Human evolution; our complex speech mechanism; (Introduction)

by David Turell , Friday, May 01, 2020, 15:48 (1456 days ago) @ David Turell

A connection in humans to the frontal cortex is found to have early evidence in macaques from 20-25 million years ago:

https://bigthink.com/mind-brain/speech-20-million-years?rebelltitem=4#rebelltitem4

"Researchers find traces of something like our arcuate fasciculus in macaque brains.

"Since the last ancestor we shared with macaques was 25-30 million years ago, this would push speech way back.

"The study suggests human speech began in the auditory cortex and eventually extended to include the executive-function areas of the brain.

"As far as we know, humans alone are capable of speech as we know it, with words and sentences. This has to do, scientists believe, with a pathway in the brain we possess. Now a new and controversial study reports the presence of this same pathway, albeit in less pronounced form, in macaques. Given that our last shared ancestor with these monkeys was 25-30 million years ago,

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"The fuss is about a neural pathway in humans called the arcuate fasciculus, or AF, that traverses our prefrontal cortex and frontal lobe. Recent research suggests it has connections to other brain regions as well.

"'This is a pathway that interconnects brain regions that are important for language. If this pathway or some of these regions it interconnects are damaged because of stroke or brain degeneration a person might immediately (because of stroke) or progressively (because of dementia) lose the ability to understand or to produce language," Petkov tells Newsweek.

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"For the study, international teams of European and US scientists pored through new imaging data of humans looking for evidence of this pathway in other regions. They found a segment of it, unexpectedly, in the auditory complexes of both brain hemispheres, though most strongly identifiable in the left one. Says Petkov, "To be honest, we were really quite surprised that the auditory system has this privileged pathway to vocal production regions in frontal cortex." He adds, "That in itself tells us that there is something special about this pathway. The link to projection from the auditory system to frontal cortex regions, which in humans supports language, is fascinating."

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"Finding an AF-like pathway in macaques may not even represent their earliest development, notes Petkov, who points out, "there may be more brain 'fossils' yet to be discovered with even earlier evolutionary origins. Or it may be discovered that the origin of this pathway traces back even further if another brain "fossil" is found.'"

Comment: Tracts in the brain have to begin development somewhere in time as evolution progressed to produce humans and their ability to have speech and language. As always I view this a God's preplanning for the future