Sunday, April 23, 2006

Breathing space

[Source: "Pulmonary surfactant biology," School of Earth & Environmental Sciences, University of Adelaide]

Last night I found this old New Scientist article, which made a big impression on me at the time, misfiled in my filing cabinet:

"Breathing space: Do lungs work because of a mutation 350 million years ago?," New Scientist, Kurt Kleiner, 11 October 1997 ... AIR breathing developed independently many times in the history of evolution. But a subtle biological mechanism that allows lungs to function seems to have developed only once, and is still used by all air-breathing vertebrates, say researchers in Australia. Lungs need to expand and contract, but if the surface tension of liquid in the lungs is too high, the tissue sticks together and breathing is impossible. So in air-breathing vertebrates, the surface tension is lowered by a coating of proteins and lipids, called the surfactant system, on cells lining the lungs. Christopher Daniels and student Lucy Sulivan of the University of Adelaide compared the surfactant systems of 18 vertebrates, including fish, lizards, chickens and humans, and found that all make use of a key protein called surfactant protein A. They conclude in this month's Journal of Molecular Evolution that the surfactant system developed once in an ocean-dwelling ancestor about 350 million years ago, and has been used again and again as vertebrates developed lungs and crawled out of the water. `It's similar to the insulin system and haemoglobin-it's one of the things you have to have for the organism to do well,' says Daniels. `Since it evolved, it hasn't changed.' Daniels thinks the surfactant system may have developed first in the gut, as a way to regulate surface tension between the organs there. Even today, there are similar surfactant proteins in the guts of rats, he says. Because the lungs and the gut are closely related in the developing embryo, Daniels believes a genetic mutation may have shifted the surfactant to the lungs and made air breathing possible. Allan Smits of Quinnipiac College in Hamden, Connecticut, who also studies pulmonary surfactants, says Daniels's research on the surfactant system is convincing. `Clearly air breathing couldn't have developed without it,' he says. `It is definitely necessary for air breathing.'"

On searching the web for more information about it, I found references to it in News in Physiological Sciences, August 2003, and in Physiological and Biochemical Zoology, September/October 2004.

I also found the following comment I had made (and forgotten) on the New Scientist article, to the Calvin Reflector in 1998 (my added emphasis):

Obviously lungs had to exist before animals could live on land, and so lungs had to be developed in water, before they were needed on land. But that was not enough. It seems that lungs out of water need a special coating called the surfactant system, which stops the lung tissue sticking together in air. So right on cue, 350 million years ago, just before it was needed on land, an ocean-dwelling fish happened to have a special mutation which gave it a surfactant system that it didn't need, so that down the track its descendants could crawl onto the land. But of course that special mutation had to have happened to the same line of fish that also developed legs underwater, before they were needed on land. No doubt it will also be found that special mutations had to appear on cue to provide special land-dwelling eyes, ears, nostrils and eggs, in readiness for the `invasion' of the land later down the track by tetrapods. Not bad going for a `blind watchmaker' process that can't plan ahead!

This, along with other major transitions like the reptilian egg will form part of my `construction project' argument from design, when I write my future book, "The Design Argument." That is, when a series of major changes occur in a line towards a specific long-term end, it is reasonable to infer a designing intelligence is the ultimate cause.

This fits with a Fred Hoyle quote I rediscovered yesterday, while compiling my Quotes Book, in which he makes the same point that Dembski makes in his Explanatory Filter, that design is reliably inferred in the conjunction of : 1) very low probability events; 2) that match an independent external specification.

Hoyle gives the example of if a sequence of numbers generated by a roulette wheel over a year turned out to match the digits of pi:

"It is not at all difficult to formulate examples of events with exceedingly low probabilities. A roulette wheel operates in a casino. A bystander notes the sequence of numbers thrown by the wheel over the course of a whole year. What is the chance that this particular sequence should have turned up ? Well, not as small as 1 in 1040000, but extremely small nonetheless. So there is nothing especially remarkable in a tiny probability. Yet it surely would be exceedingly remarkable if the sequence thrown by the roulette wheel in the course of a year should have an explicit mathematical significance, as for instance if the numbers turned out to form the digits of pi to an enormous number of decimal places. This is just the situation with a living cell which is not any old random jumble of chemicals." (Hoyle, F., "The Universe: Past and Present Reflections," Annual Review of Astronomy and Astrophysics, Vol. 20, 1982, pp.1-35, p.15)

This is the same paper that the atheist Hoyle made his famous statement that, on the basis of the remarkable coincidence between the matching resonance levels of carbon and oxygen, without which there would be a lot less carbon in the Universe and therefore no life, that this was "Another put-up job" and "A common sense interpretation of the facts suggests that a superintellect has monkeyed with physics, as well as with chemistry and biology" (my emphasis):

"From 1953 onward, Willy Fowler and I have always been intrigued by the remarkable relation of the 7.65 Mev energy level in the nucleus of 12C to the 7.12 MeV level in 16O. If you wanted to produce carbon and oxygen in roughly equal quantities by stellar nucleosynthesis, these are the two levels you would have to fix, and your fixing would have to be just where these levels are actually found to be. Another put-up job? Following the above argument, I am inclined to think so. A common sense interpretation of the facts suggests that a superintellect has monkeyed with physics, as well as with chemistry and biology, and that there are no blind forces worth speaking about in nature." (Hoyle, Ibid., p.16).

Hoyle concluded the paper with:

"Taking the view, palatable to most ordinary folk but exceedingly unpalatable to scientists, that there is an enormous intelligence abroad in the Universe, it becomes necessary to write blind forces out of astronomy." (Hoyle, Ibid., p.15. My emphasis)!

Stephen E. Jones, BSc (Biol).
"Problems of Evolution"

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