The Origins of Life on Earth

[RJM Corbet]

All I am pointing out, ad nauseam, is the certainty that it did happen, so it does happen, and if it can happen, then it can happen twice. I don't understand what Al Capone has to do with that.

I might win the lottery. I might win it twice. I might win it three times. Whatever. You keep bringing religion into it. Not me. Really, I'm off this thread now Dave.

 

[Brian G Turner]

Actually, it's interesting to note that respected astronomer Sir Fred Hoyle also thought abiogenesis was so statistically unlikely that he argued it must only have arisen once in the entire universe, and has since spread among the stars. This was the original idea for Panspermia. However, he basically had to throw out all accepted ideas of cosmology to do so.

As for deep sea vents - it's worth noting that in the early oceans, it is believed there was little if any oxygen in the water. Effectively, it was an anaerobic environment - unlike today's oceans.

And yes, like Vertigo says, abiogenesis could still be happening today - but competition for nutrients by existing life forms may prevent that from happening.

 

[Dave]

As for deep sea vents - it's worth noting that in the early oceans, it is believed there was little if any oxygen in the water. Effectively, it was an anaerobic environment - unlike today's oceans.

There would be no free Oxygen in those oceans at all. That should only come with the Blue-Green Algae, which were living things with cells and near to the end of the Precambrian, before the Cambrian explosion of life. If the 'pre-life' is living on hydro-thermal vents, gaining energy by breaking down compounds formed there, rather than by photosynthesis, then I'd expect that all the early oceans were totally anaerobic. I did my MSc. thesis on Phosphorus removal during activated sludge treatment. The anaerobic bacteria in sewage sludge are quite unusual, and the conditions are very unusual indeed. Both the chemical reactions that take place in sewage treatment, and the growth of these bacteria, are highly altered by quite small changes in pH, Oxygen level, and temperature, and that can be manipulated. If you imagine the early environment to have many, many separate small pools, each with slightly different conditions and different mixes of chemicals, then you up your chances of winning the lottery considerably. It would be like being in a syndicate rather than buying an individual ticket.

 

[Venusian Broon]

Actually, it's interesting to note that respected astronomer Sir Fred Hoyle also thought abiogenesis was so statistically unlikely that he argued it must only have arisen once in the entire universe, and has since spread among the stars. This was the original idea for Panspermia. However, he basically had to throw out all accepted ideas of cosmology to do so.

Well, he wasn't keen on Big Bang at all, given that the evidence available at the time (when he was big in cosmological circles i.e. 1950-early 60s) was limited. We've moved on leaps and bounds now with a whole raft of observations and it's very difficult to argue his position with current evidence, so we would need some completely damning evidence that kills off 'big bang'. So rather than respected, I'd say certain of his views lack credibility.

With respect to the discussion of abiogenesis, he was also lacking a great deal of knowledge that we know now. Biochemistry was a very young science at the time. We've moved on a lot and to be frank he wasn't really on the cutting edge.

However he was definitely respected for the pioneering work he did in stellar evolution and nucleosynthesis, but I think he 'backed the wrong horses' with respect to a number of theories that, as I've said, were shown to be pretty discordant with actual observations.

But, hey, old scientists tend to get stuck in their old fashioned ways. For example, Einstein never could accept modern Quantum theory, but it has been tested to death and the 'Quantum lot' appears to have easily 'won'.

With respect to panspermia: I'm not against the idea. Bacteria, say, are hardy buggers and if they were somehow implanted in the middle of a kilometer wide ice ball and propelled across the cosmos perhaps they could thrive. Or at least survive the vast distances between stars. But a number of Hoyles claims are a bit far fetched. (He stated that the 1918 flu epidemic 'came from outer space' - possibly he accepted the literal origins of the word influenza coming from the Italian for 'visitation, influence of the stars'. However it seems that this actually came from astrological concepts of illness...so basically poppycock.)

And, as it was claimed by him, that abiogenisis was exceedingly rare, then panspermia (as the only way we could have life on the planet Earth) via natural means, as you've stated Brian, requires an eternal steady-state universe (which is probably not true, given what we know now). Or possibly, as it appears Hoyle actually stated, 'directed panspermia' was at work. i.e. other beings deliberately targeting all stars with 'dirty snowballs' or some other mechanism to spread life. He was atheist btw, so these were sophisticated ancient intelligent life, I suppose. However there is no sign, at all, of what should be a galaxy full of these 'ancient ones'.

And yes, like Vertigo says, abiogenesis could still be happening today - but competition for nutrients by existing life forms may prevent that from happening.

Absolutely. We now live in a world where cells divide in minutes and can be found everywhere. Even if the original process of abiogenesis was quick, say a million years, it would now be forever disrupted right at the start by vastly superior cells hoovering up all the material just feeding. I suspect that today's most basic cells are like 'hyper-dimensional USS Enterprises/tardises' compared to the rickety 'Sumerian war waggons' of some form of basic life that a million years of abiogenesis might (just) be able to produce.