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Comment by binaryturtle | Hacker News Reader

I always found it odd that there's only one single origin of life point or even just a single common ancestor considered in history. Shouldn't entirely new life develop all the time on earth? I mean the ingredients and building blocks are still there, the environmental situation still should work out, like availability of water, temperatures, etc. We should see a constant emergence of new life all the time. Why would that process stop, just because some other life already exists? Maybe we just can't detect this, because whatever new life happens to appear —more or less— resembles life that's already there.

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I'd imagine the bar for becoming new life is much higher now, because it requires finding a niche that isn't already filled by an existing organism or requires being immediately competitive with existing life.

They're pretty sure the primordial environment was a hydrothermal vent in an anoxic high phosphorus soda lake with methane, ammonia, and UV exposure. Nowadays those lakes don't have the methane and ammonia, so that environment isn't there anymore. https://www.science.org/content/article/unusual-soda-lakes-m...

The surfaces of clay particles in these lakes have been dubbed "the primordial sandwich".

The early protocells were 'alive', they were self-replicating, but they required nutrients and metabolic processes that only existed near mineral surfaces and would starve if they drifted away. They had to evolve new enzymes to become 'free-living'.

So it looks like the LUCA was one of these early protocells with an incomplete metabolism.

> Shouldn't entirely new life develop all the time on earth?

It's possible OoL requires some exponentially unlikely step. We wouldn't realize that because of observer selection: had the step not occurred, we wouldn't be here to be thinking about it. There's a huge complexity gap between the stuff produced in OoL experiments and the simplest known life.

It's also possible OoL requires conditions that no longer exist on Earth, or that only existed in the early Earth (or wherever life got started in the Solar System). For example, if it depended on the existence of short lived radioactive isotopes or free ammonia.

>ike availability of water, temperatures, etc. We should see a constant emergence of new life all the time. Why would that process stop,

Anything that's so agreeable to abiogenesis that life might spontaneously manifest, is actually pretty tasty for things already alive. They swoop in and eat it before it gets started. So, I suspect that even what the article says isn't that they both arose in the same place, but in different places separated by distance, time, and/or environmental barriers.

Because the moment life first appears, it multiplies and fills all easily available niches, and any new life is outcompeted by the more evolved pre-existing organisms.

I may be a dumb layman, but that argument seems too tidy and absolute to me - wouldn’t it suggest, for example, that viruses could never appear because they’d be outcompeted by more advanced bacteria? Earth seems to have room for an incredible diversity of types of life.

Viruses are not newly appearing forms of life, they are co-depending on the already present forms of life and they reuse some of their machinery. Viruses are the opposite of starting from zero, they start from a functional organism and stop existing if the base organism gets extinct. However, reading other answers, it seems the great oxygenation event is an even stronger argument against basic life appearing again. They would get oxidised and die.

Nope. It would suggest that new viruses could not spontaneously appear from abiotic matter, because they'd be outcompeted by existing viruses. Which may well be true.

We don't know where exactly viruses came from, but one of the leading theories is actually that they are the descendants of bacteria which outcompeted other bacteria. When a parasitic bacterium sheds more and more of its own metabolic capabilities, because it's more efficient to steal those abilities from its host cell, it evolves in a way that looks more and more like a virus.

"More evolved" or "more advanced" in this case doesn't mean "bigger" or "more complex". You can say viruses are equally evolved as bacteria, meaning they've spent equally long being optimized for their ecological niche.

But the enviroments that have the easy/free energy that would give rise to life is almost always contaminated with life competing for and consuming that chemical energy.

It has to survive though in the sense that it has to live long enough for us to see it. If we think of life as "spontaneously" (roughly speaking) emerging from the right conditions reasonably rarely, it has to outcompete other existing life for some time. And then there's the chance that we might not recognize it as "new" at all.

A step further "novel" life (hence still simpler) made from the same raw materials as existing life would look exactly like decomposing existing life and be routinely scavenged for material.

> Shouldn't entirely new life develop all the time on earth?

The fact that it doesn't is a pretty simple solution to the Fermi Paradox.

It's probably unrelated to the Fermi Paradox. Life doesn't develop all the time on Earth largely because it's already developed. The conditions for that development are largely gone now, plus existing life easily outcompetes new life in general. This tells us nothing about the probability of the development of new life in an environment that doesn't already have life.

The ingredients and building blocks aren’t there in the same way. Because life formed, those early ingredients are now transformed, as is the environment. This blocks new life of the type that formed 4 billion years ago from forming again.

Indeed, all species branch out from that one universal common ancestor that was the first free living successful cell.

Put another way: forming life isn’t easy at all. And once it forms it changes conditions to suit its continuation, not to allow new life to form.

Life is vastly faster than random chance at producing more life. So living things go fill niches faster than random chance can use those niches to produce new life.

The building blocks will be immediately consumed by existing life. And that's just one way in which the world is radically different from the one in which life arose.

And life may have arisen from a very low probability set of circumstances ... there's no reason to expect it to be happening all the time.

> Maybe we just can't detect this

Probably this. How would we know what such 'proto-life' (perhaps even just some self-replicating soup of chemicals, no cell wall) would look like? Where to find it? How rare its occurence? Etc etc.

Scientists might not even recognise it if happened right in front of them.

I'd put my money on coming up with a more general definition of "life", and then looking for short(est) pathways from "soup of random chemicals" to "something in there that replicates (parts of) itself".

Doesn't need to look like life as we know it, as long as some elements of "self-organising structures, something being replicated" are there.

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