this post was submitted on 17 Jan 2024
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Theoretical biologist here. I haven’t looked this person up, but from the talk I’m going to assume he’s teaching an astronomy-related course. He does mention biology but I might be able to go into more detail.
I am also very skeptical about intelligent life existing in the universe. I’m certainly not saying it’s been proven false - of course it hasn’t - but from some of these responses I can’t tell if anyone has actually watched the video. I ran through it at 2x speed - it’s not technical at all - and I highly suggest watching it like that if you’re feeling like the title misrepresents factual observations. I’m not going to address the questions about astronomy, because I think the lecture covers those adequately.
First, let me say that I think it is entirely plausible that something that we could in theory come to recognize as life exists elsewhere. Please note that I am choosing my words very carefully. There is a discipline called exobiology that tries to understand what life actually is, what chemistries are compatible with the complexities we associate with living processes, and how evolutionary dynamics might affect them over time. We think that there needs to be an informational aspect as well as a physical-physiological aspect. The former provides the basis for replication and evolution, while the latter maintains integrity and what Schrödinger called “negative entropy” associated with living systems. It doesn’t have to be DNA, it doesn’t have to be in chromosomes. It will probably have to have something like a cell. It will probably need water. Other than that, I think I’m pretty open to ideas.
Complex life, and in particular life exhibiting technological intelligence (which is how most of us think of intelligent life) is a much higher hurdle. Earth - our single example - has been fairly teeming with life for around 3.5 billion years, give or take. It is evolutionarily highly dynamic (for whatever that means when your sample size is 1) with both mutation and recombination playing roles in genetic and phenotypic diversity. The sheer diversity of factors - transcription, regulation, editing, and so on all provide targets for evolution. Complexity builds upon complexity.
And, given all of that, there has been exactly one single line that has led to technological intelligence. It evolved once. And the thing of it is that, evolutionarily, it’s a really good idea - so much as to allow humans to drive themselves and wide swaths of the entire global ecosystem to the border of extinction. When good ideas occur, they tend to evolve early and often. Eyes are a great example. It’s a very good idea to be able to perceive light, and at my last count I believe eyes have evolved independently around 24 times.
If intelligence evolved once - and we’re not talking about dolphins or dogs here - despite the fact that it allowed humans to almost instantly become the apex species on the planet - that tells us it’s very hard to discover from an evolutionary point of view.
Long story (not so) short, I think it’s unlikely that humans will ever encounter an extraterrestrial technological intelligence. I think that, if we should survive the next century or two, we could likely find the equivalent of bacterial mats. This would be hugely exciting for biologists and would (in a very very literal sense) change life as we know it. We’re just not going to find big headed bug eyed aliens in flying saucers or Vulcans.
First, I want to fully admit I didn't watch the video. Apologies ahead of time if that causes me to be redundant or reductive.
Second, I'm also a biologist, although a molecular one.
Third, I agree with almost all of your premise and train of thought. We're certainly more likely to get the likes of "bacterial mats" than intelligent life anywhere, and especially within a distance that we will ever realistically encounter.
I do wonder, though, how you (or maybe the video guy, but obviously not enough to watch the source material before making an ass of myself...) conceptually reconcile the small sample number of known planets with life (n=1) with the mindblowingly impossible number of worlds.
You say that intelligent life evolving only once indicates that it is difficult for evolution to "discover", which is surely possible to be true. But given that we haven't seen the evolutionary conditions on other hypothetical worlds, from what we know, the evolution of intelligent life has a perfect 100% success rate of occurring on planets with life.
In fact, you mention the independent convergent evolution of eyes as an indication that eyes are a "good idea", and that they must be relatively easy for evolution to discover if they evolve independently, repeatedly. But evolution is subject to the whims of selective forces, so a different world would surely select for different traits. Eyes (or other extremely common evolutionary pathways... looking at you, crab body) might be less frequently selected for or be entirely useless, but intellegent decision making and tool use might evolve in ways we can't even conceptualize in our context.
This also extends to the claim of how our world is evolutionarily dynamic (which you point out is hard to quantify in context). We don't know the dynamics of evolution on other worlds, if it happens at all. Recombination could be a unique characteristic of DNA-based life on Earth or it could be extremely common. Other worlds might have longer or shorter evolutionary time lines, also, since our sun's "working life" is shorter than average due to its size and density. Without another example for reference, we don't know whether we're evolving quickly and with diversity or slowly and conservatively.
