Should whatever process created life still be occurring? Have conditions on earth changed so that the process can no longer occur? Is it the case that biologists would not necessarily recognize it when they encountered it in nature?
Thanks for your help,
Rob
I think probably a big part of the reason it’s not observed happening right now is that life exists, everywhere, and has a habit of eating or mopping up anything like the precursors of life would have been.
Plus the environment today is very different from that when life began. Life freed oxygen, so it is possible that the atmosphere and oceans are no longer conducive to the mutation of large molecules.
It depends. For years scientists believed that life first formed in early shallow seas, with a primive atmosphere without free oxygen and with plentiful UV light. But more recently, with what’s been leatrned of thermal vents, there’s been speculation that life began near such vents, and may be continuing today.
Right on, CalMeacham.
Is it too difficult to observe with current technology?
Thanks,
Rob
Well, those vents are deep in the ocean, so they’re reasonably difficult to GET to. I mean, there’s some spot down in the ocean, I believe, that we’ve only ever been to for 20 minutes…
[sub]Sorry, couldn’t resist![/sub]
I thought this was falling out of favor as these vents aren’t good for creating organic molecules.
{Just going by a story read a few months ago in some science magazine…}
That is debatable. So-called archaebacteria have a wide range of morphology and intercellular mechanisms, and many have substantial similarities to more complex eukaryotic organisms, leaving many molecular biologists to conclude that at least some archaea are degenerate forms of eukayote predecessors. Archaea aren’t just found in deep ocean vents and the like; you can also find them up at the surface in extreme environments that are antipathetic to “normal” life, such as in natural or artificial acidic tailings, or sulphurous geological vents, and they can also be found in more habitable conditions like oceans or marshes where energy is sufficient that they can successfully compete with other organisms. It is possible that some form of what we would today classify as Archaea were the first “complex” life, but the most likely hypothesis (but by no means evidentially factual) is that the first organisms developed from crystalline templates and then became self-replicating by some kind of adaptive recombination process.
As for biogenesis occurring today, it could certainly be happening. However, there are at least two and perhaps more major strikes against protolife developing independently. The first is competition; life is all about using energy gradients for respiration and replication, and a more developed, better adapted organism will tend to push out a newer, less adapted one. Given that life already exists in unimaginable multitude in every nook and cranny, it would be difficult for neolife to get a toehold.
The other problem is oxygen; the primordial atmosphere of Earth was full of relatively gentle, mostly nonvalent complete hydrocarbons like methane and ethane. These are fairly easy to “crack” for energy, but as long as you leave them alone that don’t go nipping away at your trailing ions. However, the modern atmosphere is 21% oxygen, an extremely reactive element which readily and sometimes spontaneously causes violently energetic redox reactions. Imagine, there you are, a new organism casually trying to pry a hydrogen away from a molecule of methane, and all of a sudden comes some free oxygen bully, grabbing your hydrogen and zapping you with a hot photon for your trouble. It’s just not worth it, really. Oxygen is a very dangerous toxin to simple life that has yet to build protective boundaries, and would probably prevent the formation of simple organisms from basic amino acids.
There may be other factors, including the relative transparency of air to UV (which kills simple organisms quickly when exposed), the lack of occasional but strong mutagenic sources, et cetera. It is also quite possible, as the o.p. notes, that biologists wouldn’t even recognize the process if they observe it, especially since it would probably look like random contamination to a valid experiment unless you were specifically looking for it.
The big question is, do the conditions and processes that led to the origin of life on Earth occur elsewhere, to what extent, and how linearizable are those processes, i.e. can we reasonably expect them to be naturally replicated elsewhere? Setting aside Star Trek fans and SETI advocates, this is really the interesting and probably (at this point) unanswerable question in the metaphysics of biology; are we really all alone out here?
Stranger
Would we even recognize the process if it were happening?
I suspect it is happening, but we don’t even know what to look for. Since it is such a long term process, it is not like we would find colonies of bacteria spontaniously emerging from a rock. More likely, we would simply find lower and lower forms of life that begin to become indistinguishable from non-living organic structures.
It’s true that the chemistry is not the same as it was when life first began, but the source material for organic life is all over the place.
I think Mangetout called it. The conditions for creating life probably involved having a pool of water full of complex molecules. These molecules form the basis for primitive lifeforms but they also form its food source. The first little amoebas had the advantage that they could float around in the middle of a pool full of food. But once that food was consumed they had to learn to eat other food sources - like their fellow amoebas.
But by clearing out these available molecules, the first wave of new life-forms pretty much closed the door on there being any second wave of new life-forms. There was no longer any concentration of molecules to form new life-forms and if they somehow did form they wouldn’t be able to survive.