The nature of mutation is of fundamental importance to evolutionary theory. This project revisits the foundational “fluctuation test” of Luria and Delbrück, which played a key role in establishing the core theoretical commitments in 20th century biology. The test was designed to distinguish between whether mutations are random or Lamarckian (i.e., responding directly and beneficially to the immediate environment), and its results were interpreted by many as conclusively supporting the former. Although later investigators attempted to demonstrate Lamarckism through updated studies, they could not convince the scientific community.
However, in light of (i) a new conceptual development according to which mutations could be neither random nor Lamarckian but instead long-term directed, (ii) novel methods yielding mutation rate measurements at an unprecedented resolution consistent with this concept, and (iii) recent empirical findings of molecular processes in the genome consistent with this concept, there are reasons to question the sufficiency of the past experiments’ focus on Lamarckian mutations.
Through redesigned experiments motivated by these three considerations, we aim to test whether mutations can be neither random nor Lamarckian but instead long-term directed based on information accumulating internally over generations. Given that a paradigm shift is involved in this reconsideration (“a convincing demonstration that the environment can direct even some mutations… would constitute a major change in our understanding of evolution” – Futuyma, 1998), we will publish alongside peer-reviewed theoretical and empirical articles a concise monograph that packages these elements and results together in an accessible form for wider audiences of different disciplinary expertise, and hold an academic workshop with experimental evolution experts to discuss this new paradigm and conceptualize new lines of inquiry that open up once the fluctuation test has been revisited.
