[Paleopsych] The Scientist: Darwin Meets Chomsky

[Premise Checker]

Darwin Meets Chomsky
http://www.the-scientist.com/ [I have no better URL.]

Volume 18 | Issue 24 | 16 | Dec. 20, 2004

Scientists converge in a multidisciplinary approach to understanding human
language
by Nick Atkinson
Darwin saw parallels between the evolution of species and of languages

Charles Darwin spotted it. In The Descent of Man, he wrote: "The formation
of different languages and of distinct species and the proofs that both
have developed through a gradual process are clearly the same." He'd been
struck by ideas that William Jones had advanced 50 years earlier, that the
similarities between languages as disparate as Sanskrit, Latin, and Old
Persian, suggest a common historical ancestry.

These foundations for an entirely new field of research were largely
ignored for almost a century. Language wasn't recognized as a heritable
trait, subject to processes of natural selection. Instead, studies of
biological and language evolution followed different trajectories, evidence
of which is still reflected in the departmental structure of most
universities. The divide is finally being bridged, even if a common
terminology has taken a while to establish.

"It's important to make the distinction between historical linguistics, how
a language changes over time, and studies of the evolution of language in
humans," says Partha Niyogi at the University of Chicago. He is one of a
flotilla of scientists from diverse backgrounds who are currently charting
new waters in language evolution research. Previously intractable problems,
such as how meaningful language first emerges from a more primitive
signaling system, are now being addressed with newly combined theories and
methodologies.

INNATE GRAMMAR Groundbreaking work by Noam Chomsky laid the foundations for
this type of language research, of trying to understand how human language
is possible at all. Why, for example, do children all over the world,
regardless of their backgrounds, arrive at roughly the same set of rules
governing the way they communicate? Natalia Komarova, at the University of
California, Irvine, says that such questions are important.

"Every child faces an enormously complex task while mastering her native
language. Without formal instruction, she has to figure out all the rules
of underlying grammar." Komarova points out that this goal must be achieved
using only a limited set of sentences, those actually heard, from the
infinite number of possibilities. "In fact," she says, "if you're
completely open-minded it's mathematically impossible to guess the correct
rule."

Somehow, though, children do manage this impressive feat, overcoming what
is known as the paradox of language acquisition. Chomsky's revolutionary
insight was in postulating an innate universal grammar, which helps
children navigate the infinite realm of choice. Komarova and others, such
as Harvard University's Martin Nowak, are beginning to explore the
evolutionary origins of the universal grammar by drawing on some of the
tools that evolutionary biologists have been developing over the last few
decades.

Nowak says that the complexity of the problem has hampered progress. "To
study [language] from an evolutionary standpoint requires detailed
knowledge of several fields." His own work lies at the center of a rapidly
growing literature that uses evolutionary biological tools to yield insight
into some of the basic questions on language evolution.1,2

Nowak points to limitations of current methodologies. "Most traditional
linguistic models have assumed that one party is the teacher and the other
is the student. However, that's not the case in real life," he says,
referring to recent studies of a newly emerging sign language in a
Nicaraguan deaf community, whose evolution through successive cohorts of
children has been closely followed.3 "Children appear to learn from their
peers; they arrive at a consensus by which they communicate effectively."
This research supports Chomsky's theory of an innate grammar and provides
valuable field data on how new languages evolve, but it greatly increases
the complexity of the models theoreticians must now develop. Fortunately, a
precedent already exists. Courtesy of Claude Bramble HELLO, HELLO?  Can
linguistics shed light on animal communication, such as alarm calling in
vervet monkeys? (shown above) If so, animal models might in turn help us
undestand human language.

EVOLUTION TACTICS At its simplest level, language can be viewed as a
sequence of signals between speaker and listener. This is where methods
lifted from evolutionary biology come into play. The late John Maynard
Smith championed the adoption of game theory,4 which revolutionized
ethology during the 1970s and 1980s. Game theory is now applied to a
diverse range of research questions, enabling the study of frequency
dependence: population-dynamic situations in which an individual's best
response depends on what others are doing.

Niyogi, who recently collaborated with Komarova and Nowak,1 says such a
conceptual shift is essential. Traditional linguistic approaches can't
really tackle more realistic scenarios, such as how a group of children
might learn from a more fluid set of teachers, including both peers and a
wider, age-structured group, he says. "Linguists are going to have to come
to terms with the fact that we need a more sophisticated, population-based
setting."

