In this RealClearScience article, we are informed that “A substantial proportion of Americans reject evolution. This is perhaps partly due to evolution not being terribly intuitive.”
Actually, it is terribly intuitive to some people. They see it where it isn’t.
In the lauded study,
Dave van Ditmarsch and Joao Xavier propose a pedagogical solution in the journal Trends in Microbiology: Use bacteria, some of which can reproduce within 15-20 minutes, to teach evolution. After all, seeing is believing.
The authors grew a bacterium called Pseudomonas aeruginosa on Petri plates that allowed the bacteria to “swarm,” i.e., grow outward from the middle of the plate in branch-like patterns. After 24 hours, the bacteria were collected, and a small fraction (1/1,500) of them were transferred to the middle of another plate. This process was repeated several times. By the final day of the experiment, the bacteria had evolved to become “hyperswarmers,” i.e., they no longer grew in a branching pattern but covered the entire plate.
They also grew extra flagella, which the researchers attribute to “evolution.”
The take-home message from this experiment is that bacteria beautifully demonstrate how evolution works. It is much easier to understand evolution by observing how bacteria can dramatically change over the course of roughly a week than trying to imagine how life might have changed over billions of years. And, most strikingly, the experiment shows that what appears to be a major alteration to the bacterium’s anatomy results from nothing more than a single mutation to a single gene.
In fact, the ability to mutate to grow extra flagella is likely part of the bacterium’s survival strategy, the way morphing into a temporary multicellular assembly is the way amoebae cope with starvation, then dispersing. Doubtless, some evolution was involved, but demonstrating these events happening (and then, probably, unhappening) is not demonstrating much about evolution. Especially when the entire setup is artificial, and constantly manipulated by the researchers.
It simply doesn’t follow, for example, that a lemur-like primate became a human over sixty-five million years, without intelligent guidance. It could be true, of course, but it doesn’t follow. It is an exercise of the imagination.
What we are seeing here is a good design for demonstrating bacterial adaptability.
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