Bower birds are artists, leaf-cutting ants practice agriculture,
crows use tools, chimpanzees form coalitions against rivals. The only
major talent unique to humans is language, the ability to transmit encoded
thoughts from the mind of one individual to another.
Because of language's central role in human nature and sociality, its
evolutionary origins have long been of interest to almost everyone, with
the curious exception of linguists.
As far back as 1866, the Linguistic Society of Paris famously declared
that it wanted no more speculative articles about the origin of
language.
More recently, many linguists have avoided the subject because of the
influence of Noam
Chomsky, a founder of modern linguistics and still its
best-known practitioner, who has been largely silent on the question.
Dr. Chomsky's position has "only served to discourage interest in the
topic among theoretical linguists," writes Dr. Frederick J.
Newmeyer, last
year's president of the Linguistic Society of America, in "Language
Evolution," a book of essays being published this month by Oxford
University Press in England.
In defense of the linguists' tepid interest, there have until recently
been few firm facts to go on. Experts offered conflicting views on whether
Neanderthals could speak. Sustained attempts to teach apes language
generated more controversy than illumination.
But new research is eroding the idea that the origins of language are
hopelessly lost in the mists of time. New clues have started to emerge
from archaeology, genetics and human behavioral ecology, and even
linguists have grudgingly begun to join in the discussion before other
specialists eat their lunch.
"It is important for linguists to participate in the conversation, if
only to maintain a position in this intellectual niche that is of such
commanding interest to the larger scientific public," writes Dr. Ray
Jackendoff, Dr. Newmeyer's successor at the linguistic society, in his
book "Foundations of Language."
Geneticists reported in March that the earliest known split between any
two human populations occurred between the !Kung of southern Africa and
the Hadza of Tanzania. Since both of these very ancient populations speak
click languages, clicks may have been used in the language of the
ancestral human population. The clicks, made by sucking the tongue down
from the roof of the mouth (and denoted by an exclamation point), serve
the same role as consonants.
That possible hint of the first human tongue may be echoed in the
archaeological record. Humans whose skeletons look just like those of
today were widespread in Africa by 100,000 years ago. But they still used
the same set of crude stone tools as their forebears and their archaic
human contemporaries, the Neanderthals of Europe.
Then, some 50,000 years ago, some profound change took place.
Settlements in Africa sprang to life with sophisticated tools made from
stone and bone, art objects and signs of long distance trade.
Though some archaeologists dispute the suddenness of the transition,
Dr. Richard Klein of Stanford argues that the suite of innovations
reflects some specific neural change that occurred around that time and,
because of the advantage it conferred, spread rapidly through the
population.
That genetic change, he suggests, was of such a magnitude that most
likely it had to do with language, and was perhaps the final step in its
evolution. If some neural change explains the appearance of fully modern
human behavior some 50,000 years ago, "it is surely reasonable to suppose
that the change promoted the fully modern capacity for rapidly spoken
phonemic speech," Dr. Klein has written.
Listening to Primates
Apes' Signals Fall Short of
Language
At first glance, language seems to have appeared from nowhere, since no
other species speaks. But other animals do communicate. Vervet monkeys
have specific alarm calls for their principal predators, like eagles,
leopards, snakes and baboons.
Researchers have played back recordings of these calls when no
predators were around and found that the vervets would scan the sky in
response to the eagle call, leap into trees at the leopard call and look
for snakes in the ground cover at the snake call.
Vervets can't be said to have words for these predators because the
calls are used only as alarms; a vervet can't use its baboon call to ask
if anyone noticed a baboon around yesterday. Still, their communication
system shows that they can both utter and perceive specific sounds.
Dr. Marc Hauser, a psychologist at Harvard who studies animal
communication, believes that basic systems for both the perception and
generation of sounds are present in other animals. "That suggests those
systems were used way before language and therefore did not evolve for
language, even though they are used in language," he said.
Language, as linguists see it, is more than input and output, the heard
word and the spoken. It's not even dependent on speech, since its output
can be entirely in gestures, as in American Sign Language. The essence of
language is words and syntax, each generated by a combinatorial system in
the brain.
