Retained Complexity
Friday 17 November 2023
When in last week’s newsletter I discussed golden ages of civilization, I observed that there tends to be much more interest in studying civilizational failure and collapse than in studying golden ages, but, of course, both need to be studied in conjunction with each other. Golden ages of civilizations produce unique and distinctive forms of complexity, some of which are selectively retained throughout dark ages, and which then constitute retained complexity through dark ages. Technologies and art forms invented during golden ages and which survive into dark ages are the paradigmatic form of retained complexity I have in mind — forms of complexity that remain in use and, in virtue of their survival, become the basis of a dark age society that can, if and when the society recovers, adaptively radiate under favorable conditions, and perhaps even serve as the foundation of a future golden age.
The artifacts left by vanished civilizations, however, are also a form of retained complexity, and other civilizations that come along later can make use of these retained complexities, so that through the means of living civilizations some small part of an extinct civilization lives on. While the building techniques and traditions of ancient Rome were largely lost in the West with the fall of the Roman Empire, many monuments remained to amaze and inspire medieval builders. When medieval society reached an initial threshold of maturity and could realistically contemplate its own monumental architecture, the medievals borrowed heavily from ancient ruins, resulting in the Romanesque style, which reveals its debt to Rome in its name. Monumental building techniques and traditions had to be recreated from scratch, but the ruined monuments remained as a proof of concept, and eventually medieval building techniques exceeded the sophistication of their ancient models, as, for example, with Brunelleschi’s dome on the Florence Duomo. Thus retained complexity can take different forms, and retained complexity in its different forms differently reenters the flow of history; the historical process is different in the different cases of retained complexity. (Perhaps we could call the two forms of retained complexity I have here discussed ongoing retained complexity and existence proof retained complexity.)
In recently returning to the theme of retained complexity I have found a better way to express it: retained complexity is the complement of complexity lost. All societies employ a range of complex technologies and institutions (i.e., social technologies). The complexity lost in a collapse is the background upon which retained complexity stands out, but it would be misleading to suppose that a collapse (invariably) wipes out most complexity and leaves only fragments of complexity, which, in their isolation, are all-too-easily lost in the subsequent historical turmoil. In some cases this is what happens, but we should also recognize that, in looking at the golden ages of civilizations and their notable accomplishments, we usually focus on the exemplary instances of complexity, and when these exemplary instances of complexity are lost or destroyed, we count a civilization as having collapsed, with the implication that the loss of complexity exemplars means the associated loss of other forms of complexity, when it can just as well be the case that other forms of complexity are retained. I will recur again to a passage from Joseph Tainter that I quoted previously in Epistemic Collapse:
“Collapse, as viewed in the present work, is a political process. It may, and often does, have consequences in such areas as economics, art, and literature, but it is fundamentally a matter of the sociopolitical sphere. A society has collapsed when it displays a rapid, significant loss of an established level of sociopolitical complexity. The term ‘established level’ is important. To qualify as an instance of collapse a society must have been at, or developing toward, a level of complexity for more than one or two generations. The demise of the Carolingian Empire, thus, is not a case of collapse — merely an unsuccessful attempt at empire building. The collapse, in turn, must be rapid — taking no more than a few decades — and must entail a substantial loss of sociopolitical structure. Losses that are less severe, or take longer to occur, are to be considered cases of weakness and decline.” (Joseph A. Tainter, The Collapse of Complex Societies, Cambridge: Cambridge University Press, 1988, p. 4)
Tainter is explicit that his concern is with political complexity, but his formulation of collapse can be reformulated mutatis mutandis to address any aspect of human activity: economic collapse, scientific collapse, aesthetic collapse… even epistemic collapse — in my blog post on Epistemic Collapse I provided a reformulation of Tainter specific to knowledge, and the same could be done for other aspects of human activity that represent an attained complexity that might be lost in a collapse. It is possible that a society might experience a collapse in one sector of its life, while its complexity levels remain intact in other areas — that is to say, other sectors of life remain as retained complexity even while the complexity exemplars in one particular sector of life are lost in a collapse.
The fate of complexity over historical time is not exclusively a concern of intelligence, technology, and civilization. Thinking about retained complexity in relation to the hemispheric sterilization thought experiment in newsletter 260, in which half of a biosphere is sterilized by a powerful but brief gamma ray burst (GRB), I have been trying to work though what retained complexity could survive such a catastrophe. The thought experiment, then, admits of several interesting questions, such as the question with which I began, whether the non-sterilized side of a planet would experience a catastrophic extinction cascade, and, if it did not, if it could colonize the denuded half of the planet, but there is also the question of what would survive on the denuded side of the planet. Of course, the duration and strength of the GRB would have a lot to do with what, if anything, survives. Most GRBs are brief, but some can last as long as several hours, and many planets rotate within a few hours and so the whole of their surface could be subjected to the GRB.
