Civilizations of Planetary Endemism: Part III

13 February 2016


There are a lot of Earth-like planets out there, and they vary from Earth according to physical gradients.

There are a lot of Earth-like planets out there, and they vary from Earth according to physical gradients.

In my previous posts on planetary endemism (see links below) I started to explore the ideas of how civilization is shaped by the planet upon which a given civilization arises. I began to sketch a taxonomy based on developmental factors arising from planetary endemism, but I have realized the inadequacy of this. As I have no systematic idea for a taxonomy based on a more comprehensive understanding of planetary types, I must undertake a series of thought experiments to explore the relevant ideas in more detail. This I intend to do.

I should point out that taxonomy I began to sketch in my 2015 Starship Congress talk, “What kind of civilizations build starships?” — a taxonomy employing a binomial nomenclature based on a distinction between economic infrastructure and intellectual superstructure — still remains valid to make fine-grained distinctions among terrestrial civilizations, or indeed within the history of any civilization of planetary endemism. What I am seeking to do now to arrive at a more comprehensive taxonomy under which this more fine-grained taxonomy can be subsumed, and which, as a large-scale conception of civilization, is consistent with and integrated into our knowledge of cosmology and planetology.

While I have no systematic idea of taxonomy at present taking account of types of planets, I think I can identify a crucial question for this inquiry, and it is this:

What physical gradient is, or would be, correlated with the greatest qualitative gradient in the civilization supervening upon that physical gradient?

In other words, if we could experiment with civilization under controlled condition, systematically substituting different valuables for a given variable while holding all over variables constant, and these variables are the physical conditions to which a given planetary civilization is subject, which one of these variables when its value is changed would produce the greatest variation on the supervening civilization? A qualitative change in civilization yields another kind of civilization, so that if varying a physical condition produces a range of different kinds of civilizations, this is the variable to which we would want to pay the greatest attention in formulating a taxonomy of civilizations that takes into account the kind of planet on which a civilization arises. Understood in this way, civilization, or at least the kind of civilization, can be seen as an emergent property with the physical condition given a varying value as the substructure upon which emergent civilization supervenes.

Some gradients of physical conditions will be closely correlated: planet size correlates with surface area, surface gravity, and atmospheric density. These multiple physical conditions are in turn correlated with multiple constraints upon civilization. With the single variable of planet size correlated to so many different conditions and constraints upon civilization, planet size will probably figure prominently in a taxonomy of civilizations based on homeworld conditions. Large planets and small planets both have advantages and disadvantages for supervening civilizations. Large planets have a large surface area, but the higher gravity may pose an insuperable challenge for the emergence of spacefaring civilization. Small planets would pose less of a barrier to a spacefaring breakout, but they also have less surface area and probably a thinner atmosphere, possibly limiting the size of organisms that could survive in its biosphere. Also, there may be a point at which the surface area on a small planet falls below the minimum threshold necessary for the unimpeded development of civilization.

Planets too large or too small may be inhabitable, in terms of possessing a biosphere, but may be too challenging for a civilization to arise. Any intelligent being on a planet too large or too small would be faced with challenges too great to overcome, resulting in what Toynbee called an arrested civilization. But how large is too large, and how small is too small? We don’t have an answer for these questions yet, but to formulate the question explicitly provides a research agenda.

Other important physical gradients are likely to be temperature (or insolation, which largely determines the temperature of a planet), which can result in planets too hot (Venus) or too cold (Mars), and the amount of water present, which could mean a world too wet or too dry. A planet with a higher temperature would probably have a higher proportion of its surface as desert biomes, and possibly also a greater variety of desert biomes than we find on Earth, while a planet with a lower temperature would probably possess a more extensive cryosphere and a large proportion of it surface in arctic biomes. And a planet mostly ocean (i.e., too wet), with extensive island archipelagos, might foster the emergence of a vigorous seafaring civilization, or it might result in the civilizational equivalent of insular dwarfism. Again, we don’t yet know the parameters the values of these variables can take and still be consistent with the emergence of civilization, but to formulate the question is to contribute to the research agenda.

I think it is likely that we will someday be able to reduce to most significant variables to a small number — perhaps two, size and insolation, much as the two crucial variables for determining a biome are temperature and rainfall — and a variety of qualitatively distinct civilizations will be seen to emerge from variations to these variables — again, as in a wide variety of biomes that emerge from changes in temperature and rainfall. And, again, like ecology, we will probably begin with a haphazard system of taxonomy, as today we have several different taxonomies of biomes.

Civilizations (i.e., civilizations of planetary endemism during the Stelliferous Era) supervene upon biospheres, and a biosphere is a biome writ large. We can study the many terrestrial biomes found in the terrestrial biosphere, but we do not yet have a variety of biospheres to study. When we are able to study a variety of distinct biospheres, we will, of course, in the spirit of science, want to produce a taxonomy of biospheres. With a taxonomy of biospheres, we will be more than half way to a taxonomy of civilizations, and in this way astrobiology is immediately relevant to the study of civilization.

. . . . .

Planetary Endemism

● Civilizations of Planetary Endemism: Introduction (forthcoming)

Civilizations of Planetary Endemism: Part I

Civilizations of Planetary Endemism: Part II

● Civilizations of Planetary Endemism: Part III

. . . . .


. . . . .

Grand Strategy Annex

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project astrolabe logo smaller

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