William Shatner Wants You!

[shadowinthelight]

The asteroid which slammed down in what is now Mexico (northern Yucatan, specifically) 65 million years or so ago, was certainly enough to knock a lot of material into Earth orbit and it wouldn't surprise me at all if it lsunched some up at speeds exceeding Earth escape velocity.

This material would have probably included at least some amount of thoroughly mashed dinosaurs and related species. The impact would have reduced them to the consistency of custard. In that form, who knows how far Earth's biological heritage might have traveled.

Cosmic custard from Mexico... now, I know I didn't just invent flanspermia theory, but I rather wish that I had.

I'd wager cosmologically tenderized dinosaurios would have more of a chorizo consistency.

[GlytchMeister]

I’m willing to bet $5 that such an impact would have sterilized any ejecta that made it to escape velocity. I’m not even sure tardigrades would have survived that - unless they were already desiccated and in their indestructible form... and even then, I’m not totally sure...

[Dave]

I wonder whether some of the extremophile bacteria or archaea might survive. Some of them are pretty tough even when "alive", and many bacteria can form resting spores. Endolithic (rock-dwelling) extremophiles have been found in drill cores taken from as far as 3 kilometers below the surface. Some of them seem to have very slow metabolisms (generation times of 10,000 years or more) using minerals in the rock as an energy source. A wee beastie like that might actually survive being thrown up into solar orbit and eventually landing on Mars.

[Catawampus]

Cosmic custard from Mexico... now, I know I didn't just invent flanspermia theory, but I rather wish that I had.

I'm sure that you'd receive your just desserts if you had done so.

I’m willing to bet $5 that such an impact would have sterilized any ejecta that made it to escape velocity. I’m not even sure tardigrades would have survived that - unless they were already desiccated and in their indestructible form... and even then, I’m not totally sure...

A few years ago a research team was studying 800,000-year-old ejecta from a meteorite impact in Tasmania. The meteor had landed in a swamp, and hit hard enough to transform the underlying rock into glass. But the glass formed porous, and inside of the pores they found tiny bits of cellulose and lignin and other organic samples from the swamp's peat moss, still perfectly preserved after all this time. Apparently the glass bubbles are able to keep the samples intact and safe from oxidation and decay indefinitely, so long as the bubbles themselves stay intact.

The bubbles are microscopic, of course, and so you're not going to have something such as, say, a dinosaur egg preserved whole inside of one. But it may be just barely possible that some tiny bacteria could be encased that way, thrown into space, and spend a few years traveling across to Mars (or to Earth from Mars). Maybe. And if the bacteria was something like a chemolithotroph, then it may have been able to settle right in to its new lifeless environment.

Most people who accept the theory as a possibility don't really think that something such as that actually happened, though. The more popular version of the theory is that just bits of organic matter, sterilised or not, managed to travel to Earth or other planets. These compounds then reacted with each other (somehow) and became life; even most scientific theories of abiogenesis that don't involve panspermia have life starting in that way.

The problem with panspermia theory is that it doesn't actually solve anything, it just places an extra step in the process of life starting.

[TazManiac]

There is the Inverse Cookie-Crumble Theory in which the crumbles 'like' to fit together, creating further and more complex systems.

[GlytchMeister]

I should have remembered "Life, uh... Find a way."

[GlytchMeister]

Though I don't think the porous glass would have kept living samples safe from the radiation encountered in space. But the idea of bits of organic compounds get tossed about and just end up reacting to create simple life which then ends up evolving is more believable.

But then again, I also agree with the Occam's Razor bit Cat mentioned at the end there. It's just an extra step. It's possible the organic compounds were just already in the accretion disks of the planetoids or were planted during the heavy bombardment or something. Just as a part of the planet's own formation, a natural consequence of the laws of nature in this universe. No seeding from other systems required.

[Catawampus]

But then again, I also agree with the Occam's Razor bit Cat mentioned at the end there. It's just an extra step. It's possible the organic compounds were just already in the accretion disks of the planetoids or were planted during the heavy bombardment or something. Just as a part of the planet's own formation, a natural consequence of the laws of nature in this universe. No seeding from other systems required.

Just never forget that Occam's Razor applies exclusively to logic, not to reality.

