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.

> 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.

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.

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.

> 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.

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.

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.

> 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.