Evolution’s great mystery - Michael Corballis
In the 1980s, a bonobo named Kanzi
learned to communicate with humans
to an unprecedented extent—
not through speech or gestures,
but using a keyboard of abstract symbols
representing objects and actions.
By pointing to several of these in order,
he created sequences to make requests,
answer verbal questions
from human researchers,
and refer to objects
that weren’t physically present.
Kanzi’s exploits ignited immediate
controversy over one question:
had Kanzi learned language?
What we call language is something
more specific than communication.
Language is about sharing
what’s in our minds:
stories, opinions, questions,
the past or future,
imagined times or places, ideas.
It is fundamentally open-ended,
and can be used to say
an unlimited number of things.
Many researchers are convinced
that only humans have language,
that the calls and gestures other species
use to communicate are not language.
Each of these calls and gestures generally
corresponds to a specific message,
for a limited total number of messages
that aren’t combined
into more complex ideas.
For example, a monkey species
might have a specific warning call
that corresponds to a particular predator,
like a snake—
but with language, there are countless
ways to say “watch out for the snake.”
So far no animal communication seems
to have the open-endedness
of human language.
We don’t know for sure what’s going
on in animals’ heads,
and it's possible this definition
of language,
or our ways of measuring it,
don’t apply to them.
But as far as we know,
only humans have language.
And while humans speak
around 7,000 distinct languages,
any child can learn any language,
indicating that the biological machinery
underlying language
is common to all of us.
So what does language mean for humanity?
What does it allow us to do,
and how did we come to have it?
Exactly when we acquired this capacity
is still an open question.
Chimps and bonobos
are our closest living relatives,
but the lineage leading to humans
split from the other great apes
more than four million years ago.
In between, there were many species—
all of them now extinct,
which makes it very difficult to know
if they had language or anything like it.
Great apes give one potential clue
to the origins of language, though:
it may have started as gesture
rather than speech.
Great apes gesture to each other
in the wild much more freely
than they vocalize.
Language may have begun to take shape
during the Pleistocene,
2 to 3 million years ago,
with the emergence of the genus Homo
that eventually gave rise
to our own species, homo sapiens.
Brain size tripled, and bipedalism
freed the hands for communication.
There may have been a transition
from gestural communication
to gestural language—
from pointing to objects
and pantomiming actions—
to more efficient, abstract signing.
The abstraction of gestural communication
would have removed the need for visuals,
setting the stage for a transition
to spoken language.
That transition would have
likely come later, though.
Articulate speech depends
on a vocal tract of a particular shape.
Even our closest ancestors,
the Neanderthals and Denisovans,
had vocal tracts that were not optimal,
though they likely had
some vocal capacity,
and possibly even language.
Only in humans is the vocal tract optimal.
Spoken words free the hands for activities
such as tool use and transport.
So it may have been
the emergence of speech,
not of language itself, that led
to the dominance of our species.
Language is so intimately tied to complex
thought, perception, and motor functions
that it’s difficult to untangle
its biological origins.
Some of the biggest mysteries remain:
to what extent did language
as a capacity shape humanity,
and to what extent did humanity
shape language?
What came first, the vast number
of possible scenarios we can envisage,
or our ability to share them?
