Recursive language and modern imagination were acquired simultaneously 70,000 years ago

Recursive language and modern imagination were acquired simultaneously 70,000 years ago
The lion-man sculpture from Germany (dated to 37,000 years ago) must have been first imagined by the artist by mentally synthesizing parts of the man and beast together and then executing the product of this mental creation in ivory. The composite artworks provide a direct evidence that by 37,000 years ago humans have acquired prefrontal synthesis. Credit: JDuckeck [Public domain, commons.wikimedia.org/wiki/File:Lion_man_photo.jpg]

A genetic mutation that slowed down the development of the prefrontal cortex (PFC) in two or more children may have triggered a cascade of events leading to acquisition of recursive language and modern imagination 70,000 years ago.

This new hypothesis, called Romulus and Remus and coined by Dr. Vyshedskiy, a neuroscientist from Boston University, might be able to solve the long-standing mystery of evolution. It is published in the open-science journal Research Ideas and Outcomes (RIO).

Numerous archeological and genetic evidence have already convinced most paleoanthropologists that the speech apparatus has reached essentially modern configurations before the human line split from the Neanderthal line 600,000 years ago. Considering that the chimpanzee communication system already has 20 to 100 different vocalizations, it is likely that the modern-like remodeling of the vocal apparatus extended our ancestors' range of vocalizations by orders of magnitude. In other words, by 600,000 years ago, the number of distinct verbalizations used for communication must have been on par with the number of words in modern languages.

On the other hand, artifacts signifying modern imagination, such as composite figurative arts, elaborate burials, bone needles with an eye, and construction of dwellings arose not earlier than 70,000 years ago. The half million-year-gap between the acquisition of the modern speech apparatus and modern imagination has baffled scientists for decades.

While studying acquisition of imagination in children, Dr. Vyshedskiy and his colleagues discovered a temporal limit for the development of a particular component of imagination. It became apparent that modern children who have not been exposed to full language in early childhood never acquire the type of active constructive imagination essential for juxtaposition of mental objects, known as Prefrontal Synthesis (PFS).

Dr. Vyshedskiy explains:

"To understand the importance of PFS, consider these two sentences: "A dog bit my friend" and "My friend bit a dog." It is impossible to distinguish the difference in meaning using words or grammar alone, since both words and grammatical structure are identical in these two sentences. Understanding the difference in meaning and appreciating the misfortune of the 1st sentence and the humor of the 2nd sentence depends on the listener's ability to juxtapose the two mental objects: the friend and the dog. Only after the PFC forms the two different images in front of the mind's eye, are we able to understand the difference between the two sentences. Similarly, nested explanations, such as "a snake on the boulder to the left of the tall tree that is behind the hill," force listeners to use PFS to combine objects (a snake, the boulder, the tree, and the hill) into a novel scene. Flexible object combination and nesting (otherwise known as recursion) are characteristic features of all human languages. For this reason, linguists refer to as recursive languages."

Unlike vocabulary and grammar acquisition, which can be learned throughout one's lifetime, there is a strong critical period for the development of PFS and individuals not exposed to conversations with recursive language in early childhood can never acquire PFS as adults. Their language is always lacking understanding of spatial prepositions and recursion that depend on the PFS ability. In a similar manner, pre-modern humans would not have been able to learn recursive language as adults and, therefore, would not be able to teach recursive language to their own children, who, as a result, would not acquire PFS. Thus, the existence of a strong critical period for PFS acquisition creates a cultural evolutionary barrier for acquisition of recursive language.

The second predicted evolutionary barrier was a faster PFC maturation rate and, consequently, a shorter critical period. In modern children the critical period for PFS acquisition closes around the age of five. If the critical period in pre-modern children was over by the age of two, they would have no chance of acquiring PFS. A longer critical period was imperative to provide enough time to train PFS via recursive conversations.

An evolutionary mathematical model, developed by Dr. Vyshedskiy, predicts that humans had to jump both evolutionary barriers within several generations since the "PFC delay" mutation that is found in all modern humans, but not in Neanderthals, is deleterious and is expected to be lost in a population without an associated acquisition of PFS and recursive language. Thus, the model suggests that the "PFC delay" mutation triggered simultaneous synergistic acquisition of PFS and recursive language.

This model calls for:

  • two or more children with extended critical period due to "PFC delay" mutation;
  • these children spending a lot of time talking to each other;
  • inventing the recursive elements of language, such as spatial prepositions;
  • acquiring recursive-conversations-dependent PFS;
  • teaching recursive language to their offsprings.

