My latest Mind and Matter column in the Wall
Street Journal:
Three years ago Queen Elizabeth II asked a group of speech
therapists if her father's stutter had been caused by his being
forced to write with his right hand despite being a natural
left-hander. Though it's a more plausible theory than movie
psychobabble about conflict with a domineering father (a theme of
Oscar front-runner "The King's Speech"), the experts told the queen
that this commonly held explanation for stuttering remains
unproven. It may be just an urban legend, based on the fact that
stuttering is more common among the left-handed.
The connection between handedness and speech runs deep.
Speech is controlled by the left side of the brain and so is motor
control of the usually dominant right hand. It is possible that
this connection says something about the evolutionary origin of
language, if language was first expressed through gestures rather
than speech.
Curiously, stuttering is not really a speech disorder.
Some deaf people stutter in sign language, too. This is just one of
the ways that sign language shares all the characteristics of
spoken language. For example, in Britain and many other
countries-less so in America-sign language has wildly different
dialects in different regions. Most hearing people wonder why sign
language is not internationally standardized. Answer: for the same
reason spoken language is not standardized. Language is an evolved,
not an ordained, order.
Indeed, it's probably harder for signers than for speakers
to homogenize grammar and vocabulary; they lack radio and TV and
are often isolated in a sea of speakers. Simple sign languages
become spontaneously more sophisticated when deaf children come
together, because they impose grammar on new vocabulary in a way
adults don't. In one striking case, the formation of a new school
for deaf children in Nicaragua in the 1970s led to a new form of
sign language, complete with its own grammar.
Even more remarkably, a Bedouin village in Israel where 5%
of the population is genetically deaf because of a mutation in one
of its founders has invented its own sign language, which is used
by hearing people, too.
If we all learned sign language from birth, there would be
some obvious advantages. At loud parties, on trains or during
ambushes, we could resort to signing, instead of having to shout,
distract fellow travelers or alert our quarry.
So we are all natural signers. Does this indicate that
signing was how we all used to communicate? It looks as if our
prehuman ancestors had only a modest vocabulary of shouts, screams
and whines, but a richer and subtler vocabulary of gestures, shrugs
and frowns. According to the primatologist Frans de Waal, apes,
especially bonobos, use gestures more freely and flexibly than
voice. According to another primatologist, Richard Byrne, gorillas
have a large repertoire of gestures used to express specific
meanings in the wild. And it appears that chimps learn a vocabulary
of signs more easily than a vocabulary of sounds.
But perhaps the most intriguing connection is anatomical.
The part of the brain that handles language is right in the middle
of the human motor cortex. The ancestral vocalization module lies
elsewhere, nearer the crown of the head, which fits with the fact
that the ability to swear with gusto sometimes survives intact in
stroke victims who otherwise can't speak and also in those who
stutter-as the streams of profanity in "The King's Speech"
illustrate.
As is often true in evolutionary theory, it's hard to know
how to test the idea that signing came first. Speech itself, after
all, is a form of gesture, with the lips and tongue, so no wonder
it resides in the motor cortex.
And the extraordinary facility human beings have for
learning sign languages as well as spoken languages does not
necessarily imply an ancestral connection. We also have a great
facility for learning written language, which arrived late in human
history and thus cannot be an instinct. Verdict: unproven, like the
queen's hand-forcing theory of stuttering.