Another tantalizing possibility is to define the limits of the universal
grammar. An overly intricate grammar would take too long to learn, as too
many examples would be needed to test the validity of each linguistic rule.
After all, humans have only a limited time for learning language before
they reach adulthood. "This is really where linguistics meets evolutionary
biology," says Komarova. "There is a selection pressure to make universal
grammar smaller and easier to learn." An ultracompact grammar isn't
necessarily the most efficient, though. Larger grammar pools increase
flexibility, making it possible to express more complex ideas and thus
facilitate innovation.

Cognitive scientist Gary Marcus, at New York University, is interested in
the origins of the human mind.5 He emphasizes the complexity of the task
ahead and the need for new, more flexible approaches. "It's easy to view
language as the product of natural selection, but we shouldn't see it as a
single trait shaped by a single selection pressure," he says. Instead, we
need to see it as a mixture of cognitive mechanisms, some old and some new,
each of which might be subject to numerous differing, even competing,
selection pressures.

MORE THAN A GAME Simon Kirby, reader in the evolution of language and
cognition at the University of Edinburgh, says that the cross-disciplinary
approach has helped dismantle the dogma that all languages are equal. "One
of the main contributions coming from the evolutionary biology side is that
languages improve qualitatively," he says, "so a language can become more
efficient at conveying information as it evolves.

The flow of ideas between disciplines isn't all one-way traffic. Theories
of learning are vital for any attempt to understand human language. "When
the story is finally told about how language has evolved, learning theory
will play a central role," says Niyogi. He argues that both the linguistics
and computer science communities, which together are responsible for the
major developments in learning theory, share the view that its role hasn't
been sufficiently incorporated into evolutionary models. "You can't simply
collapse 50 years of language research into a single parameter, call it "P"
and say it's analogous to cultural transmission."

Not all the findings from ethological game-theory studies necessarily map
onto linguistics research. Language is a consensus between speakers and
listeners. In other biological systems, mutualisms are often kept honest
because both partners are continually attempting to exploit one other. But
Harvard University's Steve Pinker says that the cooperative nature of
language is the most likely factor driving its evolution.

"I don't think that language could have evolved primarily as a technique of
manipulation," he says. Most animal signals are clear-cut examples of
manipulation, in which signalers and receivers exert selective pressure to
produce more effective means of exploitation and resistance, respectively.
Pinker draws a distinction between these types of interactions, such as
mating calls, and the complexity of language, which requires a huge
investment by the listener simply to decode the information. Why, Pinker
asks, would the listener bother to do this if only to be manipulated as a
result?

Nevertheless, it's clear that many of the other central evolutionary
concepts, such as kin selection, are vital to language. "Human interactions
are not entirely antagonistic. There are kin, spouses, and reciprocators,
where the relationship is largely (albeit not completely) nonzero-sum and
positive," says Pinker, drawing attention to the fact that often both
parties can benefit through successful communication. "I think the
cooperative story has to be basically right. Lying and manipulation are a
parasitic overlay."

LANGUAGE FRUIT FLY Comparing animal signals, morphologic structures,
genetic systems, and learning processes across species has paid dividends,
according to Tecumseh Fitch at the University of St. Andrews' School of
Psychology in Scotland. "Many historical linguistics methods can be
successfully applied to nonhuman systems," says Fitch. "Bird and whale-song
dialects show geographic variation and changes through time, just like
human language does." This raises the possibility of using other animal
species, what Niyogi calls a "language fruit fly," to better understand
human speech.

Clearly these are exciting times for language research. And there's no
shortage of raw materials, says Kirby. "We have an embarrassment of data.
Language is going on all the time, all around us."

References
1. MA Nowak et al,  "Computational and evolutionary aspects of language,"
Nature 2002,  417: 611-7. [PubMed Abstract][Publisher Full Text]

2. WG Mitchener, MA Nowak  "Chaos and language," Proc Roy Soc Lond B
2004,  271: 701-4. [Publisher Full Text]

3. A Senghas et al,  "Children creating core properties of language:
evidence from an emerging sign language in Nicaragua," Science 305:
1779-82. [Publisher Full Text]  Sept. 17, 2004

4. JM Smith  Evolution and the Theory of Games Cambridge University Press
1982.,

5. G Marcus  The Birth of the Mind: How a Tiny Number of Genes Creates the
Complexities of Human Thought New York: Basic Books 2004.,