Ryugu asteroid sample colonized by terrestrial life despite strict control

We have class 100 (ISO class 5) space that's a lot more stringent, but even that is less sensitive than you might expect. Our semicon customers have a bad habit of taking our carefully bagged product out in their uncontrolled warehouse to check the serial numbers, but I'm not aware of any issues that arose from this.

Things get a lot more interesting when you start working with DUV and EUV wavelengths, as now you care about more than dust. We're adding an advanced molecular contamination cleanroom (AMC) where we'll need to start restricting perfume, deodorant, and cigarette use.

There are entry protocols around what you can take in, how you swab it, and so on. Also, specific instructions around how often to go from sitting to standing, clothing materials under your smocks, and everything else.

Neither of these is the case.

Nor, strictly, is the notion that the individual (or its descendants) were necessarily evolutionarily fitter than others.

In the first instance, a common ancestor may have come long before some evolutionary chokepoint or contest in which their gene line ultimately survived whilst others died out. And in some cases (mitochondria), the alternative gene lines didnt' die out. Non-mitochondrial organisms are the prokaryotes, and they have continued (for many hundreds of millions of years) to live alongside their mitochondrial-bearing eukaryotic cousins. Bacteria are AFAIU largely prokaryotic. Even some eukaryotes have lost their mitochondria, though it seems that all eukaryotes had mitochondria at some point in their evolution. But where it comes to complex organisms, overwhelmingly mitochndria-bearing cell forms out-compete those which lack same.

As for evolution, that which is expressed in genomes requires a threefold process: variation, selection, and inheritance. That is, whatever leads to the eventual survival of a particular line of descendants must be based on an inheritable characteristic: stronger muscles, lower metabolism, superior coordination, robustness to environmental variance, faster development within a given niche, mate-selection advantage, etc., etc. (And note that what works in one selective environment may well not be suited to another.)

Other selection events are not directly heritable, or are far less heritable. Getting smacked by an asteroid is an example, though there are features (e.g., being an aquatic life-form, small body size) which may increase survival odds after a major impact. Other natural disasters (earthquakes, tsunamis, volcanoes, wildfires) etc., are to an extent random and arbitrary in what they kill, though there may be specific adaptations which increase survival odds after such events. Even given this, many species will see a fairly arbitrary selection of extinction and survival, often with little prediction for a future repeat of such an event. Which individuals survive, or don't, is pretty much a wash. Those are still selection events, but don't convey any heritable advantage.

The possibility that some common ancestor or LUCA is at least in part arbitrarily determined seems high to me.

Of course, the oxygenated atmosphere only exists due to life. Otherwise, it would just rapidly oxidize everything else.

The only thing I find truly special about our place is the moon.

The moon is really weird. Same geological material as earth, huge size for a natural satellite, appears the same size as the sun.

It's an unusual set of coincidences that (as far as I know) our solar system formation models, so far, can only explain using an extraordinary event (Theia collision, etc).

It happened 2.4 billion years ago, and wiped out most of the existing life: https://en.wikipedia.org/wiki/Great_Oxidation_Event

I know this is not directly related to what you say, but we do have right here and now whales to talk to. And elephants too! There is this idea that to find alien minds to communicate with one has to reach out to the far cosmos. But we can't even talk to the alien minds right on our doorsteps. Maybe we should try that before we theorise that communication between two races is impossible due to distance.

> all panspermia does is layer on an additional series of long-shot coincidences

Disagree. There is a lot more of not-Earth than Earth. I agree that the probability density (per unit volume of the universe) of life originating on Earth is much higher than anywhere else, but there's just so much more room out there for life to originate that the probabilistic cost of traveling to Earth is tiny in comparison.

All you need is a proto-life that's stable in an inert environment with sufficient radiation shielding. It could've originated billions of light years away and still have had enough time to arrive on Earth 4.2 billion years ago. That's a mind-boggling number of Earth-like environments.

In fact, proto-life doesn't even need to look like Earth life, so even environments that are hostile to current Earth life today could've been the cradle of origin (as a wise man once said, "life, uh, finds a way"). Additionally, environments that used to be Earth-like but eroded away are candidates too since all we need is for life to have escaped before the erosion.

In my opinion, panspermia is strictly more likely than Earth-bound abiogenesis.

Yeah nah. Ask any doctor or biologist. Humans and most other organisms are definitely not put together like that. It's pretty cool and it works very well, but many things are just... why? There's lots and lots of hacks, questionable cable management, backwards design, dead code, and leftovers from previous iterations.

Just because we're a pretty successful organism does not mean we are anywhere near the pinnacle of what can be achieved.

Omnipotence, indeed!

If much of the thousands of tons of extraterrestrial debris that falls to earth every year was teeming with microbes we might not easily tell the difference.

But I very strongly suspect this is not the case.

I have heard tales of a truly scientific rigorous civilization. Every human there replicates every study. They’re currently confirming that using cutting rocks to tear flesh is advantageous to survival.