5 minutes ago by cletus
I expect that there are some things that are "universal" and some that aren't.
For example, if life--any life--forms on a planet, it is likely that some macro-organisms will evolve that consume other organisms.
On Earth we have plants that are eaten by animals that are eaten by other animals and so forth and these all act as a form of "battery" in that solar power is converted into energy and increasingly stored in larger "blobs". This is almost necessary for large life to exist. Well, for carnivores at least (eg many whales eat krill and there are a bunch of filter-feeders).
So the chemistry of life elsewhere may be similar or it may be totally different but something like a carnivorous trait is I think almost inevitable.
Once you have that then certain other traits became almost inevitable. Flight, for example. It may be that flight is impossible given local conditions (eg high gravity, atmosphere or the lack thereof). That doesn't mean we'll end up with feathers and birds per se but evolutionary pressure will likely mean available niches are filled. On Earth almost every environment has life, only really excluding the coldest, driest, highest and deepest of places.
Also, consider sensory organs. I expect the ability to detect parts of the EM spectrum, sound, taste/smell and tactile feedback will all likely evolve with sufficient time. And that itself has consequences for what life looks like.
28 minutes ago by rendall
There's an entire genre of these kinds of books that extrapolate generalities (life throughout the Universe) from a single data point (life on Earth), but the truth is, that's not even an educated guess.
We do not know if our evolutionary pressures are universal. We do not know if the evolutionary solutions developed here are appropriate even on other Earth-like planets, much less everywhere. Sensitive dependence on initial conditions could lead to radically different planetary environments, necessitating radically different mechanical solutions, some (many, most?) of which we will never have even imagined.
What creatures would form under an intense magnetic field? In methane? In close orbit around a dim star? In a hot cloud nebula? Could we even recognize them as alive, much less intelligent? Definitely not if we're looking for bats and monkeys and octopuses
No, I think the whole genre of "life is much the same everywhere" suffers from a profound lack of imagination
7 minutes ago by aaronblohowiak
Weirās latest book goes into this. (Ex: Audible hearing is based on the distribution of frequencies generated when solid bodies collide or rub.)
On the other hand, If life is that which can use an energy differential to create more order within it (an entropy pump) then sure there are likely forms of ālifeā out there that weād have a harder time imagining (that perhaps operate at physical scales and timescales beyond us ā thinking nebulae)
an hour ago by xtracto
Great read, thanks. This is a very interesting subject to me. A couple of years ago I read a theory about alien life that was a bit different from this:
Given the age of our universe, sun, earth and humans:
Universe 14 000 million
Sun 4 600 million
Earth 4 550 million
Earth Life 3 500 million
Humans .2 million (200,000 years)
an hour ago by jbotz
First, the article wasn't about human-like technological civilization, but just about life in general. And there are species of animals alive today that have hardly changed in 100s of millions of years. So Kershenbaum would be right if we found some life-forms that vaguely resembled for example a Coelacanth on some exoplanet.
Second, you're ignoring the fact that life as we think of it can really only evolve around at least 3rd-generation stars because you need enough heavy elements. That cuts the age of the "life-capable" universe by at least half, so the window of relatively modern life on earth with respect to the age of the life-capable Universe really isn't that small... let's say 350My out of 7Gy, so about 5%.
42 minutes ago by TedDoesntTalk
What are 3rd generation stars, and why do we believe that life āas we think of itācan only evolve around them?
30 minutes ago by dogma1138
Stars that formed in nebulae that had at 2 previous cycles of star formation and super novae.
This means that the starās solar system at that point has sufficient quantities of heavy elements which cannot be produced by stellar fusion, as these elements are produced by super novae and from solar radiation.
Basically all the neutrons that are produced when a star goes boom create the elements that are above iron in the periodic table.
24 minutes ago by Jerrrry
Familar higher orders of complexity emerge far easier within systems with more states.
Due to our physical laws elements with larger rooms for reaction via chemistry are familar.
The chances of a replicating agent just anthropologically emerging from the surface of a 2nd generation hydrogen dominant star with an accumulation disc composed of little higher orders elements is inconceivably less likely than the relative petri dish organic molecules provide.
36 minutes ago by AnimalMuppet
First generation stars are stars that are formed from big-bang gas - mostly hydrogen, a bit of helium, a trace of lithium, and nothing more. Second generation stars are formed from the gasses blown off by the novas of first generation stars. Third generation stars are from the novas of second generation stars.
I suspect that the claim that life as we know it can only evolve there is because life as we know it needs a wide variety of chemical elements. We need carbon and oxygen, of course, but also iron and calcium and magnesium and potassium and so on. You're not going to get that around a first generation star. You might not get enough of it around a second generation star.
