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The Timing of Evolutionary Transitions Suggests Intelligent Life Is Rare
- dredmorbius 6y agohttps://threadreaderapp.com/thread/1331041820516769792.html https://threadreaderapp.com/thread/1331041820516769792.html
- dredmorbius 6y agoLink disambiguation: https://www.liebertpub.com/doi/abs/10.1089/ast.2019.2149 https://www.liebertpub.com/doi/abs/10.1089/ast.2019.2149
- acqq 6y ago"7. Conclusions 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) 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-anniversary-review-of-ward-and-brownlees-rare-earth/ https://www.centauri-dreams.org/2020/06/26/a-20th-anniversar...
- marshray 6y agoI just get a "Cookie Absent" redirect.
- stevenalowe 6y agoquick skim of paper, looking at final stats - 4.5Byr out of 5.5Byr planetary habitable timezone looks like a Pareto distribution - it took 80% of the planet's lifespan to evolve intelligent life; leaves me optimistic
- AgentME 6y agoIt could be that the average amount of time for intelligent life to evolve would be much longer, like 1000x a regular planet's lifespan. Then you would only very rarely have intelligent life actually evolve, and that intelligent life would generally notice that it came into existence near the end of their planet's lifespan, and that simple life happened to get started very near the beginning of their planet's lifespan (or else intelligent life probably wouldn't have had enough time to evolve).
- hprotagonist 6y agoI'm fairly amenable to the interpretation that something like prokaryotic-to-eukaryotic jump is a real high barrier. I would be pretty unsurprised to find prokaryotic life at least sometimes. I would be much more surprised to find eukaryotes possibly at all, and probably at any high frequency.
- koeng 6y agoWhy would you think that the prokaryotic-to-eukaryotic jump is higher? 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 https://www.nature.com/articles/s41586-019-1916-6
- darkerside 6y agoI wonder how often eukaryotes were created but then failed to outcompete the existing prokaryotes. Complexity often results in poorer algorithmical fit in the short term.
- est31 6y agoIndeed. It's probably the case for every step in the evolutionary ladder. As for eukaryotes, often, evolution rewards larger size, simply because if you are larger you can't be eaten as easily, you can eat larger prey more easily, etc. Compared to prokaryotes, eukaryotes are gigantic. And they seem to cover the niche of huge lifeforms really well.
- darkerside 6y agoBut would have that been the case for the first eukaryotes? The very first might have been a similar size to its predecessor, no? I wonder how many early iterations of eukaryote might have actually been smaller, perhaps, if the organism required additional energy sources to support growth.
- Imnimo 6y agoHow do you differentiate an event that is very improbable and so takes a billion years from an event that is inevitable, but requires many prerequisites, and so takes a billion years? The article seems to simply assume the former model ("We assume that once an evolutionary transition is possible (i.e., once the previous transition has occurred), it occurs at a constant average rate λi, so that each ti is exponentially distributed with an expected transition time of βi = 1/λi"), but that feels unjustified to me. Is it really the case that the transition from prokaryote to eukaryote was equally likely at any time, and things simply sat stagnant for a billion years until one day life got lucky?
- enkid 6y agoIt also seems to assume that there is only one "path" to "observer" status. For example, could there be an alternative to Eukaryote cells that would allow equivalent cognition to our own? We don't know because we only have one instance of "observers" coming around.
