(Roughly) Daily

Sometimes less is more…

Scientists have identified evolutionary modifications in the voice box distinguishing people from other primates that may underpin a capability indispensable to humankind – speaking.

Researchers said… an examination of the voice box, known as the larynx, in 43 species of primates showed that humans differ from apes and monkeys in lacking an anatomical structure called a vocal membrane – small, ribbon-like extensions of the vocal cords.

Humans also lack balloon-like laryngeal structures called air sacs that may help some apes and monkeys produce loud and resonant calls, and avoid hyperventilating, they found.

The loss of these tissues, according to the researchers, resulted in a stable vocal source in humans that was critical to the evolution of speech – the ability to express thoughts and feelings using articulate sounds. This simplification of the larynx enabled humans to have excellent pitch control with long and stable speech sounds, they said.

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Sound production mechanisms in people and nonhuman primates are similar, with air from the lungs driving oscillations of the vocal cords. Acoustical energy generated this way then passes through the pharyngeal, oral and nasal cavities and emerges in a form governed by the filtering of specific frequencies dictated by the vocal tract.

“Speech and language are critically related, but not synonymous,” said primatologist and psychologist Harold Gouzoules of Emory University in Atlanta, who wrote a commentary in Science accompanying the study. “Speech is the audible sound-based manner of language expression – and humans, alone among the primates, can produce it.”

Paradoxically, the increased complexity of human spoken language followed an evolutionary simplification.

“I think it’s pretty interesting that sometimes in evolution ‘less is more’ – that by losing a trait you might open the door to some new adaptations,” Fitch said…

“Pivotal evolutionary change helped pave the way for human speech,” from Will Dunham @Reuters.

[Image above: source]

* Leonardo da Vinci

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As we simpify, we might send thoughtfully-analyzed birthday greetings to Karl Gegenbaur; he was born on this date in 1826. An anatomist and professor, he was the first to demonstrate that the field of comparative anatomy offers important evidence supporting of the theory of evolution— of which, he became one of Europe’s leading proponents.

Gegenbaur’s book Grundzüge der vergleichenden Anatomie (1859; English translation: Elements of Comparative Anatomy) became the standard textbook, at the time, of evolutionary morphology, emphasizing that structural similarities among various animals provide clues to their evolutionary history. In a way that prefigured the research featured above, Gegenbaur noted that the most reliable clue to evolutionary history is homology, the comparison of anatomical parts which have a common evolutionary origin.

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