Consider the Bacteria of the Petri Dish

Had your fill of olive tree husbandry and stones being raised up as seed to Abraham? Looking for new gospel analogy material? Maybe this NY Times article by Carl Zimmer will help:

This social behavior [swarming to hunt and forming spores to weather famine] costs Myxococcus energy that it could otherwise use to grow, Dr. Velicer discovered. He and his colleagues allowed the bacteria to evolve for 1,000 generations in a rich broth. Most of the lines of bacteria lost the ability to swarm or form spores, or both.

Dr. Velicer discovered that some of the newly evolved bacteria were not just asocial — they were positively antisocial. These mutant cheaters could no longer make mounds of spores on their own. But if they were mixed with ordinary Myxococcus, they could make spores. In fact, they were 10 times as likely to form a spore as normal microbes.

Dr. Velicer set up a new experiment in which the bacteria alternated between a rich broth and a dish with no food. Over the generations, the cheaters became more common because of their advantage at making spores. But if the cheaters became too common, the entire population died out, because there were not enough ordinary Myxococcus left to make the spore mounds in the times of famine.

During this experiment, one of Dr. Velicer’s colleagues, Francesca Fiegna of the Max Planck Institute for Developmental Biology, discovered something strange. She had just transferred a population of cheaters to a dish, expecting them to die out. But the cheaters were making seven times as many spores as their normal ancestors. “It just made no sense,” Dr. Velicer said. “I asked her I don’t know how many times, ‘Are you sure you marked the plates correctly?'”

She had. It turned out that a single Myxococcus cheater had mutated into a cooperator. In fact, it had evolved into a cooperator far superior to its cooperative ancestors. Dr. Velicer and his colleagues sequenced the genome of the new cooperator and discovered a single mutation. The new mutation did not simply reverse the mutation that had originally turned the microbe’s ancestors into cheaters. Instead, it struck a new part of the genome.

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About John Mansfield

Mansfield in the desertA third-generation southern Nevadan, I have lived in exile most of my life in such places as Los Alamos, Baltimore, Los Angeles, the western suburbs of Detroit, and currently the northern suburbs of Washington, D.C. I work as a fluid dynamics engineer. I was baptized at age twelve in the font of the Las Vegas Nevada Central Stake Center, and on my nineteenth birthday I received the endowment in the St. George Temple. I served as a missionary mostly in the Patagonia of Argentina from 1985 to 1987. My true calling in the Church seems to be working with Cub Scouts, whom I have served in different capacities in four states most years since 1992. (My oldest boy turned eight in 2004.) I also currently teach Sunday School to the thirteen-year-olds. I hold degrees from two universities named for men who died in the 1870s, the Brigham Young University and the Johns Hopkins University. My wife is Elizabeth Pack Mansfield, who comes from New Mexico's north central mountains and studied molecular biology at the same two schools I attended. We have four sons, whose care and admonition, along with care of my aged father, require much of Elizabeth's time. She currently serves the Church as Mia-Maid advisor, ward music chairman, and choir director, and plays violin whenever she can. One day, I would like to make shoes.

6 thoughts on “Consider the Bacteria of the Petri Dish

  1. The title intentionally parallels Jesus’ invitation to “consider the lilies of the field.” Olive tree husbandry refers to the allegory in the Book of Jacob where care of the trees represents the development of the house of Israel. Stones being raised up as seed to Abraham is a figure that Jesus used to illustrate the Jews’ dispensability when it comes to God fulfilling his covenants. The second question touches on a recent post at this website by Ivan Wolfe considering the value and limitations of familiar gospel analogies.

    All the above went through my mind as I read the quoted passage from the NY Times article. I am not assigning any particular gospel meaning to this bacteria experiment; I am inviting the reader to do so. The point is to consider a scenario ripe for exploitation as material for a gospel analogy of your choice.

  2. “I am not assigning any particular gospel meaning to this bacteria experiment”

    That’s good, because that’s what I was afraid I missed.


  3. I dunno – the missionary and conversion parallels seemed pretty obvious to me.

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