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Transcript
THE EVOLUTION OF LANGUAGE
Introduction
• Humans are the only species that has evolved an
advanced system of communication between
individuals.
• Whereas other species communicate through
ritualized and repetitious songs, calls, or gestures,
humans have developed linguistic systems that
can express a literally infinite variety of separate
and distinct thoughts.
• This incredible evolutionary leap is what
distinguished humans from all other organisms
on earth.
The Evolution of Language
• Language first appeared between 30,000 and 100,000
years ago in the species Homo sapiens.
• But how did language evolve?
• Currently, there are two rival answers to this question:
the first and more common explanation is that
language was an adaptation of some sort; the second
(chiefly espoused by Stephen Jay Gould) is that
language is a spandrel, a non-adaptive element arising
as a byproduct of other processes.
• We will consider these explanations in reverse order.
Language as a Spandrel
• Some people, Stephen Jay Gould most prominent
among them, believe language to be the
byproduct of other evolutionary processes, not a
special adaptation that arose by ordinary natural
selection acting on mutations.
• As Gould puts it, "Natural selection made the
human brain big, but most of our mental
properties and potentials may be spandrels - that
is, non-adaptive side consequences of building a
device with such structural complexity" (The
Pleasures of Pluralism , p.11).
• In other words, our ancestors encountered
environments which required the type of advanced
reasoning only provided by a larger brain; however,
language capability was not one of those functions for
which the brain was selected.
• Instead, language is a result of exapting neural
structures formerly used for other functions: "Many, if
not most, universal behaviors [including language] are
probably spandrels, often co-opted later in human
history for important secondary functions" (Ibid).
• This view has been reinforced by the famous
linguist Noam Chomsky, who argues that the
brain's language capability cannot be explained in
terms of natural selection.
• He attempts to explain the brain not through
biology or engineering principles, but instead
through the effects of physical laws.
• According to Chomsky, there may be unexpected
emergent physical properties associated with the
specific structure of the brain that explain
language.
Language as an Adaptation
• The mainstream view is that language is an
adaptation, evolved in response to some
selection pressure toward improved
communication between humans.
• This explanation is associated with many
speculative possibilities and proposals for the
adaptive function of language, and some (such as
Steven Pinker) postulate "mental modules" that
compartmentalize linguistic functions.
• There are many different possible "adaptationist" explanations for
the evolution of language.
• For instance, perhaps there was a need for improved
communication between hunters at some point in the history of
Homo sapiens, and oral expressions were simply the optimal way to
solve the problem.
• More plausibly (or at least more importantly), sharing information
between individuals probably conferred an extremely major
advantage: groups of humans with language, or even "protolanguage", could share a wealth of information about local hunting
conditions, food supplies, poisonous plants, or the weather.
• It would be extremely beneficial to the survival of all members of
the tribe if only one had to encounter a poisonous plant, rather
than each member having to rediscover the fact for himself!
• It is also simple to imagine a series of "oral gestures",
perhaps indicating the presence of an animal to
another person by imitating the animal's cries.
• Steven Pinker suggests in his book The Language
Instinct, "Perhaps a set of quasi-referential calls . . .
came under the voluntary control of the cerebral
cortex [which controls language], and came to be
produced in combination for complicated events; the
ability to analyze combinations of calls was then
applied to the parts of each call" (p. 352).
• Another possible source of selection pressure
towards better linguistic abilities is the social
group.
• Social interactions between people with widely
divergent or conflicting interests "make
formidable and ever-escalating demands on
cognition" (Ibid, p.368).
• Increasing cognitive ability could easily have
focused on the improvement of language as well,
since so many social interactions depend on
effective persuasion.