I guess, I don't think you are wrong, exactly. I just think you are necessarily making assumptions based on how things work here in order to extrapolate how things might work there-- one has to! But the whole discussion (which continues, like this, to this day) revolves around just too many unknowns. We just don't know, and can't know.
Climbing down from my high-horse, though, I have to admit I'm biased, since I have a pet-belief that life is basically guaranteed to exist elsewhere (how freakish would it be for it to only happen once out of so, so many chances?). I honestly feel like there's a good shot that it's incredibly common, at least in a basic form. In essence, I suspect that if we find bacterial mats (or soup) on Enceladus or Europa then it's basically certain that life is everywhere. But we won't even likely know that in my lifetime, so... I keep dreaming!
First of all, this has been the most interesting and constructive response I have ever gotten on social media, bar none. Thank you for taking the time - I really appreciate it.
The idea I am applying is the fitness landscape. I know you know what I mean by that, but for anyone else who is happy to follow along a nerdy discussion on a post that has about three comments and seven upvotes, biology pictures systems as climbing up hills on a landscape that’s filled with mountains and valleys. It’s the same idea that physicists use to demonstrate minimizing energy by having marbles rolling downhill, except with the opposite direction. Higher means more fit, which in the simplest possible terms means having more offspring.
One question that we try to address is by what mechanism do organisms cross valleys. In one sense, we know that they can’t really be becoming “less fit” in a way that would drive them to extinction based on some future plan - the math doesn’t work like that. On the other hand, we can acknowledge that there’s a significant cost associated with developing some adaptations. The costs do have to be paid in real time, but on the other hand selection is a fickle process that has a significant noise component.
Two of the developments that have interested me are eusociality (eg ants and bees as well as pro-social behaviors in general) and the development of technological intelligence. Fortunately for me, these have come together in humans. Here’s the issue: baby humans are useless. They’re food, at best. Their bobble heads are ridiculously large, and it takes them years to even learn how to walk, much less do anything socially useful.
This creates a significant valley around what we currently believe to be a very high fitness peak. The landscape we’re talking about here is a naive construct, though, and doesn’t perfectly describe what actually constitutes fitness for humans. Instead, we need to factor in the co-evolution of social structures. There is a strong argument that the size and capacity of the human brain was in no small part developed as part of an arms race in sociological development between cooperation and exploitation.
In any case, we’ve seen both sociality and eusociality evolve independently multiple times. Still, we haven’t seen human levels of social learning. We see social learning in some mammals as well as a surprising (but still tiny) number of other species. Being a theorist, I like to fold these examples together with phenomena like DNA exchanges and so on, but at the bottom of the technological intelligence argument it’s still n=1. And the compelling piece, for me, is that technological intelligence led to the complete domination of the planetary ecosystem. If this had come about earlier, it would have. This signifies, to me, that the valley surrounding the very high peak that is technological intelligence is very deep indeed and requires the coevolution of a high degree of socialization, and quite possibly excludes organisms that due to size (like insects) or environment (like octopuses) can’t do things like carry a burning branch.
It’s still an open question, of course, but for me the fundamental physics (for want of a better term capturing the mathematics of these systems) make me absolutely reject the idea of extraterrestrial intelligence being behind things like UFO sightings. The point made in the video is that while we can calculate the number of stars or planets in the galaxy or the universe, we literally have no idea about the other, equally important component, which is the probability of life (or intelligent life) existing on another planet. If the number of planets is 10^15 but the probability of technological intelligence evolving is 10^50, it’s entirely trivial to say that we are all that there is when it comes to the universe contemplating itself.
This is still based on fit, evolution, and technology in the context of Earth and humans. Who knows how (or if) evolution could or would work on other planets. Who knows which traits fit would select for, and what process that selection would be based on.
Also, who knows how else technology could look. We have tech that HUMANS couldn't imagine just 100 years ago. How are we supposed to imagine what technology would look like on alien planets.
My point is: you shouldn't look at the probability of human technological intelligence. And we naturally can't look at non-human technology since we haven't found any. We can't know the probability. All we know is that it has happened at least once.