Evolution: Multiple paths to multicellularity (Nature)
26 February 2026
The single-celled form of a tiny, aquatic organism can turn into a multicellular version by three different routes, a Nature study reveals. The discovery adds insight to the possible origins of multicellular life, suggesting a previously unrecognized degree of flexibility.
Multicellular organisms are made up of many cells that may be similar in simple organisms, or a range of different cell types in more complex organisms. Multicellularity has evolved many times independently, and two different pathways are known. In the first, a single-celled organism divides clonally to generate a multicellular structure made of genetically identical cells. In the second, different single-celled organisms aggregate to form a multicellular structure made of genetically diverse cells. These two routes were thought to be almost always mutually exclusive, but Thibaut Brunet and colleagues challenge this concept.
The authors study a species of choanoflagellate — small, aquatic organisms that can exist as single cells and as multicellular forms — called Choanoeca flexa, in the ephemeral splash pools on the shores of the Caribbean island of Curaçao. As the pools evaporate and refill, C. flexa transitions back and forth between single-celled and multicellular forms. During these cycles, multicellularity occurred via clonal cell division, aggregation or a combination of the two processes. The authors suggest that this mixed process might be an adaption to the ever-changing environment of the splash pools, which undergo extreme fluctuations in salinity as the pools evaporate and refill.
C. flexa represents a promising model to study multicellularity as choanoflagellates are a close relative of animals, the authors note. By revealing that paths to simple multicellularity are more flexible than previously thought, this study might challenge existing views on the origins of this biological transition, suggest Jaruwatana Sodai Lotharukpong and Susana Coelho in an accompanying News & Views.
- Article
- Open access
- Published: 25 February 2026
Ros-Rocher, N., Reyes-Rivera, J., Horo, U. et al. Clonal-aggregative multicellularity tuned by salinity in a choanoflagellate. Nature (2026). https://doi.org/10.1038/s41586-026-10137-y
News & Views: Flexible paths to multicellularity
https://www.nature.com/articles/d41586-026-00292-7
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