> Do principles of cultural development such as the ones presented in "Guns, germs and steel" hold for non-Earth civilizations?
I find this particularly fascinating, because it could lead to a corollary to the Drake equation. This equation would quantify the (possibly insurmountable) barriers that a species must overcome to become a space-faring civilization: strength of the planet's gravity well, ease of access to and total planetary quantity of rare elements required to build space hardware, etc.
Basically, Guns, Germs, and Steel -- but on a planetary scale.
With no evidence of intelligent life other than ourselves, it appears that the process of starting with a star and ending with "advanced explosive lasting life" must be unlikely. This implies that at least one step in this process must be improbable. Hanson's list, while incomplete, describes the following nine steps in an "evolutionary path" that results in the colonization of the observable universe:
1. The right star system (including organics and potentially habitable planets)
2. Reproductive molecules (e.g., RNA)
3. Simple (prokaryotic) single-cell life
4. Complex (archaeatic and eukaryotic) single-cell life
5. Sexual reproduction
6. Multi-cell life
7. Tool-using animals with big brains
8. Where we are now
9. Colonization explosion.
According to the Great Filter hypothesis at least one of these steps - if the list were complete - must be improbable. If it's not an early step (i.e. in our past), then the implication is that the improbable step lies in our future and our prospects of reaching step 9 (interstellar colonization) are still bleak. If the past steps are likely, then many civilizations would have developed to the current level of the human race. However, none appear to have made it to step 9, or the Milky Way would be full of colonies. So perhaps step 9 is the unlikely one, and the only thing that appears likely to keep us from step 9 is some sort of catastrophe or the resource exhaustion leading to impossibility to make the step due to consumption of the available resources (like for example highly constrained energy resources). So by this argument, finding multicellular life on Mars (provided it evolved independently) would be bad news, since it would imply steps 2–6 are easy, and hence only 1, 7, 8 or 9 (or some unknown step) could be the big problem.
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(emphasis mine)
In other words, finding life on Mars would suggest that the Great Filter event may be ahead of us, so we're probably screwed.
It took 3 billion years from then beginning of life to the appearance of first animals (with the inventions of eukaryotes and then multicellular life as important milestones along the way).
Then it took ca. 500 million years to Homo, and 5 million years for our species to develop technology.
So I'd say the road from microbial life to cavemen was 1000x larger barrier, then the road from cavemen to technology. Also the barrier from microbial life to first animals (let's assume some kind of worms) was 10x larger than the barrier from worms to technology.
In summary, getting early microbial life to get organized into some kind of macroscopic animals, this is the hard part. When that is done, vertebrates, dinosaurs, hominids and internet will follow at 5–10x faster pace.
I find this particularly fascinating, because it could lead to a corollary to the Drake equation. This equation would quantify the (possibly insurmountable) barriers that a species must overcome to become a space-faring civilization: strength of the planet's gravity well, ease of access to and total planetary quantity of rare elements required to build space hardware, etc.
Basically, Guns, Germs, and Steel -- but on a planetary scale.