- jjoonathan 6y agoSure, all of this is speculative, but the eukaryotic jump is notorious for getting casually dismissed on account of being misunderstood. I think it's one of the better candidates for a filter, so let me advocate it for a second and make sure that if you still want to dismiss it's not due to oversight. The problem has nothing to do with having a nucleus. That's the solution. As you note, it's possible to imagine other solutions. The problem is dealing with gigabytes of genetic data instead of mere megabytes. Typically one would use units of base pairs, but in the context of talking about potential alternative forms of life I'd argue that units of information are more appropriate. In any case, the "easy" strategies suffer from a severe dead end that prevents them from going beyond a few megabytes. Lots of things go wrong at that limit, and while other forms of life would encounter those obstacles in slightly different places, the problem of "simple strategies that don't scale" is almost certainly universal. https://upload.wikimedia.org/wikipedia/commons/e/e4/Genome_size_vs_protein_count.svg https://upload.wikimedia.org/wikipedia/commons/e/e4/Genome_s... Eukaryotes, in contrast, scale. It's not an easy task. The strategies are highly elaborate and severely intrusive. They touch the most fundamental, highly conserved aspects of the genome, of cell functionality, and of reproduction. Genes have to be organized hierarchically, packed and unpacked, and everything that interacts with them has to be made compatible with that reality. Further, everything must be done in parallel. The entire architecture of the genome changes as a result. It's like a distributed system vs a monolith. It's a tough, deep-reaching transition to pull off, it's a tougher transition to justify, and that's if you're an engineer capable of things like planning, prediction, and delayed gratification! A greedy optimizer bumbling around in the dark can't rely on cognition (or even a hype cycle!) to propel itself from one mountain range of local optima to another mountain range. I'm sure there are plenty of strategies for scaling genomes, but if they're all difficult -- and the crazy elaborate mechanisms we see in Earth eukaryotes suggest that could be the case -- then they still constitute a filter. But yeah, this is all speculation. Nobody really knows.
- issa 6y agoI think that whatever our expectations are, we should all be prepared to be surprised. We simply don't have enough information to make any conclusions.
- _aleph2c_ 6y agoIntelligent life could evolve frequently, even within their model, if you consider panspermia (life transmission via rocks between star systems). The infrequent evolutionary events just have to happen once, then get spread all over the place, in the bodies of something like an alien-Tardigrade. Moreover, life could exist off planet. Here is a presentation by Freeman Dyson talking about searching for life in the Kuiper belt (where all the real estate is): https://www.ted.com/talks/freeman_dyson_let_s_look_for_life_in_the_outer_solar_system/transcript?language=en#t-520483 https://www.ted.com/talks/freeman_dyson_let_s_look_for_life_...
- AgentME 6y agoEven if panspermia is happening, that only gets other planets past the first rare transition. We know from the fossil record that the rest of the transitions happened on Earth rather than before Earth was seeded. The other planets would still need to separately make it past all of the other rare transitions to also have intelligent life.
- mindvirus 6y agoWhen you have one data point, you can fit whatever curve you want to it!
- zelienople 6y agoThis paper is a perfect illustration of garbage in = garbage out.
- mcswell 6y agoYou perhaps have specific points you wish to criticize? Or do you just prefer a different conclusion?
- raverbashing 6y agoIt makes sense. We had multiple "resets" of life on Earth (not all the way back to zero), but we only developed intelligence once it seems. As for the chance of life, very hard to predict since we only know of our case.
- Supermancho 6y ago> we only developed intelligence once it seems. Another scenario is that intelligence developed multiple times, but survived long enough to dominate once.
- flukus 6y ago> but we only developed intelligence once it seems. 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.
- Blammar 6y agoIntelligence has developed in multiple Earth species (see crows, dolphins, etc.) 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.
- at_a_remove 6y agoAs much as I like the Drake equation, sometimes I think the big breakdown ought to be "life," "intelligent life," and "intelligent life that thinks communicating with strangers is a good idea," wherein the third phase might be brief -- for one reason or another. You have an array of hypothetical explanations for the Fermi paradox (mostly drawn from sci-fi. mostly.) to bounce off of all of these estimates and I confess a great curiosity as to which estimates and explanations are true, although it is unlikely that I will ever know. Still, the silence has tilts me toward the more pessimistic explanations.
- ars 6y agoYou have a 4th level: A world with enough resources (energy) that high technology is actually possible. See: https://news.ycombinator.com/item?id=25187100 https://news.ycombinator.com/item?id=25187100
- ClumsyPilot 6y agoThis is a good point, often forgotten: imagine if dolfins are infact as smart as humans / cavemen - can you prove otherwise? They can't write or develop technology because they live in water and have no hands.
- cheese_van 6y agoPerhaps the spontaneous auto assemblage of cell life, and from there, intelligent life is merely time dependent in an absolute sense? In that scenario, all sapient life in the universe evolved at the same time. When we develop the technology to discern communication attempts, so will they. And so will all the others. It will be a Cambrian explosion, simultaneously throughout the universe. Oh happy day!
- tylerchilds 6y agoanyone that's been watching 2020 unfold could tell you intelligent life is rare.
