Biological Theory

, Volume 14, Issue 2, pp 131–140 | Cite as

Multicellular Individuality: The Case of Bacteria

  • Rafael VenturaEmail author
Original Article


Recent attention to complex group-level behavior amongst bacteria has led some to conceive of multicellular clusters of bacteria as individuals. In this article, I assess these recent claims by first drawing a distinction between two concepts of individuality: physiological and evolutionary. I then survey cases that are representative of three different modes of growth: myxobacteria (surface-attached agglomerative growth), Bacillus subtilis (agglomerative growth not attached to a surface), and cyanobacteria (filamentous growth). A closer look at these cases indicates that multicellular individuality among bacteria is remarkably complex. Physiologically, the three cases of multicellular clusters do not form physiological individuals. But matters are different when it comes to evolutionary individuality; although multicellular clusters that grow by agglomeration are not highly individuated, filament-forming groups achieve a relatively high degree of individuality. I also suggest that debates about bacterial multicellular individuality may have been obscured by a failure to see that selection on highly individuated groups is by no means the only mechanism to bring about the complex group-level behaviors that have led some to view bacteria as multicellular individuals.


Bacteria B. subtilis Cyanobacteria Individuality Multicellularity Myxobacteria 



I thank Peter Godfrey-Smith, Georg Toepfer, Maureen O’Malley, and Pierrick Bourrat for invaluable feedback on earlier versions of this paper, as well as two anonymous referees for their extremely helpful comments. I also thank Hannah Read for her help and support.


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Copyright information

© Konrad Lorenz Institute for Evolution and Cognition Research 2019

Authors and Affiliations

  1. 1.Duke UniversityDurhamUSA
  2. 2.Bilkent UniversityAnkaraTurkey

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