If there were a single sound for each word, vocabulary would be limited
to the number of sounds, probably fewer than 1,000, that could be
distinguished from one another. But by generating combinations of
arbitrary sound units, a copious number of distinguishable sounds becomes
available. Even the average high school student has a vocabulary of 60,000
words.
The other combinatorial system is syntax, the hierarchical ordering of
words in a sentence to govern their meaning.
Chimpanzees do not seem to possess either of these systems. They can
learn a certain number of symbols, up to 400 or so, and will string them
together, but rarely in a way that suggests any notion of syntax. This is
not because of any poverty of thought. Their conceptual world seems to
overlap to some extent with that of people: they can recognize other
individuals in their community and keep track of who is dominant to whom.
But they lack the system for encoding these thoughts in language.
How then did the encoding system evolve in the human descendants of the
common ancestor of chimps and people?
Language Precursors
Babbling and Pidgins Hint at
First Tongue
One of the first linguists to tackle this question was Dr. Derek
Bickerton of the University of Hawaii. His specialty is the study of
pidgins, which are simple phrase languages made up from scratch by
children or adults who have no language in common, and of
creoles, the
successor languages that acquire inflection and syntax.
Dr. Bickerton developed the idea that a proto-language must have
preceded the full-fledged syntax of today's discourse. Echoes of this
proto-language can be seen, he argued, in pidgins, in the first words of
infants, in the symbols used by trained chimpanzees and in the syntax-free
utterances of children who do not learn to speak at the normal age.
In a series of articles, Dr. Bickerton has argued that humans may have
been speaking proto-language, essentially the use of words without syntax,
as long as two million years ago. Modern language developed more recently,
he suggests, perhaps with appearance of anatomically modern humans some
120,000 years ago.
The impetus for the evolution of language, he believes, occurred when
human ancestors left the security of the forest and started foraging on
the savanna. "The need to pass on information was the driving force," he
said in an interview.
Foragers would have had to report back to others what they had found.
Once they had developed symbols that could be used free of context — a
general word for elephant, not a
vervet-style alarm call of "An elephant
is attacking!" — early people would have taken the first step toward
proto-language. "Once you got it going, there is no way of stopping it,"
Dr. Bickerton said.
But was the first communicated symbol a word or a gesture? Though
language and speech are sometimes thought of as the same thing, language
is a coding system and speech just its main channel.
Dr. Michael
Corballis, a psychologist at the University of Auckland in
New Zealand, believes the gesture came first, in fact as soon as our
ancestors started to walk on two legs and freed the hands for making
signs.
Chimpanzees have at least 30 different gestures, mostly used to refer
to other individuals.
Hand gestures are still an expressive part of human communication, Dr.
Corballis notes, so much so that people even gesticulate while on the
telephone.
He believes that spoken words did not predominate over signed ones
until the last 100,000 years or so, when a genetic change may have
perfected human speech and led to its becoming a separate system, not just
a grunted accompaniment for gestures.
Critics of Dr. Corballis's idea say gestures are too limited; they
don't work in the dark, for one thing. But many concede the two systems
may both have played some role in the emergence of language.
Search for Incentives
As Societies Grew the Glue
Was Gossip
Dr. Bickerton's idea that language must have had an evolutionary
history prompted other specialists to wonder about the selective pressure,
or evolutionary driving force, behind the rapid emergence of language.
In the mere six million years since chimps and humans shared a common
ancestor, this highly complex faculty has suddenly emerged in the hominid
line alone, along with all the brain circuits necessary to map an
extremely rapid stream of sound into meaning, meaning into words and
syntax, and intended sentence into expressed utterance.
It is easy to see in a general way that each genetic innovation,
whether in understanding or in expressing language, might create such an
advantage for its owners as to spread rapidly through a small
population.
"No one will take any notice of the guy who says
`Gu-gu-gu'; the one
with the quick tongue will get the mates," Dr. Bickerton said. But what
initiated this self-sustaining process?