- ArtWomb 6y agoEric Drexler? Now there is a name I have not heard since the "nano machines" days ;)
- Jweb_Guru 6y agoAnd the fact that absolutely none of that stuff has panned out should make you appropriately skeptical here.
- therealbilly 6y agoI think Enrico Fermi had it right. We should have seen something by now. It makes us rare and special.
- meowface 6y agoI sometimes wonder about the odds of the most chilling questions. What are the chances we're the only intelligent life currently in existence? ("We" including other primates, dolphins, etc.) The only intelligent life to have ever existed? The only intelligent life to have ever existed and that will ever exist? Even the first and last instance of any kind of life at all? 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.
- Enginerrrd 6y agoI'm not so sure. I recall seeing calculations that show that, unless an intelligent species was deliberately sending out very high energy, very well targeted signals, it's really unlikely we'd detect them.
- boltzmann_brain 6y agoExcuse me, I may be dumb, but I never understood this. Given the sheer size of the universe, and accepting the fact that we cannot overcome speed of light, wouldn't it be more plausible that indeed, the universe is teeming with life, but everything is so far away that the chances of two civilizations ever making contact is miniscule. Even the light we see in our sky is millions or billions of light years old, so it's quite likely the "observation window" to spot somebody out there is just too damn small.
- titzer 6y agoI don't find this argument terribly convincing, especially since it (and apparently all of the author's reasoning[1]) rest upon the unstated assumption that we are randomly distributed over possible observers of the universe. The endpoint of that whole (bs) line of reasoning is that we are all Boltzmann brains[2]. In the end I am only convinced that the authors' main specialty is grabbing headlines. [1] from browsing a paper he co-authored with Nick Bostrom, offender #1 of bad probabilistic thinking [2] https://en.wikipedia.org/wiki/Boltzmann_brain https://en.wikipedia.org/wiki/Boltzmann_brain
- Symmetry 6y agoI'd actually written something very similar, without the rigour, a few years ago. http://hopefullyintersting.blogspot.com/2018/03/the-drake-equation-again.html http://hopefullyintersting.blogspot.com/2018/03/the-drake-eq...
- cambalache 6y agoWhat rigor? The article is just one baseless speculation after another
- AgentME 6y ago>So just looking at the timelines involved it seems like the origin of life wasn't the hard part. 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.
- JoeAltmaier 6y ago"Intelligent life"? What about dogs? Dolphins? May as well argue about "Civilizations that produce iPhones are rare" - the definition is particular to humans. Monkey-troupe intelligence may indeed be rare, and insectoid emergent reasoning the norm. Or whatever.
- est31 6y agoThe metric they used was the oldest artwork. The table contains a citation to "Pääbo (2014)" in the line where intelligent life forms. Of course, question is, what do you consider as art :). Is a dolphin frolicking in the water performing a piece of art? Our own judgement might be clouded.
- JoeAltmaier 6y agoWe may not even perceive their artwork - it may be 3D images projected via sonar or some such. That's my point - if we define intelligence as "what humans do" its missing the point. And leaving out a possible universe of intelligent beings.
- AntiImperialist 6y agoCareful with that one. Francine Patterson has been attacked by her "intelligent" peers for all these years because she was able to teach sign language to Koko the gorilla... and since a gorilla obviously cannot be intelligent, she must have faked the reports... or the best one: even though it looked like the gorilla was using the sign language, what was really happening was that it was just imitating the humans for the treats. Something about saying that animals are intelligent triggers some people, specially the "scientist" types.
- sikli15 6y agoThere are legitimate issues with Patterson's work that do cast doubt on her results. Things like speaking for Koko or "correcting" for her when it seemed like Koko was signing something nonsensical. For example, Koko had an apparent fascination with nipples. In front of cameras, Patterson would always say Koko actually meant something else because nipple rhymes with whatever word she's trying to say but in private, according to other caretakers who worked with Koko, Patterson often showed her nipples to Koko almost like a greeting and made other female workers do the same to their discomfort. She would also ask Koko leading questions to get desired responses for cameras which doesn't demonstrate intelligence. Patterson apparently also spoiled Koko, feeding her things that weren't good for her nutritionally, but went to great lengths to keep Koko to herself, going so far as to keep her separated from the male they brought in to keep Koko company. So while I would be excited at the prospect of intelligent animals, I think Koko is unfortunately not a good example.
