Reference is here made to the fact, established by Forbes, that the quechua-Indians of the high plateaus of Peru show a striking development of lungs and thorax, as a result of living constantly at high altitudes.
"Darwin and Modern Science"
A.C. Seward and Others
For the rest, the Incas endeavoured to spread the language of Cuzco, the quechua, throughout their empire.
"Lectures on the Origin and Growth of Religion as Illustrated by the Native Religions of Mexico and Peru"
Albert Réville
A careful examination of the table tends to prove that certain Nahuatl, quechua and Maya words had a common origin and shows that a closer connection existed between the Nahuatl and quechua languages than between Nahuatl and Maya or the quechua and Maya.
"The Fundamental Principles of Old and New World Civilizations"
Zelia Nuttall