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Language competence in non-human primates

Lieven Vandelanotte lieven.vandelanotte at student.kuleuven.ac.be
Tue Apr 27 13:12:19 EST 1999


Dear readers of alt.biology, bionet.neuroscience and bionet.general,

At http://pages.hotbot.com/edu/nhp.language, a paper discussing the
linguistic abilities of apes was published last week. Some of the main
arguments are inserted below.
This type of research seems relevant (among others) to the question of
the evolution of language. The suggestion of Savage-Rumbaugh, explained
further in section 2.8 (A glimpse of the evolutionary approach) of the
online paper, is that language is a kind of evolutionary by-product of
developing bipedalism. That is to say that the language competence was
already there, but was only 'realized' once our vocal apparatus was
suited to produce consonants. The selective benefit of language to our
species (which is not altogether well protected due to our bipedalism)
would then lie in the enhanced ability to plan ahead, to make social
arrangements, etc.
Any thoughts on the subject?
Can any of you deny or confirm that current evolutionary biology favours
gradual mutations above sudden, giant mutations (cp. infra, abstract)?
Can anyone confirm or deny that the only difference between the brains
of humans and of apes is a *quantitative* one (i.e. that there are no
new *structures* to be found in apes' brains)?
And do you believe that studying PET scans of apes' brains is relevant
to determining the extent to which they have a basic language faculty,
comparable to ours?

Kind regards, LV

(Abstract inserted below)

Language competence in NHPs
An assessment of the field in the light of a 'universal grammar' 
Main argument
http://pages.hotbot.com/edu/nhp.language
nhp.language at hotbot.com

[This 'abstract' consists of scraps of emails, and some quotes from the
online paper. For a full account of it, please visit the nhp.language
website, where you can read the paper online.]

