Editing Origin of language (section)

==== The "mother tongues" hypothesis ====
The "mother tongues" hypothesis was proposed in 2004 as a possible solution to this problem.<ref name="Fitch2004">{{Cite book |last=Fitch |first=W. T. |title=Evolution of communication systems: a comparative approach |publisher=MIT Press |year=2004 |isbn=978-0-262-15111-5 |editor-last=Griebel |editor-first=Ulrike |location=Cambridge, MA |pages=275–296 |chapter=Kin selection and 'mother tongues': a neglected component in language evolution |editor-last2=Oller |editor-first2=D. Kimbrough |chapter-url=https://homepage.univie.ac.at/tecumseh.fitch/media/files/FitchKin2004_large.pdf}}</ref> [[W. Tecumseh Fitch]] suggested that the Darwinian principle of "[[kin selection]]"<ref>{{Cite journal |last=Hamilton |first=W. D. |year=1964 |title=The genetical evolution of social behaviour. I, II |journal=Journal of Theoretical Biology |volume=7 |issue=1 |pages=1–52 |bibcode=1964JThBi...7....1H |doi=10.1016/0022-5193(64)90038-4 |pmid=5875341 |s2cid=5310280}}</ref>—the convergence of genetic interests between relatives—might be part of the answer. Fitch suggests that languages were originally "mother tongues". If language evolved initially for communication between mothers and their own biological offspring, extending later to include adult relatives as well, the interests of speakers and listeners would have tended to coincide. Fitch argues that shared genetic interests would have led to sufficient trust and cooperation for intrinsically unreliable signals—words—to become accepted as trustworthy and so begin evolving for the first time.<ref>{{Cite book |last=Knight |first=Chris |title=The Evolutionary Emergence of Language |publisher=Cambridge University Press |year=2000 |isbn=978-0-521-78157-2 |pages=99–120 |chapter=Play as Precursor of Phonology and Syntax |doi=10.1017/cbo9780511606441.007 |s2cid=56418139}}</ref>

Critics of this theory point out that kin selection is not unique to humans.<ref name="Tallerman2013">{{Cite book |last=Tallerman |first=Maggie |title=The evolutionary emergence of language: evidence and inference |publisher=Oxford University Press |year=2013 |isbn=978-0-19-965485-7 |editor-last=Botha |editor-first=Rudolf P. |pages=77–96 |chapter=Kin selection, pedagogy and linguistic complexity: whence protolanguage? |editor-last2=Everaert |editor-first2=Martin}}</ref> So even if one accepts Fitch's initial premises, the extension of the posited "mother tongue" networks from close relatives to more distant relatives remains unexplained.<ref name="Tallerman2013" /> Fitch argues, however, that the extended period of physical immaturity of human infants and the postnatal growth of the human brain give the human-infant relationship a different and more extended period of intergenerational dependency than that found in any other species.<ref name="Fitch2004" />