Yes, but by evolutionary chance the biggest brained group of land dwellers, the vertebrates, happened to end up with a mere four limbs. When you look at a broader spectrum of creatures, there are a great many with six, eight or even more limbs; that makes it much easier to free up at least one pair for specialized purposes besides locomotion. I think that at least in that way the evolution of tool using intelligence on Earth has been handicapped by evolution; if vertebrates had evolved with six or more limbs perhaps hands and brains capable of technological civilization would have evolved earlier since there would have been no need to evolve bipedalism along with them.
Assuming a single ‘species’ could dominate all others, which I don’t think is impossible, that species could develop a self correcting ‘genetic’ structure that prevents further evolution. I am hypothesizing that couldn’t happen to the life forms we know, because they seem to based on a structure and form of reproduction that encourages evolution. But it’s not impossible for some other structure to form which produces only clones, eliminating variation. It then could develop a self correction mechanism. Something that either corrects mutations, or makes mutations non-viable. If that structure produced a creature which is hostile to variants, even mutations which confound the self-correction mechanism would still not survive.
I’m not looking at this as something likely to happen. But imagine the eventual development of a self-reproducing machine. The machines might be able to survive a catastrophe that ends life on Earth, yet keep on reproducing. Or they might be send out to the stars to colonize lifeless planets. Those machines might have a core programmatic structure that maintains the self correction. Seen by intelligent life forms who are unaware of their origins, they might be indistinquishable from what we call life. And only by a dogmatic definition would they not be life forms.
Is there any measureable chance of that happening? I doubt it. But I considered the original question in its hypothetical extremes. So I would say that evolution does not have to continue once started, in that extremely hypothetical sense.
This is just restating the assertion, not explaining it.
Let’s imagine that raccoons magically became the only organisms on Earth tomorrow. The single species displaces all other. How could it then “develop a self correcting ‘genetic’ structure”?
Even if such a thing did evolve, it would never become fixed. Any organism that lacked that structure would have an advantage under some conditions, and so you would immediately have two lineages, one that evolves and one that does not. Very rapidly you would have two species, one that evolves and one that does not, then 2 species that evolve and one that does not, then 2, 000 that evolve and one that does not and…
How does that work? The vast majority or organisms are hostile to competing conspecifics right now. Pointless aggression of the type you describe would only decrease the organisms fitness.
It is impossible for such an organism to exist in practice.
There is no such thing as a perfect copy, and there is no such thing as perfect error correction, and no such thing as perfect error correction of the error correction ad infinitum. So long as units remain autonomous eventually an error will slip in, and that will then affect all future duplicates. Such errors will inevitably render the error correction less useful, and as soon as a single organism evolves the ability to cheat by negating the error protection it will produce out of control. It will be a parasite with an infinite number of helpless hosts. The only way to prevent that is to have the error correction system be mutable, ie able to evolve. And if the error correction evolves then so must the entire organism. It’s a truism that as soon as you have any self replicating organism, the laws of physics mandate that it must evolve. You can’t prevent that in any way at all because of entropy. In simplified terms, there are always multiple ways to produce a working imperfect copy of something, and only one way to produce a perfect copy. And that applies to the error correction process as much as to the organism. Since you can’t eliminate the imperfections they will accumulate over time at some point they will bypass the error correction altogether.
You aren’t talking about an end to evolution here. By definition these organisms never did evolve. They were designed to have an immutable, error-free form. You can’t end something that never started.
Multi-cellular life is not a necessary end result of evolution.
Well, yes. But its not an uncommon way to start off an explanation
Racoons are a bad example. How about life forms that evolve to take most of their components of growth from the environment rather than feeding on other life forms. So something closer to plants.
Not if the life form was already in a stable evolutionary stage and the fixed structure was advantageous. The variable life form may get totally displaced.