The hypothesis is named after the celebrated twin founders of Rome, Romulus and Remus. Similar to legendary Romulus and Remus, whose caregiver was a wolf, the real children's caregivers had an animal-like communication system with many words, but no recursion. Their parents could not have taught them spatial prepositions or recursion; children had to invent recursive elements of language themselves. Such an invention of a new recursive language has been observed in contemporary children, for example among deaf in Nicaragua.

"The acquisition of PFS and recursive language 70,000 years ago resulted in what was in essence a behaviorally new species: the first behaviorally modern Homo sapiens," concludes Dr. Vyshedskiy. "This newly acquired power for fast juxtaposition of mental objects in the process of PFS dramatically facilitated mental prototyping and led to fast acceleration of technological progress. Armed with the unprecedented ability to mentally simulate any plan and equally unprecedented ability to communicate it to their companions, humans were poised to quickly become the dominant species."

Humans acquired an ability to trap large animals and therefore gained a major nutritional advantage. As the population grew exponentially, humans diffused out of Africa and quickly settled in the most habitable areas of the planet, arriving in Australia around 50,000 years ago. These humans were very much like modern humans since they possessed both components of full language: the culturally transmitted recursive language along with the innate predisposition towards PFS, enabled by the "PFC delay" mutation.


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More information: Andrey Vyshedskiy, 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, Research Ideas and Outcomes (2019). DOI: 10.3897/rio.5.e38546
Provided by Pensoft Publishers
Citation: Recursive language and modern imagination were acquired simultaneously 70,000 years ago (2019, August 5) retrieved 23 August 2019 from https://phys.org/news/2019-08-recursive-language-modern-simultaneously-years.html
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Aug 05, 2019
""A dog bit my friend" and "My friend bit a dog.""

This is an argument that only really works in non-inflected languages, like modern English. It would not work in Latin, Sanskrit, or ancient Greek, and thus probably in Proto-Indo-European because they mark agents and patients of verbs with case.


Aug 05, 2019
It's just an example, put in terms English speakers can comprehend.

Aug 05, 2019
I'm always annoyed by assertion of absolute when discussing scientific matters, e.g.
"...individuals not exposed to conversations with recursive language in early childhood can never acquire PFS as adults."

Still, the major thesis & its support is interesting, i.m.o.

Aug 05, 2019
I'm sorry, but I don't buy it. Perhaps because there is not enough information to distinguish it from certain Christians who "established" that the Earth was invented 30000 years ago by God.

Anyway, perhaps the author, having explained about the difference between "A dog bit my friend" and "My friend bit a dog", could now explain to me the difference between "Mx farb zxeb tropt fuuxp" and "Tropt fuuxp zxeb Mx farb", and how those dumb apes 70000 generations ago didn't even wear shoes.

Ohh! I'm sorry, 70000 generations ago they DID wear shoes!

Aug 05, 2019
I'm sorry, but I don't buy it. Perhaps because there is not enough information to distinguish it from certain Christians who "established" that the Earth was invented 30000 years ago by God.

Anyway, perhaps the author, having explained about the difference between "A dog bit my friend" and "My friend bit a dog", could now explain to me the difference between "Mx farb zxeb tropt fuuxp" and "Tropt fuuxp zxeb Mx farb", and how those dumb apes 70000 generations ago didn't even wear shoes.

Ohh! I'm sorry, 70000 generations ago they DID wear shoes!

And it took some imagination...

Aug 05, 2019
This is very much an ad hoc "just so" hypothesis to explain a putative difference between human groups. While the author of the paper suggests tests, he does not suggest the obvious one of the genetic basis, which is arguable. The PFS plasticity trait is not tied to genetics of PFC development, and the hypothesis that the upstream regulator region of MEF2A gene is under purifying selection in Africans but not in European/Asians 300 kyrs ago [ https://genome.cs...full.pdf ] depends on the unknown variation and the bottlenecks in both.

We certainly know that Neanderthals and Denisovans - as well as Africans to a lesser degree - bottlenecked and hence lost unknown variation. We also know that we have just two whole genomes from Neanderthals and one [!] from Denisovans [ https://www.natur...-44877-x ].