41 minutes ago by TedDoesntTalk
His article completely ignores the possibility of engineered life. Engineered life can bypass evolution and natural selection, even if the species responsible for the engineering was a product of evolution.
36 minutes ago by piyh
Strong arguments can be made that the ability to become a multi-planetary civilization requires you to master the tech tree that includes engineered life.
26 minutes ago by dogma1138
Engineered life still follows evolutionary pressure and natural selection it just might not hit the same walls as life that is only driven forth by random mutations and opportunistic gene exchange does.
36 minutes ago by xwolfi
Heh and what if the engineer even introduces evolution and what he truly engineers is code-based chemical cells that can conquer, survive, evolve and expand from anywhere ? :D
I'd do a life myself, I'd make it post-metallic, post-silicon, post static: I'd make it use water and carbon, so that it can exist everywhere. I would make it so that it can become intelligent on a small time scale, say a few billion years, all on its own, from scratch, on any rock :D
Not saying we have an engineer, but you think of engineered life as you are now as a simple software programmer. But an engineer in 500k years trying to expand more, would probably think of chemical automata that can evolve and adapt in harsh conditions. Say for instance if humanity decided it would be enjoyable for life to exist on Jupiter. It'd have to make something that can try a lot of variations with a very simple first formula to consume whatever gas there is there and survive whatever pressure.
34 minutes ago by piyh
It'd be like explorers dropping goats on islands to come back to harvest them later.
31 minutes ago by jacquesm
Creationists may be on to something after all ;)
an hour ago by roberttod
Unless we just happen to have evolved very early on compared to what's normal, we should expect a lot of intelligent life with just a little bit of variance on these numbers. And some of that could easily be millions of years old. Interestingly, even if a life form populated new solar systems at a rate of a thousand years per system (where each populated solar system in turn populates more of them), they'd still fill up the Galaxy in only a couple million years.
an hour ago by willis936
This is assuming independent genesis. Panspermia has a lot of merit.
an hour ago by echelon
Panspermia is fascinating conjecture.
The preferred chirality of organic molecules could absolutely have arisen by chance, but it's an interesting to see this in meteorites.
On the unrelated subject of handedness, I saw an interesting thread on Twitter today [1] speaking about how we're starting to synthesize reverse chirality polymers and enzymes, most notably DNA and replication enzymes.
There are a lot of interesting implications.
You can't get rid of L-DNA without reverse DNase, leading to an accumulation of information and transcription. So they need to remake all the enzyme steroisomers.
That alone is interesting, but you can take it further to the limit and produce reverse biology that synthesizes reverse sugars that can't be metabolized by much of extant life [2]. Suddenly a lab-escaped reverse autotroph can out-compete all of us right-handed lifeforms because nothing can eat them. Bacteria, plankton, the entire food web collapses. When we have nothing left to fish or farm, we die too.
Never thought nanotech's grey goo was plausible. Now I see something that rhymes with it, and I could see it happening within our lifetimes.
It'd make a crazy MAD bioweapon on par with or potentially worse than nukes.
Wild tangent, sorry.
[1] https://twitter.com/eigenrobot/status/1420952351968432130
23 minutes ago by piyh
A MAD weapon like that just becomes an AD weapon. A nuclear lab leak kills under 1,000 people. A living weapon lab leak would kill (nearly) every other living thing.
an hour ago by radicaldreamer
I'm getting similar vibes to out of control gene drives created with crispr...
an hour ago by wizzwizz4
> because nothing can eat them
But I assume they're not immune-invulnerable.
an hour ago by machiaweliczny
I think terdigrades might already be alien. How they evolved on earth?
an hour ago by superduperycomb
I believe if you look at their genetics they fit snugly within the tree of life
an hour ago by stefs
tardigrades might have some very cool properties, but nothing out of the ordinary.
an hour ago by jnwatson
The first life we encounter from another civilization might not be evolved at all. Presumably a civilization with the capability of interstellar travel might also have the technology to manipulate the underpinning of life itself.
In fact, if we do discover something from another civilization, it is quite reasonable that it would be some sort of Von Neumann probe. It might be made of mechanical parts, "biological" parts, or something in between.
A Von Neumann probe would be highly engineered, and might have no trace of evolution to it.
an hour ago by drdeadringer
I recall a scifi story by Stephen Baxter where a human-made probe on Mars eventually evolved into advanced, aware, spacefaring Von Neumann probes. After a few million years, one curious probe traces serial numbers back to Earth in search of their creators. However, humans had devolved back into a type of monkey that was directly symbiotic with a literal tree of life. The probe concluded that such a primitive creature could never have developed technology, and left.
