October 18, 2006

Listening in on Our Ancestors

What if I told you that with all the structural complexity of our language-written and vocal-at its very base, is no different than communication between bacteria?

It is not too foreign of a concept, considering that the beginnings of life were in fact bacteria, which congregated into giant colonies, forming structures called stromatolites 3,500 million years ago. These stromatolites lined the salty, otherwise lifeless beaches of the planet, rising to heights of dozens of feet, monuments of a greater future under a new sun. Communication between these organisms was necessary for any attempt at joint effort.

Are we any different? Basically our bodies are nothing more than the result of the cooperation of tens of trillions cells passing information-genetic and chemical-to regulate the macro organism, the human being. Every cell is connected, streaming all sorts of vital information-regulation of nutrients, presence of outside stimuli, reaction measures and presence of alien substances.

Recent research exploring colonial bacteria has illustrated the level of linguistic complexity within these colonies. Modern theoretical linguistics has opened studies of communication in many fields, including biology, and given us a view of language as entirely structural; "words" (or chemical signals analogous to words) have no inherent meaning, only the meaning that one applies to them.

From an evolutionary perspective, this rings true. There are myriad examples of one structure becoming useful in another function (exaptations): lungs becoming useful as swim bladders, sturdy fins become useful as walking legs, insulating feathers become useful in staying aloft, etc.

The same goes for biochemical elements. A molecule by itself has no inherent function until it is contextualized, placed in a functioning system.

Communication among bacterial colonies is incredibly complex. They exhibit the same basic social intelligence observed in human beings. (Social intelligence is a term applied to the functions of the mind outside of academic pursuits, specifically the exchange of information to organize in groups, and therefore exhibit a group identity.)

Experiments have exhibited specific examples of such behavior. The phenomenon of antibacterial resistance (a looming, potentially catastrophic problem in the future) has provided scientists with a chance to observe colonial propagation in the face of destruction. The bacteria resistant to the agent are able to exchange chemical information among the survivors, relaying their dire situation. The individuals respond in concert, immediately initiating conjugation. The colony begins replacing the lost members with new, resistant ones.

They identify in this manner as one organism. Mass communication has allowed the United States and other information age nations to respond similarly to catastrophic events. September 11 comes to mind.

The complexity deepens. In starvation conditions, most bacteria are able to assume the form of spores (through sporulation). These spores are incredibly durable (many can survive the vacuum of space), and do not need to feed in order to persist. When conditions become favorable again, the bacteria can change back into a fully function individual. In colonial species, the bacteria can detect the nature of the environment (food or no food) and notify the rest of the colony by releasing biochemical messages. Each individual is able to receive the message, evaluate the circumstances and "vote" on whether or not the colony should sporulate.

Species-specific communication within the colony has to be fine tuned and complex since, in the natural world, colonies coexist with dozens of other colonies of other species, sending their own messages in their own languages.

Our mouths are a perfect example of this. At any given time, you have about 20 species of bacteria inhabiting the tissue of your gums, each trying to organize feeding and procreation (at least until the next time you brush). Their messages need to be clear and purposed-as scant molecules among trillions-to extend the life of the colony.

These are just a few examples among dozens (among hundreds as more research is done). The entire story, however, cuts deeper, closer to home.

In each one of these cells lies the secret to our success: energy producing structures called mitochondria.

Mitochondria generate the flow of energy that makes everything possible, gleaning ions from the constant stream of nutrients into our mouths, absorbed through our digestive tract. They have made our lives as multicellular, eukaryotic organisms possible.

Mitochondria have their own genetic information, their own blueprint for life, distinct from the blueprint for our own body, making them the odd structure out in the plan of the cell. So odd, in fact, that scientists think that this is enough evidence to posit the mitochondria as a benefactor from the ancient past; in essence, the mitochondria is a separate entity in the cell, a life giving, incorporated bacterium in each of our cells.

We have not left our past behind. Our lives depend on it.

Originally published here.

1 comment:

  1. Wow!

    Everytime I visit your site, I learn something new. Thank you!

    ReplyDelete