RT Journal Article
SR Electronic
T1 Development of behavioral modernity by hominins around 70,000 years ago was associated with simultaneous acquisition of a novel component of imagination, called prefrontal synthesis, and conversion of a preexisting rich-vocabulary non-recursive communication system to a fully recursive syntactic language
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 166520
DO 10.1101/166520
A1 Andrey Vyshedskiy
YR 2019
UL http://biorxiv.org/content/early/2019/04/17/166520.abstract
AB There is an overwhelming archeological and genetic evidence that modern speech apparatus was acquired by hominins by 600,000 years ago 1. On the other hand, artifacts signifying modern imagination, such as (1) composite figurative arts, (2) bone needles with an eye, (3) construction of dwellings, and (4) elaborate burials arose not earlier than 70,000 years ago. It remains unclear (1) why there was a long gap between acquisition of modern speech apparatus and modern imagination, (2) what triggered the acquisition of modern imagination 70,000 years ago, and (3) what role language might have played in this process. Our research into evolutionary origin of modern imagination has been driven by the observation of strict dependency between childhood use of full recursive syntactic language and imagination. Modern children, who are not using recursive syntactic language in early childhood, will never acquire a particular component of imagination, specifically, the type of active constructive imagination called Prefrontal Synthesis (PFS). Unlike vocabulary and grammar acquisition, which can be learned throughout one’s lifetime, there is only a short critical period for the development of PFS and individuals not exposed to recursive syntactic language in early childhood, can never acquire PFS as adults. If early hominins (during the period of 600,000 to 70,000 years ago) were not exposed to recursive syntactic language before the end of critical period, they would have never acquired PFS and this would explain their pre-modern behavior. Their communication system would have been lacking flexible syntax, spatial prepositions, and recursion that depend on the PFS ability. Furthermore, just as modern individuals without the PFS ability, they would not have been able to learn these recursive elements of language later in life and, therefore, would not be able to teach these elements to their children. Thus, the need to acquire recursive syntactic language in early childhood creates an evolutionary barrier for behavioral modernity. A mathematical model suggests that a synergistic confluence of three events: (1) a genetic mutation that extended the critical period by slowing down the prefrontal cortex development in two or more children, (2) spontaneous invention of recursive elements of language, such as spatial prepositions, by these very children and (3) their dialogic communications using these recursive elements, resulted in simultaneous acquisition of PFS and conversion of the non-recursive communication system of their parents to recursive syntactic language around 70,000 years ago.