700 Comparative Morphology of Chordates 



The most striking biologic peculiarity of the human primate is his 

 propensity for modifying his environment — achieving ends by use of 

 means external to his body. Perhaps no aspect of his life better illus- 

 trates this than his production of sound and his responses to sonic 

 stimuli. Equipped with an excellent cochlea attached to a restless, 

 curious, and inventive brain (these are obviously not anatomically 

 descriptive terms; they refer to the behavior which is somehow cor- 

 related with the brain), he is discontented with the vocal production 

 of his own larynx and not satisfied by the multiplicity and diversity of 

 sounds proffered him by "Nature," both animate and inanimate. 

 Accordingly, he has devised a great variety of sound-producing mecha- 

 nisms. He provides himself with an accessory and extraneous larynx by 

 inserting into his mouth a suitably contrived tube of wood or metal. 

 By forcibly ejecting his breath into it, sound is produced by vibration 

 of the air in the external tube instead of that in his own respiratory 

 tube. He builds a mighty "organ," a compound larynx comprising 

 hundreds of laryngeal pipes, their activating breath supplied by an 

 electric pump, and all operated by his hands and feet. He makes great 

 tympani (kettledrums) whose vibrations impinge upon his own tym- 

 panic membrane. He creates hybrid mammalian voices by the unique 

 device of drawing hairs from horses' tails across cords of catgut. By 

 use of external mechanisms, he is able to amplify greatly the volume 

 of his own voice and of other sounds, to extend the distance — even to 

 thousands of miles — over which his voice and other sounds may be 

 heard, and to cause precise repetition of sonic vibrations days or years 

 after they were produced and in complete absence of their original 

 sources. 



Not content with hearing one voice at a time, he listens to a chorus 

 of hundreds of voices singing, not in unison, but in four or five parts 

 whose sounds differ in pitch, sequence, and duration. He assembles a 

 hundred or more players on most diverse instruments. All playing at 

 once, they produce a sonic ensemble which, in complexity at a given 

 instant and in the intricate interweaving of the many different se- 

 quences of tones, must far surpass any vibratory atmospheric dis- 

 turbance that ever before assailed a vertebrate ear. The resulting 

 complexity of events in the organ of Corti is unthinkable. The incoming 

 stimuli are transmitted, all in proper order, to the acoustic center in 

 the medulla of the brain and thence relayed forward to various cor- 

 relating centers and also to the cerebral cortex. Apparently it is from 

 the cortex that they somehow (we know not how) emerge into the 

 higher levels of consciousness. At a particular instant, the sensation is 

 that of a relatively simple and pleasing (depending on the composer) 

 harmony. The successive harmonies integrate into a musical idea or 



