Symbiogenesis
Characteristics
Blaise Agüera y Arcas:
"The idea that evolution is driven by symbiotic mergers, the earliest of which preceded biology as we know it, has far-reaching implications. One is that the boundary between life and non-life is not well defined; symbiogenesis can involve any process that, one way or another, is self-perpetuating. Evolutionary dynamics are thus more like a physical law than a biological principle. Everything can be subject to evolution, whether we consider it to be “alive” or not.
The symbiogenetic view also renders the idea of distinct species, classified according to a Linnaean taxonomy, somewhat ill-defined—or at best, of limited applicability. Such taxonomies assume that only branching takes place, not merging. Bacteria, which promiscuously transfer genes even between “species,” already challenge this idea.13Taxonomies break down entirely when we try to apply them to even more fluid situations, like the possible proto-life in black smokers, or microbiomes, or the more complex symbioses we’ll explore later.
Perhaps most importantly, symbiogenesis explains evolution’s arrow of time, as classical Darwinian theory alone cannot. When life branches, specializing to adapt to a niche—like Darwin’s finches with their differently shaped beaks, each optimized for a specific food source—those branches are in general no more complex than their ancestral form. This has led some classical evolutionary theorists to argue that the increasing complexity of life on Earth is an anthropocentric illusion, nothing more than the result of a random meander through genetic possibilities.14Relatedly, one sometimes hears the claim that since all extant species are of equal age—as it seems they must be, since all share a common single-celled ancestor some four billion years ago—no species is more “evolved” than any other."
(https://whatisintelligence.antikythera.org/)
Discussion
H.J. Spencer:
"In the course of her research, Margulis discovered that an American anatomist, I. E. Wallin proposed in the 1920s that several vital cell components, like mitochondria and chloroplasts, originated as symbiotic bacteria. When he was not being ignored, he was strongly condemned for daring to suggest that 'germs' could contribute anything positive to life forms that were rigidly believed to exist as only animals or plants. Additionally, in reading old biology books, Margulis did find links to the symbiogenesis ideas of Merezhovsky. This stimulated her focus on the role of bacteria and her laboratory evidence that symbiotic associations between prokaryotic bacteria were absorbed into eukaryotic cells in the form of forerunners of distinct, independent organelles in a process that Margulis called Endosymbiosis (some symbionts living within a larger organism). Since Margulis proposed that this process had occurred several times over extended timeframes, she added the word 'serial' to emphasize its recurrence; so this is why she has described her theory as Serial Endosymbiosis Theory(or SET)."