Generalizing the central dogma as a cross-hierarchical principle of biology.

The central dogma of molecular biology, as originally proposed by Crick, asserts that information passed into protein cannot flow back out. This principle has been interpreted as underpinning modern understandings of heredity and evolution, implying the unidirectionality of information flow from nucleic acids to proteins. Here, we propose a generalization of the central dogma as a division of labour between the transmission and expression of information: the transmitter (nucleic acids) perpetuates information across generations, whereas the expressor (protein) enacts this information to facilitate the transmitter's function without itself perpetuating information. We argue that this generalization offers two benefits. First, it provides a unifying perspective for comparing the central dogma to analogous divisions of labour observed at vastly different biological scales, including multicellular organisms, eukaryotic cells, organelles and bacteria. Second, it offers a theoretical framework to explain the central dogma as an outcome of evolution. Specifically, we review a mathematical model suggesting that the central dogma originates through spontaneous symmetry breaking driven by evolutionary conflicts between different levels of selection. By reframing the central dogma as an informational relationship between components of a system, this generalization underscores its broader relevance across the biological hierarchy and sheds light on its evolutionary origin.This article is part of the theme issue 'Origins of life: the possible and the actual'.