O. Jespersen & Edward Sapir 
The origin of human speech [EPUB ebook] 

Speech is so familiar a feature of daily life that we rarely pause to define it. It seems as natural to man as walking, and only less so than breathing. Yet it needs but a moment’s reflection to convince us that this naturalness of speech is but an illusory feeling. The process of acquiring speech is, in sober fact, an utterly different sort of thing from the process of learning to walk…
One theory is that primitive words were imitative of sounds: man copied the barking of dogs and thereby obtained a natural word with the meaning of ‘dog’ or ‘bark.’ To this theory, nicknamed the bow-wow theory, Renan objects that it seems rather absurd to set up this chronological sequence: first the lower animals are original enough to cry and roar; and then comes man, making a language for himself by imitating his inferiors. But surely man would imitate not only the cries of inferior animals, but also those of his fellow-men, and the salient point of the theory is this: sounds which in one creature were produced without any meaning, but which were characteristic of that creature, could by man be used to designate the creature itself (or the movement or action productive of the sound).
ABOUT THE AUTHORS

Otto Jespersen (often referred to as
O. Jespersen ) was a Danish linguist born on July 16, 1860, in Randers, Denmark, and he passed away on April 30, 1943. Jespersen made significant contributions to the field of linguistics, particularly in the areas of language philosophy, phonetics, and language teaching.
Edward Sapir was born on January 26, 1884, in Lauenburg, Pomerania, which is now part of Poland. He later moved to the United States with his family. Sapir made significant contributions to the fields of linguistics and anthropology, and he is considered one of the founding figures of modern anthropology.
Frederick William Mott , commonly known as
F. W. Mott , was a British neurologist and psychiatrist. Born on July 16, 1853, in Brighton, England, he played a significant role in the fields of neuropathology and psychiatry during the late 19th and early 20th centuries.