192 STUDIES IN PHYSIOLOGY 



horse of to-day there is nothing to suggest this long story 

 with the exception of two so-called splint bones along the 

 sides of the lower leg ; these are the remains of the two meta- 

 carpal bones to which the two side fingers were attached. 



Peculiarities of the Human Skeleton. In the human body 

 there is no bone or set of bones that is not found in varied 

 form in all the mammals and in most other vertebrates; 

 indeed so far as we can learn from the structure of his skele- 

 ton, man is much more closely .related to the gorilla and the 

 chimpanzee than are these animals to the lower monkeys. 

 Yet there are certain general peculiarities of form that are 

 found in the skeleton of man alone, these distinctive charac- 

 teristics being due in a great degree to his erect position. 



In the first place, in even the highest monkeys the length 

 of the arms is nearly equal to that of the legs. For while 

 the gorilla can walk on two feet, all four appendages are 

 often employed in locomotion. In man, on the other hand, 

 the legs are much longer than the arms, an advantage that 

 permits of long strides in walking. 



Again, no other animal has the four curves in the spinal 

 column and the arched instep. These provisions are more 

 necessary in man because the head rests on the top of the 

 spinal column, and any sudden jar would be transmitted to 

 the brain were it not for the presence of these elastic springs. 



The human skull is nearly balanced on the top of the 

 spinal column, while that of other animals is attached to the 

 anterior end of a more or less horizontal backbone. Man's 

 cranium is much larger than the skeleton of the face, whereas 

 even in the highest monkeys the heavy face bones more than 

 balance the bones of the brain-case, and thus it is difficult 

 for the animal to hold its head erect for any length of time. 



Finally, the gradual increase in the size of the vertebrae 

 from the neck to the sacrum and the breadth of the pelvis 

 (both characteristics peculiarly human) give a stable base 

 on which the erect trunk is supported by the legs. 