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- regularemployee 6y agoI've always wondered, given enough time could any species on Earth become "intelligent"? If one day humans all left Earth, then in a million years when we come back to visit, is it possible for Octopus to have made octopus space suit and fly in octopus craft and visit the moon? I think its possible. I think if humans just helped them a little it make take alot less than a million years. It would be cool for Humanity to just foster civilizations in all species on earth. It would really interesting to see how other species's approach to technology.
- SubiculumCode 6y agohttps://www.goodreads.com/series/41134-the-uplift-saga https://www.goodreads.com/series/41134-the-uplift-saga
- regularemployee 6y agovery cool. thanks for sharing.
- xwdv 6y agoThis is called uplifting, and it should be possible to do it in the 21st century by using genetic engineering to give creatures progressively bigger and better brains with each generation. 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.
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- bmitc 6y agoI knew I recognized the author somewhere. I recall him from his fun article about a torus Earth. http://www.aleph.se/andart/archives/2014/02/torusearth.html http://www.aleph.se/andart/archives/2014/02/torusearth.html
- robertofmoria 6y agoThis article seems to take the wrong stance that evolution is a slow change over extended time in population. The new models of evolution is actually population change happens rapidly in a few generations caused by outside stimuli. The resulting change lasts a long time until new stimuli cause population change. Evolution if graphed is steps instead of a curve. Did they even address the cause for "intelligence?" As I see it two possible signs of intelligence before documented communications (ie. Pictures and what not) would be simple tools and fire. It is outside the scope of this paper(maybe), but, I think they did to be able to address if humans today are actually any more intelligent than humans in the past, or human record knowledge is the cause of human advancement today. Also I did not see them define intellgence as it pertains to nonintellgent life.
- tuatoru 6y agoAccording to Wikipedia symbiogenesis[1] is the leading theory for the development of eukaryotes. If this holds, then multicellularity is not at all a hard step from eukaryotes. It's just more of the same. From a similarly naive viewpoint, once you have evolution, predation, and liminal environments, intelligence is going to be selected for to some degree.[2] It's by no means any kind of saltation. So one hard step, abiogenesis (maybe-I have doubts about that too). 1. https://en.wikipedia.org/wiki/Symbiogenesis https://en.wikipedia.org/wiki/Symbiogenesis 2. And that's what we have, some degree of intelligence but not much. We can barely understand the input from a few thousand pixels in our foveas (we live about 80 ms in the past), and mostly can't operate our eyes and speech processing centres at the same time.
- fotdutah 6y agoThe argument regarding intelligence is that the type of intelligence which humans show is rare on Earth as a evolutionary strategy. Other highly intelligent animals do not seem close to even the first steps of space exploration. Perhaps a better term than intelligence is 'culture'. 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.
- Hitton 6y ago>Other highly intelligent animals do not seem close to even the first steps of space exploration. Ten thousands years ago humans didn't seem close to it either and yet they were same as us (and also same as their ancestors for dozens thousands years). 100,000 years is nothing on evolutionary scales and yet during this time our ancestors managed to outcompete other intelligent specie, Neanderthals and probably caused their demise. Considering what our species did to environment it's likely that as long as humans exist, another intelligent species can't evolve here.
- fotdutah 6y agoThe comparison is not just with other animals today but across time. Dinosaurs dominated the planet for 100 million years but do not appear to ever have been as close to space exploration as the humans of 30,000 years ago. Octopuses have been around for 500 million years. For most of this time humans were not holding back or inhibiting their propensity to study, receive signals from, send messages to, or travel to, other stars.
- htk 6y agoTangential to this, but one of the authors, Anders Sandberg, has a great page on transhumanism that I loved reading a long time ago. If anyone is interested: http://www.aleph.se/Trans/ http://www.aleph.se/Trans/
- bambax 6y agoAll fine and well but this tries to draw significant statistical conclusions from a sample of one, and it's unclear if that's even remotely possible or wise. The instant we find a counter example all this nice thinking will have to be trashed.
- sunstone 6y agoThe diverse examples of octopus, dolphins, elephants, parrots and great apes strongly suggests that intelligent life is not particularly rare. However the combination of a species' intelligence and an anatomy that can take advantage of the synergy between intelligence and tool making might be rare.