SETI bioastro: Explaining why language evolved isn't so easy

From: Larry Klaes (lklaes@bbn.com)
Date: Thu May 04 2000 - 05:40:40 PDT


Explaining why language evolved isn't so easy

No matter how much language a chimpanzee is able to use, there is still a
huge gap between it and us. After all, we don't just have language - we
have Shakespeare. But the question for scientists is, where did language
come from?

Linguist Noam Chomsky has, from time to time, speculated that something
sudden and extraordinary must have happened to the human brain to equip it
with language - something even outside the realm of normal evolution. Most
linguists with a biological bent don't buy that, but they've had a tough
time showing how language could have evolved in the same way as our colour
vision or two-legged posture.

Now, however, some progress is being made. Researchers at the Institute for
Advanced Study at Princeton University (where Einstein spent his last
years) have recently used game theory to reveal how language has
significant survival value.

Game theory is a way of quantifying the benefits or disadvantages of a
given behaviour. So for instance, if all the powerful males of a species
are busy displaying their colourful plumage to females, game theory might
suggest that there is an opportunity for small, plain males to sneak in and
mate with one of the female onlookers. However, game theory would also
predict that there would be an upper limit to the number of such males who
were successful.

Game theory can also be applied to the evolution of language. Why are
thousands of languages world-wide assembled from sounds and words put
together in a certain order governed by sometimes complicated rules?

Is all that complexity actually necessary? David Premack, one of the first
to attempt to teach language to a chimp, once wondered if it would have
been necessary for our ancestors to be able to say: "Beware of the short
beast whose front hoof Bob cracked, when, having forgotten his own spear
back at camp, he got in a glancing blow with the dull spear he borrowed
from Jack."

Martin Nowak and his colleagues seem to be in the process of answering
Premack's question by showing how important steps in the increasing
complexity of language would have benefited those using it.

You have to begin with the assumption that some sort of slick communication
system, like language, would be useful to social animals like humans in the
first place. That seems pretty obvious. But Nowak's group has added two
critical steps.

One is that language is like the old game of broken telephone: errors
inevitably creep in. You could create a rudimentary language with just the
sounds of vowels, but as the need to communicate more and varied
information grew, you would have to recruit new sounds. The more there
were, the more they would begin to sound like each other. However, you can
keep the number of different sounds at a manageably low number by stringing
them together to get the variety you need.

This is just the process of putting letters together to make words. It
multiplies the possibilities: "god" and "dog" do not require different
sounds.

Game theory says that this ability would have survival value for
individuals who are sending and receiving messages all the time.

Nowak's group have now used the game theory approach to show that once
language appeared, it wouldn't be long before sentences and rules for
ordering the words in them would appear.

Adding new words for every new experience is a losing proposition: it makes
much more sense to use one word in different ways by moving it around in
the sentence: "Dog bites man" versus "man bites dog."

One big advantage of using the same word in different ways is the reduction
in the total number of words you have to remember. It also means you can
talk about new things that there are no words for.

But nothing comes without a cost. Word order gives language flexibility,
but you must pay attention to it, attention that wasn't previously
committed. But again game theory shows that paying attention is worth it
whenever life is complicated and lots of messages are being exchanged.

We have never in our long evolution been a physically impressive species,
but we have been communicative. Yes, a big brain is crucial, but it's the
language created by that brain that made us human. Literally.

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