There is a common myth in Spain that King Ferdinand was born with a lisp.

As the story goes, this speech impediment led to the Spanish pronunciation of “z” and “c” with the soft “th” sound, as Ferdinand’s courtiers imitated his lisp.

This Spanish pronunciation of “z” as “th” differs from the “z” as “s” spoken in western Spanish-speaking countries.

In reality, the “s” sound exists in the Spanish language; it is just not applied to “z” or “c” (the latter, when followed by “i” or “e”). 

Thus, it follows that the differences in pronunciation across Spanish-speaking cultures are not due to a lisping king, but rather to the natural regional differences that develop in living languages.

In the same way that American pronunciation of English varies from British pronunciation, peculiarities of living languages emerge across many groups, regions, countries, etc.

While King Ferdinand’s story is nothing but an urban legend, culture and genetics really do work together to create physiological differences related to speech.

Here’s how.

Genes & Culture Interact

Herbert Gintis’ paper titled, “Gene–culture coevolution and the nature of human sociality,” defines the gene-culture coevolution theory as follows:

“Gene–culture coevolution is the application of sociobiology, the general theory of the social organization of biological species, to humans—a species that transmits culture in a manner that leads to quantitative growth across generations.”

Cultural differences have produced changes in brain size, body size, and other aspects of human anatomy across the human species.

Last week, we talked about how genes and culture worked together to alter our diet – specifically, our ability to consume milk products – and how that ability varies across cultures according to their cultural history.

In the same way, gene-culture coevolution has symbiotically shaped human speech and communication.

Speech & Communication

Gintis goes on to explain how gene-culture coevolution is readily apparent in the physiological evolution of human speech and facial communication.

He writes that genetic alterations that improve speech are propagated due to the increasing importance human society places on communication. 

In early humans, speech production was facilitated by the evolution of regions in the motor cortex, including the adaptation of muscles and nerves in the tongue, larynx, and mouth that help produce speech.

Other physical attributes that have adapted over time in humans to improve speech include a low larynx in the throat, a shorter oral cavity, and the hypoglossal canal of the tongue, all of which both help produce sounds.

The Wernicke’s and Broca’s regions in the cerebral cortex are either absent or are very small in other primates; they’re large in humans, enabling comprehension and speech.

Human facial musculature is also more highly developed, allowing the eyes and lips to impart nonverbal communication.

Considering the development of these attributes that facilitate speech in humans, you can see that genes and culture have worked closely together to evolve the human species.

Next week, we’ll talk about how these physiological aspects of speech differ across cultures.

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