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Comment by merpnderp | Hacker News Reader

If you look at all the crazy coincidences that were required for life to develop on Earth, it starts to make sense that we're alone. Single star in the system, need a big Jupiter to block space rocks, our target is a rocky planet close to star, but needs to be hit by an abnormally large moon right as the lithosphere is cooling, ripping out 1/3rd of it so that the planet can have giant continents barely covered with water part of the time, then submerged the rest of the time to the cadence of this moon, oh and has to be the right star type, and etc etc etc.

If it takes something like all that for life to spontaneously erupt, we're likely alone.

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That's one example of how life is formed. By someone's definition on wiki, life could be defined as

> self-sustained chemical system capable of undergoing Darwinian evolution

Meaning in a different environments with different moons, stars, temperatures, as long as the environment could support abiogenesis (could be different from what we currently know), life would be able to be sustained but it might be a hell of a lot different.

I don't really know what I'm talking about but surely a different life form would've existed at some point somewhere... Right?

Jupiter directs more rocks towards earth than deflects. But life on earth appeared immediately after it cooled suggesting that the process to start life is relatively straight forward. And life by default adapts and evolves based on it's environment, so how crucial the moon is for life says more about how life on earth adapted than how it can possibly form.

We don't know that any of those conditions are necessary. Right now what it looks like is certain chemistry, which happens to be pretty common, an energy gradient of sufficient magnitude, and relative stability.

If we look at it as crazy coincidences, we can say that the earth is in a very unique state due to the crazy coincidences such that theres nowhere else just like it, but then, theres nowhere like anywhere else and everything that exists is the result of crazy coincidences. So, combinations of crazy coincidences that create very unique places are pretty common, ubiquitous even. So there's likely a lot of very unique places out there with very interesting processes going on.

I don't know if we will ever discover life. I don't know if we will ever observe another intelligence that spontaneously developed. But one thing I'm certain of, there are things going on out there that are more interesting than dead rocks circling even bigger dead rocks.

My theory on this is that intelligence, language and culture are surrounded by very high local maxima and we only got over the hump and down into our minima by incredibly slim chance.

So our original evolutionary advantages were persistance hunting & rock throwing (ranged weapons). This gave us such a huge advantage that we had enough excess energy we could start to develop bigger brains, language and culture (tools). For it to be possible we needed:

* Huge evolutionary advantages (rock throwing? fire to cook? walking upright? sweating?)

* Vocal chords that would let us develop language

* Hands that would let us make tools

And once we have that we can start to evolve intelligence and shared culture. But for a very very long time this was evolving a trait that is an actual hinderance. So we also need for that to be our 'peacocks tail'. A costly trait that is selected _for high cost and total uselessness_. And that trait could've been practically anything else!

Imaigne all the worlds where ranged weapons are developed by a species which just can't do language. Or where they can't make tools only throw rocks they find with their evolved longbow like limbs. They'd conquer the world but that would be it. And that world is now too well optimised for another animal to develop intelligence, they can't afford it.

If this is the case life could be wildly abundant but 'intelligence' more or less unheard of. This is infact what we see in the historical record on earth, there were many epocs of dinosaurs, as far as we know none of them shaped rocks for throwing, had language or developed cultures. In the time we've been around no indepdent intelligent species have evolved (we only see evidence of ones with a common ancestor.)

I think the drake equation suffers from the same fallacy that seems to beset everyone talking about AI. Intelligence is over-rated, it is not a linear thing or a super power where more of it is always better and can solve any problem. It's incredibly costly and often quite useless. Our actual problem solving is more down to trial and error at the level of culture than we like to admit to ourselves.

While I don't really have an opinion either way on whether we're likely alone or not, I just want to point out that the blindspot in this argument is that all those things are truly necessary for life.

This is like a form of the anthropic principle [1], where we think that just because those conditions appear to have been necessary for our evolution (and since Earth life is the only example of life we know), that exactly those conditions must be necessary for life elsewhere.

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

We may only think that because we evolved here and thus think you must need all of that as we can't think of it any other way.

On another note, you probably are absolutely right and we do need at least some of that. Not too hot or cold. No massive asteroids to destroy everything...etc. I think some of the rest may be negotiable though. Like do you need water? I think yes, buuut maybe some other liquid could work?

The universe is big.

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