The life forms we know of work as you describe. I think the origin of life here may be from the simplest virus-like chains of genetic code that went around infecting each other until chance began to create more complex forms. That ability to accept new coding is what makes the life we know so variable. But I don’t think its impossible for an organism to develop progressively towards mutation resistance. That would seem to limit evolution, but if the change was gradual enough so that the organism had reached a stage of development where it could maintain dominance in its environment before it slowed the evolutionary process, circumstances could allow it to survive. The slower evolutionary pace would tend to limit the number of competing organisms to start with, making survival more likely. At the stage where resistance to change becomes prevalent, variants might be treated as threats, so hostility would be an integral part of the survival strategy.
I think there is some much weaker form of this concept in place in the known life forms that keeps variation and mutation in check, allowing organisms to adapt to niches. So in a more consistent, single niche environment, a single species might end up eliminating all competition.
That’s hard to argue with. Unless you include the factor of intelligence and ability to manipulate all aspects of the environment, including the organisms themselves. More on that below.
Well entropy is likely to get us all in the end. But it’s not really a factor in the practical life span of an environment that supports life.
Copies don’t have to be perfect though. They just have to be good enough to prevent a counteracting change. But your best argument is in the copy process. The counteracting change may be just as likely, or more so, than the change that created the static condition in the first place.
But it depends on the construction of the life form. We only have one working system to examine.
Here you are referencing machines rather than organisms as we know them. Which leads to my interest in evolution in the first place. I don’t have much background in biology, I look at evolution and it’s results for the application toward machines. And organisms are machines as well. The machines we control may one day be ourselves. We may become constructed biology, or leave the biological realm altogether (probably necessary to have a chance of beating entropy). Organisms could, hypothetically, evolve to the point where they overtake the evolutionary process. We are not there yet, and I doubt we are as close as some pop-sci speculation assumes, but I don’t see it as impossible.
Does any of this apply to the conventional way the OP is discussed? No. The idea life on earth will stop evolving short of its destruction is, as you said, impossible in practice. But in the vastness of the universe, and human ability to reach beyond on our planetary niche, something else might happen.
What difference does that make?
By definition it wouldn’t. That’s how natural selection works. Only organisms that are less fit can be eliminated. Organisms that are equally fir or more fit can’t be eliminated.
This violates the laws of physics. There has to be some outside energy source, and some limiting resource. An ecosystem can’t just exist of creatures that eat each other.
And as soon as any resource becomes limiting you necessarily have organisms that are reproductively superior.
I think it is impossible, which is why I would like you to explain how it could be possible, rather than repeatedly asserting that it is possible.
Yes, but not survive as well as the billions of other organisms that retained genetic adaptability. That’s the problem with your whole premise. If even one organism exists that retains even shred of adaptability it will inevitably evolve into a super parasite or super predator and eliminate those organisms that can;t adapt to its predations.
How? If an ecosystem can support X organisms then it will inevitably support X organisms. What difference does it make what the pace of evolutionary change is?
Once again, most organisms today are antagonistic towards competitive conspecifics. What you are proposing is aggression towards non-competitive conspecifics, which would reduce the fitness of your organisms.
So a form of the principle that prevents an organism from adapting to new niches allows organsiss to adapt to new niches? How does that work?
Again, this is just a restatement of the assertion, not an argument for it. If this was possible, why has no organism on Earth ever eliminated all other organism, including predators and parasites, in its niche?
It’s a major factor in why perfect copies aren’t possible. There are vastly more ways of make a functioning non-identical copy than an identical copy. As a result any copying process must run inevitably towards imperfection.
Any imperfect copy *is *a counteracting change.
Yes, that’s why I would like you to explain how you think such a thing is even possible. We only have one system to examine, but we can test whether any hypothetical alternative is logically possible.
Only if they cease to reproduce altogether. ie if they cease to be alive.
Well, yes, including the existence of the gods of Valhalla. But there’s no evidence that it is possible.
Hi Blake,
This is fun. I’m too tired to go on tonight, I hope to have time over the weekend to respond. I don’t think I’ll change your mind, but some of the points have explanations.
Still, its a pleasure to engage in debate with you on this topic.
TriP