Selection of the fittest or selection of the luckiest: the emergence of Goodhart's law in evolution

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Main Authors: Mallein, Bastien, Paparella, Francesco, Schertzer, Emmanuel, Talyigás, Zsófia
Format: Preprint
Published: 2025
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author Mallein, Bastien
Paparella, Francesco
Schertzer, Emmanuel
Talyigás, Zsófia
author_facet Mallein, Bastien
Paparella, Francesco
Schertzer, Emmanuel
Talyigás, Zsófia
contents Biological evolution depends on the passing down to subsequent generations of genetic information encoding beneficial traits, and on the removal of unfit individuals by a selection mechanism. However, selection acts on phenotypes, and is affected by random contingencies. Thus, a combination of fitness and luck determines which individuals will successfully reproduce and give rise to the next generation. To understand how randomness in the selection mechanism affects the long-term patterns of evolution, we studied an idealized evolution model. We show through simulations and mathematical analysis, that the speed of adaptation increases with increasing selection pressure only up to a threshold. Beyond the threshold, any increase of the selection pressure results in more weight given to random effects rather than on genetic fitness in determining which individuals will successfully reproduce. This severely reduces the speed of adaptation and the diversity in the gene pool. Our findings may be considered as a biological instance of Goodhart's law: "When a measure becomes a target, it ceases to be a good measure". Finally, we show that this intricate response of evolution to natural selection can be mathematically explained by a novel phase transition for pulled traveling waves.
format Preprint
id arxiv_https___arxiv_org_abs_2503_21849
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Selection of the fittest or selection of the luckiest: the emergence of Goodhart's law in evolution
Mallein, Bastien
Paparella, Francesco
Schertzer, Emmanuel
Talyigás, Zsófia
Populations and Evolution
Probability
Biological evolution depends on the passing down to subsequent generations of genetic information encoding beneficial traits, and on the removal of unfit individuals by a selection mechanism. However, selection acts on phenotypes, and is affected by random contingencies. Thus, a combination of fitness and luck determines which individuals will successfully reproduce and give rise to the next generation. To understand how randomness in the selection mechanism affects the long-term patterns of evolution, we studied an idealized evolution model. We show through simulations and mathematical analysis, that the speed of adaptation increases with increasing selection pressure only up to a threshold. Beyond the threshold, any increase of the selection pressure results in more weight given to random effects rather than on genetic fitness in determining which individuals will successfully reproduce. This severely reduces the speed of adaptation and the diversity in the gene pool. Our findings may be considered as a biological instance of Goodhart's law: "When a measure becomes a target, it ceases to be a good measure". Finally, we show that this intricate response of evolution to natural selection can be mathematically explained by a novel phase transition for pulled traveling waves.
title Selection of the fittest or selection of the luckiest: the emergence of Goodhart's law in evolution
topic Populations and Evolution
Probability
url https://arxiv.org/abs/2503.21849