No, those microbes are not cooperating

One of the things I love about watching marked wasps on a nest is that I can see what is happening. What drew me into social wasps at the very beginning was this ability to watch behavior, then figure out why the wasps were doing what they were doing. They have a dominance hierarchy. The female at the top lays the most eggs. The hierarchy is expressed as aggression. Well, I could go on for hundreds of pages. Actually, I have done just that over my career. If you want to watch wasps, I have quite a few videotapes here.

Some people might complain about the anthropomorphism in social behavior studies. We don’t tend to say a certain wasp is angry, but we might say she is queen. I don’t see a problem with this because we are specific. We are careful to generate testable, falsifiable hypotheses. We count actions, wasps, and nests. We measure wasp size, genetic relatedness, and nest success, for example.

Unfortunately, the situation is not so clear with microbes. The literature is full of unsubstantiated claims of what might be called bestial love, since it is cooperation usually only reserved for family members extending across species. Why have microbiologists been so ready to claim cooperation where none exists? Do they not know how many fundamental facts of natural selection they violate when they claim one species dies out to prepare the environment for the next species? Are the microbial wars not apparent enough?

This kind of unsupported anthropomorphism is dangerous to our understanding of microbial interactions. And understanding microbial interactions is important. It is very important to our health, to our preservation of the environment, and to our understanding of our planet.

It is true that microbes interact in subtle ways to the human eye. They release chemicals that might have the same effect as one wasp stinging another, but they are not so apparent. We cannot always tell if an interaction is predator-prey or mother-child. Therefore we should not assume we can tell when we cannot.

This is a long lead-in to an excellent paper that I think should be required reading for all microbiologists. It is by Kevin Foster and Thomas Bell, of Oxford and Silwood Park, respectively. It is called: Competition, Not Cooperation, Dominates Interactions among Culturable Microbial Species, and came out in Current

Kevin Foster and David Queller, brilliant social behavior theorists, in Kevin’s office in Magdalen College, Oxford

Biology. This paper simply and clearly demonstrates that microbes in multi-species pools are generally not cooperative. The communities they looked at are the lovely pools of water that gather at the bases of beech trees. They measured productivity with a carbon dioxide assay, visualized with pH-based color changes. This is big science. They did not mess with all the details of how bacteria talk to each other, eavesdrop on each other, or kill each other. They looked at the outcome and did not find cooperation.

So, the big picture is competition, not cooperation. For understanding species-by-species interactions, microbiologists should delve deeply into the behavioral ecology literature where social behavior and evolution is most clearly explained. You could also follow my Wikipedia Course on the topic if you want study questions to the book and more. Just as we can learn from decades of excellent work by microbiologists on what microbes secrete and how they secrete it, they can learn from us on how evolution works on interactions.

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About Joan E. Strassmann

Evolutionary biologist, studies social behavior in insects & microbes, interested in education, travel, birds, tropics, nature, food; biology professor at Washington University in St. Louis
This entry was posted in behavioral ecology, Microbes and tagged , , , , , , , . Bookmark the permalink.

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