Sunday, March 22, 2009

Smart bacteria

Last week Ken was at a meeting at the Santa Fe Institute, which was discussing the problem of the traditional concept of the 'gene' in the face of all the new discoveries of DNA-based functions that are very different from simple protein codes. That could be the subject of a future posting, but at the meeting was a well-known microbiologist, Jim Shapiro from the University of Chicago. In the course of conversation, we learned of a recent paper of Jim's that points out how sophisticated even a single bacterial cell is (you can get this from his website: scroll to the bottom and click on the second to last paper, Bacteria are small but not stupid). Indeed, Jim refers to 'cognition' in single cells.

This paper points out how very complex a single cell is, in terms of its internal structure, its diverse ability to sense and evaluate the environment, and its repertoire of responses. He stresses that a cell is not a stupid automaton in that sense. This is wholly consistent with points we tried to make in our book, and is sobering for attempts to boil even more complex traits, like multicellular organisms, into simple genetic causation. Of course genomes contribute to behavior of cells and organisms, but not in ways that are always simple. An important question is how enumerable such genomic effects are, and how 'hard-wired' even single cells are. Like so many other terms one might use, 'cognition' is a word with social or human-specific meanings, but using it for bacteria it is probably an important challenge to our hubris about ourselves. Bacteria may be 'just' bags of chemicals....but so are our brains. Where automated responses end and evaluative, facultative ones begin is not an easy question to answer.

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