37 minutes ago by TedDoesntTalk
Story name?
an hour ago by sandworm101
>> A Von Neumann probe ... might have no trace of evolution to it.
Except that the very fact that it exists represents many evolved traits. If they are sending probes then their are either curious or expansionist, both evolved traits tied to competition for resources and/or survival. A species totally devoid of any history of evolutionary pressures wouldn't act that way, which is one of many possible great filters: once we have access to the infinite resources of space, perhaps we just stop caring and don't bother expanding. Such logic allows us to learn much simply from the existence of an otherwise silent Von Neumann probe.
an hour ago by sigg3
In all likelihood, yes.
But when dealing with infinity, we must appreciate the likelihood of the unlikely too.
Personally, I favor the prospect of the insanely lucky idiot race, that clumsily and completely by chance manage to launch a probe so seemingly sophisticated that every sentient race that discovers it readily submit to its perceived superiority.
an hour ago by sandworm101
There are no real infinities. The universe might be infinite, but the bit of it we can see and/or ever interact with is not (speed of light + expansion). So there are a finite number of stars that we will ever be able to touch before the universe goes dark. And the universe seems to have had a finite starting point. So we can calculate which stars may ever reach out to us. These are very big numbers, but they are not infinite.
Unless star trek is real. Faster than light travel opens up the door to infinities.
an hour ago by XorNot
Well also, a Von Neumann probe is a type of life. It's very unlikely that a self-replicating machine would not develop it's own technological drift in the replication protocol.
27 minutes ago by rthomas6
Or it could be designed to be very small so as to efficiently send out at near light speed, and designed to quickly adapt and replicate in any hospitable environment.
Maybe we are the Von Neumann probe.
an hour ago by legrande
> It might be made of mechanical parts, "biological" parts, or something in between
Or just a digital clone of a once-biological being that can live for infinity exploring the Universe. Why would you explore the Universe in a meat suit?
an hour ago by LaMarseillaise
You enjoy proximity to other meat suits?
Without that, it sounds to me more like hell than heaven.
an hour ago by ignoranceprior
If Star Trek taught me anything, it's that most aliens look like humans, except for some bumps on their forehead. Hodgkin's Law of Parallel Planetary Development.
an hour ago by ramboldio
If any life on earth was extraterrestrial, I would bet on fungi. It somehow works too well.
9 minutes ago by actusual
My grass is in heavy agreement. Mushrooms pop up in my yard within hours of watering.
an hour ago by Andrew_nenakhov
Soviet writer/philosopher Ivan Yefremov (probably, the most influential soviet Sci-fi writer) argued rather convincingly, that humanss have ideal body size and layout for intelligent beings, and that extraterrestrial life would probably look somewhat similar.
31 minutes ago by TedDoesntTalk
The article mentions that we have 4 limbs only because the creature that left the sea had 4 fins. It could easily have been 6 or 8. He makes it seem as though 4 was just plain random.
12 minutes ago by Andrew_nenakhov
Having more limbs is less efficient biomechanically - the creature would need a larger heart to pump blood through al organs, that requires more energy, so such creature would need more food.
Now, it is known that creatures can lose limbs through evolution, but never gain them, so it is likely that multi-legged species would gradually lose extra limbs over time.
4 minutes ago by Joker_vD
> creatures can lose limbs through evolution, but never gain them
Wait, so where did the limbs come from anyway, if they could not be gained?
an hour ago by genesis126
God: "I thought so too"
an hour ago by roberttod
I hope that also applies to the evolution of morals for intelligent lifeforms. I think it's safer to assume any aliens will have bad intentions but maybe any lifeform that can build interstellar technology has come to the same conclusions that we (albeit slowly) are coming to.
an hour ago by fairity
I think itās safe to assume any highly evolved alien species will have moral constructs that support self-preservation.
Whether those morals extend to preserving other intelligent life forms (I.e. humans) seems unlikely since the prosperity of other life forms will inevitably lead to more competition for scarce resources.
The fact that human moral constructs apply to other intelligent species seems to be a bug that arises solely from the fact that weāre currently capable of out competing all other intelligent species.
11 minutes ago by benlivengood
My optimism says that radical consensual transhumanism might be a universal Schelling point and that if humanity reaches that point we'd fit fairly well into any advanced alien culture that reached the same values. Probably the biggest value difference at that point would be the morality/consciousness thresholds for tiers of personhood.
I don't think any morally advanced culture would be willing to accept an indefinite policy of "live and let live" between the cultures as a whole; there are some injustices (slavery, murder, torture) that wouldn't be tolerable to exist in the known universe.
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