Category Archives: communication

On Combinatorial Construction of Language

Figure 1

It’s rather fortuitous that the article I’m about to discuss popped up right after my last post, a discussion of how critters’ need for audio-specific brain adaptations depends in part on the complexity of their vocalizations.

The piece of work I’m referring to is a relatively brief description of research on the putty-nosed monkey (figure 1). The finding is that these animals use two types of calls, so-called “pyows” and “hacks” in a combinatorial way: they string together these two words (if you will) to form longer phrases1.

The authors demonstrate that different combinations (pyow hack pyow pyow, vs. hack hack pyow pyow, or something to this effect) can code for distinct predators (leopard vs. hawk). Further, they indicate that novel combinations of the sounds elicit different group behaviors, and that the animals behave differently when the certain calls come from a within-group male rather than a stranger.

This smacks of the beginnings of language to me, in part because one feature of our sentential grammar is iterative construction. Noam Chomsky and others pointed out this method of building up of new sentences with new meaning by tacking extra bits onto the old ones.

References:

1. Arnolda, K & Zuberbühler, K (2008) Meaningful call combinations in a non-human primate. Curr. Biol; 18(5):R202-R203

On Quorum Sensing and Antibiotics

In your body, cells belonging to other organisms are more numerous than your own1. Most of these are not parasitic, we benefit significantly from some of our inhabitants. This is one of the reasons that traditional antibiotics are potentially harmful. Their action is indiscriminate, targeting both harmful and helpful bacteria. The wholesale killing off of our microbial boarders makes many vacancies, providing an opportunity for more virulent creatures to invade. As if this weren’t bad enough, left behind after a course of antibiotics are any bacteria that might have developed immunity to the drugs that put down their brethren. Thus, prescribing such medications also amounts to a selective pressure, an evolutionary nudge towards ever stronger infectors.

Once in your body, harmful bacteria must wait until their colony reaches a certain size for their attacks to be effective. This means that they must posses the ability to detect how many individuals of their species are present. Indeed, this behavior has been the subject of extensive research, and is referred to as Quorum Sensing (QS). The way this works is actually rather simple, each bacterium secretes a small molecule called an autoinducer (AI) at an approximately constant rate (in time and across individuals). Once the concentration of AI is high enough, the colony knows their population has risen to a level where the release virulence factors stands a good chance of successfully inducing pathology.


from reference 2

This example of cell-to-cell communication, in addition to providing a unique system to study such information transfer systems, presents an opportunity to attack unwanted microorganisms in a more species selective way. Thus avoiding both of the issues with antibiotics mentioned above.

Just such a feat was accomplished several years in the laboratory of Hiroaki Suga at SUNY Buffalo. This team of researchers was able to successfully reduce the virulence of Pseudomonas aeruginosa which is the main infectious killer of those with weakened immune systems, such as cancer, AIDS, and cistic fibrosis patients3. This was a great triumph, but another entry in this category has come along which further bolsters the case for attacking the bacterial-telegraph-system.

A group led by Kim Janda at Scripps was able to have a similar impact on Staphylococcus aureus. This bacteria is the main cause of infections in hospitals, and thus represents one of the strains most likely to evolve immunity to antibiotics4. Beyond this and in contrast to the earlier work, these authors were able to use antibodies to target the AIs, making the work potentially generalizable and inexpensive.

It is impossible to understate the beneficial effects that penicillin and it’s derivatives have had in western medicine. As we move forward, however, we must find ways to keep pace with our miniscule counterparts. These two examples of top notch research are exactly the kind of thinking that we need.

References

1. French, K. Randall, D & Burggren, W. (2001) Eckert Animal Physiology. W.H. Freeman

2. Waters, C.M. & Bassler, B.L. (2005) Quorum Sensing: Cell-to-Cell Communication in Bacteria. Annu. Rev. Cell Dev. Biol. 21:319–446

3. Smith, K.M. Yigong, B. & Suga, H. (2003) Induction and Inhibition of Pseudomonas aeruginosa Quorum Sensing by Synthetic Autoinducer Analogs. Chemistry & Biology 10:81-89

4. Park, J. Jagasia R. Kaufmann, G.F. Mathison, J.C. Ruiz, D.I. Moss, J.A. Meijler, M.M. Ulevitich, R.J. & Janda, K.M. (2007) Infection Control by Antibody Disruption of Bacterial Quorum Sensing Signaling. Chemistry & Biology 14:1119-1127

Ode to Sentences

Why are we so averse to long sentences? Is there some inherent property rendering them anathema to our natural mode of communication? There is certainly no grammatical rule excluding their use. In fact, some of the most gorgeous sentences in all of English prose are those which might be labeled run-on! Consider the following lead sentence from William Faulkner’s Absalom, Absalom!:

“From a little after two oclock until almost sundown of the long still hot weary dead September afternoon they sat in what Miss Coldfield still called the office because her father had called it that – a dim hot airless room with the blinds all closed and fastened for forty-three summers because when she was a girl someone had believed that light and moving air carried heat and that dark was always cooler, and which (as the sun shone fuller and fuller on that side of the house) became latticed with yellow slashes full of dust motes which Quentin thought of as being flecks of the dead old dried paint itself blown inward from the scaling blinds as wind might have blown them.”

