opposite femora. 



The resultant freeing of the forelimbs from strictly 

 locomotive duties has often been noted, but what is not 

 generally realized is the fact that this great advance in 

 their use as hands is already in full swing among the 

 anthropoid apes, in which it is likewise associated with the 

 ability to examine things closelv with both eyes at once. 



If space permitted, we might profitably review these 

 matters in much greater detail and we might also follow 

 the e\olution of the jaws from their origin as « pair of 

 enlarged gill-bars in the earliest true fishes to their sub- 

 sequent modification through the varied use of the sheath- 

 ing bones surrounding the primary or inner jaws, .And 

 from this point, which is fully represented in the air-breath- 

 ing, lobe-finned fishes, in the ancestral amphibians and 

 early reptiles, we could trace the profound transformation . 

 of the jaws and teeth during the period of the e\olution 

 of the mammal-like reptiles and the emergence of the 

 lower mammals, and finally of man. But as I have des- 

 cribed these things in many previous communications to 

 scientific societies, I merely refer to them here in passing, 

 as I desire to touch upon some of the social results of all 

 these changes during the long road of ascent from fish 

 to man. 



The Penalty of Being Homo Sapiens 



\\ hen the ancestors of man left the forests and were 

 changed into primiti\e men their brains rapidly grew much 

 larger than those of their more backward relatives, the 

 known anthropoid apes. But increased brain power was 

 h}' no means an unmixed blessing, for though on the one 

 hand it was indeed necessary for permanent advance in 

 the mental world, its possession subjected the owners to a 

 multitude of evils undreamed of in the relatively peaceful 

 and unintelligent world of the anthropoid apes. 



We do not have to commit ourselves in advance to 

 an)- particular theory of the relations between mind and 

 matter, but since we must admit from the evidence as- 

 sembled by comparative neurologists that there has been 

 a progressive evolution of the nervous system, we must 

 further assume that psychic side of nervous activity has 

 likewise become more complex. The evidence at hand in- 

 dicates that in the relativelv simple ner\-ous system of 

 the shark the responses to sensory stimuli occur with a 

 minimum of complexities and delays, whereas in the highly 

 complex brain of the higher mammals the neopallium or 

 new brain forms a most elaborate detour which is im- 

 posed on top of and between the more direct pathways of 

 the primitive vertebrate brain. Such is the speed of nerve 

 currents, however, that the slight delay in response is far 

 overshadowed in importance by the superior initial ad- 

 vantages of the new method. For no matter what may be 

 the physical basis of memory, it is at least certain that 

 mammals have a peculiarly good memory for whatever 

 classes of events happen to be of interest to them. 



Thus each new stimulus, giving rise to a specific desire 

 for action of some sort, is confronted with the memories ^ 

 (pf what happened the last time when a similar impulse was 

 not restrained. The animal soon remembers the best 

 way to respond so as to attain his immediate objective. 

 Thus w-e have the basis of learning, that is. of progressive- 

 ly improved adjustments to familiar situations. 



(Continued on Page 6) 



