Source: Spectrum.

“The inference of a biological trait’s “purpose” or “function” from its surface form is always rife with difficulties. [Richard] Lewontin’s remarks in The Triple Helix (2001) illustrate how difficult it can be to assign a unique function to an organ or to a trait even in the case of what at first seems like a far simpler situation: bones do not have a single, unambiguous “function.” While it is true that bones support the body, allowing us to stand up and walk, they are also a storehouse for calcium and bone marrow for producing new red blood cells, so they are in a sense part of the circulatory system. What is true for bones is also true for human language.” From Robert C. Berwick and Noam Chomsky: Why Only Us: Language and Evolution.  MIT Press, 2016.