Why Decades of Bacterial Observation Point to "Devolution" Rather Than Macroevolution
Initiated in 1988 by biologist Richard Lenski, the Long-Term Evolution Experiment (LTEE) started with 12 identical populations of Escherichia coli in test tubes or flasks in a glucose-limited medium. Each day a sample of each flask was transferred to a new flask with fresh medium. It has tracked these 12 colonies of bacteria across tens of thousands of generations. The experiment was designed to observe random mutations and natural selection in a controlled laboratory environment.
While many biology textbooks cite LTEE as evidence for evolution, the results showed that NO new proteins were created. Worse yet, protein information that was supposedly created by evolution over thousands or millions of years was lost. Why? Because certain proteins were beneficial in a natural environment, but not in a lab environment with an unnatural supply of sugar.
One population developed the ability to use citrate as an energy source in the presence of oxygen. But see below.Lenski's experiment failed to demonstrate progress in the overall complexity observed. Over seventy thousand generations have resulted in bacteria that reproduce faster in their specific flask environments, but this was achieved primarily through genetic degradation rather than creating new complex DNA.
Biochemist and intelligent design proponent Michael Behe has analyzed the LTEE extensively, most notably in his book Darwin Devolves. Behe argues that the experiment provides a proof of what he calls the First Rule of Adaptive Evolution: "Break or blunt any gene whose loss would increase the number of offspring."
Behe points out that after trillions of individual cells replicated across decades, no fundamentally new protein folds (3D shape of proteins) or complex molecular machinery emerged. The bacteria adapted to an unnatural controlled lab environment by narrowing their capabilities and breaking functional components, demonstrating that natural selection can act as a powerful de-volutionary force.
The most celebrated breakthrough of the LTEE occurred around generation 31,500. One line of E. coli developed the ability to utilize citrate as an energy source in the presence of oxygen (the Cit+ phenotype). Evolutionary advocates claimed this was a brand-new complex metabolic pathway. Wow!
However, analysis reveals a much simpler reality.
Wild-type E. coli already possess the complete metabolic pathway and the necessary transporter gene (citT) to move citrate into the cell under anaerobic (oxygen-free) conditions. But in the wild it is only turned on in anaerobic conditions. In Lenski's experiment, a mutation copied the citT gene to a location next to an "on switch" (rnk promoter) that turned it on when oxygen was present. [Nature] In addition, some single point mutations, including some in citT, worked to improve citrate metabolism. This was accomplished with no significant addition of information.
As Behe pointed out, the mutations did NOT change the 3D structural complexity of a fold of a protein, they merely tinkered with minor point changes. If you paint a house white it may reflect sunlight and stay cooler (an advantage in the summer, but not in the winter), but the structure of the house is unchanged. A little adaptation, but not the kind of complex change needed to start turning a house into an airplane.Lenski's experiment demonstrates that there are boundaries of what random mutation and natural selection can achieve. Rather than showcasing the creative potential of Darwinian mechanisms to construct new types of organisms, it demonstrated that unguided processes are confined to microadaptive modifications.
LTEE discarded proteins that are valuable in a natural environment. Proteins that were supposedly created by thousands or millions of years of evolution. Is it honest to call that progress?