Even in the case of an entire planetary biosphere being exposed to a GRB, there would be the survival of extremophilic organisms under rocks (hypoliths), inside rocks (endoliths), and in deep subsurface rocks (lithophiles), all of which would be sheltered from the destructive radiation of a GRB by their rocky environments. If the only life to survive a catastrophic GRB were extremophilic microorganisms, that would mean the reduction of the biosphere to a low point of retained complexity, but it’s not the same as life starting over from scratch, as eukaryotic and multicellular organisms would still be represented and could adaptively radiate when favorable conditions obtain.
What has occurred to me since first writing about my hemispherical sterilization thought experiment is that significant biotic communities that would survive in caves even on the exposed side of a planet hit by a GRB. I have a copy of Dark Life: Martian Nanobacteria, Rock-Eating Cave Bugs, and Other Extreme Organisms of Inner Earth and Outer Space by Michael Ray Taylor, which is all about the unlikely forms of life and ecosystems that are to be found in cave systems, many of which could survive a direct GRB. It doesn’t take all that many feet of rock to effectively shield organisms from even a strong dose of radiation, so in the case of a GRB hitting a biosphere, much of the life in caves would at least initially survive. Here too, as with the surviving life on the other side of the planet, there would be a question of whether, with the surrounding ecosystem destroyed, a catastrophic extinction cascade would result in the end of all life even protected in caves. While this might well be the case with life near the mouth of a cave, which is still robustly integrated with the ecosystem beyond the cave, ecosystems deep in caves are effectively sealed off from the outside world and are nearly closed ecosystems that could continue to exist even if the ecosystem beyond the cave was destroyed.
In deep subsurface lakes and rivers fish would survive, and that means that vertebrates would survive, and vertebrates represent a significant degree of retained complexity. I suspect that salamanders and the like would also survive in caves, so land dwelling vertebrates could survive, which represents another significant level of retained complexity. For that matter, fish and their aquatic ecosystems could also survive in deep ice-covered lakes (subglacial lakes in Antarctica, for example, such as Lake Vostok), since ice is also an effective radiation shield, and some lakes under ice have been effectively isolated as ecosystems and could continue even in the event of the destruction of the surrounding surface ecosystems. I suspect that, in a planetary biosphere partially sterilized by a GRB, there would be many unlikely survivals of isolated ecosystems protected by their isolation, but precisely because they are isolated they would have difficulty colonizing the denuded regions of the planet. Given sufficient time, however, even these isolated ecosystems eventually could find their way to the surface and adaptively radiate.
The best case for colonizing denuded regions of a partially sterilized planet would be life that survives in caves, since caves often have an opening to the surface (which may open and close repeatedly over geological time), but they also often have deep underground passages that could shelter life for a long period of time — millions of years, if need be — before life reemerges into the light. Caves, as we know, shelter bats, and if bats survive that means that mammals would survive, and mammals represent even greater retained complexity than fish or salamanders. We can imagine a scenario in which bats, formerly hunting outside the cave at night, would go deeper in the cave system to prey on insects that remain inside the cave, i.e., insects the entire life cycle of which takes place inside the cave. No doubt the bat population would collapse to very low numbers, but as long as some species survive, the complexity represented by mammalian evolution is retained. The shift from animals at the mouth of the cave going out to forage to going deeper into the cave system to forage could be a process that went on for millions of years before the denuded exterior began to be slowly colonized by land plants and then small prey, tempting the cave dwellers back out into the open.
This scenario, then, suggests another thought experiment: what would an ecosystem look like that was recolonized only from animals that formerly were cave dwellers? Suppose that bats were the sole surviving mammals, and when they emerged again from their cave, the clade experienced an adaptive radiation which meant that all mammals that colonized the denuded side of the planet were descended from bats. As the adaptive radiation proceeded, there would bat predators and bat prey, bat herbivores and bat carnivores, and bat apex predators that were essentially bat wolves.
In the case of a planet that retained a viable ecosystem on the non-denuded half of the planet, while the denuded half of the planet was recolonized by life from caves and subsurface bodies of water, there would be a roughly circular line around the biosphere, analogous to the Wallace line running through the Malay archipelago, dividing flora and fauna from the non-denuded hemisphere from fauna and flora recolonized from caves. This hemispherical division of biotic communities would be a visible trace of a hemispherical ecological catastrophe in the distant past of such a planet.
I hope that this discussion of retained complexity demonstrates the extent to which apparently very different cases like astrobiological thought experiments and the golden ages of civilizations are unified when seen through the lens of emergentism. It seems likely to me that the more we can expand and refine that conceptual framework of emergentism, the more parallels we will find among forms of complexity that are prima facie distinct. The emergentist framework is inherently a big picture perspective, and as such it reveals knowledge that remains hidden from us at the smallest scale — the scale of details that are the focus of science conducted in compartmentalized silos — only appearing when we step back and see the world whole, making it possible for us to see that the many parts of the whole are all of a piece.
