Evolution and humans: speech and muscle complexity (Evolution)

by David Turell @, Tuesday, November 01, 2016, 17:21 (405 days ago) @ dhw

The muscles that control proper human speech are more than 100. Human speech involves anatomic changes of an arched palate, a lower larynx with an epiglottis trap door to protect the lungs and complex breathing controls to clip the air bursts that create intelligible human speech. this requires complex brain controls:

http://www.wsj.com/articles/the-brain-wiring-behind-a-frustrating-speech-disorder-14779...

"New research on the intricate patterns of brain activity needed to produce speech is giving scientists fresh insights into what goes wrong in various speech disorders.

"Speaking is among the most complex human behaviors the brain controls. Normal speech depends on the precise coordination of more than 100 muscles, spread across the mouth, lungs and vocal cords. The brain issues a series of rapid-fire commands directing these muscles to move in the exact pattern needed to voice specific syllables and words.

"Dr. Chang says his work using brain electrodes reveals how neurons control a series of so-called articulators—including the larynx, lips, facial muscles and tongue—that work together to coordinate speech.

"Some articulators shape the breath. Others push air up through the vocal cords. Still others move the tongue, cheeks and lips. When one of these players falls out of line, speech can sound slurred, shaky or choppy and raspy, as in spasmodic dysphonia.

Comment:The article goes on to discuss the research in terms of spasmodic dysphonia:

"Spasmodic dysphonia, which is incurable, is characterized by uncontrollable voice breaks, strained speech and excessive breathiness. It usually strikes in midlife, when patients hit their personal and professional prime."

Comment: The main point for me is the complexity of over 100 muscles being coordinated, along with the required anatomic changes. There is nothing like this in the ape world. This is a giant evolutionary gap gap explained only by saltation. Humans are obviously different in kind.


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