[lumpypua]

They're not looking at things like antibiotic resistance, they're looking at genes core to biological function like cell membrane proteins and ribosomes—and those look like they came from a common ancestor. So, your options:

1. Common ancestor.

2. Not common ancestors, but with enough random chance common biochemistry that this core function gene could be usefully used by the new microbe, and is functional enough in the new host that it isn't ejected immediately, and managed to stay functional and evolve past the original core function gene in terms of fitness so that original core function gene could be ejected, and the original core function gene did get ejected and the microbes with the new core function gene managed to outcompete all the microbes with dual core-function genes.

The latter is highly, highly unlikely.

[niels_olson]

There's a whole body of literature on how quickly a pile of nucleic acids can self-assemble and self-select to end up with a functioning ribosome. I'm pretty sure we're talking time scales of less than months. More like 10s or hundreds of hours. There's a lot of molecules in the ocean. For example, the water content of the ocean is about 4 x 10^46 water molecules. How frequently are valence electrons available for reaction, per second? A billion? The number of possible configurations over a billion years reels the mind.

[civilian]

From Nick Lane's article "How did LUCA make a living? Chemiosmosis in the origin of life" http://www.nick-lane.net/LAM%20BioEssays.pdf

> The concept of organic soup is nowadays closely allied to the idea that the origin of life and the origin of replication are the same thing. Natural selection remains the only mechanism known in which more complex forms can evolve, and natural selection requires a replicator. Regarding the nature of that replicator, there is currently no viable alternative to the idea that some kind of ‘RNA world’ existed, that is, there was a time before proteins and DNA, when RNA was the molecular basis of both catalysis and replication. Some elements of the RNA world concept are almost certainly correct. However, there is a strong version of this theory which states that RNA was once the only catalyst as well as the only replicator and so all the basic chemistry of life was invented by RNA.(4) This ‘RNA first’ theory is difficult to accept from the standpoint of the biochemistry of modern cells. For example, many essential enzymes are metalloproteins that contain mineral centres, such as iron-sulphur clusters, at their heart.(5) There is every reason to believe that such clusters, with the structures of inorganic minerals like greigite,(6,7) have more ancient roots even than those of RNA.

> The recent abiotic synthesis of nucleotides using UV radiation and phosphate to purify intermediates(8) seems to lend support to the idea that the primordial oceans became a warm broth filled with nucleotides, which spontaneously polymerised into RNA, able to catalyse its own replication as well as organic transformations that ultimately yielded cells with lipid membranes, proteins and DNA – a purely Haldanian distillation, eight decades after Haldane’s essay. But the fact that nucleotides can be synthesised in ‘warm pond’ conditions hardly makes an oceanic RNA world more likely; by the same measure, the circumstance that amino acids can be present in some meteorites does not mean that life must have arisen in outer space. Setting aside the absence of geochemical evidence that a primordial soup ever existed, there are grave difficulties with the soup theory. To give a single example, polymerisation into RNA requires both energy and high concentrations of ribonucleotides. There is no obvious source of energy in a primordial soup. Ionizing UV radiation inherently destroys as much as it creates. If UV was the primordial source of energy, why does no life today synthesise ATP from UV radiation? Worse, every time an RNA molecule replicates itself, the nucleotide concentration falls, unless nucleotides are replenished at an equal rate. UV radiation is an unlikely energy source for rapid polymerisation and replication, and an unpromising initiator of natural selection

The ocean's not as warm or as concentrated as the experiments you're referencing.

[niels_olson]

That's some highly biased writing you just quoted. Rather than respond here, perhaps I shall at some point write a more detailed essay. But for the time being, re-read that with an eye toward how many times he sets up a strawman and then knocks it down saying "there's no evidence". Seriously? Did you do a lit search before you reposted someone else's writing?

For example: no evidence of primordial soup? Go diving much? Craig Venter brings back genes unseen by man just driving his boat through the Indian Ocean and this guy waves his hands saying there's no evidence of primordial soup?

[civilian]

I'm quoting the author of the book that this thread is discussing, this isn't a random cherry-pick. :)

Craig Venter wasn't sailing around the world 3 billion years ago.

//edit

okay, so, I was trying to explain what the state-of-the-research was, and what this book says. I used to think that the RNA-world hypothesis was also the most likely! You have a good understanding of biology, and you're smart enough to make decent arguments, but you just aren't up to date.

I don't think anything I say will persuade you. You should go read The Vital Question and publish in a journal when you prove Nick Lane wrong.