Tecumseh Fitch 1

1 University of St. Andrews, , St. Andrews

Although human language and music are unique to our species, the 

apparatus used to produce speech and song is surprisingly 

conservative: both the physical principles and the physiological 

mechanisms we use to produce these distinctive signals have deep roots 

in vertebrate evolution.  This is interesting because many other 

animals with the capacity for vocal learning use novel mechanisms to 

produce their "songs", for example birds have evolved the novel 

syrinx, and dolphins and toothed whales use a nasal bursae system 

associated with the blowhole.  I will give a brief tour of the 

evolution of the larynx and vocal tract, showing that the mammalian 

larynx has some distinctive features but is homologous to the organ of 

voice in frogs and alligators.  As mammals, humans are rather 

ordinary, with no fundamental differences between our larynx, tongue 

or vocal tract than those in most other terrestrial mammals.  The 

reconfigured vocal tract of humans, with a descended larynx and tongue 

root, was long thought to be uniquely human, but has now been shown to 

be shared with a number of other species including several deer and 

large cat species.  Thus, human speech and song are produced using the 

same fundamental vocal mechanism as other primate vocalizations, and 

the fundamental roots of these abilities are to be found in the brain, 

rather than the periphery.  The most fundamental distinction between 

humans and other primates is that we possess direct connections 

between motor cortex, and the motor neurons which control the larynx 

and vocal tracts.