- tbctd -

Aug 05, 2019
- ctd -

The latter reference (from 2019) mentions that when the human whole genome variation was extended to 1,000 modern humans, the number of recently fixed sites which were ancestral in Neanderthals and Denisovans went down to 1/3 of the original number (from 30,000+ to 10,000+). I did not have the energy to see if the MEF2A site remained as "recently fixed" - which is purifying, negative selection, not the adaptive, positive selection the MEF2A references suggest - but the likelihood is that when we have more sequencing done the presumed variation differences has changed.

And that is while we still don't know the bottleneck effects. Other problems with the hypothesis is the suggestion of 70 kyrs based on tools and arts (but not fire and cooking, oddly enough) when both those records are very much in flux regarding who did what and what biases the scant record has.

Aug 06, 2019
This is very much an ad hoc "just so" hypothesis

Yes, a "just so" story to stimulate the imagination... successfully.

Aug 06, 2019
I'm not quite convinced this came down to a revolutionary invention by two kids, 70000 years ago.
Many animals are clever enough to know something they cannot sea anymore is behind something else. Expressing that in words would be 'recursive language' at a first level. Their brains can already conceptualise the idea. And some animals have vocalisations combined with pointing that can already convey that information. Apes are further along this path. Humans could have just built slowly on that capacity to stack references deeper. Kids taking ever longer to grow up, creating capacity for culture to build/transfer.

Aug 07, 2019
Okay, so I was getting wrapped up in a maze of thoughts thinking about the maturation of the common squash and evolution. How heat, water, the good, the bad and the ugly effect the size of a squash when it starts to ripen and how long a period from fertilization to then might be. I was trying to figure the Dr in question had the horse before the cart. Then it dawned on me, the whole thing is poppy cock. Folks imagined and communicated abstractly long before spoken languages. For instance, "the beast is coming," "that's a snack," or "that's a (particular snack.) How do we get to be becoming a Dr. these days? Sign me up.

Aug 07, 2019
What's the test group? Do we have a bunch of kids to run around without spoken language but other forms of communication. Then a way to test their imagination. |Going forward it's conceivable that spoken language, words as they were, may limit imagination. Why is imagination and communication limited before "words."

Aug 07, 2019
"Prefrontal Synthesis"
Could just be Narcissism.

I mean, Narcissists can't admit fault.
If you told them:
"Your dog bit my friend", they'd respond, "No, your friend bit my dog."
It's called "projection".

Plus:
Elaborate funerals?
Sewing needles?

Aug 07, 2019
Plus:
All the rest of it is "narcissistic", too.

"Compositive figural arts" - that's another way of saying that they started making art that involves themself. Instead of cave painting animals, they're making animals humanoid. i.e. Like themself.

Elaborate funerals - that's too obvious.

Sewing needles - for clothes. They're covering up imperfections.

Aug 07, 2019
And ...the PFC mutation seals it.

2 year maturation versus 5 year maturation.
They got to be babies for 3 more years.

Narcissists - are big babies.

Aug 12, 2019
I don't think many of you realize how profound this is.

What the authors are calling "recursive languages" are what computer scientists call "recursively enumerable languages" (or Type 0 languages, or Turing languages). Language and computation are identical, and recursively enumerable languages are the set of languages that, according to the Church-Turing Hypothesis, are capable of computing anything computable.

All human natural languages are recursively enumerable languages, and most complex processes that execute on computers (including quantum computers) are expressing what are equivalent to recursively enumerable statements in language.

There are languages which are non-recursively enumerable (more expressive), but we have no way to define those languages, much less to express what they can express.

Until humans developed recursively enumerable natural language, they couldn't have expressed the complex ideas that we can think and can program computers to compute.

Aug 12, 2019
They may have had modern language capability but they didn't show it. They could have done a string of cave art to write a story. They could have used stick figures. We don't see that. The new mental development can be used for something other than language. Don't we call that imagination? Imaginative language does not imply the ability or need to tell folklore. The Neanderthal had music. Their pentatonic flute would inspire a sequence of notes but generated by the audio cortex. We had the complex language potential and the Neanderthal had the ability to organize the synthesis of imagination as song. We hybridized. What we lacked was the trigger of knowledge. Modern knowledge evolves. The recent invention of cities, agriculture, kings, the two million pound stone's of Baalbek, god's and war was due to our genetic trigger. We are living in the last 15 sec of a 3.7My day. The pressure of living in an ecosystem prevented development until we made our own artificial sun and moon.

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