Besides Dr. Bickerton's suggestion of the transition to a foraging
lifestyle, another idea is that of social grooming, which has been
carefully worked out by Dr. Robin Dunbar, an evolutionary psychologist at
the University of Liverpool in England.
Dr. Dunbar notes that social animals like monkeys spend an inordinate
amount of time grooming one another. The purpose is not just to remove
fleas but also to cement social relationships. But as the size of a group
increases, there is not time for an individual to groom everyone.
Language evolved, Dr. Dunbar believes, as a better way of gluing a
larger community together.
Some 63 percent of human conversation, according to his measurements,
is indeed devoted to matters of social interaction, largely gossip, not to
the exchange of technical information, Dr. Bickerton's proposed incentive
for language.
Dr. Steven Pinker of the Massachusetts Institute of Technology, one of
the first linguists to acknowledge that language may be subject to natural
selection, disputes Dr. Dunbar's emphasis on social bonding; a fixed set
of greetings would suffice, in his view.
Dr. Pinker said it was just as likely that language drove sociality: it
was because people could exchange information that it became more
worthwhile to hang out together.
"Three key features of the distinctively human lifestyle — know-how,
sociality and language — co-evolved, each constituting a selection
pressure for the others," Dr. Pinker writes in "Language Evolution," the
new book of essays.
But sociality, from Dr. Dunbar's perspective, helps explain another
feature of language: its extreme corruptibility. To convey information, a
stable system might seem most efficient, and surely not beyond nature's
ability to devise. But dialects change from one village to another, and
languages shift each generation.
The reason, Dr. Dunbar suggests, is that language also operates as a
badge to differentiate the in group from outsiders; thus the Gileadites
could pick out and slaughter any Ephraimite asked to say "shibboleth"
because, so the writer of Judges reports, "He said
sibboleth: for he could
not frame to pronounce it right."
Language in the Genome
From Family Failing First
Gene Emerges
A new approach to the evolution of language seems to have been opened
with studies of a three-generation London family known as
KE. Of its 29
members old enough to be tested, 14 have a distinctive difficulty with
communication. They have trouble pronouncing words properly, speaking
grammatically and making certain fine movements of the lips and
tongue.
Asked to repeat a nonsense phrase like
"pataca pataca
pataca," they
trip over each component as if there were three different words.
Some linguists have argued that the KE family's disorder has nothing
specific to do with language and is some problem that affects the whole
brain. But the I.Q. scores of affected and unaffected members overlap,
suggesting the language systems are specifically at fault. Other linguists
have said the problem is just to do with control of speech. But affected
members have problems writing as well as speaking.
The pattern of inheritance suggested that a single defective gene was
at work, even though it seemed strange that a single gene could have such
a broad effect. Two years ago, Dr. Simon Fisher and Prof. Tony Monaco,
geneticists at the University of Oxford in England, discovered the
specific gene that is changed in the KE family. Called FOXP2, its role is
to switch on other genes, explaining at once how it may have a range of
effects. FOXP2 is active in specific regions of the brain during fetal
development.
The gene's importance in human evolution was underlined by Dr. Svante
Paabo and colleagues at the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany. In a study last year they reported that
FOXP2 is highly conserved in evolution — in other words, that the precise
sequence of units in FOXP2's protein product is so important that any
change is likely to lead to its owner's death.
In the 70 million years since people and mice shared a common ancestor,
there have been just three changes in the FOXP2 protein's 715 units, Dr.
Paabo reported. But two of those changes occurred in the last six million
years, the time since humans and chimps parted company, suggesting that
changes in FOXP2 have played some important role in human evolution.
Sampling the DNA of people around the world, Dr. Paabo found signs of
what geneticists call a selective sweep, meaning that the changed version
of FOXP2 had spread through the human population, presumably because of
some enormous advantage it conferred.
That advantage may have been the perfection of speech and language,
from a barely comprehensible form like that spoken by the affected KE
family members to the rapid articulation of ordinary discourse. It seems
to have taken place about 100,000 years ago, Dr. Paabo wrote, before
modern humans spread out of Africa, and is "compatible with a model in
which the expansion of modern humans was driven by the appearance of a
more proficient spoken language."
