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 – the Romulus and Remus hypothesis

Abstract

There is overwhelming archeological and genetic evidence that modern speech apparatus was acquired by hominins by 600,000 years ago. There is also widespread agreement that behavioral modernity arose around 100,000 years ago. We attempted to answer three crucial questions: (1) what triggered the acquisition of behavioral modernity 100,000 years ago, (2) why there was a long gap between acquisition of modern speech apparatus and behavioral modernity, and (3) what role language might have played in the process. We conclude that the communication system of hominins prior to 100,000 years ago was finite and not-recursive. It may have had thousands of words but was lacking flexible syntax, spatial prepositions, verb tenses, and other features that enable modern recursive language to communicate an infinite number of ideas. We argue that a synergistic confluence of a genetic mutation that dramatically slowed down the prefrontal cortex (PFC) development in monozygotic twins and their spontaneous invention of recursive elements of language, such as spatial prepositions 100,000 years ago resulted in acquisition of special type of PFC-driven constructive imagination (called mental synthesis) and converted the finite communication system of their parents into infinite recursive language.peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/166520 doi: bioRxiv preprint first posted online Jul. 20, 2017; 2 1. Acquisition of modern speech apparatus from 2 million to 600,000 years agoThe articulate speech of humans is unique among primates. The vocal tract of our closest relatives, chimpanzees is extremely limited in its ability to modulate sound. While there is no theoretical limit on the number of different vocalizations nonhuman primates can generate 1 , attempts to teach chimpanzees articulate speech have failed 2 and the range of distinct vocalizations observed in the wild is limited to between 20 to 100 [3][4][5][6] . On the contrary, human languages contain tens of thousands of different words easily generated by the modern human vocal apparatus. Paleoanthropologists study the evolution of articulate speech and the underlying vocal tract as an indicator of language evolution [7][8][9] . The modern vocal apparatus developed as a result of changes of the structure and the position of many organs that play a role in generating and modulating vocalizations: larynx, tongue, musculature of the mouth, lips, and diaphragm as well as the neurological control of the associated musculature. While cartilaginous and soft tissue is not preserved in the fossil record, we can draw conclusions about the evolution of vocal apparatus from the bony structures which do survive. Three lines of converging evidence point to acquisition of modern speech apparatus by 600,000 years ago: 1) the changes in hyoid bone, 2) the flexion of the bones of the skull base, and 3) the evolution of the FOXP2 gene.1. The changes in ...

Neuroscience of imagination and implications for human evolution

“…Third, the number of wounds received in close combat with large animals had to come down as a result of preferential use of trapping of megafauna. Fourth, PFS must have dramatically increased cohesion between tribe members through religion and syntactic language 92 . Fifth, PFS facilitated the process of discovery of new tools, such as spear throwers and bow-and-arrows 61 .…”

“…Although mental rotation has been demonstrated in baboons 96,97 , rhesus monkey 98 , and sea lion 99 , the latest experimental data question the assumption that animals use the same flexible neurological mechanism as humans 100 . It is likely that acquisition of integration of modifiers coincided with acquisition of speech around 2 million to 600,000 ya 92,101 . Acquisition of speech could have also facilitated the acquisition of mental rotation by the LPFC as the following data from modern deaf individuals unequivocally show.…”

“…PFA acquisition by hominins can be easily followed by looking at the stone tools culture that was slowly improving from about 3.3 million ya 57 . The most advanced mechanism of imagination, PFS, was acquired phylogenetically only 70,000 ya 92 and develops in children between ages of 3 and 4 121 .…”