The Long-Term Evolution Experiment (LTEE) with Escherichia coli, initiated by Richard Lenski in 1988, is frequently hailed as a premier exhibit for Darwinian evolution in action. By tracking bacteria for tens of thousands of generations, researchers have observed them adapt to their laboratory environment, becoming demonstrably “fitter” than their ancestors. The paper “A Comparison of Methods to Measure Fitness in Escherichia coli” by Michael Wiser and Lenski himself, delves into the technical minutiae of how best to measure this fitness gain. While the authors’ meticulous work is commendable from a methodological standpoint, its use as evidence for the creative power of unguided evolution is profoundly misplaced. The experiment does not demonstrate the origin of new biological information, but rather showcases a well-understood process of adaptive decay, where organisms achieve a short-term advantage by breaking or losing pre-existing genetic information.
A Meticulous Measurement of Change
Wiser and Lenski’s paper addresses a practical challenge in experimental evolution: as an evolving population becomes significantly fitter than its ancestor, measuring this difference becomes less precise. In a standard competition assay, the less-fit ancestor is rapidly outcompeted, its population dwindling to numbers too small to count accurately. To solve this, the authors tested two alternative methods against the “Traditional” one. The “Altered Starting Ratio” (ASR) method began the competition with more of the ancestral strain, while the “Different Common Competitor” (DCC) method pitted the evolved strains against a moderately fit competitor from an intermediate generation.
After performing 480 competition assays on samples taken over 50,000 generations, the authors’ direct finding was that neither of the new methods offered a significant improvement in precision. All three methods confirmed the same general trend: the bacteria experienced a decelerating increase in relative fitness, reaching a competitive advantage of approximately 88% over their ancestor. The paper successfully validates the robustness of the traditional measurement technique for the scope of the LTEE, but it does not, and was not intended to, identify the genetic source of the fitness increase itself.
What Kind of “Fitness” is Being Measured?
The central claim of neo-Darwinism is that the creative engine of evolution is random mutation coupled with natural selection. This engine, over vast eons, is purported to build new genes, new proteins, and entirely new body plans. The LTEE, however, provides no evidence for this creative process. The “fitness” gained by Lenski’s bacteria is not a product of invention, but of degradation.
This is a direct prediction of what biochemist Michael Behe calls “the first rule of adaptive evolution”: the fastest and easiest way for an organism to adapt to a new environment is to break or blunt any existing gene whose function is no longer needed or is now detrimental. In the hyper-simplified, sterile environment of the LTEE flask—a constant temperature with a single food source (glucose)—many of the bacteria’s pre-existing genes, designed for survival in the complex and variable natural world, become useless baggage. By disabling these genes through mutation, the bacteria can save the energy required to express them, leading to faster replication and a measurable “fitness” advantage in their artificial home.
The most famous adaptation in the LTEE, the evolution of citrate metabolism in one of the twelve lines, is a textbook case of this principle. The bacteria did not invent a new pathway. The genes for transporting and metabolizing citrate were already present but were normally repressed in the presence of oxygen. The “evolutionary” event was a series of mutations that broke the regulatory switch, permanently turning on the pathway. This is a loss of regulation, not a gain of new, specified information. The fitness trajectory measured by Wiser and Lenski is the cumulative effect of many such degenerative events.
This phenomenon powerfully illustrates the principle of Genetic Entropy. The genome is an information-bearing system, and like all such systems, it is subject to decay under the Second Law of Thermodynamics. While natural selection in the LTEE’s massive populations can strongly favor a few “beneficial” mutations, these mutations are overwhelmingly information-losing. Meanwhile, a relentless tide of nearly-neutral deleterious mutations accumulates in the background, invisible to selection. The LTEE does not refute Genetic Entropy; it demonstrates a specific, isolated case where the fitness benefit of breaking things in an artificial environment temporarily outpaces the general, inexorable decay of the genome as a whole. The bacteria are becoming highly specialized “hothouse flowers,” but their overall genetic library is being corrupted.
A Better Explanation: Designed Adaptation and Decay
A model based on engineering and information science provides a more causally adequate explanation for the results of the LTEE. Organisms were not created as static entities but were front-loaded with sophisticated genetic potential to allow for rapid adaptation to changing environments. The changes observed in Lenski’s bacteria are best understood as the operation of this designed system within a context of overall decay.
The primary mechanism at work is adaptive degeneration. The ability for a complex system to shed costly, unused components in a simplified environment is an elegant design feature for optimization. An astronaut on a long-term space mission would jettison any unnecessary equipment to save mass and energy; Lenski’s bacteria are doing the same at the genetic level. They are not evolving “upward” by creating new functions; they are specializing “downward” by discarding information that was designed for a more complex world. This explains the local fitness gain measured by Wiser and Lenski while being fully consistent with the global principle of Genetic Entropy.
Furthermore, some adaptations may arise from pre-programmed adaptive systems, where environmental stress can trigger non-random genetic changes mediated by elements within the genome. This “Nonrandom Evolutionary Hypothesis” (NREH) suggests that organisms have built-in toolkits to generate targeted, adaptive responses far more efficiently than waiting for a lucky random accident. While this paper does not investigate the genetic mechanisms, this model provides a far more plausible cause for rapid and repeatable adaptations than the blind search algorithm of neo-Darwinism.
Conclusion: Measuring Specialization, Not Creation
Wiser and Lenski’s paper is a fine piece of methodological science, confirming that the way we measure adaptation in the lab is reliable. However, it is a profound error to extrapolate these findings as evidence for the grand theory of molecules-to-man evolution. The LTEE has failed to demonstrate the origin of a single new gene or protein. The observed 88% fitness gain is not a step towards a new kind of organism but a testament to the power of devolution.
When viewed through a design-based framework, the results are perfectly predictable. The bacteria are adapting by breaking and discarding genetic information that is superfluous in their artificial world. This process of adaptive degeneration provides a temporary, local fitness advantage, but at the cost of overall genomic integrity. The LTEE, therefore, does not show life’s creative potential. It is a 50,000-generation experiment that powerfully illustrates the universal principle of decay.
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