I believe that Evolution is universal, but obviously I can’t prove it either way. Simply imagining that it is not in effect on other planets in the Universe has a drastic effect on the probabilities of life on other planets, what “life” is, what “intelligent” life is, etc. It just seems too contrary to common sense, but common sense has bitten me before…
Can anyone think of an argument that Evolution MUST be universal? Or conversely, can anyone think of a way for Evolution to NOT be universal?
I know I am assuming some things:
that evolution is the process that guides life on earth
that there are other planets that could sustain life
If you want to argue these assumptions, I think there are other threads here that already address them, it’s best if you go there.
The theory of evolution does not address the origin of life, but the broader term “science” does. If you take a scientific approach to the world, then “science” is universal. If you take a religious approach, then you might conclude that “God did it”.
Once life takes hold, there is every reason to believe that evolution would come into play, just as it does on earth. Unless, of course, some supernatural being makes it otherwise.
At it’s simplest, the Theory of Evolution is nothing more than the rather obvious statement that things with qualities amenable to lasting will last, and ones which don’t have these qualities will not. Given enough time, almost everything you see will be something which had the ability to last.
While there is certainly plenty of space dust in the universe, it’s fairly certain that most of it has compacted down to form a planet star or whatever because given even the slightest gravitational pull and enough time, everything will have a tendency to collect. Planets and stars are the survivors.
You might look at the solar system and think that the odds of all these planets, initially traveling on some random course through space, have ended up in a nearly perfect orbit around a central mass that will last for billions of years is nearly zero. And it is. But given enough bodies and enough time, those which happened to hit on an orbit will last, those which don’t will have long been sucked into a star, or have ended up circling some other star.
For a very broad definition of “Evolution”, these are just a couple of the examples of it that we can observe outside our own planet. But the idea is so simple and so obvious–though it’s ramifications are of course rather complex to grasp–that it simply must be a universal truth. If you choose a random point in time, on a tremendously long scale, practically everything you see will be the items which had the qualities to survive.
It’s difficult to see how there could be a system of living organisms (or similar) in which it would not occur - without variability, nothing could ever develop from one form to another, and if there is variability, some variants will tend to prevail over others.
If there’s competition or survival pressure of any kind, there will either be evolution or extinction.
I think the main issue would be mutations . . . the fact that Earthly life experiences random mutations that can ultimately succeed or fail. Conceivably, there could be life that simply does not mutate, either due to its nature or the nature of its environment. No mutations = no evolution.
The problem with that is you have to account for the transition from non-life to life. That is a blurry line, and is more of a process than an event. You would have to have change (mutations), and then suddenly no change (no mutations). I suppose that is possible, but hardly likely. Without mutations, it is also likely that any life would have trouble surviving changes in the environment.
I agree. I think it would be possible for non-live to produce life without evolution in a fairly broad sense, even if that’s probably difficult, but it would be difficult for anything that we would call life to exist without some kind of inherent (flaws in the) mechanism that would result in evolution. That sort of life would by definition be completely impervious to change (at least, if we don’t postulate an intelligent designer), probably very very simple (since how else would it have come into existence in the first place) and probably outcompeted if not outright eaten by evolving life forms.
I really don’t know anthing about the mathematics of evolution, however from a topical standpoint evolution seems to require things like fragile organic creations, limited natural resources that those creations need to keep existing, and the ability for changes in those creations to be carried out over time (rather than rubber banding back to an earlier state). Among other things.
So I really don’t know. If there is a planet that has so much geothermal and sunlight energy that nothing needs to compete, then who knows. If the planet it somehow designed that life can never reach saturation point relative to natural resources (ie there is never the opportunity to create enough life to use all the energy and raw materials available on that planet) then evolution might not exist. Here on earth we have evolution largely because the life forms (plants, herbivores, omnivores, microbes, etc) are all competing against each other for natural resources. Microbes attack us, so our immune system evolves and there is an arms race. We eat plants and animals, so they evolve.
So assuming there are abundant natural resources and life forms are not competing, then maybe evolution wouldn’t exist there (at least nothing like it does here). Or a planet where the life forms cannot maintain changes to their organic structures over time, or they cannot pass changes on to offspring. With life here a DNA mutation can be passed on for millions of generations. However changes in your own physiology due to life experience (or life experience itself) cannot be passed on to children. Only DNA and memes (as far as I know) can.
All resources are limited, even if the limit is very large. But if a resource is very abundant, that just means that you’ll get more and more organisms, until eventually, there are so very many of them that competition for resources is significant after all.
>I think the main issue would be mutations . . . the fact that Earthly life experiences random mutations that can ultimately succeed or fail. Conceivably, there could be life that simply does not mutate, either due to its nature or the nature of its environment. No mutations = no evolution.
Ok. Let me throw a couple of seeds out there…
What if an entity itself could not mutate, but there were sufficient numbers of variants somehow continually created that could “stand-in” for mutation.
Here’s one scenario: there is an entity that somehow generates a large variety of children. It’s always the same large variety (i.e. variety#1 through variety#n). Say most of them die, but some do live and so the species carries on. There is no mutation, but there is variety. Is that sufficient over the very long term?
You may be tempted to say no, there will – eventually – be an environment where all variants of that species dies, i.e. goes extinct. But remember that mutation (on earth) does not guarantee the survival of a species either, there can always be an environment where all current mutations do not survive.
