Difference between revisions of "Flaws in Richard Lenski Study"

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Revision as of 19:42, 12 July 2008

Richard Lenski rejected a request to release his data to the public,[1] but the following serious flaws are emerging about his work[2] even without a full disclosure of the data:

1. Lenski's "historical contingency" hypothesis, as specifically depicted in Figure 3, is contradicted by the data presented in the Third Experiment in Table 1 of his paper.

2. Lenski incorrectly included generations of the E. coli already known to contain Cit+ variants in his experiments.[3] Once these generations are removed from the analysis, the data disprove Lenski's hypothesis.

3. Lenski's largest experiment failed to support his hypothesis with statistical significance. Even though this largest experiment was nearly ten times the size of his other experiments, Lenski did not weigh this largest experiment correctly in combining his results.

4. Lenski's paper is not clear in explaining how the results of his largest experiment failed to confirm his hypothesis with statistical significance, even with the incorrect inclusion of the Cit+ variant generations. Instead, his paper refers to his largest experiment as "marginally ... significant," which serves to obscure its statistical insignificance. Other works published in PNAS are clear in defining statistical significance in the traditional way, which Lenski's third experiment (even with incorrect inclusion of the above-referenced generations) failed to satisfy.[4] Lenski's largest experiment was nearly ten times as large as his other two experiments.


  1. See Conservapedia:Lenski dialog.
  2. Lenski et al., "Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli, 105 PNAS 7899-7906 (June 10, 2008).
  3. Lenski incorrectly included generations 31,500, 32,000 and 32,500.
  4. See, e.g., www.pnas.org/cgi/content/full/0701990104