UV light may have sparked life on Earth

NewScientist.com ^ | May 28, 2003

[StupidQuestions]

UV light may have sparked life on Earth

18:18 28 May 03

NewScientist.com news service

Ultra-violet light, long thought to be an impediment to the early formation of long organic molecules, may in fact hold the key to the origin of life, according to a new study.

Intense UV rays from a young Sun bombarded the early Earth and were thought likely to destroy any exposed organic molecules. But a new mathematical model implies the radiation actually helped select out the molecular seeds of life.

The earliest life on Earth is widely thought to have been based on RNA, the chemical cousin of DNA. RNA is made of subunits called nucleotides, which link together to form long polymer chains.

Certain components of RNA absorb UV light and act as "protectors", thereby giving it a survival advantage over other molecules, says Armen Mulkidjanian. Mulkidjanian, a biophysicist at Osnabrück University in Germany, led the team that developed the theoretical model.

"Simple RNA molecules can evolve under certain conditions - this is a well-developed field. But the question left is: how do you get the first long enough RNA polymer?" says Mulkidjanian. "Our model offers some physically plausible explanation of how long RNA polymers could emerge."

"This paper is important because it attacks that crucial problem," says Michael Yarus, an RNA world expert at the University of Colorado at Boulder. "If this problem could really be solved in a way that people agreed on, the RNA world would become a fact rather than a speculation."

Peculiar properties

Life on Earth is thought to have evolved about 3.7 billion years ago, when there was no protective ozone layer encasing the planet and UV radiation was 100 times more intense than today.

The nucleotides that make up RNA have three components - a sugar, a phosphate and nitrogen-containing base. "And these bases have very peculiar properties of being extremely efficient at quenching UV light," says Mulkidjanian, protecting the sugar and phosphate components which form the spine of the chain.

The team fed data on the photochemistry of various organic molecules into a computer model designed to simulate the effects of UV light on stability. "The effect was very pronounced in RNA," he says. In the presence of strong UV light, RNA was much more likely to form long chains than other molecules. -more-

[StupidQuestions]

That is one possible reason why abiogenesis does not rule out a creator. To my thinking, neither abiogenesis nor evolution says anything about the existence of God. But, I have no belief that our Universe is Anthropic by design. It might be but I have no firm belief that it is.

[plusone]

They did exactly such an experiment in the 50's. A jar was half-filled with simple liquid compounds thought to be present in the ancient, primordial sea. A mixture of a few gases above formed what they thought to be the early atmosphere. Applying an electric spark (lightening) did cause amino acids, the precursors of protein, to be formed. It was an interesting experiment, but one thing not widely reported was that the aminos had to be withdrawn from the vial as they were created, otherwise the same spark that formed them would also blast them back into their original components.

[b4its2late]

You done good on the first post.

[js1138]

Despite any first impression I might have formed of you, I have no problem with the Anthropic Principle. I'm not sure it contributes anything to the hard work of discovering the history of life, but it doesn't impede it either.

[RightWhale]

Yes, I'm not coming up with the name of the scientist, but the experiment was of vast societal import. One of the pivotal science demonstrations.

[plusone]

Sorry, I'm not up to speed today. That was sarcasm? (But why?)

[RightWhale]

No, it was a pivotal experiment. What was his name?

[Focault's Pendulum]

Than you for the ping. I don't respond to these threads all that much....but I sure as hell enjoy reading them.

[PatrickHenry]

I don't respond to these threads all that much....but I sure as hell enjoy reading them.

I ping you so that we'll have quality lurkers.

[plusone]

I'll have to do a web search...

[js1138]

Stanley Miller.

[plusone]

It was Stanley Miller.

[BMCDA]

A spontaneously generated placemarker ;)

[BibChr]

Desperate Substitute Theory #34792

"Yeah... yeah: ultraviolet light. That's the ticket!"

Dan

[John Valentine]

This article does not expound a theory. It does not even set forth a hypothesis. It is a mere speculation and is a rather wild one at that.

As long as we are engaging in speculation about the origin of life on Earth, I'd recommend Thomas Gold's "The Deep Hot Biosphere" as a reasoned speculation far more interesting and potentially far more important. Why? Becasue it is far more likely to be correct.

[RightWhale]

Stanley Miller. I read the story in the NYT. They used to have a great paper. Such an ordinary name, Stanley Miller. Now, of course they find amino acids in the gas clouds between stars. Seems to be something nature does without our assistance. It was next to unbelievable at the time; but now we say, of course, how could it be otherwise?

[RightWhale]

Wow! You're in Korea. How is the atmosphere? Tense, expectant, same old same-o?

[Kudsman]

Ultra-violet light, long thought to be an impediment to the early formation of long organic molecules, may in fact hold the key to the origin of life

In a zero sum game I might say; 'yup maybe it did'. But my next thought would be of where the UV light originated and who turned the lights on anyway?;-)

[Focault's Pendulum]

I ping you so that we'll have quality lurkers.

I'm flattered that you would use the word "quality", and my screen name in the same sentence.

[js1138]

Folks have dug pretty deep for Thomas's Gold without finding any. I'd love to see him proved right, but so far no joy.