# Life as a Categorical Information-Handling System: An Evolutionary Information-Theoretic Model of the Holobiont

## TL;DR

This paper proposes a new model of evolution using information theory and category theory to unify different levels of biological organization.

## Contribution

A novel categorical framework for evolutionary processes that unifies gene-centric and systemic perspectives through information handling.

## Key findings

- Evolutionary change can be summarized through a measure of information generated at different levels.
- The framework accommodates both allele-frequency changes and complex interactions like symbiosis.
- Holobiont dynamics generalize earlier information-theoretic models of non-random mating.

## Abstract

We define an abstract world of Information Handlers (IHs), entities that absorb and process information from their environment, generating functional meaning aimed at persistence and multiplication. Formalized through category theory, this architecture provides a unified framework for evolutionary processes ranging from simple to complex. The same categorical scheme can represent basic allele-frequency change as well as more elaborate scenarios involving reproductive interactions or symbiosis. A key feature of the framework is that evolutionary change at different levels can be summarized through a measure that quantifies the information generated. To motivate this approach, we briefly review two contrasting views of life and evolution: a reductionist or gene-centric perspective, which places genes at the center of evolutionary change, and a relational or holistic perspective, which emphasizes interactions and systemic organization. Without taking sides, we show that starting from the basic replicator model, but interpreting replicating entities as information handlers, allows us to explore scenarios involving cooperation, symbiosis, and hierarchical organization. In these contexts, replicator-type equations quantify the information generated as handlers undergo changes associated with survival and reproduction. The proposed categorical framework accommodates both gene-centered and systemic perspectives. Finally, we show that this informational approach extends naturally to holobionts, revealing a general structure that also encompasses earlier information-theoretic models of non-random mating.

Living systems can be understood as organized entities that capture, transform, and reproduce information. Classical gene-centered models explain adaptation through frequency changes driven by differential fitness, yet they often overlook the higher-order organization and causal closure that characterize living systems. Here we revisit several evolutionary frameworks, from the replicator equation to group selection and holobiont dynamics, and show that evolutionary change in population frequencies can be expressed as a Jeffreys divergence. Building on this foundation, we introduce a categorical model of Information Handlers (IHs), entities capable of self-maintenance, mutation, and combination. This abstract architecture illustrates the usefulness of category theory for framing evolutionary processes that range from very simple to highly complex. The same categorical scheme can represent basic allele-frequency change as well as more elaborate scenarios involving reproductive interactions, symbiosis, and other organizational layers. A key feature of the framework is that different levels of evolutionary change can be summarized through a measure that quantifies the information generated, thereby distinguishing diverse types of evolutionary transformation, such as individual and sexual selection, mate choice, or even holobiont selection. Finally, we show that the informational partition associated with host–microbiome pairings in holobionts generalizes the information-theoretic structure previously developed for non-random mating, revealing a common underlying architecture across biological scales.