Personally, given the apparent abundance and prevalence of organic compounds all over the solar system and other stars, I'd say it's likely that any "seeding" from other sources simply dropped organic compounds into the middle of other organic compounds that were already there.

Which would fit in with another theory, that life on Earth actually started multiple times independently. Either the different events happened sequentially (life started and began to develop, then went extinct, then restarted and began to develop again, until finally it took hold and became what we have now), or simultaneously (either with one track of lifeforms outperforming the others and causing the rest to go extinct, or with the different tracks merging into one overall planetary ecology).

[TazManiac]

All of these ideas are very thought provoking, even if we don't reeeeeeealy know how it all came to be- one thing to remember is the ridiculously long spans of time we are talking all this took place in.

They, (you know- 'they') just published something where the tool use of Humans was pushed back to a span covering 350,000 years or more. Three Hundred and Fifty THOUSAND Years or more... and counting.

(Looking for a cite I see 'tool use' goes back more than two and a half Million Years, but I'm still looking for the article that pushed a commonly recognized milestone that stood for a long time @ 10,000 years to more than a Quarter Million trips around the Sun.)

[Dave]

http://humanorigins.si.edu/evidence/beh ... tone-tools

https://www.sapiens.org/evolution/homo- ... ol-making/

Humans of one sort or another have been using simple tools for well over two million years.

I think the 350kyear date you mention, was the earliest known date of the manufacturing of certain more sophisticated sorts of hand tools... the point at which the simple hand axe was supplemented by more specialized tools that required a certain level of brainpower to plan and make, or which required special processing of the materials e.g. heating some kinds of rock in the fire to change their characteristics.

[TazManiac]

(yeaaah, it's a very incomplete post on m y part, lacking in specifics and detail...)

btw- Pun Master Dennis approves of 'FlanSpermia' reference. He's the go-to touchstone for all-things-punny.

[GlytchMeister]

I think there is some evidence, maybe?, of simultaneous genesis events with merging branches in mitochondria - I’m really not entirely informed on the topic and it’s been a WHILE since I looked it up, and I’m a bit too busy to go dig it all up now, but I recall a theory of mitochondria being a prokaryotic life form that was incorporated into eukaryotic life as a kind of symbiotic relationship, eventually becoming an organelle. Mitochondria apparantly have their own DNA. I have no idea how it works, btw, but there ya go.

[Alkarii]

"Flanspermia" sounds like a health code violation and an arrest. Just sayin' (while chuckling, because my mind is the reason the gutter is dirty).

[Dave]

I think there is some evidence, maybe?, of simultaneous genesis events with merging branches in mitochondria - I’m really not entirely informed on the topic and it’s been a WHILE since I looked it up, and I’m a bit too busy to go dig it all up now, but I recall a theory of mitochondria being a prokaryotic life form that was incorporated into eukaryotic life as a kind of symbiotic relationship, eventually becoming an organelle. Mitochondria apparantly have their own DNA. I have no idea how it works, btw, but there ya go.

Yes, that's the theory that evidence seems to support (according to most researchers in the field), and it goes even deeper than that.

Eukaryotic cells seem to be the result of a very old fusion and symbiosis, between an archaeon and a bacterium.. this created the basic "cell wall, body, and nucleus" structure. Later on, some additional joinings took place... a bacterium which was capable of aerobic respiration took up residence in a eukaryote, becoming a symbiont that provided energy in return for a sheltered place to live... and these bacteria eventually became the mitochondria in eukaryotic cells. They still contain some functional DNA, separate from what's in the cell nucleus.

An additional symbiosis occurred in which a bacterium capable of photosynthesis became a symbiont of a eukaryote... and these bacteria became the chloroplasts which allow plants to photosynthesize (chloroplasts also contain some DNA separate from that in the cell nucleus).

In both cases (mitochondria and chloroplasts) researchers have a fairly good idea as to which family of bacteria became the symbionts... they've been able to match the residual DNA in these organelles against the DNA from living members of the bacterial families in question. In the last few years there have even been some identifications made which might point to a certain clade of the archaea as being the closest relatives of the archaea which originally "adopted" some bacteria and thus became the first eukaryotes, lo those billions of years ago.