The second section of the online paper, called 'Kanzi and Beyond',
should demonstrate that apes are definitely capable of a far higher
level of language competence than merely using a 'banana' symbol in
order to obtain a banana, as long as they are raised like children, i.e.
exposed from an early age to a language-rich environment (without
explicit, formal trial and reward training):
" Symbolic communication arose spontaneously in Kanzi, "without the need
for shaping or planned reinforcement of specific skills"
(Savage-Rumbaugh et al. 1996:176). He understands the meaning of both
lexigrams and spoken English. Vocalizations, glances and gestures are
used to reinforce his intentional communications, and his utterances
show some grammatical structure. Such constructions as recursion and
conditional sentences are understood by Kanzi (e.g. "Kanzi, if you give
Austin your monster mask, I'll let you have some of Austin's cereal",
Savage-Rumbaugh and Lewin 1994:170). " (Belsack et al. 1999: online)
Of course, we cannot and should not expect apes to communicate as humans
do (cp. infra). They will never ever talk to us, and they will never
ever communicate at the same level as we do, using some other means of
communication (such as sign language or lexigrams - arbitrary geometric
symbols). This is no reason to go on pretending that the question
whether they have a language faculty is a simple yes-or-no-question. It
has been convincingly shown in Savage-Rumbaugh et al. 1993, a
comparative study between the well-known bonobo Kanzi and the human
child Alia, that they do acquire the level of 2 to 3 year old children
in. Contextual cueing (the infamous "Clever Hans Phenomenon" was
precluded by placing the experimenter behind a one way mirror, where he
or she was invisible to Kanzi and/or Alia.)
A "protogrammatical ability", comparable to that in a 2,5 year old
child, has equally been demonstrated for Kanzi. Among the thirteen
sentence types for which he and Alia, a human child, were tested, was
one that included recursivity ('Go get the carrot THAT IS in the
kitchen'). Some grammatical rules have also emerged from a study of
Kanzi's two and three symbol productions. (cp. '2.5 Kanzi's grammar' in
Belsack et al. 1999:online)
As already mentioned in passing, there are insurmountable upper limits
to an ape's abilities: its vocal apparatus does not allow it to produce
consonants (and it's consonants that allow us to divide the continuous
air stream we produce as we speak into meaningful units), and its brain
size is only a third of ours. Note, however, that the latter is only a
*quantitative* difference: no evidence of any different structure has
been found up to date. This implies that Chomsky's idea of a language
module or language acquisition device unique to human beings remains
entirely speculative (of course, there is nothing wrong with speculative
hypotheses as such). All the areas that are taken to be associated with
language, such as Broca's and Wernicke's area, are also present in apes'
brains.
Of course, language is presumably innate at some level in evolution. We
would not want to attribute a language faculty to an oyster. Innateness
does not, however, necessarily imply uniqueness, as Chomsky would have
it. His theory suggests some sort of vast unbridgeable gap between
animals and humans, very much like Descartes, to whom animals were
'automata' ("machines" deprived of any rational thought). It is hard to
understand why he relentlessly resists the idea of a continuum of
language faculties - and in fact, even closes off the debate ("There is
no debate, so I have no opinion", "The question whether it has a
language faculty is a meaningless question and therefore nobody should
talk about it"). Apparently, current evolutionary biology tends to
disprove sudden giant mutations (such as the one that would be needed to
support Chomsky's view), preferring instead gradual, smaller mutations.
The main argument for positing a uniquely human brain structure
responsible for language acquisition seems to be the fact that children
start producing utterances virtually without mistakes, even though
parents don't correct grammatical mistakes.
The point stressed by Savage-Rumbaugh and by Elizabeth Bates (important
researchers in ape and child language acquisition, respectively), is
that comprehension precedes production in normal language acquisition.
(There is empirical evidence for this.) Because children and infant apes
already understand a great deal before they actually begin to produce
utterances, they do not make many mistakes - and the ones they do make,
are usually overgeneralizations of rules (e.g. verb forms such as 'I
goed'). Note that comprehension is in a sense more fundamental and more
difficult than production (whereas Chomsky's transformational grammar is
very much a 'production' grammar): it is easier to put your own ideas
into words, than to understand what other people have to say, as the
latter precludes foreknowlegde: you do not know what the other is going
to say. This also provides a motivation for the child to learn language,
as it wants to know what the other person is going to do (to it).
Incidentally, it would appear that parents *do* tend to correct
grammatical mistakes of their children. In addition, the Chomskyan view
of semantics seems (on the face of it) extremely simple. There is far
more to learning how to use symbols than simply learning a word list
(see the section '2.3.2 Learning how to mean' in Belsack et al.
1999:online).
So much for Chomsky's arguments, and possible counterarguments. The
ultimate *reason* why he doesn't even consider the possibility of a
continuum remains as much a mystery as how children (or infant apes)
come to understand that words refer to things, events, etc. Only the
second mystery ("Quine's dilemma") is far more fascinating :-) The
problem with Chomksy's position in linguistics is that he is almost
revered by many of his 'followers', leading to a rather dogmatic,
non-open-minded brand of TG. For similar critiques on Chomksy's
scholarly attitudes, see Seuren 1998.
" In sum, recent research on language in non-human primates is a model
of critical but open-minded, multidisciplinary scientific research,
carried out with the greatest methodological concern. In addition, it
has been of immense 'practical' importance to severely mentally retarded
children and their families, as it was found that lexigram keyboards can
be used succesfully to allow such children to communicate in spite of
their handicap (cp. Savage-Rumbaugh and Lewin:chapter 7). On the whole,
it is extremely sad that a significant part of the scientific community
is not even prepared to engage in a serious debate of some sort. "
(Belsack et al. 1999:online)

Reference list

Belsack, Marian; Peter De Gryse; Vincent Spincemaille and Lieven
Vandelanotte (1999). Language competence in non-human primates. An
assessment of the field in the light of a 'universal grammar'. Online
publication at http://pages.hotbot.com/edu/nhp.language.
Savage-Rumbaugh, E. Sue; Jeannine Murphy; Rose A. Secvik; Karen E.
Brakke; Shelly L. Williams; and Duane M. Rumbaugh (1993). "Language
Comprehension in Ape and Child". With Commentary by Elizabeth Bates and
a Reply by E. Sue Savage-Rumbaugh. Monographs of the Society for
Research in Child Development, 58 (3-4, Serial No. 233).
Savage-Rumbaugh, Sue and Roger Lewin (1994). Kanzi: The Ape at the Brink
of the Human Mind. London: Doubleday.
Savage-Rumbaugh, E. Sue; Shelly L. Williams; Takeshi Furuichi; and
Takayoshi Kano (1996). "Language perceived: Paniscus branches out". In
W. C. McGrew, L. F. Marchant and T. Nishida (eds.), Great Ape Societies.
Cambridge: Cambridge University Press. 173-184.
Seuren, Pieter A.M. (1998). Western Linguistics: An Historical
Introduction. London: Blackwell.



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