# A New Classification Framework to Understand Evolutionary Transitions in Individuality

**Authors:** Saskia Wilmsen, Christian Kost

PMC · DOI: 10.1002/bies.70098 · 2026-01-22

## TL;DR

The paper introduces a new framework to classify biological entities based on physiological and evolutionary components, helping understand evolutionary transitions in life forms.

## Contribution

The novel contribution is a classification framework that categorizes biological units into six types based on physiological and evolutionary components.

## Key findings

- The framework identifies six types of structural organization based on physiological and evolutionary components.
- The framework enables comparison of different biological units to understand evolutionary processes.
- The approach provides a systematic way to study evolutionary transitions beyond canonical examples.

## Abstract

Life on Earth has evolved as a series of evolutionary transitions, during which lower‐level units merged to form a new and more complex higher‐level entity. Besides few canonical examples, many life forms exist for which it remains unclear whether or not they are about to complete the transition. This paucity of mechanistic understanding is likely due to an overemphasis on few model systems and a lack of criteria to compare disparate biological units. Here, we aim at filling this gap by proposing a new framework to classify different forms of biological organization, which considers two fundamental aspects: (i) the physiological component and (ii) the evolutionary component. Categorizing different biological units according to whether and how these aspects are represented yields six types of structural organization. Our framework allows to compare different organizational forms, and, in this way, provide insight into the evolutionary processes giving rise to these arrangements.

Classifying biological entities based on whether and how the two fundamental aspects physiological and evolutionary components are represented yields six types of structural organization. The resulting framework allows to compare different forms of organization, and, in this way, provides insight into the evolutionary processes giving rise to these arrangements.

## Full-text entities

- **Diseases:** type V to type VI (MESH:C536047), polyps (MESH:D011127), III (MESH:C537189), genetic defects (MESH:D030342), transmissible skin cancer (MESH:D012878)
- **Species:** Candidatus Karelsulcia muelleri (species) [taxon 336810], Chlorophyta (green algae, phylum) [taxon 3041], Homo sapiens (human, species) [taxon 9606], Pyrrhocoris apterus (species) [taxon 37000], Acyrthosiphon pisum (pea aphid, species) [taxon 7029], Escherichia coli (E. coli, species) [taxon 562], PX clade (clade) [taxon 569578], Equus asinus x Equus caballus (mule, species) [taxon 319699], Dictyostelium discoideum (species) [taxon 44689], Dysdercus fasciatus (species) [taxon 633931], Candidatus Palibaumannia cicadellinicola (species) [taxon 186490], Apis mellifera (bee, species) [taxon 7460], Tetrabaena (genus) [taxon 47789], Bombus terrestris (buff-tailed bumblebee, species) [taxon 30195], Aliivibrio fischeri (species) [taxon 668], Buchnera aphidicola (species) [taxon 9], Euprymna scolopes (species) [taxon 6613], Bacteria Latreille et al. 1825 (Bacteria stick insect, genus) [taxon 629395], Tequatrovirus T4 (species) [taxon 10665]

## Figures

5 figures with captions in the complete paper: https://tomesphere.com/paper/PMC12828248/full.md

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Source: https://tomesphere.com/paper/PMC12828248