Joan E. Strassmann , Ph.D.

Charles Rebstock Professor of Biology

Washington University in St. Louis

Born in 1953 in Washington, DC
Studied Zoology at the University of Michigan Ann Arbor and at the University of Texas at Austin


The Major Evolutionary Transitions in Organismality



The organism is the central unit of biology because it is what natural selection operates on most directly. Organismal boundaries mark the main divisions of the living world. Beyond is the world of Darwinian competition, but inside harmony mostly rules, with the parts cooperating for the good of the whole. Yet, how organisms are defined is fundamentally unclear. The main insight, which will be elaborated in this work, is that organisms can be defined as the living unit in which cooperation is at a maximum with minimal internal conflict.
It is not possible to generalize the principles of organismality from organisms we all recognize - ducks, elephants, oaks, or crickets. Nor is it possible to generalize from traits once thought to define an organism - functional integration, physical contiguity, indivisibility, genetic co-transmission, and development from a single cell, to name the most prominent. The historical problem is that microbes and their interactions have not been considered. Yet, there is more free-living microbial mass than all animals and plants combined. Do these microbes interact in ways that make higher structures organismal? What about the fungal filaments that pervade every shovelful of soil? What about biofilms? What about the tight bonds between fungi and algae that we call lichens? What about sucking insects and their intracellular bacteria? What about social insect colonies? Will our definition help us understand these complex life forms?
There are many other examples that challenge traditional views of organismality. How do we consider the angler fish male that fuses with a female, ultimately sharing a circulatory system with his much larger mate? What makes him any more than an externally acquired gonad? The Portuguese-man-of-war is considered a colony of organisms; this view is supported by development and observation of its relatives, but not by observation of its behavior or how evolution operates on it. What do we do with marmosets that are genetic chimeras of twins, aphid clones, fungi that share nuclei, or even the transmissible facial cancer of Tasmanian devils? My ambitious goal is to answer these questions.

Recommended Reading

Strassmann, J. E. and D. C. Queller (2014). "Privatization and property in biology." Animal Behaviour 92: 305-311.
Strassmann, J. E. and D. C. Queller (2011). "Evolution of cooperation and control of cheating in a social microbe." Proc. Natl. Acad. Sci. USA 108: 10855-10862.
Strassmann, J. E. and D. C. Queller (2010). "The social organism: congresses, parties, committees." Evolution 64: 605-616.

Publications from the Fellows' Library

Strassmann, Joan E. ( 2017)
Cooperation and conflict : microbes to humans

Strassmann, Joan E. ( 2011)
Evolution of cooperation and control of cheating in a social microbe

Strassmann, Joan E. ( Washington, DC, 2011)
In the light of evolution V: cooperation and conflict : [includes articles from the Arthur M. Sackler Colloquium of the National Academy of Sciences In the Light of Evolution V: Cooperation and Conflict, held January 7- 8, 2011, at the Arnold and Mabel Beckman Center ... in Irvine, CA] Proceedings of the National Academy of Sciences of the United States of America ; 108.2011, Suppl. 2

Strassmann, Joan E. ( 2010)
The social organism : congresses, parties, and committees

Strassmann, Joan E. ( 2009)
Beyond society : the evolution of organismality

Strassmann, Joan E. ( 2007)
Exploiting new terrain: an advantage to sociality in the slime mold Dictyostelium discoideum

Strassmann, Joan E. ( 2004)
Aggression and worker control of caste fate in a multiple-queen wasp, Parachartergus colobopterus

Strassmann, Joan E. ( 2004)
Sociobiology goes micro

Strassmann, Joan E. ( 2004)
The phylogeny of the social wasp subfamily Polistinae : evidence from microsatellite flanking sequences, mitochondrial COI sequence, and morphological characters

Strassmann, Joan E. ( 2004)
Genetic conflicts and intercellular heterogeneity