Wednesday, August 11, 2010

ant synonyms and linguistics envy

A cute analogy: Similar molecules which differ slightly in chain length cause similar behavioral reactions in ants. Therefore, similar chemicals are like lexical synonyms in human language. This is a rough paraphrase of the brief post Chemical Ant Language Has Synonyms.

But is the analogy valid?

The blog was referring to a study that investigated what appeared to be a pretty straight forward stimulus-response reaction. Ants were exposed to a variety of chemicals which differed minimally and their reactions were recorded. Upon first pass, it appears as though no sort of cognitive processing occurred in the ants (I cannot speak with any authority on the state of cognitive processing in ants, but I'm guessing it's limited at best). The blog post author took the sysnonym analogy straight from the original study Deciphering the Chemical Basis of Nestmate Recognition (full citation below). From the abstract:

This study contributes to our understanding of the chemical basis of nestmate recognition by showing that, similar to spoken language, the chemical language of social insects contains “synonyms,” chemicals that differ in structure, but not meaning (emphasis added).

Linguists have been justly accused of having both physics envy and biology envy for our tendency to borrow concepts from those fields to help understand linguistic processes. This, however, may be a case of linguistics envy. The use of language as a metaphor for anything remotely communicative is all too familiar to many of us and typically wrong. And the public's love of animal language stories fuels the fire.

Clearly the findings are interesting to the extent that they show a certain categorical response. Apparently ants respond to a set of chemicals in a similar way and this set of chemicals might be loosely compared to a set of synonyms like run, jog, trot, scurry, scamper, sprint, etc. But the most interesting thing about lexical synonyms is that they DO differ in meaning and distributional properties. Even if the differences are nuanced, they are real. Their semantics are related, but it's the differences that are the object of linguistic inquiry. So, if the ant response is to be a viable analogy to lexical synonyms, we're going to have to see that each chemical variant produces a similar but interestingly different response in ants.

Now, what might be a closer linguistic analogy is that of phonemes. Here we have a well undersood phenomenon whereby a set of similar but interestingly different sounds are perceived as belonging to a single class. There is also the interesting categorical perception phenomenon where slight differences in sounds can be perceived as whole category differences, not unlike molecules of different chain length causing a similar reaction in ants (I think).
Wilgenburg, E., Sulc, R., Shea, K., & Tsutsui, N. (2010). Deciphering the Chemical Basis of Nestmate Recognition Journal of Chemical Ecology, 36 (7), 751-758 DOI: 10.1007/s10886-010-9812-4


Michael Scott Long said...

I never meant to imply that ants communicate on a level comparable to humans.

On the other hand, your main point that I was fast and loose with the term "synonym" bears consideration. In my defense, however, in the text of my post, I did put "chemical synonyms" in quotes. Again, your thoughts have given me something to think about.

My posts often talk about things like "synthetic cells" and "synthetic genomes," but I always try to be careful to explain how they're nowhere near as complex as a real cell or a real genome.

Incidentally, ants can solve problems, and honeybees have a limited sense of numbers, suggesting that their cognitive abilities may be under-appreciated.


Chris said...

Scott, thanks for the thoughtful response. I certainly didn't mean any critique of your post. I enjoyed it. It just sparked a thought about what a synonym really is and why they're interesting. I do think the phoneme analogy might be more accurate for the ant behavior the study reviewed. And I'd be interested to find out more about what sort of cognitive processing may or may not be involved. Again, I know nothing about ants and little about chemistry.

Michael Scott Long said...

I admit that I had to look up the word "phoneme." I'm not a linguist, so maybe you can help me out here.

As I understand it, two words are synonyms if they have very similar yet sometimes distinguishable meanings, and a phoneme is the smallest unit of speech that distinguishes one word from another.

If my definitions are right, then the chemicals in the ant research could be classified as either synonyms or phonemes, depending on the chemical (and the phoneme results are possibly more interesting than the synonym results).

For different chemicals that elicit a different ant aggression response, the difference between the chemicals is the phoneme.

For different chemicals that elicit the same ant aggression response, the chemicals are synonyms (they could one day elicit different responses because the chemicals are in fact slightly different).

Am I off-base here? I appreciate the chance to sort out issues like this with people who clearly know a lot more about a topic than I do, and I always like commentary on my blog posts.


Chris said...

Scott, happy to discuss this more. When thinking about phonemes try not to think about words. Phonemes are best thought of as a set of sounds that are treated as one within a language. A good example from English is aspirated stops.

Try this (I used to have my intro to linguistics students do this): Put your hand about 2 inches from you mouth and say the words pit and spit one after the other two or three times. If you're a native speaker of English you should be able to notice that the /p/ in pit produces a short burst of air (called aspiration) but the /p/ in spit does not. It turns out that English speakers aspirate voiceless stop consonants when they occur at the beginning of syllables like pit but not when they are syllable internal like spit. You should find similar results with /t/ and /k/.

This is a variation in the physical phonetic realization of the single phoneme /p/, but we still consider both of them to be examples of /p/. Not all languages do this, btw. Hindi would consider them different.

So we can say that English has a single /p/ phoneme with two phonetic realizations.

Now let me step out of my comfort zone and into yours. Let's look at sugars of which there are various molecular realizations because it refers to a class of carbs including sucrose, lactose and fructose (thank you Wikipedia! haha). They are similar but interestingly different and they all are referred to as sugars.

Off the top of my head, I don't know if sugars are better analogized as phonemes or synonyms. What do you think?

Michael Scott Long said...

I now definitely think your phoneme interpretation of the ant research makes more sense.

What the scientists seem to be doing is making phonemes of each other. Adding an extra methyl unit means that one of the hydrogen atoms in the molecule has been replaced by the methyl unit. You've changed one "sound" (the hydrogen atom) for another (the methyl unit), making something entirely different in the process, which the ants may or may not be able to distinguish.

For two molecules to be synonyms, they'd have to be entirely different on a structural basis, yet still elicit generally similar responses from the ants. Teacher and instructor are words of similar meaning, but have a different number and arrangement of letters.

If molecule A, entirely and fundamentally different from molecule B, elicits the same response from an ant as molecule B, molecules A and B are treated as synonyms. If molecule A only differs from molecule B by one very small chemical subunit, as in the ant research, and a different ant response is observed, phoneme may be the more appropriate classification.

Glucose, fructose, etc are definitely structurally different, but they're also similar (same number of hydrogen, carbon, and oxygen atoms), so I think the phoneme vs synonym classification could go either way in that case.

Assuming you've helped me get on the right track here, this has been very useful -- thanks! I'm linking to this whole discussion on my blog post to clear things up.


Chris said...

Scott, yes, I think you're onto the right idea. Synonyms are structurally different, but elicit similar responses ("meanings") while phonemes are sets of structurally similar items. that rough first pass, anyway.

Sean Roberts said...

Another way to think about this is optionality. Just as a human may choose to say 'teacher' or 'instructor' or a bilingual may choose one language over another, ants respond in the same way to different molecules (of course, ants don't 'choose' the molecules, but bear with me).

Optionality is found at all levels of language. Perhaps a closer analogy to chemical compositions is optionality in syntax. I could say "Mary gave John a book" or "Mary gave a book to John"- slightly different orders with the same basic meaning. If I change the order too much, the meaning becomes different (e.g. John gave Mary a book).

A related set of studies is interspecies communication where, for example, Diana Monkeys respond to alarm calls of their own species and also Campbell's Monkeys (Zuberbuhler, 2000).