Once again, do you consider viruses alive? They certainly evolve, after all.
But I think we can agree that evolution does not consider how the first replicating molecules arose. It definitely does consider how single celled creatures arose. So the boundary is somewhere between these, but who knows where, and does it really matter?
As for SW, you don’t need to really worry about what someone who still believes in geocentrism things about how to classify Pluto.
Yes, on viruses. Not sure about prions.
And yes, it really matters. If the first replicating molecules are not alive, but the first single-celled creatures are, and evolution begins in the middle… well, that kind of bolsters the creationist argument, doesn’t it?
I think that’s more an issue with the state of the art in abiogeneisis than with evolutionary theory. Some (e.g., John Bernal) argue that selection may have kicked in sometime between the rise of biological monomers and the rise of biological polymers…both of which were well before anything we could call “alive” (since we’re still dealing with chains of molecules at this point).
Not that I’m saying I agree one way or the other, just that the issue is not as cut and dried as many seem to believe. Evolution does not strictly require “living” things, and there is a continuum between “non-living” and “living” such that there is probably no clear demarcation for when evolutionary mechanisms absolutely cannot work vs. when they absolutely can.
For the time being, we can safely disregard abiogensis in discussions of evolution, but I suspect that it won’t be terribly long before the two are integrated.
Evolution begins where it begins. Evolution may well have begun with some reactions/molecules that we don’t consider to be alive today, but the definition of life is tricky like that. As far as I know, what we know for sure is that living organisms evolve, and some things that are nearly alive (but need other living things to reproduce) evolve too.
It’s possible that our kind of life started when there was already other life and RNA/DNA based life just outcompeted it. I don’t know. But what I do get from biology is that it’s very hard to place borders anywhere. Everything sort of blends into something else. But evolution per se doesn’t explain the origin of what we call life today with any kind of satisfying detail. “Here some new ideas are needed”.
How? If they agree with us about viruses, then they have to admit that we can create life, and there goes its specialness. If not, then they have to agree that nonliving things evolve. Game, set and match. The big misconception of the creationists I’ve run across is that abiogenesis (or evolution) says that a bunch of chemicals got together and formed a cell. I don’t think they ever want to consider the subtleties of when life begins.
And thanks for bringing up prions. I was thinking about them, but don’t really know enough to say much. They might be on the other side of the life/non-life divide from viruses. Does anyone who does know have an opinion?
Why make up a special category of “living” things when we can describe “life” much more accurately as the sum of many different functions? Maybe I’m ignorant, but there seems to be no reason to mandate that only living things may evolve, and then scratch heads about whether prions and such should be classified as living or not, and therefore allowed to be called evolving or not.
The prion is content just being a collection of molecules that respond to outside pressure, why should we create confusion over what’s essentially a meaningless label?
Life is meaningless. 
Got it.
Anyone got some rope?
As John Mace has already pointed out, you’re trying to fit things into neat boxes when that’s not how they’re meant to be packed.
Ask Really Not All That Bright.
No, life is but a dream.
Sh-boom
No, it doesn’t. The precursors of life didn’t require evolution because they were simple enough that chance and the rules of chemistry could make them. It’s only high levels of complexity that require explanation; that explanation being evolution.
And creationism doesn’t explain anything. It just pushes questions back a step onto God and then commands everyone to stop questioning further.
Would there not have been a variety of candidates with different properties? Would they not have enjoyed differential success and failure within the context of whatever environment they arose in? If so, that’s evolution.
I disagree. Evolution can occur in very simple systems - such as computer simulations of imperfect self-replicators.
If there’s self-replication and selection, there’s evolution.
I wouldn’t call that a simple system
The computer is complicated, and perhaps even the simulation, but the replication system is simple. Gotta be fair here - we don’t include the entire universe (or even the whole biosphere) when assessing the complexity of a single species’ evolution.
It’s simple though because it doesn’t face the “hardware” difficulties of a biological replicator. In biology, hardware and software are pretty much merged; for a fair comparison, you need to compare it to the computer + software, not the software alone.
Huh? Adding 2 + 2 is simple, no matter if you do it on your fingers or use a supercomputer.
Simple replicators are not actually biological, (except in the sense of organic chemistry) but chemical. I don’t think anyone knows what the simplest self-replicating molecule is - it is certainly simpler than RNA. When we move from chemistry to biology is just about the same question as when we move from non-living to living - more a matter of human categorization than anything important. Thinking that there is something fundamentally different isn’t all that far from thinking there is some sort of a life force.
Without knowing how abiogenesis works or what conditions it occurred under, the answer would be “we don’t know.” It’s possible the reason we only see the descendants of one abiogenesis event today is because only one event of abiogenesis ever occurred.
Possible, but it seems particularly unlikely. If the chemicals that combined to form the proto-life replicators consisted of a lone set of molecules, it would be quite difficult for them to become a population of on-their-way-to-living things.
“We don’t know” doesn’t mean “We shouldn’t hypothesise”, neither does it mean we shouldn’t consider certain likely things more likely than certain unlikely things.
So, (and this is based on the assumption that there was no supernatural poofing of things)…
Whatever the proto-life was, it must have required, and have been based on resources - that would most likely have been a pool (maybe even quite literally) of resources.
Whatever can happen once can happen more than once - it is not improbable that the interaction of molecules that formed our proto-life ancestor was one example out of a collection of similar candidates within the resource pool.
We know it had to be a replicator (or else it would have gone nowhere and we would not be here)
We know it had to be an imperfect replicator (or else the world would contain nothing but lots and lots of perfect copies of the original proto-life)
We can quite reasonably assume that the imperfections in the copying process would introduce differential efficiency of function, differential durability in different conditions, differential success in further replication.
And that’s all that is required for a process of evolution to be occurring. It’s not biological evolution, but it is evolution (and not just in a wishy-washy ‘change happening’ sense)