Evolution of human vocalization

Of the many things we take for granted on a daily basis, our ability to vocalize and  speak, the mechanisms behind this and how this ability came to be is one of the most important. 


Can you imagine how different our society would be, if it would even exist, without our ability to vocalize our ideas and emotions?  Would we have developed advanced sign language or rely on some sort of chemical communication in order to elicit olfactory responses from our friends and family?  The development of human vocalization is particularly amazing in that we are able to produce a seemingly endless array of sounds from percussive articulations to the more melodious sounds that our vibrating larynxes produce.

The evolution of this very important human feature is particularly difficult to study since the majority of the vocal production apparatus does not fossilize and there are no pre-human recordings of primate vocalizations.  However using comparative anatomy from extant and extinct species we can get a pretty good idea of how we came to sound the way we do.

Probably the biggest contributing factor that makes human vocalization so special in comparison to other extinct and extant primates is the descent of our larynx.  The descent of the larynx means that humans have pharyngeal cavity that is unique to us (specifically that it is two-tubed and enlarged).  This change in our anatomy increased our vocal capacity (along with the ability in movement from our lips and tongue) to give us a vast vocal production repertoire.

 

Notice the difference in placement of the larynx between an extant primate and that of the modern human.

Whatever the cause of the changes in our vocal production apparatus, we can see the social and biological ramifications of our lowered larynx in the competition for mates.  Though it may seem silly when you think about, if a male thinks they are physically dominant to their opponent, they will address them with a lowered pitch.  Also, it has been found that men with lower-pitched voices dominate social and physical settings.  I think that though this may be a strong trend in evolutionary history, that it too could be changing much like human society.  With ever-increasing gender and sexual equality it will be interesting to see if this sexual dimorphism holds true in a society where the availability of resources sometimes outweighs the physical prowess of the mate.

Whatever the cause of the changes in our vocal production apparatus, we can see the social and biological ramifications of our lowered larynx in the competition for mates.  Though it may seem silly when you think about, if a male thinks they are physically dominant to their opponent, they will address them with a lowered pitch.  Also, it has been found that men with lower-pitched voices dominate social and physical settings.  I think that though this may be a strong trend in evolutionary history, that it too could be changing much like human society.  With ever-increasing gender and sexual equality it will be interesting to see if this sexual dimorphism holds true in a society where the availability of resources sometimes outweighs the physical prowess of the mate.


Now, we know that the descent of the larynx was a huge evolutionary step to modern human vocal production, but there is still a lot of debate as to if selection for speech is the reason that this actually happened.  Various theories exist as to why the lowering of the larynx actually occurred.  A byproduct of a lowered larynx is lower resonance frequencies that could have been selected for in order to exaggerate body size.  Also, there are some that believe that this occurred because of the shifting of our cranial bones in our head’s transformation to that of one with a comparatively abbreviated face

-Matt M.

Ghanzafar, Asif.  Rendall, Drew.  Evolution of Human Vocal Production.  Current Biology.  Retrieved from: http://webscript.princeton.edu/~asifg/publications/pdfs/Ghazanfar&Rendall_Evolutionofvocalproduction.pdf.
Graulin, Steven. Puts, David. Verdolini, Katherine.  Dominance and the evolution of sexual dimorphism in human voice pitch.  Evolution and Human Behavior. Retrieved from: http://www.anth.ucsb.edu/faculty/gaulin/Puts_Gaulin_Verdolini_2006.pdf.