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The Real Origin of Species: Lynn Margulis’s “Symbiotic Planet”

This is the first part in our short series on evolution. Please also see “Evolution & the Natural Sciences” and “Evolution & the Social Sciences.

The Prevalence of Symbiosis

In Symbiotic Planet: A New View of Evolution (1998), Lynn Margulis (1938-2011) outlines what could be considered an expanded and interconnected argument to that of Peter Kropotkin’s (1842-1921) mutualism, called serial endosymbiotic theory (SET) [for discussion of Kropotkin’s arguments on mutualism, see “Evolution & the Natural Sciences“]. This argument expands that of Kropotkin’s in at least two ways.

First, its scope is that of the broader category symbiosis, defined by Margulis as “the living together in physical contact of organisms of different species… literally touching each other or even inside each other, in the same place at the same time.” (p. 2). The breadth of symbiotic relations encompasses mutualism (known as cooperation when taking place within individuals of the same species, rather than between species), commensalism (wherein one species benefits and the other receives neither benefit or harm), parasitism (where the parasite benefits at the expense of the host), and competition (where both species are harmed).

Second, serial endosymbiotic theory can be seen to encompass greater temporality, seeking to explain the very origin of species and the emergence of life from the inorganic.

Margulis points out that, ironically, Darwin’s The Origin of Species (1859) had little to say about the actual emergence of life. In explaining the origin of species, she invokes the concept of symbiogenesis: “the origin of new tissues, organs, organisms–even species–by establishment of long-term permanent symbiosis. She notes that symbiosis is crucial to evolutionary novelty and that the idea of species requires symbiosis. In support of this, she notes that bacteria (simple organisms) do not have species (p. 6).

Interestingly, Margulis believed symbiosis helps to explain and reinforce the phenomenon of punctuated equilibrium:

[Niles] Eldredge and [Stephen Jay] Gould argue that the fossil record shows evolution to be static most of the time and to proceed suddenly: rapid change in fossil populations occurs over brief time spans; stasis then prevails for extended periods. From the long view of geological time, symbioses are like flashes of evolutionary lightning. To me symbiosis as a source of evolutionary novelty helps explain the observation of “punctuated equilibrium,” of discontinuities in the fossil record.

Lynn Margulis, Symbiotic Planet (1998), p. 8.

A primary argument of Margulis’s is that symbiosis is not rare, but abundant: “We abide in a symbiotic world.” Amoeba speciation involved symbiosis and has been observed in the laboratory. This symbiogenesis constitutes a special type of Lamarckism, wherein organisms do not inherit acquired characteristics, but entire other organisms and their gene sets (p. 8-9). “The tendency of ‘independent’ life is to bind together and reemerge in a new wholeness at a higher, larger level of organization” (p. 11).

Margulis finds another variant of Lamarkism in the work of Tracy Sonneborn (1905-1981) and Jannine Beissen:

Sonneborn, longtime professor of genetics at Indiana University, with researcher Beissen reported that if Paramecium cilia are surgically removed in clumps with their bases and turned around some 180 degrees on the cell’s surface, then replaced, the cilia will appear in offspring cells, for many future generations, in this reversed position. In other words, the cilia reproduce and the change experimentally induced by the scientists was inherited, for at least two hundred generations after the operation. Here was a laboratory example of the so-called inheritance of acquired characteristics that orthodoxy dismissed as Lamarkianism [sic].

Lynn Margulis, Symbiotic Planet (1998), p. 27.

Proof for SET comes from the study of the cytoplasm and organelles within nucleated cells. For instance, plastids and mitochondria affect heredity, in addition to the nucleus (p. 24). The central idea is that “the origin of cells with nuclei is exactly equal to the evolutionary integration of symbiotic bacterial communities” (p. 29):

My theory of the symbiogenetic origin of plant, animal, and other cells with nuclei employs four provable postulates. All four involve symbiogenesis, incorporation, and body fusion by symbiosis. The theory precisely outlines the steps that must have occurred in the past, especially in relation to the bright green cells of plants…. The idea is straightforward: four once entirely independent and physically separate ancestors merged in a specific order to become the green algal cell.

Lynn Margulis, Symbiotic Planet (1998), p. 33, 34.

Margulis’s remarkable argument that “[a]ll organisms large enough for us to see are composed of once-independent microbes, teamed up to become larger wholes,” is highly ecological, relational, and potentially challenges concepts such as “individuality.”

Further, her notion is reminiscent of the holon, used by Arthur Koestler (1905-1983) to describe the dual nature of many things that are simultaneously whole, and a part. All of this is very sympathetic to dialectical interpretation.

In attempting to determine how life first emerged, Margulis notes the presence of cell-like systems and cell-like membranous enclosures. “[W]e think that pre-life, with a suitable source of energy inside a greasy membrane, grew chemically complex.” For this, an energy source was needed, most likely solar: “controlled energy flow led to the self-hood that became cell life” (p. 71-72).

It is interesting to mention that Margulis was influenced by the Russian evolutionary school, which includes Kropotkin and his Mutual Aid: A Factor of Evolution (1902). Stephen Jay Gould (1941-2002) noted that the Russian evolutionists of Kropotkin’s time are to this day little understood in the Western world, having hardly been translated into English. Research into this area may yield additional exciting insights.

Margulis’s work has the potential to expand evolutionary theory past the limitations of Darwin by offering an actual proposal for the transition from the inorganic to the organic, and a specific explanation for the ultimate origin of species. Her work testifies to the prevalence of mutualism and symbiosis in the natural world, possibly calling into question the extent to which competition is actually the overriding factor driving evolutionary change. Additionally, we note that competition is the most harmful form of symbiosis, wherein both organisms or species engaging in competition are harmed.

Many strange, pseudo-scientific theories are currently gaining popularity (“flat earth” and similar theories immediately come to mind), as well as attacks on evolution, ecology, and the ecological crisis generally. Serial endosymbiotic theory, along with concepts like mutualism and punctuated equilibrium, represent exciting, legitimate challenges to the “modern synthesis“–an extended evolutionary synthesis. These developments, along with having potential social scientific relevance, may lead to insights for the preservation of species and strategies for mitigation of the ongoing, worsening, ecological crisis.

Lynn Margulis and her popularization of serial endosymbiotic theory is but one exciting and lesser-known (at least among the public) aspect of ecology and evolutionary biology that lends itself to scientific, social scientific, and dialectical interpretation.

Charles Imboden is a social ecologist with expertise in non-profits, solar energy, and liberatory technology. He specializes in arid lands and is based in the American Southwest. Contact him here.

Margulis, L. (1998). Symbiotic Planet: A New View of Evolution. Basic Books: New York, NY.

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