Or the following from James Joyce’s Finnegan’s Wake:

(To say nothing of course of the ends of either Wake or Ulysses, which descend into language completely lacking in punctuation.)

“His husband, poor old A’Hara (Okaroff?) crestfallen by things and down at heels at the time, they squeak, accepted the (Zassnoch!) ardree’s shilling at the conclusion of the Crimean war and, having flown his wild geese, alohned in crowds to warnder on like Shuley Luney, enlisted in Tyrone’s horse, the Irish whites, and soldiered a bit with Wolsey under the assumed name of Blanco Fusilovna Bucklovitch (spurious) after which the cawer and marble halls of Pump Court Columbarium, the home of the old seakings, looked upon each other and queth their haven ever more for it transpires that on the other side of the water it came about that on the field of Vasileff’s Cornix inauspiciously with his unit he perished, suying, this papal leafless to old chap give, rawl chawclates for mouther-in-louth.”

The former is perhaps a bit more intelligible at first blush than the latter, but both prove a point. Long sentences allow for a different kind of expressive hue.

Beyond their aesthetic appeal, the existence of (semi) meaningful long sentences serves another purpose: they speak to one goal of Noam Chomsky’s theory of generative grammar.

In brief, linguistics prior to Chomsky was a taxonomic science, sure in the descriptive quality of its program to catalog the “corpus” of a language: all the phonemes (sounds) and morphemes (combinations of sounds). Amongst several issues Chomsky raised with this system was the fact that there are an infinite number of possible sentences, making any attempt to index them an impossible task, and generally pointing to the inadequacy of such a strategy. Beyond this, however, Chomsky was interested in exposing some sort of mentally internalized grammar, some system at work in each of us when we compose sentences.

The standard example cited to demonstrate that there are unending possibilities for sentence construction is an example of some iterative procedure such as: “The man whose house had a roof that sagged at the point where the ladder had fallen when the repairman lost his balance while looking at the woman who was passing because…” In my opinion, these examples don’t really go far towards characterizing such a lumenous system for building sentences because we do not use anything like them in speaking or writing. Though we are clearly capable of deducing the meaning of the instance cited above, the fact that we don’t employ them also speaks to the nature of whatever subconscious lingual machinery we’ve got.

I suppose I’ve not clarified the question of sentential length, but what I have tried to do is point to the fact that sentence length is somehow reflective of the possible modes of expression that one can achieve as defined by our personal grammars. Perhaps we will find that as we evolve, the need for ever more subtle communications will lead to long dense sentences like those above. Another possibility is that such objects will remain in their traditional home of stylized prose. In any case, none of us should be afraid of the dreaded run on.

Trees Can Talk to Each Other

How do plants converse with each other? As human beings, we posses probably the most sophisticated communication abilities of any species on the planet. This makes it very easy for us to forget that every form of life has some ability to transmit information between individuals. This is true even at a microscopic level where bacterial cell-to-cell signaling is a popular research topic (ref 1).

Having been around for a very long time and being unable to move much, it is no surprise that plants have developed many sophisticated adaptations for the purpose of communication. Plants can communcate in a host of ways, see (ref. 2) for a brief overview. One of the most fascinating of these is the use of “smoke signals.”

Ten years ago, researchers interested in plant biology and forest fires discovered that exposing seeds to smoke or certain nitrogenous compounds in smoke will induce germination (ref. 3). The evolutionary advantage of this behavior is presumed to be that forest fires leave an area rife for new growth.

The greater significance of this ability is our ongoing opportunity to learn from biological organisms. Although we use our intelligence to guide us in solving problems, we still use trial and error extensively. The greatest expert on trial and error is evolution. The process of evolving progressively more sophisticated life forms has relied on the use of trial and error for the last 3.7 billion years, and we would do well to realize that when it comes to the challenges of existing on earth, we’ve got a teacher who’s got a valuable store of experience.

References

1. Melissa B. Miller & ­ Bonnie L. Bassler Quorum Sensing in Bacteria Annual Review of Microbiology 55: 165-199 [doi:10.1146/annurev.micro.55.1.165]

2. Ragan M. Callaway & Bruce E. Mahall Plant ecology: Family roots Nature 448, 145-147 [DOI: 10.1038/448145a]

3. Jon E. Keeley & C. J. Fotheringham Trace Gas Emissions and Smoke-Induced Seed Germination Science 276: 1248-1250 [DOI: 10.1126/science.276.5316.1248]