So, it looks as if bacteria and archaea are the two first "kingdoms of life" to exist, and eukaryotes are derivatives of both.

Whether bacteria and archaea have a single common ancestor that we would call "alive" is an open question. These two families have some very important biological processes and structures in common, but have others that are very different... this holds for both the chemistry, and the DNA coding which drives it. Nobody really knows what the biology of the last common ancestor of all life was... whether it had DNA yet, or whether the cell as such existed yet.

[GlytchMeister]

One theory I liked most was a matabolitic proto-life form with no DNA that formed in the pores of pumice or something that were already filled/soaked with some kind of environmental cytoplasm, perhaps the product of acid rain reacting with the rock or something, using the rock’s pores as its cell walls, and grew by infesting neighboring soaked pores. DNA and it’s enzymes were created by accident, one then the other - neither really being of any use until both were encountered in the same protocol-organism... the fact that they didn’t have membranes and just infested neighboring pores would have allowed for mixing of different metabolitic processes that created the different bits needed for DNA coding... perhaps precursor to plasmid trading... once all of those were combined, the resultant proteins that came from certain codings of DNA lead to the creation of beneficial structures like a cell membrane that provided structure without environmental help - allowing the organism to spread beyond that rock’s pores. And once the DNA was there, errors led to mutations of all sorts, divergences, crossovers, plasmid trades, etc.

Of course, there’s trillions upon trillions of rocks with pores that are wet, and that environment was around for a long time, so the genesis events of life were really just a sort of Monte Carlo eventuality.

[Dave]

Yes, I rather like that family of theories. One thing that's attractive about it, is that rocks in a body of water tend to be exposed to gradients of temperature, and to gradients in the concentrations of chemicals leached from the minerals in the rocks. It's these gradients which makes it possible for an active chemical system to develop... a sort of abiotic "metabolism" which can become the basis for a living metabolic system.

It's also impressive how many of the essential biochemicals of life can be created out of the basic elements just by mixing them and then exposing them to an energy source (heat, UV, electrical discharge). Sugars, amino acids, RNA nucleotides, lipids... the basic atomic physics of the Universe tends to create molecules which are useful building blocks for life. This is happening out in space, constantly, and almost certainly occurred on Earth once it cooled down enough.

Lipids can self-assemble into sheets that resemble a simple cell membrane (and it's posited that they might have done just that, inside of pores in rock).

The really fascinating question for me, is how did the whole "information storage" system get started? How did life develop the trick of using RNA (and, probably later, DNA) to act as a template, to "drive" the protein-assembly mechanism which makes the enzymes and other proteins that make the cell work, including the very one which duplicate and process and repair the RNA/DNA themselves? What was the first version of this "self-referential" feedback system to appear, and what did life look like before it did?

[GlytchMeister]

I personally prefer the “millions of monkeys banging on keyboards will eventually make the complete works of William Shakespeare”.

If you think of it, the complete works of William Shakespeare WAS the result of millions of monkeys banging on language.

[Warrl]

One theory I liked most was a matabolitic proto-life form with no DNA that formed in the pores of pumice or something that were already filled/soaked with some kind of environmental cytoplasm, perhaps the product of acid rain reacting with the rock or something, using the rock’s pores as its cell walls, and grew by infesting neighboring soaked pores.

THE reason we will almost certainly never know how life on earth really originated is because there are too many contending hypotheses which could have worked, and - aside from finding ways to prove that some of them actually couldn't work - no way at this late date to test which one (or ones) actually happened.

Just the major categories of hypotheses (with at least a couple more detailed hypotheses in each category):
* open-ocean near-surface
* deep sea vents
* where ocean meets land
* where ocean meets ice
* where ocean meets a river outflow
... and I may be missing some.

[TazManiac]

THE reason we will almost certainly never know how life on earth really originated is because there are too many contending hypotheses which could have worked, and - aside from finding ways to prove that some of them actually couldn't work - no way at this late date to test which one (or ones) actually happened.

Just the major categories of hypotheses (with at least a couple more detailed hypotheses in each category):
* open-ocean near-surface
* deep sea vents
* where ocean meets land
* where ocean meets ice
* where ocean meets a river outflow
... and I may be missing some.

One of Robert Heinlein's characters dun thunk us up into being.