The Timing of Evolutionary Transitions Suggests Intelligent Life Is Rare

eg "more likely to find simple life on Mars."

That ape and octopus exist, says that earth didn't win the intelligence lottery, we are watching the long slow grind of compound interest.

When you look at our world we see that the lipid bilayer is preserved, that rna is preserved in every living thing, but eyes have evolved independently many times. That the last common ancestor of octopus and human was a little wriggly thing, leads me to believe that forming a boundary between self and non self is hard (the bilayer), that forming a system of heredity is hard (first rna then dna). That the accumulation of processes that use energy, resources and information from the environment in new ways is a long relentless grind. The basic body form, multicellularity and a gut were, big difficult changes, but maybe intelligence is just paint on a hard won foundation.

In support of this idea, the Cambrian explosion of large (large relative to microbial life) multicellular organisms happened immediately after the 2 billion years of work by blue-green algae had produced enough oxygen into the atmosphere to make larger organisms possible.

https://en.wikipedia.org/wiki/Great_Oxidation_Event

https://www.sciencedaily.com/releases/2010/12/101217145647.h...

I suspect that' gnawing for any research like this. But I could suggest that if we can show that a lot of fundamental changes have come from external shock rather than internal processes, then we might be closer. Further, if the theory of "puncture equilibrium" is true[1], that this would tend to be the case. If we can show that many evolutionary steps involved such external shocks, then we might be closer to this also.

The question would be whether external shocks inevitably produce advances or whether such advances are indeed lucky.

[1] https://en.wikipedia.org/wiki/Punctuated_equilibrium

This looks to me like a hubristic level of extrapolation from a single data point.

If it is engulfment of organelles like mitochondria, that happens all the time. There are fairly good models of the evolutionary tree and how it could happen over time[1].

On the other hand, the ribosome is an amazingly complex machine, which I would expect would be much harder to create. Even synthetically, the path to build a synthetic eukaryote seems a lot easier than the path to build a synthetic ribosome.

[1] https://www.nature.com/articles/s41586-019-1916-6

It's also possible that earlier similar transitions occured but were overwhelmed by the surviving eukaryotic line, whether due to greater metabolic effectiveness, superior repair capabilities, or other factors.

The OP twitter thread has a very interesting counterargument to this point in your article:

>Life emerged fairly early on Earth: evidence that it is easy and common? Not so fast: if you need multiple hard steps to evolve an observer to marvel at it, then on those super-rare worlds where observers show up life statistically tend to be early.

At least this does just amplify your conclusion, that intelligent life is more likely to be exceedingly rare rather than die out prematurely.

The fact that human abilities are very limited in some ways supports this. For most evolutionary branches it was a much better strategy to develop excellent eyesight, hearing, running or fighting than to trade off mediocre ones against a sort of general-purpose intelligence and communication skills.

It took approximately 4.5 billion years for a series of evolutionary transitions resulting in intelligent life to unfold on Earth. In another billion years, the increasing luminosity of the Sun will make Earth uninhabitable for complex life. Intelligence therefore emerged late in Earth's lifetime. Together with the dispersed timing of key evolutionary transitions and plausible priors, one can conclude that the expected transition times likely exceed the lifetime of Earth, perhaps by many orders of magnitude. In turn, this suggests that intelligent life is likely to be exceptionally rare. Arriving at an alternative conclusion would require either exceptionally conservative priors, finding additional instances of evolutionary transitions, or adopting an alternative model that can explain why evolutionary transitions took so long on Earth without appealing to rare stochastic occurrences. The model provides a number of other testable predictions, including that M dwarf stars are uninhabitable, that many biological paradoxes will remain unsolved without allowing for extremely unlikely events, and that, counterintuitively, we might be slightly more likely to find simple life on Mars."

BTW, the first book that extensively wrote about the basic idea is 20 years old:

"Rare Earth: Why Complex Life Is Uncommon in the Universe" 2000, by Peter Ward, a geologist and evolutionary biologist, and Donald E. Brownlee, a cosmologist and astrobiologist.

https://en.wikipedia.org/wiki/Rare_Earth_(book)

A 20-th anniversary review, covering some details we have learned since then:

https://www.centauri-dreams.org/2020/06/26/a-20th-anniversar...

When a brain is of sufficient capacity for consciousness to emerge, we can begin to educate these sentients, and teach them all we know, leaving them to figure out how they can apply our knowledge to their perspective of the world, which is alien to us.

Octopus for instance may begin to construct tools that will allow for them to practice aquaculture and build more civilized social structures that move them away from hunter-gatherer lifestyles. When they are not farming, they could develop written language to record their history and debts. Surely if you checked back in tens of thousands of years you would find advanced cities and societies as complex as human ones, except entirely underwater with occasional structures breaking above the surface.

Other creatures like chimpanzees could be taught how to work with humans as a cheap form of labor, digging ditches or mining resources.

For a long time, I thought surely these probabilities must basically be zero, due to the sheer amount of dice that can be rolled (tons of space + tons of time), but after hearing a lot of smart people talk about it, I think all of these things do carry a non-zero possibility.

Of course, we'll probably never know, though. There could be some galaxy clusters teeming with life and visible structures but they could be so incredibly far away from us that they basically don't exist from our perspective, and vice versa.

Something about saying that animals are intelligent triggers some people, specially the "scientist" types.

Depends on where your cutoff point of "intelligence" is, we've seen some form of intelligence evolve at least 3 times in birds, mammals and cephalopods. If it's evolved independently 3 times on earth I'd say it's quite likely elsewhere.

Intelligence isn't what separates humans from crows. It's our ability to time bind information past our lifetime. We can use oral traditions, or write down what we have learned. And the next generation doesn't have to start from scratch. And thus you get exponential growth in knowledge.

It is complex language that separates us.

As a data point, it is true some crows have taught their nestlings how to use cars to crack shells to get at the tasty tidbits inside, but that learning doesn't seem to have propagated very far.

Another scenario is that intelligence developed multiple times, but survived long enough to dominate once.