Why has language only evolved once?

[koganbot]

I'm reading a book by Terrence W. Deacon called THE SYMBOLIC SPECIES: The Co-evolution of Language and the Brain that I pulled off the philosophy shelf at Barnes & Noble and then borrowed from the library, and I'm loving it. The author is unknown to me (which doesn't tell you anything about how well-regarded he might be; but a book that's on store shelves a decade after it was published is sure doing better than my book), I don't have the background to evaluate whether he's doing right by the information he's drawing on, and I don't know the linguistics discourse he's responding to so am only provisionally assuming he's right in his presentation of other people's ideas.

What I like is that he asks questions, and they seem like good questions, and it seems to make sense that he's asking them. Here's something that needs to be explained, he's saying, and he's saying that he doesn't like the explanations given so far, so he's going to come up with his own.

Deacon was talking to an elementary school class, and an eight-year-old asked him, "But don't other animals have their own languages?"

Deacon responded by explaining how human language is different from any other form of communication in its precision and its capacity to combine elements logically but with open-ended possibilities.

"Do animals just have SIMPLE languages?" the kid continued.

Deacon said that though animals have calls and such they have nothing like words, nouns, verbs, or sentences.

Another child asked, "Why not?"

And this stumped Deacon, who had no idea how to answer. So he poses a question in his preface: "Why are there no simple languages with simple forms of nouns, verbs, and sentences?"

This leads to another question: why has language only evolved once? If animal communication is a primitive or less-developed form of human language, the only difference being capacity, it would seem preposterous that over 650 million years no other creature similarly developed the use of words, nouns, verbs, and sentences, even in simple form, and that no current creatures have anything like sentences. (I'm not sure that this is altogether true, this last bit, but my guess is that it's true enough.) Human language is an anomaly that has to be explained. Deacon uses the analogy of fur and porcupine quills; it would be ludicrous to say that all fur was a primitive form of porcupine quills.

And here he puts forth a hypothesis that I wasn't expecting. He suggests that to acquire human language would conflict with some normally advantageous feature of animal communication; that to develop or (if you're a pet, say) learn a language would require something analogous to the unlearning of useful communication skills and their replacement by others. So it would be rare for evolution to select for the loss of adaptive communication skills, even though these skills interfere with the development of something potentially more adaptive: language.

So that's where Deacon starts. He goes on to try to explain what we've got that animals don't - basically, our way of relating words to other words - and what interferes with this, which is the ability to tie specific signs to specific other phenomena, an ability that animals do have. This section of the text is murky, but if I understand Deacon right, the "unlearning" involves a shift in attention from what we've actually experienced as associating with something else and replacing it with knowledge of what can associate with something else, whether we've seen it or not.

Deacon doesn't like the concept of Universal Grammar, that our grammatic ability is built into our brains, because he doesn't think it explains anything. He says that it tells us that we have the skill, but it doesn't explain how we got it. He tries to develop a more useful explanation. I don't have time to post about it now, but it involves both something like "unlearning" (more accurately, "not learning too soon") and the idea that languages evolve much faster than human brains do, and that the basic features of language must evolve so as to be learnable by toddlers, so in effect toddler brains are the instrument of natural selection for the basics of human language.

I'm about a third of the way through.

Comments

[martinskidmore.livejournal.com]

The totally simple answer to that development is that if language is an evolutionary advantage, in being able to warn about more complex dangers than just 'snake!', in being able to cooperate and plan better, for instance, then natural selection favours those with brains that can handle it. From what I know about baby and infant brain development (quite a bit!), there are huge numbers of connections made, then they are whittled down or reinforced according to their value. A very simple linguistic example is that Japanese babies don't need the ability to distinguish the sound R from L, so lose it - nothing genetic there, entirely environmental. That particular example has been very well researched, but is too basic to help us much, though I would say it could be that there may be abilities potentially in the baby brain to handle a whole range of different types of grammar, and in the same way some are discarded and some strengthened as they proof useful or irrelevant. We don't by any means need to assume a natural ability in some platonic grammar. (This is an argument for the Sapir-Whorf hypothesis, that language shapes the way we can think.)

Nonetheless, assuming greater inborn talent for some structures than others doesn't seem implausible either, though I have no idea how we could study or prove this. Natural selection and the tendency of incremental development of language can reinforce each other as time goes on.

I am not expert enough on different languages to know how wide the diversity of grammars might be, but I have read bits that suggest some work in ways that I can't get my head around at all - this may suggest that there is no basic pattern that the brain naturally prefers, but I am sure there is a vastly greater range of possible grammars than I could ever remotely imagine. We need to meet a range of aliens, see how theirs work.