FOXP2 gives geneticists what seems to be a powerful entry point into
the genetic and neural basis for language. By working out what other genes
it interacts with, and the neural systems that these genes control,
researchers hope to map much of the circuitry involved in language
systems.
Ending the Silence
Linguists Return to Ideas of
Origins
The crescendo of work by other specialists on language evolution has at
last provoked linguists' attention, including that of Dr.
Chomsky. Having
posited in the early 1970's that the ability to learn the rules of grammar
is innate, a proposition fiercely contested by other linguists, Dr.
Chomsky might be expected to have shown keen interest in how that
innateness evolved. But he has said very little on the subject, a silence
that others have interpreted as disdain.
As Dr.
Jackendoff, the president of the Linguistic Society of America,
writes: "Opponents of Universal Grammar argue that there couldn't be such
a thing as Universal Grammar because there is no evolutionary route to
arrive at it. Chomsky, in reply, has tended to deny the value of
evolutionary argumentation."
But Dr. Chomsky has recently taken a keen interest in the work by Dr.
Hauser and his colleague Dr. W. Tecumseh Fitch on communication in
animals. Last year the three wrote an article in Science putting forward a
set of propositions about the way that language evolved. Based on
experimental work by Dr. Hauser and Dr. Fitch, they argue that sound
perception and production can be seen in other animals, though they may
have been tweaked a little in hominids.
A central element in language is what linguists call recursion, the
mind's ability to bud one phrase off another into the syntax of an
elaborate sentence. Though recursion is not seen in animals, it could have
developed, the authors say, from some other brain system, like the one
animals use for navigation.
Constructing a sentence, and going from A to Z through a series of
landmarks, could involve a similar series of neural computations. If by
some mutation a spare navigation module developed in the brain, it would
have been free to take on other functions, like the generation of syntax.
"If that piece got integrated with the rest of the cognitive machinery,
you are done, you get music, morality, language," Dr. Hauser said.
The researchers contend that many components of the language faculty
exist in other animals and evolved for other reasons, and that it was only
in humans that they all were linked. This idea suggests that animals may
have more to teach about language than many researchers believe, but it
also sounds like a criticism of evolutionary psychologists like Dr. Pinker
and Dr. Dunbar, who seek to explain language as a faculty forced into
being by specifics of the human lifestyle.
Dr. Chomsky rejects the notion that he has discouraged study of the
evolution of language, saying his views on the subject have been widely
misinterpreted.
"I have never expressed the slightest objection to work on the
evolution of language," he said in an e-mail message. He outlined his
views briefly in lectures 25 years ago but left the subject hanging, he
said, because not enough was understood. He still believes that it is easy
to make up all sorts of situations to explain the evolution of language
but hard to determine which ones, if any, make sense.
But because of the importance he attaches to the subject, he returned
to it recently in the article with Dr. Hauser and Dr. Fitch. By combining
work on speech perception and speech production with a study of the
recursive procedure that links them, "the speculations can be turned into
a substantive research program," Dr. Chomsky said.
Others see Dr. Chomsky's long silence on evolution as more
consequential than he does. "The fact is that Chomsky has had, and
continues to have, an outsize influence in linguistics," Dr. Pinker said
in an e-mail message. Calling Dr. Chomsky both "undeniably, a brilliant
thinker" and "a brilliant debating tactician, who can twist anything to
his advantage," Dr. Pinker noted that Dr. Chomsky "has rabid devotees, who
hang on his every footnote, and sworn enemies, who say black whenever he
says white."
"That doesn't leave much space," Dr. Pinker went on, "for linguists who
accept some of his ideas (language as a mental, combinatorial, complex,
partly innate system) but not others, like his hostility to evolution or
any other explanation of language in terms of its function."
Biologists and linguists have long inhabited different worlds, with
linguists taking little interest in evolution, the guiding theory of all
biology. But the faculty for language, along with the evidence of how it
evolved, is written somewhere in the now decoded human genome, waiting for
biologists and linguists to identify the genetic program that generates
words and syntax.