[ExI] After the Great Filter

[BillK]

On Tue, 15 Dec 2020 at 07:45, Rafal Smigrodzki via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
>
> A recent article in Communications Earth & Environment:
>
> https://www.nature.com/articles/s43247-020-00057-8
>
> attempts to model the likelihood of Earth-like planets to remain continuously habitable for 3 billions of years and comes to the conclusion that the overall success rate would be very low (0.0145). I have doubts about the approach, in part because I don't really understand how the results were generated and I am too lazy to read the Methods section where the assumptions are explained. Well, actually I skimmed through the methods and I think one assumption is a major blooper - that 3 By of continuous habitability are needed for intelligent life to evolve. That really doesn't make sense. The whole modeling effort seems like trying to squeeze way too much knowledge out of way too little data. Or maybe I am not sophisticated to see the general applicability of the method?
>
> Still, the article's conclusion is probably correct - even on planets blessed with all the right ingredients there is going to be a lot of instability, due to various instantaneous perturbations (asteroids, supervolcanism) and the interplay of long-term forcings. We know that complex life on Earth was reset multiple times, so it's plausible that the same is happening everywhere. Life-sustaining planets most likely all have plate tectonics, since this is a very powerful stabilizing mechanism without which the chemical composition of the atmosphere would almost certainly degrade continuously until water is lost (Mars) or a runaway heating occurs (Venus). But plate tectonics implies mantle convection and convection is likely to produce plumes which trigger supervolcanism. So every living planet is most likely primed to erase large animals on a regular basis.
>
> I do not believe that dinosaurs or the theriodonts were in some substantial way more primitive than modern mammals - most likely they were functionally equivalent to the bulk of modern mammals and the only reason they did not give rise to intelligent forms is because they got creamed by climate perturbations too early.
>
> Intelligence most likely appears randomly with some reasonable probability once you have large animals running around long enough - but exactly how long is the average time to first evolved sophont is unclear. Probably not less than 100 million years (Myr), since there were two epochs on Earth when large animals evolved uninterrupted, more or less, for similar periods (the above-mentioned theriodonts and dinosaurs) and still did not manage to evolve intelligence. If we are a lucky throw of the dice, and the average time to intelligence is e.g. 500 Myr, then even on lucky planets with all the right ingredients for life there would never be intelligent life because random resets due to supervolcanism would happen too frequently.
>
> Too much uncertainty, too little data. Anyway, my guess, which I mentioned here before, is that Earth already passed through the Great Filters. We are just a couple of decades away from spreading to other planets. I don't believe that superintelligent AI is a filter, at least not a filter preventing intelligence survival - even if all humans perish in the robot wars, intelligence of the inorganic variety will still survive and spread.
>
> We are on the last millionth part of the last sprint of the longest race in our galaxy, the race to space-colonizing intelligent life. I sure hope we don't trip up at the last possible moment.
>
> Rafal
> _______________________________________________


This article implies that not only the habitability of Earth depended
greatly on random chance, but Evolution itself did as well.  Every so
often, random events wiped out great swathes of species from the
earth.
The idea that humans are the peak of a steady step by step improving
evolution is just not right. It is more like evolution is making the
best of a bad job, making do with what was left after disasters
struck.

If there are other habitable planets out there evolution probably took
a rather different path. I quite fancy being an evolved Tyrannosaurus
Rex, after evolving bigger arms of course.


BillK