Wednesday, March 31, 2010

Bacterial Sentience? Intelligence? Civilizations?

What counts as “intelligent life” and who (or what) possesses it? These are the central questions raised in Slonczewski’s Children Star. As mentioned in class on 30 April, the difficulty we face in pinning down a definition of “intelligent life” in the novel stems from the author’s use of many different words with overlapping meanings. For example, the novel assumes that intelligent life is sentient, but not all sentient life is intelligent. The characters’ struggle to define intelligent life mirrors our own philosophical and biological struggle to decide what makes life intelligent, or at least sentient. Though sentience is roughly understood in the novel—witness the protesting electric sentients fighting for their civil rights—intelligent life is harder to recognize. Unfortunately for the creatures of Prokaryon, the answer to this question will determine the rest of their lives, intelligent or not.

Questioning the boundaries of sentience and intelligent life is not confined to science-fiction. Like Sarai in her mountain laboratory studying microzooids in hopes of understanding their behaviors, Jacob, Becker, Shapira, and Levine,[1] study bacterial growth patterns and argue that some bacteria, like Paenivacillus vortex and Paenibacillus dendritiformis (pictured top left), are not only sentient, but intelligent as well (assuming intelligent life is necessarily sentient). The researchers base this conclusion on these bacterial colonies’ abilities to “cooperatively make drastic alterations to their internal genomic state and transform into different cells (369).” Bacteria, like humans, are able to transfer genetic material between themselves, i.e. sex, however, unlike humans, bacterial “horizontal genetic transfer” does not lead to reproduction. Thus, the bacteria studied above are able to adjust the genetic composition of their colonies in order to thrive in particular environments, which, in this case, is a Petri dish.

There is nothing new about the above findings. Mircobiologists recognized the genetic capabilities of bacteria decades ago. What is novel, however, are the conclusions Jacob, Becker, Shapira, and Levine, draw from their controlled laboratory studies. One of the central questions arising from these documented bacterial genetic adaptations is how does the colony morph, as a whole, into different, more life preserving shapes? For as the study demonstrates, both bacteria, when placed in an adverse environment, selected a pattern “that maximizes the rate of colony expansion (370).” This beneficial selection, the researchers modestly claim, “hints that the colonial morphotype manipulation is applied to attain better adaptability (370).” These findings hint (show?) that bacteria choose survival and expansion over stagnation and death. Does this choice, even if it be at the genetic level, i.e. unconscious, point toward bacterial sentience?

And what about bacterial intelligence? Intelligence, like sentience, is a value laden term, more so than the term “life.” A tree that grows is alive, so is a barking dog, but are trees and dogs sentient, much less intelligent? Based upon the above findings, it is easy to conclude that the simple act of choosing life is an intelligent choice in itself. However, as Tyler Volk explains in his book Death,[2] autolysis, or self-dissolution, i.e. cellular suicide, is, in many cases, needed for a bacterial colony to continue expanding. Volk illustrates the workings of autolysis by looking at the case of myxococcus, which uses cellular suicide in order to form stalks—harder support structures made from the corpses of sacrificial cells (Volk, 29). Based upon Volk’s work with the suicidal cells of myxococcus (on left), it appears that death is sometimes the most intelligent, and dare I say it, the most telenomical choice.

At this point, after reviewing the findings of Jacob, Becker, Shapira, and Levine, and in light of Volk’s work with autolytic, and perhaps telenomic cells, the question of bacterial intelligence can be answered along two different lines of thought, one biological in nature, the other philosophical in nature. However revealing the philosophical implications of a seemingly telenomic entity might be, this route of analysis will be saved for a forthcoming essay. At present, the issue of bacterial intelligence will be considered from a biological perspective.

So how does a colony of bacteria decide which genetic mutations afford the greatest chance of survival and expansion? Jacob, Becker, Shapira, and Levine, hold that bacteria communicate among themselves, writing, “It is clearly essential to figure out how the bacteria can obtain semantic meaning, so as to initiate, for example, the proper context-dependent transitions between different operating states of the genome (370-371).” Though the researchers do not understand the process(es) by which bacteria code messages and send them, Jacob, Becker, Shapira, and Levine do conceive that bacteria have shared social communicative abilities, which, because of the nature of language, implies a shared knowledge of the semantic meanings of their codes (371). Based on these speculations, it would indeed appear that not only are bacteria sentient (by choosing), and intelligent (by communicating), but that they are also socially organized (but civilized?).

At the moment there is no definitive answer to the question of bacterial sentience, much less intelligence. Unlike the Petri dish bound bacteria above, we humans have yet to codify the semantic meanings of the words “sentience” and “intelligence.” (Which is odd, and perhaps a little telling, because we assume we possess both traits but are unable to define them.) But does there need to be a definitive answer? Biologist John Bonner, best known for his work with amoebae (left), which behave similarly to the bacteria described above, in an interview with Eduardo Punset in Mind, Life, and Universe,[3] refuses to answer the question of bacterial intelligence with a yes or no. Rather he states, “I prefer the idea of continuity and admit the difficulty in defining intelligence,” which Punset interprets as, “Therefore you believe that intelligence is a question of degrees and not, as many hold, that we are intelligent and other animals are not,” to which Bonner replies, “Exactly.” Bonner’s perspective is, I believe, more open mindedly curious and more scientifically sound than a simple yes or no. While Bonner’s non-answer to the question of bacterial intelligence would undoubtedly lead to the destruction of the fictional planet Prokaryon, his unique, and in many ways Buddhist perspective, heightens my sense of mystery and wonder about the microcosmic world I am.

Joan Slonczewski, Children Star, 2010, Phoenix Pick, Rockville, Maryland.
[1] In “Bacterial linguistic communication and social intelligence,” TRENDS in Microbiology, 12.8, August 2004.
[2] Tyler Volk, Death, 2009, Chelsea Green Publishing Co., White River Junction, Vermont.
[3] Lynn Margulis and Eduardo Punset eds. Mind, Life, and Universe: Conversations with Great Scientists of Our Time, 2007, Chelsea Green Publishing Co., White River Junction, Vermont.

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