In Evoluition on earth, there is mutation but also crossover. Crossover is where you get a trait from one parent and a trait from another. Could there be a planet where there is no mutation, only cross-over? Or does there have to be both?
My understanding is that mutation is very rare, and that crossover produces more variants.
Also, I know there are species on earth that do not have mates, they are asexual and reproduce without mating (yes, there’s a joke in there somewhere! :p). I do not know however, if crossover occurs for them or if there is some other mechanism that produces more variety than just mutation.
Even with abundant resources, variation in the way they are exploited may bring about differential reproductive success. This won’t bring about the elimination of the less successful forms (at least not until the resource limit), but it would affect the population numbers of different forms.
Well not really, but you have uncovered an assumption I’ve made: if there is “life” – whatever that is — then there is “death” as well. I personally think it’s a valid assumption and so to skip the philosophical arguments, I’d like to just go ahead and assume it.
Now, aren’t both required? That is, reproduction is necessary to replicate members of the species to accommodate for deaths ***and ***variants are necessary to accommodate environmental changes.
Just to double check: If there is death in a species, then there must be reproduction to get the population count back up. Correct? Is there any other way to do that without some sort of reproduction mechanism? I can’t think of one, but maybe there is…
And isn’t the generation of variants necessary to accommodate environmental changes? i.e. there must be a way to accommodate environmental changes, and the only mechanism possible is to have enough variants “handy” such that one of them survives the new environment? This seems pretty self-evident, but at this point, I’d like to throw it out there anyway…
Note this uncovers yet another assumption I’ve made: there is, and will always be, environmental changes.
A situation I was thinking of would be life arising in a giant crater where underground sources and the external environment provided enough energy and raw materials for the life there. However because of space limitations (the life could not get out of the crater and populate the rest of the planet) they could never use all the natural resources or energy available to them. So the life would never need to steal each others raw organic materials or block out each other’s access to the sun.
However in that situation they might evolve ways to compete against their neighbors anyway, since the ones that are best at reproducing would still end up taking over the whole crater.
These are either tautological truisms or not strictly correct, depending how literally we take them.
It depends on what you mean. As it stands this is just saying “when you subtract, you have to add to the equivalent amount to retain the same value.” That’s a truism. There’s no way around it.
However it’s easy to imagine a phoenix type species where “death” occurs without what we would normally call reproduction. This occurs in some microbial species on Earth where, under stressful situations, two individuals fuse, exchange genetic ,material and then encyst. The two organisms that emerge from the cyst when conditions improve are not genetically the same as either parent because there has been a rearrangement. So effectively the parents are dead.
“The only way to deal with change is to have the capacity to deal with change” is a tuatological truism.
However variation doesn’t necessarily mean generation of new *generational *variants. With a sufficiently complex genome it’s perfectly possible for a single individual to respond to environmental changes. We see this all the time in plants and microbes which, because of limited mobility, have developed some staggeringly complex and sensitive mechanism for gene expression.
In theory a single genetically identical plant could fill every single niche on the planet. Through the use of Lamarckian style mechanisms it would be perfectly possible for the one plant to produce true-breeding roses, oak trees, cactuses and water lillies despite the fact that all those plants have identical genomes. It’s just a matter of deciding which genes are expressed and which are not.
To take it to a higher level, our plant could be a literal single organism connected by underground filaments, each of which produces a different above-ground structure, like the fruiting bodies of mushrooms.
So although there are variants in this single-organism system, it is a variation that does not use evolution in any way that we currently understand it. No changes in gene frequency whatsoever, and no lower reproductive success of any genes. It doesn’t matter if the oak trees outcompete the cactus because the oak tree carries a complete working cactus genome.
That really is a universal. Anywhere in the universe the temperature will vary by thousands of degrees within a few thousand kilometres, gas pressure will vary by even greater amounts. Within water based systems the availability of liquid water will disappear within millimetres. Those are unchangable facts no matter what.
Even if the environment is temporally stable it is physically variable, and it is that physical variation that drives evolution as much as anything else.
Is there any question that the universe we know has evolved since the Big Bang? So everything in it must evolve too. Even before ‘life’ there is evolution and eventually ‘intelligence’ will evolve beyond need of physical form just as it needed to evolve ‘life’ to express itself.
All that you have done in this scenario is made space your limiting resource rather than energy or raw materials. Whatever organism can steal the most space is going to outcompete all the others.
Space is a resource all by itself. People often forget this basic fact because it’s so obvious. A case of not seeing the plain for the forest that now covers it.
In this situation an organism like a strangler fig that can literally steal space by removing any organisms currently occupying it is going to dominate in very short order. That is, unless other organisms can develop mechanisms to prevent it. By removing any constraints aside from space-garnering efficiency you’ve created a situation that applies maximal evolutionary pressure.
There’s no might here. You’ve created an extremely limiting resource. You bet they’re gonna fight over it, and because they only need to evolve to be better at getting that single resource and don’t need to worry about disease, water etc. they are gonna get mighty good mighty fast.
I think you pretty much hit the nail on the head, but this raises an interesting question. If say humans are able to one day conquer all selective influences (universal roboticized resource gathering, perpetual life in a non biological medium, and so on) and spend the rest of time until the heat death of the universe without undergoing change, would you still call that evolution? By your definition I think even a completely static existence, just one that was permanently amenable to lasting, could be called evolution, but that seems contradictory.
No logical step between any two clauses in this post makes any sense to me.