How inevitable was modern human civilization - data

by taw 2 min read20th Aug 2009104 comments


We have a sample of one modern human civilization, but there are some hints on how likely it was to happen.

Major types of hints are:

  • Time - if something happened extremely quickly; or extremely late, it suggests how likely it was.
  • Independent invention - something that was invented independently multiple times is likelier; something invented only once in spite of plenty of time, isolation, and prerequisites is less likely.

Data for:

  • Life seems to have developed extremely quickly after creation of Earth. [Origin of life]
  • Multicellularity seems to have evolved multiple times independently, at least in animals, fungi, and plants. [Evolution of multicellularity]
  • Similar process also happened multiple time on higher level - eusociality developed in aphids, thrips, mole rats, termites, and at least 11 times in Hymenoptera (ants, bees, and wasps). [Eusociality]
  • Life did not die out on Earth, or on any particular environment where it previously thrived, in spite of major changes in temperature, composition of atmosphere, and multiple large scale disasters. This suggests life is very resilient. Every time life is wiped out in some part of Earth, it is quickly recolonized.
  • Many different lineages of animals developed societies. [Social animal]
  • Many different lineages of animals developed communication. [Animal communication]
  • All transitions from Middle Paleolithic onwards happened relatively fast to extremely fast on evolutionary scale. [Paleolithic]
  • Invention of Mesolithic and Neolithic culture including agriculture, bow, boats, animal husbandry, pottery were all invented multiple times independently, in Afroeurasia, and Americas. [Stone Age]
  • Likewise many of latter inventions including metallurgy, writing, money, and state were developed multiple times independently.

Data against:

  • Universe is not filled with technical civilizations. Some (dubious due to zero empirical evidence) models suggest once such civilization develops anywhere in the galaxy, it is very likely to colonize the entire galaxy in relatively short period of time. As it didn't happen, it's a strong evidence that there are very few, perhaps no, advanced technical civilizations in our galaxy; or anywhere else in the universe if our galaxy is a good representative. [Fermi paradox]
  • Life can survive in a very wide range of circumstances, so there are plenty of places where we might expect to find life if its development was also likely. Mars, Venus, moons of Jupiter and Saturn, and perhaps some other places just in the Solar System might be sufficiently friendly to life. Yet, as far as we know, none ever developed in any of them, what puts strong limits on inevitability of life. [Extremophile]
  • In spite of all the theories proposed, we know of no mechanism under which creation of life seems even remotely plausible. Somewhere between the primordial soup (or equivalent) to the first replicator with reasonably stable heredity and metabolism (or equivalent), there's a large number of unknown steps of unknown but most likely extremely low probability. [Origin of life]
  • Nervous system evolved only once, about 3 billion years after life started, and nothing analogous to it ever evolved in any other lineage. [Urbilaterian]
  • It took life 3 billion years to reach stage of reasonably complex animals, what suggests it is not very likely. [Cambrian explosion]
  • Almost all animals seem to have very low encephalization quotients, suggesting that high intelligence is unlikely to develop. The only two major exceptions are primates and dolphins. [Brain size and EQ]
  • Anything resembling human language developed only once. [Origin of language]
  • It is far from certain, but it seems that Neanderthals had the same capacity for speaking language as modern humans. This pushes development of language very far back, and suggest development of civilization even given language is unlikely. [Neanderthal]
  • Transition from animal life to something as complex as early Homo life (Lower Paleolithic), like manufacturing of tools, control of fire etc. seem to have happened only once in history of life, and extremely late. [Human evolution]
  • Likewise transitions to Middle Paleolithic, and Upper Paleolithic seem to have happened only once. It could be argued that if it was  isolated human populations had chance of developing innovations contained in them independently, but didn't.
  • Some inventions like wheel, and iron smelting were invented only once. However by this time the world was going so fast and globalized enough that it's very weak evidence for their difficulty. Inventions later than antiquity also provide little evidence due to little time and little isolation.

To me it looks like life, animals with nervous systems, Upper Paleolithic-style Homo, language, and behavioral modernity were all extremely unlikely events (notice how far ago they are - vaguely ~3.5bln, ~600mln, ~3mln, ~200k or ~600k, ~50k years ago) - except perhaps language and behavioral modernity might have been linked with each other, if language was relatively late (Homo sapiens only) and behavioral modernity more gradual (and its apparent suddenness is an artifact). Once we have behavioral modernity, modern civilization seems almost inevitable. Your interpretation might vary of course, but at least now you have a lot of data to argue for your position, in convenient format.