[koganbot]

Well, if language is simply an evolutionary advantage, then it should have evolved time and time again in the 650 million years since multi-cellular creatures appeared. So Deacon is asking what blocked (and blocks) other animals from evolving it, and what is the human difference that didn't/doesn't block it for us. He argues that "brain size" isn't an explanation either, since if the brain evolved in concert with language (the subtitle of the book is The Co-evolution of Language and the Brain) we'd expect that other animals could have evolved larger brains once they got language, for the exact same reason we did. (There are structural reasons why we can support large brains, but those structures evolved in us, and I'd expect they could have evolved in other creatures too.)

[martinskidmore.livejournal.com]

It's very hard to come up with an explanation for language that doesn't involve it being an evolutionary advantage - and it's easy to see lots of ways in which it is, so I am not really inclined to doubt that. We could say the same about making tools - a few animals use tools in some simple ways, but none make them. There are quite a few things that have only evolved once, so the fact that it hasn't happened more than once is no evidence for it not being advantageous. I don't find it hard to believe that a combination of a particular environment, vocal apparatus that had some flexibility, a certain kind of social structure, brains big and complex enough and maybe other factors (a wide range of dangers from many directions, say) combined to make the start towards advanced language a useful and possible thing. I don't think we have any precise knowledge of when it evolved (hard to see how that could be determined), so the above is admittedly vague speculation.

If we assume that some such combination of factors might be needed to make it both possible and useful, and believe that they are rare, which I suspect they are, we don't have to explain why it didn't happen with, say, other primates. Evolution has never worked by finding one perfect solution, it works by sort of random (well, within complexity and chaos theory!) chance and some things working - the advantage may have been small at first, or it may be that other creatures managed the same sort of communication and cooperation in other ways, so didn't need it. Those ways may have been more limited, but enough to mean our kind of language in its early stages couldn't provide them with significant extra advantages, so wouldn't take hold.

I am strongly suspecting some teleological tendencies in the arguments you are quoting. Maybe not, but it reminds me of a lecture I went to some weeks ago about what alien life would be like, which succumbed to the usual tendency to think that what we have as evidence (life on Earth) is pretty much the way it inevitably has to be, so alien life will therefore be pretty similar to ours. Anything leaning towards universal grammar makes me think of that weak argument.

[martinskidmore.livejournal.com]

Actually I am being a little unfair to the lecturer, in that he did try to justify his reasoning, by thinking through what seemed necessary and what didn't, but I thought he did a poor job of that. For instance, claiming a support structure something like a skeleton was necessary was unconvincing given the huge and very long success of cephalopods, for instance. Still, sensory apparatus and ways to process that, preferably near the apparatus to process with maximum speed, is a sensible basic requirement, so his arguments were far from worthless.

[koganbot]

Deacon is being the opposite of teleological. He's not arguing that language must have eventually developed or that events happened in the past so that it would develop, or that it was somehow waiting to happen. He's arguing, as you are, that the circumstances are obviously rare, that language is an anomaly, not a pre-ordained outcome. But he's giving a real interesting explanation as to why it's rare, one I'd never heard before.

I'm not sure where your line of thought is different from Deacon's, actually, except that your simple statement "language is an evolutionary advantage" doesn't explain why language is rare. It seems to me that we have at least two alternatives here: (1) proto-language, proto-grammar, is only a selective advantage in rare circumstances; and (2) proto-language is only possible in rare circumstances, and once those circumstances arise it's got an obvious selective advantage. Of course, there can be ways of mixing the two - e.g., language can be possible only in fairly rare circumstances and can be a selective advantage in only fairly rare circumstances, and the two obviously have to occur together. And I'll see where Deacon ends up, because he's trying to put together the outline of a story of how language and the brain evolved together.

[jauntyalan.livejournal.com]

-- Well, if language is simply an evolutionary advantage, then it should have evolved time and time again

consider the prerequisites for language to develop to be achievable, then your 'why has language only evolved once' could also becomes why is there only one species in the genus 'homo', and so on.

[jauntyalan.livejournal.com]

what's fun about this is the proliferation of theories because there isn't a fossil record to check with. it's a lot of clever ideas covering various fabulous grounds, some productive and suggestive, but with no decisive winner.

not only is there no record, but we are so far ahead in linguistic complexity to the 2nd-place species (whatever that might be considered to be) that it's everyone's guess what of the many differences contributed.