Wallace's Problem?
Yet Darwin was never able to specify just how language evolved. Wallace's concern, which has come to be known as “Wallace's Problem,” assumed that language evolved as a unitary entity. It is now widely recognized, however, that language did not emerge full blown. Words had to evolve before grammar.
source: https://cupblog.org/2020/02/14/alfred-wallaces-problem-can-the-theory-of-evolution-explain-language-by-herbert-s-terrace/#:~:text=Yet%20Darwin%20was%20never%20able,had%20to%20evolve%20before%20grammar.
References:
Bickerton, D. (2014). More Than Nature Needs: Language, Mind, and Evolution. Cambridge, MA, Harvard University Press.
Darwin, C. (1869). Letter to Alfred Russell Wallace, March 27, 1869. Darwin correspondence. https://www.darwinproject.ac.uk/entry-6684.
Darwin, C. (1871). The Descent of Man in Relation to Sex. London, Murray.
Hrdy, S. B. (2009). Mothers and Others: The Evolutionary Origins of Mutual Understanding. Cambridge, MA, Belknap Press of Harvard University Press.
Müller, M. (1862). The Science of Language. New York, Charles Scribner.
Wallace, A. R. (1870). Contributions to the Theory of Natural Selection: A Series of Essays. London, Macmillan and Company.
