Editing Origin of language (section)

=== The Romulus and Remus hypothesis ===
{{See also|Recursion#In language|Prefrontal synthesis}}

The Romulus and Remus hypothesis, proposed by neuroscientist [[Andrey Vyshedskiy]], seeks to address the question as to why the modern speech apparatus originated over 500,000 years before the earliest signs of modern human imagination. This hypothesis proposes that there were two phases that led to modern recursive language. The phenomenon of [[Recursion#In language|recursion]] occurs across multiple linguistic domains, arguably most prominently in [[syntax]] and [[Morphology (linguistics)|morphology]]. Thus, by nesting a structure such as a sentence or a word within themselves, it enables the generation of potentially ([[Countable set|countably]]) infinite new variations of that structure. For example, the base sentence [Peter likes apples.] can be nested in [[Irrealis mood|irrealis]] clauses to produce [Mary said [Peter likes apples.]], [Paul believed [Mary said [Peter likes apples.]]] and so forth.<ref>{{Cite book |last=Carnie |first=Andrew |author-link=Andrew Carnie |url=https://books.google.com/books?id=MFZ1UV3YGtgC |title=Syntax: A Generative Introduction |publisher=Wiley-Blackwell |year=2012 |isbn=978-0-470-65531-3 |edition=3rd |location=West Sussex |pages=20–21}}</ref>

The first phase includes the slow development of non-recursive language with a large vocabulary along with the modern speech apparatus, which includes changes to the hyoid bone, increased voluntary control of the muscles of the diaphragm, and the evolution of the FOXP2 gene, as well as other changes by 600,000&nbsp;years ago.<ref>{{Cite journal |last1=Dediu |first1=Dan |last2=Levinson |first2=Stephen C. |year=2013 |title=On the antiquity of language: the reinterpretation of Neandertal linguistic capacities and its consequences |journal=Frontiers in Psychology |volume=4 |page=397 |doi=10.3389/fpsyg.2013.00397 |issn=1664-1078 |pmc=3701805 |pmid=23847571 |doi-access=free}}</ref> Then, the second phase was a rapid [[#Chomsky's single-step theory|Chomskian single step]], consisting of three distinct events that happened in quick succession around 70,000&nbsp;years ago and allowed the shift from non-recursive to recursive language in early hominins.
# A genetic mutation that slowed down the [[prefrontal synthesis]] (PFS) critical period of at least two children that lived together.
# This allowed these children to create recursive elements of language such as spatial prepositions.
# Then this merged with their parents' non-recursive language to create recursive language.<ref name="Vyshedskiy2019">{{Cite journal |last=Vyshedskiy |first=Andrey |date=29 July 2019 |title=Language evolution to revolution: the leap from rich-vocabulary non-recursive communication system to recursive language 70,000 years ago was associated with acquisition of a novel component of imagination, called Prefrontal Synthesis, enabled by a mutation that slowed down the prefrontal cortex maturation simultaneously in two or more children&nbsp;– the Romulus and Remus hypothesis |journal=Research Ideas and Outcomes |volume=5 |doi=10.3897/rio.5.e38546 |issn=2367-7163 |doi-access=free}}</ref>

It is not enough for children to have a modern prefrontal cortex (PFC) to allow the development of PFS; the children must also be mentally stimulated and have recursive elements already in their language to acquire PFS. Since their parents would not have invented these elements yet, the children would have had to do it themselves, which is a common occurrence among young children that live together, in a process called [[cryptophasia]].<ref>{{Cite journal |last=Bakker |first=Peter |date=July 1987 |title=Autonomous Languages of Twins |journal=Acta Geneticae Medicae et Gemellologiae: Twin Research |volume=36 |issue=2 |pages=233–238 |doi=10.1017/S0001566000004463 |issn=0001-5660 |pmid=3434134 |doi-access=free}}</ref> This means that delayed PFC development would have allowed more time to acquire PFS and develop recursive elements.

Delayed PFC development also comes with negative consequences, such as a longer period of reliance on one's parents to survive and lower survival rates. For modern language to have occurred, PFC delay had to have an immense survival benefit in later life, such as PFS ability. This suggests that the mutation that caused PFC delay and the development of recursive language and PFS occurred simultaneously, which lines up with evidence of a genetic bottleneck around 70,000&nbsp;years ago.<ref>{{Cite journal |last1=Amos W. |last2=Hoffman J. I. |date=7 January 2010 |title=Evidence that two main bottleneck events shaped modern human genetic diversity |journal=Proceedings of the Royal Society B: Biological Sciences |volume=277 |issue=1678 |pages=131–137 |doi=10.1098/rspb.2009.1473 |pmc=2842629 |pmid=19812086}}</ref> This could have been the result of a few individuals who developed PFS and recursive language which gave them significant competitive advantage over all other humans at the time.<ref name="Vyshedskiy2019" />