People love to put things into neat boxes so that we can somehow reduce them to a single concept.

Unfortunately the real world is usually a bit more messy than that. This is one example that makes it pretty obvious that our model is a little bit overly reductive, and at least to me the "Is this life?" question seems to have an answer that is on a spectrum rather than binary.

> A closed loop metabolism is indeed a good boundary marker.

Presence of metallic catalysts is just an environmental factor. Not counting the organisms that can't live without them as life would be as not counting as life something that can't do metabolism without liquid water.

Life at time of LUCA just had a bit stricter environment requirements, but it should still be counted as life.

So I wouldn't read this as discovering that life evolved twice. Life just evolved a hack for dealing with environments without metallic catalysts twice.

The Big Bang is the precursor to everything, including to nucleic and amino acids.

Just curious, are there lifeforms today that rely on these metals to live in anaerobic environments? Maybe the hydrothermal vents that are talked about?

Do you think complex life could develop (perhaps by moving backwards) in a way that they rely on an anaerobic metal-rich environment?

I guess the oxidation event maybe was necessary for life to develop enzymes (since there wasn't sufficient evolutionary advantage for it to develop in an anaerobic environment?) but maybe something could go backwards? I'm just curious if there might be advantages for live in that sort of environment.

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.

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.

> 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.

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.

> 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.

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.

It could be happening on my kitchen counter right this very second. But my kitchen counter, despite a recent cleaning, is absolutely lousy with microorganisms. So the new proto-life is immediately starved or more likely eaten by existing life. There's very few places on Earth that has not been colonized by some sort of life so there's very few places a new form of life could form and succeed long enough to itself grow and spread without being starved or eaten.

The article does make it clear, though the headline misleads.

Well, it's Science Alert - not exactly a bastion of level-headed reporting.

I have absolutely no doubt that the next LLM/ML startup will be able to confidently, rapidly, productively and correctly fill in the missing data. Onward science!

The Great Filter is only one possible answer to the Fermi Paradox.

Not if it's just microbial life. Anyway it's just one case or another. We knowing what's the case doesn't change it. If the news never break it would be just as bad, perhaps even slightly worse, as we would not have early warning to prepare.

It is definitely in the Bible. Cynically, God seems to swing wildly between mercy and vengeance, but it's clear he would feel justified in a lot more vengeance than he takes but doesn't because he loves people. Less cynically, he's planning for Jesus and salvation the whole time, and sorta trying to keep the evil from getting out of hand with the occasional smiting. You can make the logic work if you want to.

This is edging into religious debate, which the guidelines ask people to keep off HN

> The idea that living things, which are far more intricately organized at every level than any machine we have made, could have arisen by some unknown series of chance steps is a fairy tale.

Really? Because when you look at something like the human retina, the organization is embarrassing.

Especially since there are older, extant examples with better organization.

Interesting comment. FWIW the idea of God as Being accords with Spinoza's philosophy, which in turn accords with Greek philosophy and ultimately accords with biblical philosophy. These are roots among the many roots of our modern world.

What we learn from these philosophies is that God is necessarily the author of life and love, but as well hatred and destruction. Worth noting that the latter are most (but not exclusively) expressed in human conduct. Among all animals humans have the most developed ability to decide how to act. That ability is not absolute, often enough logic or reasoning is bypassed and emotion rules.

Naturally cognition is not unbounded, we are limited by constraints of our construction. It means aspects of the universe are unknowable, we can't know what we're missing.

But knowing what we can know is an obligation of our privileged existence. As knowledge expands it exposes the utter complexity of all things emerging from common fundamental processes.

Seeing what is seen, a human may for a moment get a glimpse of the hand that binds everything together. That's a gift if there ever was one.

> There is likely simple basic life as advanced as bacteria around the universe

What is the basis for this assertion?

Its an exciting time to be alive because as of recently we certainly can detect planetary atmosphere major components out to at least 700 or so light years.

https://en.wikipedia.org/wiki/WASP-39b

There are astronomers actively working on minor component, more biologically interesting spectrographs like chlorophyll rather than spectrograms of carbon dioxide. That'll be harder to detect and limited to shorter ranges.

At some point, probably very soon, like less than a decade, we'll be able to definitively state that we have atmospheric data in an onion layer shaped shell where we have unequivocable proof that out to X lightyears from Earth there's no planetary scale chlorophyll higher than a minimal level aka there's no earth-like plants on that planet. That shell will likely expand over time. Or, perhaps we will find a forested, or at least algae covered, planet, some light years away, which would be very interesting indeed.

The question is rapidly changing from a purely philosophical belief to scientific observation, like right now, in real time, in the 2020s. What a cool time to be alive!

This follows old, old stuff from radio astronomy along the lines of how far away could a 1960s radio telescope realistically detect life on earth. The answer IIRC was not very far LOL. But there's been a lot of progress in radio astronomy, etc.

With respect to fermi filters etc people need to pay attention to how far away the Earth can be detected using radio telescopes. That distance has imploded since the end of analog UHF TV broadcasts. We still broadcast absolute swill, in fact more than ever, but digital detection range is much lower than analog AM carrier detection range from analog TV. The Earth has, to some extent, recently gone radio-quiet, which is interesting because we are still here, in fact more of us than ever. So WRT fermi filters of not being able to detect civilizations, disappearance of 1950s/1960s signals does not necessarily imply disappearance of civilization. Another example, if any aliens are watching the high altitude freon contamination of our atmosphere they're likely really confused right about now.

I agree. The Fermi Argument, and the apparent rarity of K3 civilizations in other galaxies, is to me powerful evidence of the scarcity of life. At the least, this suggests SETI should focus on distant galaxies where the Fermi argument doesn't bite as much.